Skip to Main Content

ABSTRACT

Reconstructing the drainage from glacial Lake Agassiz to explain episodes of abrupt climate change during the last glacial termination has a long and colorful past. The type strandlines in the basin are named for the towns of Herman, Norcross, Tintah, and Campbell. Optically stimulated luminescence dating of these and other strandlines from the southern basin of Lake Agassiz enables estimating times of water level stability and outlet incision. Tracing strandlines to the north is complicated by their increasing number and often discontinuous nature. Much of the meltwater entering the Mississippi River was channelized through Lake Agassiz’s southern outlet. The spillway is floored by boulder lags and bedrock. Two cores penetrating through to bedrock have provided the most detailed history of southerly lake drainage. On the first day of the trip, we will travel to strandlines on both sides of the southernmost Agassiz basin and view the glaciolacustrine stratigraphy at Fargo, North Dakota; on the second day, we will visit more strandlines and the southern outlet spillway.

Introduction

Reconstructing the paleogeography and history of glacial Lake Agassiz has been ongoing for more than a century. Much of the original work was pulled together by Upham (1895) in a U.S. Geological Survey monograph, followed by studies of strandlines by Leverett (1932) and Johnston (1946). A summary of this earlier work is available in Elson (1983). Volumes that specifically address Lake Agassiz were published in 1967 (Mayer-Oakes, 1967), 1983 (Teller and Clayton, 1983) and 1996 (Thorleifson, 1996). A thematic issue of the Journal of Quaternary Science Reviews guest edited by Teller and Kehew (1994) emphasized proglacial lake and meltwater runoff in which Lake Agassiz played an important role. The 1994 volume illustrates an area of research that continues, in which Lake Agassiz was a trigger for episodes of abrupt climate change by suddenly shifting the time and location of meltwater delivery to varying ocean basins during deglaciation (e.g., Broecker et al., 1989; Fisher et al., 2002; Teller and Leverington 2004). Another avenue of research has been reconstructing lake evolution by dating ice margins, strandlines and outlet history. When the latter is fully known, the significance of the former will be better understood. This overview to the fieldtrip will primarily focus on the later, outlining the lake’s paleogeography and evolution.

During various points in its history, Lake Agassiz existed in what are now the states of Minnesota, South and North Dakota, and the Provinces of Ontario, Manitoba and Saskatchewan (Fig. 1). The areal extent of the lake in Figure 1 is time transgressive and thus does not represent the extent of the lake at any single point in time. Lake Agassiz developed as the Laurentide Ice Sheet receded northward from the Big Stone Moraine that hosts the subcontinental drainage divide. Lake Agassiz formed as continental runoff and glacial meltwaters ponded between the Laurentide Ice Sheet (LIS) and a drainage divide to the south. Note that this is a simplification of earlier work on the initial beginning of the lake; see Fenton et al. (1983) or Hobbs (1983) for more detail. Initial drainage was southward through the southern outlet (Fig. 1), a large spillway occupied by the Minnesota River that joins the Mississippi River just east of Minneapolis. Significant deltas formed where the Sheyenne, Pembina, and Assiniboine rivers entered the lake from the west as the ice sheet receded northward opening up these drainage routes. The tracing of strandlines northward from the southern outlet has demonstrated that the number and elevations of strandlines increase toward the north, reflecting differential glacioisostatic adjustment of the crust in the region. Concurrent with northward recession of the southern margin of the LIS was the incision of the southern outlet. The combination of outlet incision and differential crustal rebound ultimately produced five relatively stable lake levels in the southern end of the Lake Agassiz basin. The discontinuous nature of the preserved strandline features of these and other lake stages can make the tracing of ancient water planes a challenging enterprise. Additional information on strandlines will come below.

The final introductory comments have to do with the history of the outlets. Prior to 2005, it had long been assumed that the receding LIS had opened an outlet to the northwest of Lake Superior (older eastern outlets [OEO] on Fig. 1) by 11,000 14C yr B.P., resulting in meltwater entering the Great Lakes basin then draining to the north Atlantic Ocean. This event was postulated to have triggered Younger Dryas cooling (Broecker et al., 1989). The eastern outlet was to have drawn the lake down ∼50 m to a lowstand known as the low-water Moorhead Phase. A readvance in the Superior basin was to have closed the outlet returning flow to the southern outlet. Subsequent recession in the Superior basin was to have opened eastern outlets further north (Fig. 1). More recently, focused research (Lowell et al., 2005; Teller et al., 2005; Lowell et al., 2009) dating ice margin retreat in northwest Ontario suggests that an eastern outlet was not open when the Moorhead Phase began. A northwestern outlet (Fig. 1) was speculated upon by Upham (1895), and further suggested by Elson (1967) and Smith and Fisher (1993). It may turn out that a northwest outlet was only briefly occupied by Lake Agassiz after the Younger Dryas chronozone, but an earlier, regional lake(s) may have had an important role in the development of a large spillway that has been attributed to drainage from Lake Agassiz (Fisher et al., 2009). Additional background on outlets is presented below.

Figure 1.

Maximum coverage area of glacial Lake Agassiz during its ∼6000 calendar year history. OEO—older eastern outlets.

Figure 1.

Maximum coverage area of glacial Lake Agassiz during its ∼6000 calendar year history. OEO—older eastern outlets.

Strandlines

Strandlines, here used as a general term for beach ridges, spits, and escarpment (Elson, 1967; Fisher, 2005), record former water planes in lake basins. Strandlines have been traced throughout the Lake Agassiz basin. During European settlement, towns were built on the higher ground of former beaches of Lake Agassiz that are now linked by Highway 9 in Minnesota. Upham (1895) used the names of these towns for the beaches (Table 1). Local elevations are assigned to these beaches, but vary depending on where the elevation is taken from the strandline (high point, low point, break in slope etc.).

Initial work by Upham (1895) and Leverett (1932) was followed by Johnston (1946) and Elson (1967) whose field work expanded shoreline distribution northward to a proposed northwest outlet. A common result from mapping strandlines from the southern outlet is that the number and elevation of strandlines for a named beach increases northward (Fig. 2). For example, at the southern outlet the Herman Beach consists of a scarp and a few spits at its type location to which an elevation can be assigned. However, near the border with Canada, ∼400 km further north, up to 12 individual Herman strandlines have been mapped (Johnston, 1946). Thus tracing water planes northward becomes complicated. A close examination of 7.5’ topographic maps with 5’ (1.5 m) contour intervals resulted in the addition of a fifth named strandline called the Upham strandline at 1020–1030’ (311–314 m) elevation because of the well-developed, albeit small, spits at that elevation between the Campbell and Tintah levels (Fisher, 2005). It should be noted that strandlines are found at any elevation in the southern outlet area between 1100’ and 975’ (335–297 m) elevation, but well-developed scarps and spits at ∼20 ft (6 m) intervals indicate short-lived still stands. Until recently the strandlines adjacent to the southern outlet were undated as a result of difficulties usually attributed to oxidation of organic material within the strandlines. Optically stimulated luminescence (OSL) dating has been successfully applied to age dating strandlines with reproducible results for the same waterplane from multiple sites, and is consistent with radiocarbon ages from northwest Minnesota and Canada (Lepper et al., 2011). OSL ages from strandlines at the southern outlet, the Wheatland transect west of Fargo (Stop 2 on this field trip), and from the Ojata Beach on the Grand Forks Airforce Base are listed in Table 2.

TABLE 1.

NAMED BEACHES AND ELEVATION ADJACENT TO THE SOUTHERN OUTLET

BeachElevation
Milnor1090’ (332 m)
Herman1065’ (325 m)
Norcross1040’(317 m)
Tintah1000’ (305 m)
Campbell980’(299 m)
BeachElevation
Milnor1090’ (332 m)
Herman1065’ (325 m)
Norcross1040’(317 m)
Tintah1000’ (305 m)
Campbell980’(299 m)

Radiocarbon age assignments to the Campbell Beach compare favorably with the two OSL dates from the Campbell Beach. Three maximum limiting ages of 9460 ± 90 (TO-2269); 9380 ± 90 (TO-4873); 9350 ± 100 (WIS-1324) when converted to calendar years (Intcal09, Reimer et al. 2009) and combined, yield an age of 10.6 ± 0.2 ka cal from beneath the upper Campbell Beach at Wampum, Manitoba (Risberg et al., 1995; Teller et al. 2000) and the Swift site (Björck and Keister, 1983). Keep in mind that OSL ages produce an age from the beach sediment itself, probably recording a time near abandonment of the strandline, and that the radiocarbon ages are maximum ages from beneath the beach sand. To the extent this geomorphic correlation is valid, it implies the two dating methods yield overlapping results and that the age of the Campbell Beach lies between 10.6 and 10.3 ka cal (Lepper et al., 2011). From these data, and from new results for the type beaches to be presented during an upcoming technical session, we propose the following ages with standard deviation for four of the five strandlines: Herman—14.1 ± 0.3 ka cal; Norcross—13.6 ± 0.2 ka cal; Upham—13.5 ± 0.1 ka cal; Campbell—10.5 ± 0.3 ka cal. Too few samples from the Tintah strand have been analyzed and its age remains unresolved at present.

Stratigraphy

The stratigraphy of sediments deposited within the Agassiz basin is summarized in Fenton et al. (1983) and outlined in detail by Harris et al. (1974) and Arndt (1977). Three main stratigraphic units have been associated with the lake: the Brenna, Poplar River, and Sherack formations. We will observe the latter two, and possibly the top of the Brenna Formation at Stop 2 in Fargo, North Dakota. These formations reflect the general water history of the lake: an initial high level when the southern outlet was active known as the Lockhart Phase, a low-water level when the southern outlet was abandoned called the Moorhead Phase, and a subsequent higher water level when the southern outlet was reactivated called the Emerson Phase. The Brenna Formation is associated with the Lockhart Phase, the Poplar River Formation with the Moorhead Phase, and the Sherack Formation with the Emerson Phase. Following final abandonment of the southern outlet continuously lower eastern outlets were opening and Lake Agassiz drained into Lake Superior during the Nipigon or Morris Phase with the offshore sediment deposited in Lake Agassiz still referred to as the Sherack Formation. Once the ice margin had retreated far enough north, Lake Agassiz is believed to have merged with glacial Lake Ojibway in northwestern Ontario, during the Ojibway Phase before final drainage of these combined lakes into Hudson Bay at ca. 8.2 ka (Clarke et al., 2003; Teller and Leverington, 2004).

Figure 2.

Strandlines traced northward along the southeast corner of Lake Agassiz illustrating upwarping to the north, with older higher beaches experiencing the greatest upwarping. From Weller and Fisher (2009).

Figure 2.

Strandlines traced northward along the southeast corner of Lake Agassiz illustrating upwarping to the north, with older higher beaches experiencing the greatest upwarping. From Weller and Fisher (2009).

TABLE 2.

PUBLISHED OPTICALLY STIMULATED LUMINESCENCE (OSL) AGES FOR AGASSIZ BEACHES

StrandlineField and Lab #Age (ka)Uncertainty(ka)Reference
HermanKL0505, 0506613.9 ± 0.31.3Lepper et al. (2007)
*HermanKG0504 (vfsand)14.3 ± 0.21.3Lepper et al. (2011)
*HermanKG0504 (fsand)14.1 ± 0.21.3Lepper et al. (2011)
HermanKL090114.0 ± 0.31.2Lepper and Sager (2010)
NorcrossKL050713.7 ± 0.31.4Lepper et al. (2007)
*NorcrossKG0503 (vfsand)13.6 ± 0.31.3Lepper et al. (2011)
UphamKL0508, 0601, 060213.5 ± 0.51.4Lepper et al. (2007)
*Upham?KL1004 (vfsand)13.6 ± 0.21.1Lepper et al. (2011)
*Upham?KL1004 (fsand)13.4 ± 0.31.1Lepper et al. (2011)
*CampbellKG0505 (fsand)10.0 ± 0.20.9Lepper et al. (2011)
*CampbellKG0505 (vfsand)10.3 ± 0.20.9Lepper et al. (2011)
**OjataKL060310.9 ± 0.31.2Fisher et al. (2008)
**OjataKL060411.1 ± 0.31.2Fisher et al. (2008)
StrandlineField and Lab #Age (ka)Uncertainty(ka)Reference
HermanKL0505, 0506613.9 ± 0.31.3Lepper et al. (2007)
*HermanKG0504 (vfsand)14.3 ± 0.21.3Lepper et al. (2011)
*HermanKG0504 (fsand)14.1 ± 0.21.3Lepper et al. (2011)
HermanKL090114.0 ± 0.31.2Lepper and Sager (2010)
NorcrossKL050713.7 ± 0.31.4Lepper et al. (2007)
*NorcrossKG0503 (vfsand)13.6 ± 0.31.3Lepper et al. (2011)
UphamKL0508, 0601, 060213.5 ± 0.51.4Lepper et al. (2007)
*Upham?KL1004 (vfsand)13.6 ± 0.21.1Lepper et al. (2011)
*Upham?KL1004 (fsand)13.4 ± 0.31.1Lepper et al. (2011)
*CampbellKG0505 (fsand)10.0 ± 0.20.9Lepper et al. (2011)
*CampbellKG0505 (vfsand)10.3 ± 0.20.9Lepper et al. (2011)
**OjataKL060310.9 ± 0.31.2Fisher et al. (2008)
**OjataKL060411.1 ± 0.31.2Fisher et al. (2008)
*

Wheatland transect.

**

Redwood Loop site (drowned beach).

The following descriptions come from the work of Harris et al. (1974). The Brenna Formation is characterized by dark gray to slate blue (when wet) massive to laminated, plastic clay and contains small white calcareous fragments 1–30 mm in size with rare carbonate and crystalline clasts. It extends from near the south end of the lake basin northward into Manitoba in the central part of the lake basin where it is up to 45 m thick (Harris et al., 1974). The Poplar River Formation is entirely sand or gravel and often is highly fossiliferous. It is found as linear bodies incised into older stratigraphic units from <1 to >3 m thick and interpreted as a fluvial deposit when Lake Agassiz had dropped below the southern outlet and rivers flowed across the Agassiz basin to a shoreline thought to be somewhere north of Grand Forks, North Dakota. Yansa and Ashworth (2005) described organic remains from a delta sequence along the banks of the Red River at Fargo, North Dakota, and Moorhead, Minnesota, that they classify also as the Poplar River Formation. Radiocarbon dates from the Poplar River Formation in the Fargo-Moorhead region are summarized in Table 3. Fisher and Lowell (2006) discussed the Moorhead Phase deposits in considerable detail emphasizing the importance of using in situ organics for reconstructing water levels. Fisher et al. (2008) provide an extensive list of Moorhead Phase ages and from drowned in situ organic material suggest a different duration age model for the Moorhead Phase, starting later, but lasting longer (Fig. 3).

The Sherack Formation consists of laminated silty clay, clay, and silt with varying amounts of sand, finer toward the center of the basin. Laminations are usually only a few millimeters thick, and in places the sediment is folded. The sediment is yellowish-gray to olive-brown when oxidized and light-gray when unoxidized. Often the lower meter is fossiliferous, but barren above that. The lower contact with the Brenna Formation is sharp and in places is conformable with the Poplar River Formation. The Sherack Formation is found in the center of the Red River valley extending north into Manitoba and was deposited offshore in Lake Agassiz (Harris et al., 1974).

Outlets

Southern Outlet

The southern outlet spillway consists of several channels that eventually merge into the lowest central channel with Big Stone, Traverse, and Mud lakes in its bottom (Fig. 4). Above the individual spillway channels are broad areas up to a few kilometers wide with scattered boulders and streamlined hills 100s of meters to a few kilometers in length referred to as upper scoured zones (USZ), and represent sheetflows up to 5 km wide (Fig. 5). The main spillway channel, or inner channel, is up to 70 m deep and 2–3 km wide. Elongated closed depressions, mapped as scour depressions, are found in the USZ and the inner channel of the spillway (Fig. 5). Some of these scours are up to 2 km in length, and in conjunction with the streamlined hills, give a fluted appearance to the terrain (Mustinka spillway—Fig. 5B, 5C; Fig. 6). Often, streamlined bars (erosional remnants) have proximal or lateral scour depressions, giving the bar a lemniscate loop morphology. Similarly scaled broad scoured areas within inner channels and streamlined residual forms were described by Kehew (1982) from the Souris spillway.

The highest spillway segment is the west branch of the Milnor channel (Figs. 4, 5A). The Milnor spillway can be discontinuously traced north of the town of Milnor, North Dakota, to the Sheyenne River. Baker (1966) regarded this discontinuous channel with a poorly developed eastern boundary to be an ice-marginal channel, assumedly the ancestral route of the Sheyenne River. The sill elevation of the Milnor spillway is 1085’ (331 m) (Fig. 3). South of this sill the spillway margin is poorly defined, with a bulbous morphology and an eastern edge difficult to define. Numerous streamlined hills within the channel have their counterparts at elevations up to 1100’ (335 m) east of the spillway with weakly defined channels similar to the overflow channels between spillways in North Dakota described by Kehew and Lord (1986). The Milnor channel (Figs. 4, 5A) has a complex wetland and lake environment at 1075’ (328 m) elevation, the elevation necessary for flow through the channel. The channel bifurcates northeast of New Effington, where the east branch trends into the lower Cottonwood spillway. The Cottonwood spillway (Figs. 4, 5A) has a sinuous USZ at 1075’ elevation, and a nearly continuous wetland complex at 1030’ (314 m) along its length. Although the depth of the wetland is unknown, the edge of the wetland near Rosholt at 1030’ indicates the spillway would be abandoned when the lake dropped below that elevation. The 1075’ elevation of the sills in the east Milnor and Cottonwood spillways indicates they were operating contemporaneously until incision of the Cottonwood below 1075’ abandoned the Milnor channel.

TABLE 3.

AGES ON MOORHEAD LOW WATER PHASE ORGANICS IN THE FARGO-MOORHEAD AREA

AuthorSite14C ageCalendar ages1Type
Arnold and Libby (1951)Moorhead Water Treatment11298 ± 70012374–14048solid carbon
Rubin and Alexander (1958)Moorhead Water Treatment9930 ± 28011089–11992standard
McAndrews (1967)Seminary9900 ± 40011050–1203standard
Yansa and Ashworth (2005)Trollwood10230 ± 8011802–12090AMS
Yansa and Ashworth (2005)Trollwood10040 ± 12011315–11768AMS
Yansa and Ashworth (2005)Trollwood9920 ± 6011235–11402AMS
Rock (2009)Moorhead 28th Street9737 ± 5311137–11226AMS
Rock (2009)Moorhead 28th Street9911 ± 6811226–11403AMS
Rock (2009)Moorhead 28th Street9872 ± 5611218–11322AMS
Rock (2009)Moorhead 28th Street9952 ± 10411245–11504AMS
Rock (2009)Fargo-UPC9885 ± 9811205–11408AMS
Rock (2009)Fargo-UPC10011 ± 3511392–11505AMS
Rock (2009)Fargo-UPC9953 ± 7211251–11410AMS
Rock (2009)Fargo-UPC9849 ± 5711206–11287AMS
AuthorSite14C ageCalendar ages1Type
Arnold and Libby (1951)Moorhead Water Treatment11298 ± 70012374–14048solid carbon
Rubin and Alexander (1958)Moorhead Water Treatment9930 ± 28011089–11992standard
McAndrews (1967)Seminary9900 ± 40011050–1203standard
Yansa and Ashworth (2005)Trollwood10230 ± 8011802–12090AMS
Yansa and Ashworth (2005)Trollwood10040 ± 12011315–11768AMS
Yansa and Ashworth (2005)Trollwood9920 ± 6011235–11402AMS
Rock (2009)Moorhead 28th Street9737 ± 5311137–11226AMS
Rock (2009)Moorhead 28th Street9911 ± 6811226–11403AMS
Rock (2009)Moorhead 28th Street9872 ± 5611218–11322AMS
Rock (2009)Moorhead 28th Street9952 ± 10411245–11504AMS
Rock (2009)Fargo-UPC9885 ± 9811205–11408AMS
Rock (2009)Fargo-UPC10011 ± 3511392–11505AMS
Rock (2009)Fargo-UPC9953 ± 7211251–11410AMS
Rock (2009)Fargo-UPC9849 ± 5711206–11287AMS
1

Using CALIB 6 Stuiver et al. (1998) and the Reimer et al. (2009) dataset. AMS—accelerator mass spectrometry.

Figure 3.

Lake phase diagram for Lake Agassiz at the southern outlet. Modified from Fisher (2005) and Fisher et al. (2008).

Figure 3.

Lake phase diagram for Lake Agassiz at the southern outlet. Modified from Fisher (2005) and Fisher et al. (2008).

Figure 4.

Overview of the southern outlet region. Modified from Fisher (2005). H—Herman, U—Upham, T—Tintah, C—Campbell, N—Norcross, WR—White Rock, North Dakota.

Figure 4.

Overview of the southern outlet region. Modified from Fisher (2005). H—Herman, U—Upham, T—Tintah, C—Campbell, N—Norcross, WR—White Rock, North Dakota.

Figure 5.

Geomorphology of the southern outlet spillway. Modified from Kehew et al. (2009). NWO—northwestern outlet; LIS—Laurentide Ice Sheet; A—Lake Agassiz; EO—eastern outlet; SO—southern outlet; T.L.—Traverse Lake; M.L.—Mud Lake; BdS.R.—Bois de Sioux River.

Figure 5.

Geomorphology of the southern outlet spillway. Modified from Kehew et al. (2009). NWO—northwestern outlet; LIS—Laurentide Ice Sheet; A—Lake Agassiz; EO—eastern outlet; SO—southern outlet; T.L.—Traverse Lake; M.L.—Mud Lake; BdS.R.—Bois de Sioux River.

Figure 6.

LiDAR image of grooves and residual bars in the Mustinka spillway.

Figure 6.

LiDAR image of grooves and residual bars in the Mustinka spillway.

North and northeast of Traverse Lake, there are three spillway segments. The two segments up the Mustinka River valley are subtle, with the west branch containing only a few scour depressions (Fig. 5A). Boulder piles alongside farm fields are common in this region. Downstream of where the west and east branches join, fluvial scour is very evident from numerous streamlined hills and scour depressions, which is evident from a light detection and ranging (LiDAR) digital elevation model (Fig. 6). Once the lake dropped below 1005’ (306 m), these spillways were abandoned, leaving only the main spillway open.

The main spillway channel cuts through the Big Stone Moraine (Fig. 5) and has a few terraces along its inner channel, especially around Brown’s Valley, where the spillway widens (Fig. 5B). These terraces are armored with boulders forming a pavement. The widening and shallowing of the spillway at the south end of Big Stone Lake is most likely in response to the bedrock lithology that changes from shale to granite. Here, the streamlined bars are either granite bedrock or pendant bars consisting of bedrock knobs with gravel in their lee side (Matsch, 1983; Patterson et al., 1999). Fisher (2004) used a cross section of the valley just south of Ortonville, Minnesota, and the size of boulders to estimate flow discharge down the spillway. The resulting discharge maximums were between 100,000 and 360,000 m3s–1.

The Fish Creek spillway is cross-cut by the central spillway (Fig. 5B). This spillway was briefly mentioned by Matsch (1983) as the outlet for the earliest stage of Lake Agassiz at the Milnor level, a poorly defined level of the lake ∼10 m above the Herman level. The Fish Creek spillway does not have an USZ, but does contain streamlined bars and scour depressions at its end. The lack of an inner channel suggests that there wasn’t sufficient time for one to develop.

Because many strandlines grade to the southern outlet at different elevations, it’s clear that the spillway was occupied for a long period of time. One approach to determining its chronological history is to use radiocarbon techniques to date organics from the floor of the spillway now occupied by lakes. Two cores were collected from the spillway (Fisher, 2003). A rotosonic core (BVF99) through the dyke at the south end of Traverse Lake penetrated through fan, lake and flood deposits overlying shale bedrock (Fig. 7). The second core (BSL-00) was recovered from lake ice using split-spoon and finally mud rotary methods.

The BVF core records two episodes of spillway flooding while the BSL core only records one. An active spillway is inferred from the large granite boulder (bedload or lag deposit) and the gravel units within the cores, whereas an abandoned spillway is represented by delta, fan, or lacustrine sediment, analogous to modern lake conditions. The outlet may have been occupied more than two times because there are unconformities beneath unit e in the BVF core and unit b in the BSL core. Due to the erosive nature of spillways the onset of spillway flooding is not known. However, the radiocarbon ages within the spillway gravel and overlying lacustrine sediment provide estimates of spillway abandonment. Radiocarbon dates from the BVF core suggest that the spillway was first abandoned after 10,680 14C yr B.P. The younger ages of 10,400 and 10,500 14C yr B.P. from lacustrine sediment are consistent with the age of the low-water Moorhead Phase. A radiocarbon date of 9500 14C yr B.P. in unit e gravel and sand is a maximum limiting age for a subsequent spillway-flooding event.

Radiocarbon dates from the BSL-00 core provide further detail on the timing of the second outlet occupation. Radiocarbon dates within the fine gravel of unit b are not in stratigraphic sequence, suggesting retransporting and redeposition. The Scirpus (bulrush) seeds (9480, 9780 and 9890 14C yr B.P.) show little evidence of abrasion and likely reflect a local riparian source or minimal reworking of older lake sediment within the outlet. The youngest date of 9460 14C yr B.P. from unit b is used as the closest limiting age for the gravel, and the youngest date of 9390 14C yr B.P. from an unabraded seed in the overlying lacustrine sediment of the BSL core, suggests spillway abandoned by 9400 14C yr B.P. The similar ages of gravel from both cores (9500 14C yr B.P., unit e, BVF core; 9460 14C yr B.P., unit b, BSL core) indicate that they record the same spillway occupancy event with final spillway abandonment around 9400 14C yr B.P., or 10.4–10.8 ka cal, which agrees with the current OSL age assignment of 10.5 ± 0.3 for the Campbell Beach, the lowest beach graded to the southern outlet.

Eastern Outlets

The eastern outlets are not well understood, from a spatial and chronologic viewpoint. The spillways are difficult to access with few researchers studying them. Because strandlines have never been traced from the main Agassiz basin to eastern outlets starting at the subcontinental drainage divide between the Great Lakes and Hudson Bay drainage, workers have relied upon projecting water planes northeastward (e.g., Teller and Thorleifson, 1983) to where they meet spillways mapped by Thorleifson (1983), Teller and Thorleifson (1983) and Leverington and Teller (2003). For a long time it was thought that abandonment of the southern outlet coincided with opening an eastern outlet west of Thunder Bay, Ontario (e.g., Broecker et al., 1989). The new lower outlet was to have drawn the level of Lake Agassiz down to a shoreline somewhere north of Grand Forks, North Dakota, resulting in the low water Moorhead Phase in which fluvial sediment of the Poplar River Formation was deposited. However, intensive searching in 2003 for the spillway channel west of Thunder Bay, Ontario, was unsuccessful (Lowell et al., 2005).

Numerous channels and spillways have been mapped in the eastern outlet area (Figs. 1, 8). The Kaministikwia (Kam) channels have been explained by local drainage events (Zoltai, 1965) not requiring drainage from Lake Agassiz. Sub-bottom acoustic surveys in Lake Superior were unsuccessful in finding large submerged fans off Thunder Bay (Steve Coleman, 2010, personal commun.). Large fans were found, however, in Nipigon and Black bays likely recording flow from the Kelvin channels further north (Gary et al., 2011). The Kelvin channels are the outlets usually thought of as the eastern outlets. They consist of numerous channel systems west of Lake Nipigon labeled the Kaiashk, Kopka, Pillar, Armstrong, and Pikitigushi channel systems (Thorleifson, 1983) based on earlier work by Elson (1967) and Zoltai (1967). It is assumed that these channels drained water from Lake Agassiz into Lake Kelvin, a higher stage of Lake Nipigon. Two elevations are shown for Lake Kelvin in Figure 8. The higher gray area should be considered a maximum stage as suggested by Thorleifson (1983), and diagonal lines for that part of the basin only is a minimum value as suggested by Leverington and Teller (2003). The history and origin of some of these channels may be more complex than generally realized, because some of them contain eskers within them (Fig. 8), suggesting in part, a subglacial origin as well. The third channel system associated with the eastern outlet is the series of channels shown as black thick lines that extend from the Nipigon (Kelvin) basin into Lake Superior.

Figure 7.

Lithostratigraphic columns for two cores to bedrock from Big Stone Lake (BSL-00) and Brown’s Valley fan (BVF-99). Accelerator mass spectrometry radiocarbon ages from terrestrial woody material are shown. Modified from Fisher (2003).

Figure 7.

Lithostratigraphic columns for two cores to bedrock from Big Stone Lake (BSL-00) and Brown’s Valley fan (BVF-99). Accelerator mass spectrometry radiocarbon ages from terrestrial woody material are shown. Modified from Fisher (2003).

The most recent results from minimum radiocarbon ages from lakes and wetlands associated with moraines in northwest Ontario (Lowell et al., 2005; Teller et al., 2005; Lowell et al., 2009) indicate a much younger deglaciation that the previously available few bulk-dated radiocarbon ages. The traditional reconstruction had assumed that deglaciation in this area had occurred by the beginning of theYounger Dryas cold period at ca. 11,000 14C yr B.P. The detailed work on obtaining ages for three sets of moraines by Lowell et al. (2009) determined that Lake Agassiz could not have drained into the Great Lakes basin until after the Younger Dryas event, presumably through the Kelvin channels. Thus, if an earlier eastern outlet was not open, where did the water go to draw the lake down to the Moorhead Phase?

Figure 8.

Overview of eastern outlet channels. Large dashed arrow in southwest corner indicates original hypothesis of a Kaministikwia (Kam) spillway draining Lake Agassiz eastward. Other than small spillways associated with local lakes that are not shown, a spillway has never been found, thus the eastern outlets now refer to the Kelvin Channels further north. The Nipigon Channels drained water from the Nipigon basin into the Superior basin. Inset photograph illustrates an esker within a channel, requiring that some channels were not active during the last deglaciation, and spillway channels likely develop through repeated deglacial cycles and subglacial flooding activity. Map modified from Teller and Thorleifson (1983).

Figure 8.

Overview of eastern outlet channels. Large dashed arrow in southwest corner indicates original hypothesis of a Kaministikwia (Kam) spillway draining Lake Agassiz eastward. Other than small spillways associated with local lakes that are not shown, a spillway has never been found, thus the eastern outlets now refer to the Kelvin Channels further north. The Nipigon Channels drained water from the Nipigon basin into the Superior basin. Inset photograph illustrates an esker within a channel, requiring that some channels were not active during the last deglaciation, and spillway channels likely develop through repeated deglacial cycles and subglacial flooding activity. Map modified from Teller and Thorleifson (1983).

Northwestern Outlet

The remaining outlet from Lake Agassiz is a northwestern outlet in northwest Saskatchewan. Interest in this outlet was renewed by a series of papers advocating northwest drainage (Smith and Fisher, 1993; Fisher and Smith, 1994). Higher strandlines and glaciolacustrine sediment mapped by Fisher and Smith (1994) were interpreted as a more extensive lake in the upper Churchill valley (Fig. 1) than reconstructed by previous workers (Fisher et al., 2009). Subsequent work by Rayburn (1997) and Rayburn and Teller (2007) tracing the Campbell Beaches across Manitoba and Saskatchewan determined that isobases have a more east/west orientation than previously recognized indicating that greater glacial isostatic adjustment depression would result in deeper water near the head of the U-shaped Clearwater-lower Athabasca River valley, a former spillway (CLAS). Critical to whether Lake Agassiz drained northward is (1) the timing with which deglaciation occurred for a route permitting drainage northward over the Mackenzie/Churchill drainage divide, into the Mackenzie River system, and (2) whether or not the receding ice margin allowed Lake Agassiz to expand westward to the drainage divide in the northwest. Current strandline data do not support northwest drainage from Lake Agassiz until the lake reached the Campbell level at ca. 9400 14C yr B.P. Higher strandlines have not been mapped north of the Saskatchewan/Manitoba border, indicating that the upper Churchill River valley had not been deglaciated yet or Lake Agassiz was below the level of the northwestern outlet sill. The second data set consists of isochrones based on accelerator mass spectrometry (AMS) radiocarbon age dating of terrestrial material from lakes adjacent to moraines in the Fort McMurray, Alberta area (Fisher et al., 2009). Along with isochrones, minimum ages on flood gravels associated with the spillway indicate a northwestern route could not have opened until ca. 9800 14C yr B.P. (Smith and Fisher, 1993). Currently, formation of the CLAS is explained by a larger regional lake (glacial Lake Churchill) and its formation preceded when Lake Agassiz rose to the Campbell Beach level and began draining northwestward through the Wycherely channels (base of the northwest outlet arrow on Fig. 1, Fisher and Souch, 1998; Fisher et al., 2009) originally noted by Elson (1967). Abandonment of the Wycherely channels and scour lakes in the head of the CLAS (tip of the arrow on Fig. 1) was between 10,800–10,200 Cal yr B.P. (Fisher, 2007) which is consistent with the radiocarbon and OSL ages of the Campbell strandlines (Lepper et al., 2011).

We now arrive at a conundrum. If the southern outlet is abandoned around the beginning of the Younger Dryas chronozone so that lake level drops to the Moorhead Phase in which peat and fluvial sediments are deposited, what caused the lake level to drop if neither an eastern nor a northwestern outlet is open? In the absence of other data the working hypothesis is evaporation. Carlson and Clark (2009) comment that this is unlikely, that an eastern outlet must be open to explain isotopic signatures in marine sediment in the Gulf of St. Lawrence. Lowell and Fisher (2009) responded by suggesting that caution be used in any calculations when the paleogeography of Lake Agassiz directly controlled by ice margins is only weakly constrained. From a terrestrial point of view, the isochrones at the eastern and northwestern outlet regions are very well dated compared to most ice margins for the LIS, and it is unclear which isochrones, if any, are incorrect. For the purpose of discussion, emphasis has usually been placed on subaerial sources of water, such as drainage from proglacial lakes to explain isotopic excursions in the ocean (Broecker et al., 1989). Recent work reveals that ponded melt-water beneath the Antarctic ice sheets is transient (Fricker et al., 2007) and a subglacial source of water should not be ruled out. Previously, Shaw (1989) and Blanchon and Shaw (1995) suggested similar, but larger scaled effects, and subglacial delivery of meltwater to ice margins in the Great Lake basin may be an alternative water source.

Lake Phases And Summary

Understanding the chronology of Lake Agassiz is made complex by its sheer size (∼1,500,000 km2), numerous outlets, isostatic rebound, and the low density of radiocarbon ages associated with moraines. Lake phases correspond to outlet history, in general using the names of towns in the Red River Valley. The precise time when Lake Agassiz began as a proglacial lake is uncertain. The Milnor stage refers to the time when the highest strandlines developed and the Milnor channel in the southwest corner of the lake was active. The Lockhart Phase refers to the time between ca. 12,100 and 10,800 14C yr B.P. when the ice margin had retreated far enough north for Lake Koochiching to merge with the lake in the Red River Valley (Hobbs, 1983). The southern outlet (Fig. 3) was abandoned at the end of the Lockhart Phase when water levels dropped below the sill level, with evaporation being the working hypothesis, initiating the low-water Moorhead Phase. At this time, the southern basin was subaerially exposed and the fluvial Poplar River Formation was deposited. During, or after deposition of the Poplar River Formation, but still during the Moorhead Phase, the lake transgressed southward, driven by isostatic rebound. Burial of a delta at Fargo, North Dakota (Fig. 1A) at 9900 14C yr B.P. by the Sherak Formation sediments (Yansa et al., 2002; Yansa and Ashworth, 2005) records the transgression, but it is uncertain whether the transgressive lake reached the southern outlet before the northwestern outlet opened. The most recent work by Fisher et al. (2008) suggests that the Emerson Phase ended at ca. 9500–9400 14C yr B.P., rather than at 9900 14C yr B.P. (Fenton et al., 1983).

The timing of the Emerson Phase is also uncertain. Assuming that the Campbell strandlines are transgressive in nature (cf. Teller, 2001), then a variety of strandline ages are expected due to the continual reworking of material (cf. Bajc et al., 2000). Ages of 9350 14C yr B.P. (Mann et al., 1997) and 9400 14C yr B.P. (Risberg et al., 1995) from the Upper Campbell beach coincide with abandonment of the northwestern outlet at 9800–9200 14C BP (Fisher, 2007) and a brief reoccupation of the southern outlet before closure of the southern outlet by 9400 14C yr B.P. (Fisher, 2003). However, the seeds in the Big Stone Lake core dated by Fisher (2003) are reworked, the Lower Campbell beach extends all the way to the southern outlet, and Aharon (2003) reports a meltwater spike in the Gulf of Mexico at 9100 14C yr B.P., all of which may indicate that the southern outlet was not finally abandoned until ca. 9100 14C yr B.P. An estimate for recession of the Rainy Lobe from west of Lake Nipigon (Fig. 1A) opening eastern outlets (Teller and Thorleifson, 1983) is 9400 14C yr B.P., based on a minimum deglacial date from Lower Vail Lake west of Lake Nipigon (Teller et al., 2005). The eastern outlet spillways west and northwest of Lake Nipigon remain undated; nevertheless, deglaciation around Lake Superior was well under way by 9400 14C yr B.P. (Saarnisto, 1974; Fisher and Whitman, 1999) permitting the passage of Agassiz water southeastward through the Great Lakes.

Field Stops, Day 1

The field trip begins with an ∼4 h drive west from Minneapolis to the Lake Agassiz basin.

Stop 1A. Lake Agassiz Strandlines (Hobbs)

46.94327°N, 96.42788°W (WGS 83); 333 m (1093’)

This gravel pit was originally operated by Kost Brothers, which is now part of Aggregate Industries. It is only intermittently active, and used for cattle grazing in between pit operations. This gravel pit occupies a wide bench below a scarp identified as a Herman strandline (Leverett, 1932; Weller and Fisher, 2009). In this area (Fig. 9), the classic Herman to Campbell beaches are close together, spanning ∼2 mi east-west over 100 ft (∼30 m) of elevation (1100–1000’; 335–305 m).

No beach crest is visible here. I suspect it has already been mined out, along with the best gravel. The remaining faces expose only ∼10–12 (∼3–3.6 m) ft of sand and gravel. Presumably they are mining down to wave–washed till. The lower parts of the mined faces are generally obscured by sand slumping from above. Beach sediment ranges from coarse gravel to fine sand, though most of it is sandy gravel and gravelly sand. Overall bedding is flat and low-angle crossbedding. One sample at 7 ft (2.1 m) depth showed the (gravel) sand-silt-clay ratio as (34) 92-53. This is clean but not super-clean.

The 1–2 mm sand fraction was examined under a low-power microscope; the grains are carbonates from the Winnipeg lowlands and various igneous and metamorphic rocks from the Canadian Shield, mostly granites. No shale from North Dakota–Manitoba or red rocks from the Lake Superior basin were seen. This assemblage is called “Winnipeg provenance” by the Minnesota Geological Survey. The grains are somewhat rounded, the carbonates more so than the crystalline rocks. The surface tills in this part of the Lake Agassiz basin do contain some gray Cretaceous shale, because one of the flow lines that brought glacial debris into the area crosses an extensive area of Pierre Shale. However the flow lines from the Winnipeg area to the north were dominant in the late-glacial, and the percentage of shale grains ranges from the teens down into single digits. The shale was further reduced by wave action and longshore transport, so that many samples contain little or no shale. This is good news for the construction industry, because shale particles are deleterious for concrete.

There are much thicker bodies of sand and gravel not far below the beach gravels; in some places these deposits were eroded by Lake Agassiz waves and incorporated into beach deposits. These bodies were laid down along a northeastern-sourced ice margin that invaded a much earlier phase of Lake Agassiz. (There is some question whether the term Lake Agassiz is even appropriate for this water body, but it was dammed by ice to the north and higher ground to the south.) These gravel bodies are so thick that they are generally dredged out of standing water.

The beach sequence is capped by a stone line, overlain by an unbedded silt-fine sand layer in which the modern soil is developed. In places, the upper part of the sequence under the stone line is unbedded sand and silt. The stone line is interpreted as a lag from wind erosion, and the sand-silt above is interpreted as an eolian deposit. The deflation that concentrated the stones presumably began as soon as the lake level dropped low enough that the beach was no longer wave-washed. The deposit that buries the stone line was derived from the broad intermediate-depth lake bottom deposits of silt and fine sand when the lake had dropped far enough to expose them. This could have happened for the first time during the Moorhead low-water phase, and again following final drainage of the lake. There is no visible break in sedimentation, but such a break could be hidden in the modern soil profile.

Figure 9.

Location map of field stops for Friday.

Figure 9.

Location map of field stops for Friday.

Stop 1B: Lacustrine Sand, Ditch Exposure (Hobbs) 46.94870°N, 96.50212°W; 284 m (932’)

This is a brief stop to look at Lake Agassiz sand exposed in the banks of a cleaned-out ditch. We are at ∼930 ft (∼283 m) in elevation, 160 ft (∼ 49 m) below the beach sediment at Stop 1A. The sand at the surface here was probably not deposited in 160 ft of water though, because water levels went down in stages as the southern outlet was eroded, and shallow water sediments were laid down on top of deeper water deposits. It is still below the lowest beach in the area, the lower Campbell.

The banks of the ditch are composed of clean fine sand, with no noticeable bedding. The bedload of the ditch is medium sand, ripple-marked, with many tiny snail shells. Presumably the bedload is derived from upslope, where the sand gradually gets coarser closer to the beaches. In the other direction, to the west the surface slopes imperceptibly toward the Red River, and the surface sediment grades from fine sand, through silt, and finally clay. Leaving Stop 1, we descend into the Lake Agassiz basin passing through subtle strandlines as we head toward Fargo, North Dakota, along the floor of the Agassiz basin.

Stop 2. Stratigraphy and Implication of Basin Stratigraphy (Ashworth)

46.92567°N, 96.78598°W; 265m (870′)

Moorhead Low-Water Phase Deposits of Lake Agassiz in North Fargo, North Dakota

Allan Ashworth (Department of Geosciences, North Dakota State University, Fargo, North Dakota 58108-6050, USA), Jessie Rock (Department of Geosciences, North Dakota State University, Fargo, North Dakota 58108-6050, USA), and Catherine Yansa (Department of Geography, Michigan State University, East Lansing, Michigan 48824-1115, USA)

Figure A.

Location of Lake Agassiz deposits in North Fargo.

Figure A.

Location of Lake Agassiz deposits in North Fargo.

Lake Agassiz beds in the Fargo-Moorhead area consist of the upper Sherack Formation (6 m), the middle Poplar River Formation (0–2 m) and the lower Brenna Formation (26 m). The Brenna Formation is only observed in deep excavations or in boreholes. The section we will examine is located in a cut bank of the Red River north of the Fargo Wastewater Treatment Plant (Fig. A). At the base of the section is ∼1 m of dark gray, banded silts and clays of the Poplar River Formation, containing shells of the freshwater bivalves Pisidium and Sphaerium, lymnaeid gastropods, wood, cones and seeds and skeletal remains of insects, especially beetles (Fig. B). Studies of the Poplar River Formation organics in the Fargo-Moorhead area have been made by Rosendahl (1948), McAndrews (1967), Kompelian and Schwert (1986), Yansa and Ashworth (2005) and Rock (2009). AMS ages on nearby organics are between 10,230 and 9900 14C yr B.P. The dark-colored organic beds are overlain by ∼3 m of light gray and buff laminated silts and clays of the Sherack Formation deposited during the deep-water Emerson phase of Lake Agassiz. Collectively the fossils indicate a range of habitats from aquatic to well-drained sandy substrates. The range of plants and invertebrates is consistent with the interpretation that the organics accumulated in the Moorhead delta, a feature associated with progradation of the proto-Sheyenne River into Lake Agassiz during the low water Moorhead Phase of Lake Agassiz (Brophy and Bluemle, 1983). The eutrophic wetland was comprised of marshes and bogs drained by shallow stream channels. The sand bar plant community included Picea (spruce), Larix (tamarack), Salix (willow) and Populus (poplar) (Yansa and Ashworth, 2005). The deposits span the transition from the Younger Dryas to the Holocene. There is no evidence of climate change at the Holocene boundary based on stratigraphic examination of assemblages of plant macrofossils and fossil beetles. A quantitative estimate of paleotemperature based on fossil beetles indicates a mean July temperature of 17 °C or about –4 °C cooler than the present day (Rock, 2009). Today, a similar mean July temperature is characteristic of the southern Boreal Forest ∼450 km north of Fargo. The majority of the plant and insect species identified from fossils currently inhabit Delta Marsh, an extensive wetland at the southern end of Lake Manitoba which we consider to be a good analog for the wetlands of the low water Moorhead Phase of Lake Agassiz (Yansa and Ashworth, 2005).

Figure B.

Contact between the Sherack and Poplar River Formations of Lake Agassiz.

Figure B.

Contact between the Sherack and Poplar River Formations of Lake Agassiz.

Figure 10.

Digital elevation model of strandlines of Lake Agassiz west of Fargo. Modified from Lepper et al. (2011).

Figure 10.

Digital elevation model of strandlines of Lake Agassiz west of Fargo. Modified from Lepper et al. (2011).

Leaving Stop 2, we are heading west ∼25 mi to the Town of Wheatland, North Dakota, across the floor of the Agassiz basin (Fig. 9). Elevation gradually increases and other than incised streams and drainage ditches, the first sign of topographic relief is the Campbell scarp (Figs. 10, 11). The Campbell scarp along this transect is a significant topographic feature on the lake margin and marks a significant transgression of the lake into the southern basin after the Moorhead Low. OSL ages of 10.3 ± 0.2 ka and 10.0 ± 0.2 ka (KG0505; Lepper et al., 2011) were obtained from the lakeward scarp face in the wooded area just north of the Wheat-land cemetery. We will proceed westward along County Highway 10 in western Cass County to the Norcross strandline where we will disembark and examine the sediment and geomorphology.

Traveling west from the Campbell scarp. We pass over an additional 2 mi of lake plain, marked by several under fit gulley features (G1, G2 on Fig. 11). The next strandline encountered is a ridge with an elevation of 310 m that could be correlated to the Tintah (see Fig. 11), however the strand is discontinuous and splays in places. OSL ages obtained just lakeward of the ridge crest were 13.4 ± 0.3 ka and 13.6 ± 0.2 ka (KL1004; Lepper et al., 2011); ages that are more consistent with Upham beach ages near the southern outlet. Westward from the 310 m ridge we traverse a landscape marked by ∼10 gentle linear undulations that trend SSW to NNE with lengths ranging from 3 to >6 mi. These forms are recognized on U.S. Department of Agriculture soil survey as having sandy upper pedons.

This series of undulations culminates in the next significant ridge with an elevation of 325 m. This ridge extends for several miles northward (see Fig. 11) and is interpreted as the Norcross ridge. We will stop here to examine beach deposits. A robust OSL age of 13.6 ± 0.3 ka was obtained from this ridge (KG0503; Lepper et al., 2011), which correlates well to our OSL results for the Norcross strandline near the southern outlet.

Stop 3. Wheatland, North Dakota, Strandline Traverse with OSL Dated Strandlines (Lepper)

46.920703°N 97.407269°W; 325 m (1066’)

Here we can examine the strandline on foot, and examine a pit dug into the ridge.

Figure 11.

LiDAR digital elevation model of strandlines along the Wheat-land transect. Modified from Lepper et al. (2011).

Figure 11.

LiDAR digital elevation model of strandlines along the Wheat-land transect. Modified from Lepper et al. (2011).

Approximately 1.5 mi farther west, County Highway 10 passes over the Herman beach ridge complex with an elevation of 335 m. OSL ages of 14.1 ± 0.2 ka and 14.3 ± 0.2 ka (KG0504; Lepper et al., 2011) were obtained from a small abandoned borrow pit in the Herman ridge. The sample site for KG0504 lies between two sites where mammoth remains have been described. Approximately 2 mi south of the field trip transect along the Herman ridge is the Embden Mammoth site reported by Harington and Ashworth (1986). This site was revisited in 2009 and sampled for OSL dating. An age of 14.0 ± 0.3 ka was determined (Lepper and Sager, 2010). Similarly, ∼4.5 mi north of the field trip transect along the Herman ridge is the Ripon Mammoth site discussed by Warren Upham, in his 1895 monograph on Lake Agassiz. He describes mammoth remains recovered from the base of a gravel quarry in Herman beach deposits at Ripon (present day Absaraka), North Dakota. The remains included three teeth, two vertebrae, and a tusk measuring 11 ft (∼3.3 m) long. Upham was, however, quite specific in indicating that “they [the mammoth remains] were embedded in the top of the till, and the overlying beach formation has yielded no bones, shells, or other fossils” (Upham 1895, p. 322).

Leaving Stop 3. The remainder of the day’s drive (∼1.5 h) is retracing our route back to Interstate 29 near Fargo and then south to the South Dakota state line where we are staying at the Dakota Magic Casino. The elevation along the way is gradually increasing to where we cross the same set of strandlines just viewed. After crossing the Wild Rice River, the elevation increases as we “climb” onto the Big Stone Moraine. Immediately to our west and south is the Milnor spillway, where water first drained through the Big Stone Moraine (Fig. 5). Tomorrow, we will explore more strandlines and the southern outlet spillway.

Field Stops, Day 2

This morning we will be driving across many of the strandlines, first at the mouth of the southern outlet spillway, second within and along the spillway, and finally explore the erosional landforms (granite outcrop) and deposits (granite boulders) within the spillway before driving back to Minneapolis.

From our hotel we will proceed north and east across the strandlines pausing briefly at an Upham spit, and remaining in the bus, before our first stop at a borrow pit in a well-developed (but small) spit (Fig. 12).

The topography around the Dakota Magic casino is characterized by aligned small hills and ridges orientated ∼NW-SE between the Milnor and Herman levels, referred to by Fisher (2005) as the Milnor bars (Fig. 13). The sampling of three ridges by auger and vibracore has revealed that constituent materials are lake sediments.

Pause 4. Upham Double Spit on the La Mars 7.5’ Quadrangle

45.970488°N, 96.700844°W; 313 m (1030’)

This spit has been investigated twice. Fisher reasoned that spits are important strandlines for reconstructing paleolake levels because they record an interval of a stable lake level. Results from a coring traverse (Fisher, 2005) across the lagoon, spits and into the open lake is shown in Figure 14. The spit ridges are composed of gravel that laterally grades to thin sand deposits in the lagoon and spit platform. Thin sequences of laminated silty sand were found between the sand and underlying diamicton. The small size of the spit and thin sedimentary sequence is suggestive of a short occupancy of the lake at this elevation. The second investigation focused on obtaining an OSL age for the spit (Lepper et al., 2007). The sample was obtained from cross-stratified sand between beds of cross-stratified pebbly gravel resulting in an age of 13.5 ± 0.2 ka (KL0601). From Pause 4 we will travel southeast across the strandlines to Stop 5 (Fig. 13).

Stop 5. Norcross Strandplain Pit

45.905595°N, 96.642156°W; 319 m (1049’)

At this pit, which has existed for at least 17 years, beach ridge and spit ridges are exposed. We are at the Norcross level and littoral transport is to the south and west into the mouth of the Cottonwood spillway. This spillway is assumed to have operated in tandem with the central spillway at the Herman and Norcross stages, with the Cottonwood spillway abandoned once the lake dropped to the Upham level (Fig. 3). The purpose of the stop is for you to examine the internal stratigraphy and sedimentology of these shoreline features. An OSL age from this pit (Lepper et al. 2007) from cross-stratified sand between pebbly sand resulted in an age of 13.7 ± 0.4 (KL0507). From Stop 5 we will proceed northeastward a few miles to the floor of the central spillway.

Pause 6. Central Spillway Channel

45.920859° N, 96.592292° W, 297 m (976’)

Here the central spillway is 4.5 km wide and 15 m deep (Fig. 12). Large stone piles are found along the spillway bottom, and a lag of clasts that in places verges on being a pavement, can be seen within some ditches. After the southern outlet was abandoned by ca. 9400 14C yr B.P. (Fisher, 2003), the drainage divide was somewhere between Mud Lake and White Rock, Minnesota close to where we are at now. Because the land in the bottom of the spillway is so flat, the precise location of the paleodivide is unknown. The location of the sill at higher lake stages is even more uncertain, but was likely further south, having migrated northward as lake level dropped responding to headward erosion. Once the lake dropped below ∼974 ft (∼297 m), the southern outlet was abandoned. A boulder lag is exposed in shallow borrow pits and ditches along the White Rock dam road that crosses the spillway. A boulder lag beneath organic muck and overlying diamicton was revealed by extensive borings made in this area by the United States Army Corps of Engineers during construction of the White Rock dam (Fig. 5). When Lake Traverse was dry in 1934, a historical photograph reveals a boulder lag on the lake bottom (Fig. 15), indicating that the boulder lag covers much of the floor of the central spillway. Similar boulder lags capping terraces, in particular above the upper end of Big Stone Lake, have been observed and commented on by past researchers (e.g., Matsch, 1983; Matsch and Wright, 1967).

Figure 12.

Northern half of the morning’s field trip route.

Figure 12.

Northern half of the morning’s field trip route.

Figure 13.

LiDAR hillshade of strandlines northwest of the spillway.

Figure 13.

LiDAR hillshade of strandlines northwest of the spillway.

Figure 14.

Cores in and associated with the Upham double spit. Modified from Fisher (2005).

Figure 14.

Cores in and associated with the Upham double spit. Modified from Fisher (2005).

Pause 7. Grooves and Barforms in Mustinka Spillway

45.89555°N, 96.49086°W; 305 m (1000’)

We are now in the Mustinka spillway above the central spillway that was abandoned when the water levels dropped below the Tintah level. Contour lines with a 5 ft (1.5 m) interval and aerial photographs hinted at streamlined bar forms and scour depressions within the spillway. With the release of LiDAR imagery, such barforms and grooves are readily apparent (Fig. 16). Note the low escarpments over which many of the grooves are initiated.

Figure 15.

Historical photograph (1934) from the Wheaton Historical Society of a family having a picnic on the floor of Traverse Lake.

Figure 15.

Historical photograph (1934) from the Wheaton Historical Society of a family having a picnic on the floor of Traverse Lake.

We now head south to the Town of Wheaton then southwest-ward along the shore of Traverse Lake (Fig. 12). On both sides of the lake alluvial fans have developed from gullies and streams incised into the valley walls. A few short vibracores were recovered from Traverse Lake in the late 1990s, but with only a few thousand years of gritty mud recovered. Traverse Lake is separated from Big Stone Lake by the Brown’s Valley fan constructed by the Little Minnesota River coming in from the west. Upham (1895) noted that Traverse Lake has 6 ft (1.8 m) of annual variability, drying to stagnant pools during the summer. The historical museum in Wheaton, Minnesota, has photographs of the lake bottom on fire and a picture of a family sitting on boulders having a picnic (Fig. 15) illustrating that the boulder lag at the base of the spillway is if not extensive, sporadic. Where the road and lake bend to the south, the gap on the west valley wall is where the Cottonwood spillway rejoins the central spillway. The border between South Dakota and Minnesota passes down the center of the lake (Fig. 5).

Stop 8. Brown’s Valley Fan Core

45.59858°N, 96.84861°W; 299 m (981’)

Upham (1895) described the land at Browns Valley between Traverse and Big Stone Lakes as the drainage divide, well before reservoirs and dams were constructed in the spillway bottom. Before growth of the Browns Valley fan separated Traverse and Big Stone Lake sometime during the Holocene, the earlier lake drained south as a tributary to the Mississippi. Once the lakes were separated by growth of the Browns Valley fan, Lake Traverse eventually rose high enough to drain northward past White Rock at Pause 6 as the Bois de Sioux River. The Red River of the North starts where a series of rivers join the Bois de Sioux River at Wahpeton, North Dakota, 60 km north of White Rock.

The Browns Valley Fan 99 (BVF99) core was collected from the top of earthen dam with a rotosonic drill rig. Details of the core were presented earlier in the guidebook where more details can be found (Fig. 7). One approach to reconstructing spillway history is to collect cores from spillway lakes and radiocarbon date the lowermost organics to provide a minimum age for outlet abandonment. In the BVF99 core, two units of gravel separated by mud was interpreted as recording a minimum of two outlet occupation events. Wood ages in the gravels are maximum ages for deposition of the gravel. The data from these two cores indicates spillway occupation ended sometime after 10,680 and 950014C yr B.P. A minimum age from overlying mud from the Big Stone Lake core to the south of us recorded final spillway abandonment by 9400 14C yr B.P. The hiatus in spillway activity recorded by lacustrine sediment is corroborated by an age of 10,330 ± 60 14C yr B.P. at the base of an alluvial fan further down the spillway (Hudak and Hajic, 2002; Fisher, 2003), suggesting also that the spillway had effectively formed during the earlier activity. Thus available data records two spillway occupation events, but there could have been more because of the erosional nature of the lower contact of the gravel units.

After driving through Brown’s Valley, we drive up the valley wall (Fig. 17). Note a prominent terrace littered with boulders. On a terrace along the northwest side of Big Stone Lake the clasts form a pavement. Shale bedrock outcrops in at least one spot along Traverse Lake, but has not been reported along Big Stone Lake. The southern outlet is also termed River Warren (by Upham after General G.K. Warren), and there have been numerous suggestions about how the outlet, with terraces may have developed. Matsch (1983) points out that there is agreement between the number of beaches at the head of the spillway and number of terraces within the spillway, and there has been some discussion on how incision progressed. Matsch and Wright (1967) promoted lake stabilization by boulder armored spillway floors. Episodic incision by more competent flows resulted in knickpoints migrating upstream initiating episodic lake level lowering. It should be noted that the depth of the spillway beneath Big Stone Lake is 25 m lower than the valley floor at Ortonville, recording significant scour in River Warren.

Stop 9. View of Big Stone Lake

45.42810°N, 96.69202°W; 338 m (1110’)

The purpose of this brief stop is for the view of the spillway floored with Big Stone Lake. The BSL00 core was taken a little south of here during the winter with a conventional drill rig on 18 inches of ice (with some very nervous drillers). Just below us, another core was collected along with Tom Lowell using a hydraulic-assisted Livingstone corer, and stopped at 25 m depth (4 m of water) without hitting the base of the lacustrine sediments.

Figure 16.

Residual bars and grooves in the Mustinka Spillway.

Figure 16.

Residual bars and grooves in the Mustinka Spillway.

Figure 17.

Location map for the last three field stops.

Figure 17.

Location map for the last three field stops.

We now continue southward along Big Stone Lake to Ortonville, Minnesota, and then a few miles further down valley to our final stop.

Stop 10. Big Stone Wildlife Refuge (Boulders)

45.25546°N, 96.40285°W; 294 m (965’)

Granite outcrops along the floor of the spillway and is responsible for most of the valley bottom topography. Many granite outcrops are streamlined parallel with the spillway. The surface of the granite is jointed, and rock slabs have developed from exfoliation processes. On the surface of outcrops, smaller-scale forms (220 m) resemble whalebacks. Elsewhere the surface is ornamented with flutes, grooves, rimmed depressions and undulating surfaces, all of which record flow parallel with the valley (Fisher, 2004).

Large granite boulders occur in the spillway bottom on top of granite bedrock, in places striated (Patterson and Boerboom, 1999). Some boulders may have their origins as corestones and others were presumably sourced from till and morainal material and transported by River Warren. Evidence for fluvial transport is the presence of sculpted bedrock beneath boulders, and the non-random distribution of boulders. Interestingly, only large boulders are found on the sculpted bedrock outcrops, smaller caliber sediment gravel is not present unless it underlies the wetlands.

Geomorphological and paleohydrological studies of the southern outlet began with Upham (1895), then Matsch and Wright (1967), Matsch (1983), and is briefly reviewed by Johnson et al. (1998). Using the Manning equation, Matsch (1983) outlined a variety of flow parameters to calculate discharges that ranged from 0.017 to 0.13 Sv in different areas along the spillway with 1 Sv not being unreasonable. 1 Sv = 1 × 106 m3s–1. Rare discharges of 0.3 Sv every few hundred years were suggested by Wiele and Mooers (1989), and they augmented their meltwater production rate of 0.05 Sv by catastrophic drainages into Lake Agassiz from other lakes and possible surging of the ice sheet displacing water from the lake basin to generate the 0.3 Sv discharge (Mooers and Wiele, 1989). Becker (1995) used HEC-2 model simulations for peak outflow when the lake was at the Campbell (0.014 Sv) and Tintah (0.027 Sv) stages, resulting in values less than those calculated by Matsch (1983), and concluded that average discharge at the Campbell stage was probably less than 0.005 Sv. The distribution of boulders in clusters and linear trains records the interaction of clasts during transport and deposition. The geomorphology of the spillway with streamlined erosional remnant hills (Figs. 5, 17) is characteristic of other large flood spillways. Using the Manning equation and a variety of empirical equations to determine paleovelocity, preferred discharges between 0.364 and 0.102 Sv were calculated. These high discharges agree well with other flood discharges, and most likely represent ephemeral and catastrophic flood events linked to either episodic incision at the outlet or the result of rapid inputs of meltwater to Lake Agassiz. The point here is that the bedrock is sculpted by meltwater and boulders are arranged in clusters.

This stop, with lunch, concludes the field trip. We return to Minneapolis via Highway 12.

References Cited

Aharon
,
P.
,
2003
,
Meltwater flooding events in the Gulf of Mexico revisted: Implications for rapid climate changes during the last deglaciation
:
Pale-oceanography
 , v.
18
, no.
4
, p.
1079
,
Arndt
,
B.M.
,
1977
,
Stratigraphy of offshore sediment of Lake Agassiz
:
North Dakota Geological Survey Report of Investigations
 , v.
60
, p.
1
58
.
Arnold
,
J.R.
Libby
,
W.F.
,
1951
,
Radiocarbon dates
:
Science
 , v.
113
, p.
111
120
,
Bajc
,
A.F.
Schwert
,
D.P.
Warner
,
B.G.
Williams
,
N.E.
,
2000
,
A reconstruction of Moorhead and Emerson phase environments along the eastern margin of glacial Lake Agassiz, Rainy River basin, northwestern Ontario
:
Canadian Journal of Earth Sciences
 , v.
37
, p.
1335
1353
,
Baker
,
C.H.
,
1966
,
The Milnor channel, an ice-marginal course of the Sheyenne River, North Dakota
:
U.S. Geological Survey Professional Paper
 , v.
550B
, p.
77
79
.
Becker
,
W.M.
,
1995
,
Reconstruction of late glacial discharges in the upper Mississippi Valley
[
Unpublished M.Sc.
 ]:
University of Wisconsin-Madison
.
Björck
,
B.
Keister
,
C.M.
,
1983
,
The Emerson Phase of Lake Agassiz, independently registered in northwestern Minnesota and northwestern Ontario
:
Canadian Journal of Earth Sciences
 , v.
20
, p.
1536
1542
,
Blanchon
,
P.
Shaw
,
J.
,
1995
,
Reef drowning during the last deglaciation: Evidence for catastrophic sea-level rise and ice-sheet collapse
:
Geology
 , v.
23
, no.
1
, p.
4
8
,
Broecker
,
W.S.
Kennett
,
J.
Flower
,
B.
Teller
,
J.
Trumbore
,
S.
Bonani
,
G.
Wolfli
,
W.
,
1989
,
Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode
:
Nature
 , v.
341
, p.
318
321
,
Brophy
,
J.A.
Bluemle
,
J.P.
,
1983
,
The Sheyenne River; Its geological history and effects on Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Geological Association of Canada Special Paper 26
 , p.
173
186
.
Carlson
,
A.E.
Clark
,
P.U.
,
2009
,
Comment: radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns
:
Quaternary Science Reviews
 , v.
28
, p.
2546
2547
,
Clarke
,
G.
Leverington
,
D.
Teller
,
J.
Dyke
,
A.
,
2003
,
Superlakes, mega-floods, and abrupt climate change
:
Science
 , v.
301
, no.
5635
, p.
922
923
,
Elson
,
J.A.
,
1967
,
Geology of Glacial Lake Agassiz
,
in
Mayer-Oakes
,
W. J.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
37
96
.
Elson
,
J.A.
,
1983
,
Lake Agassiz – discovery and a Century of research
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Geological Association of Canada
, p.
21
42
.
Fenton
,
M.M.
Moran
,
S.R.
Teller
,
J.T.
Clayton
,
L.
,
1983
,
Quaternary stratigraphy and history in the southern part of the Lake Agassiz Basin
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Geological Association of Canada
, p.
49
74
.
Fisher
,
T.G.
,
2003
,
Chronology of glacial Lake Agassiz meltwater routed to the Gulf of Mexico
:
Quaternary Research
 , v.
59
, no.
2
, p.
271
276
,
Fisher
,
T.G.
,
2004
,
River Warren boulders: paleoflow indicators in the southern spillway of glacial Lake Agassiz
:
Boreas
 , v.
33
, p.
349
358
,
Fisher
,
T.G.
,
2005
,
Strandline analysis in the southern basin of glacial Lake Agassiz, Minnesota and North and South Dakota, USA
:
Geological Society of America Bulletin
 , v.
117
, no.
11/12
, p.
1481
1496
,
Fisher
,
T.G.
,
2007
,
Abandonment chronology of glacial Lake Agassiz’s northwestern outlet
:
Palaeogeography, Palaeoclimatology, Palaeoecology
 , v.
246
, p.
31
44
,
Fisher
,
T.G.
Lowell
,
T.V.
,
2006
,
Questioning the age of the Moorhead Phase in the glacial Lake Agassiz basin
:
Quaternary Science Reviews
 , v.
25
, p.
2688
2691
,
Fisher
,
T.G.
Smith
,
D.G.
,
1994
,
Glacial Lake Agassiz: its northwest maximum extent and outlet in Saskatchewan (Emerson phase)
:
Quaternary Science Reviews
 , v.
13
, no.
9–10
, p.
845
858
,
Fisher
,
T.G.
Souch
,
C.
,
1998
,
Northwest outlet channels of Lake Agassiz, isostatic tilting and a migrating continental drainage divide, Saskatchewan, Canada
:
Geomorphology
 , v.
25
, no.
1–2
, p.
57
73
,
Fisher
,
T.G.
Whitman
,
R.L.
,
1999
,
Deglacial and lake level fluctuation history recorded in cores, Beaver Lake, Upper Peninsula, Michigan
:
Journal of Great Lakes Research
 , v.
25
, no.
2
, p.
263
274
,
Fisher
,
T.G.
Smith
,
D.G.
Andrews
,
J.T.
,
2002
,
Preboreal oscillation caused by a glacial Lake Agassiz flood
:
Quaternary Science Reviews
 , v.
21
, no.
8–9
, p.
873
878
,
Fisher
,
T.G.
Waterson
,
N.
Lowell
,
T.V.
Hajdas
,
I.
,
2009
,
Deglaciation ages and meltwater routing in the Fort McMurray region, northeastern Alberta and northwestern Saskatchewan, Canada
:
Quaternary Science Reviews
 , v.
28
, p.
1608
1624
,
Fisher
,
T.G.
Yansa
,
C.H.
Lowell
,
T.V.
Lepper
,
K.
Hajdas
,
I.
Ashworth
,
A.C.
,
2008
,
The chronology, climate, and confusion of the Moorhead Phase of Glacial Lake Agassiz: new results from the Ojata Beach, North Dakota, U.S.A
:
Quaternary Science Reviews
 , v.
27
, p.
1124
1135
,
Fricker
,
H.A.
Scambos
,
T.A.
Bindschadler
,
R.A.
Padman
,
L.
,
2007
,
An active sublgacial water system in West Antarctica mapped from space
:
Science
 , v.
315
, p.
1544
1548
,
Gary
,
J.L.
Colman
,
S.M.
Wattrus
,
N.J.
Lewis
,
C.F.M.
,
2011
,
PostMarquette discharge from Glacial Lake Agassiz into the Superior basin
:
Journal of Paleolimnology
 ,
Harington
,
C.R.
Ashworth
,
A.C.
,
1986
,
A mammoth (Mammuthus primigenius) tooth from late Wisconsin deposits near Embden, North Dakota, and comments on the distribution of woolly mammoths south of the Wisconsin ice sheets
:
Canadian Journal of Earth Sciences
 , v.
23
, p.
909
918
,
Harris
,
K.L.
Moran
,
S.R.
Clayton
,
L.
,
1974
,
Late Quaternary stratigraphic nomenclature, Red River Valley, North Dakota and Minnesota
:
North Dakota Geological Survey Miscellaneous Series
 , v.
52
, p.
47
.
Hobbs
,
H.C.
,
1983
,
Drainage relationships of glacial Lake Atikin and Upham and early Lake Agassiz in northeastern Minnesota
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Newfoundland
,
The Geological Association of Canada
, p.
245
260
.
Hudak
,
C.M.
Hajic
,
E.R.
,
2002
,
Appendix E- geomorphology survey profiles, sections, and lists
,
in
Hudak
,
G. J.
Hobbs
,
E.
Brooks
,
A.
Sersland
,
C. A.
Phillips
,
C.
, eds.,
A predictive model of precontact archaeological site location for the state of Minnesota, Final Report
 :
St. Paul, Minnesota Department of Transportation.
Johnson
,
M.D.
Davis
,
D.M.
Pederson
,
J.L.
,
1998
,
Terraces of the Minnesota River Valley and the character of Glacial River Warren downcutting: Contributions to Quaternary studies in Minnesota
:
Minnesota Geological Survey Report of Investigations
 , v.
49
, p.
121
130
.
Johnston
,
W.A.
,
1946
,
Glacial Lake Agassiz, with special reference to the mode of deformation of the beaches
:
Geological Survey of Canada Bulletin
 , v.
7
, p.
20
.
Kehew
,
A.E.
,
1982
,
Catastrophic flood hypothesis for the origin of the Souris spillway, Saskatchewan and North Dakota
:
Geological Society of America Bulletin
 , v.
93
, p.
1051
1058
,
Kehew
,
A.E.
Lord
,
M.L.
,
1986
,
Origin and large-scale erosional features of glacial-lake spillways in the northern Great Plains
:
Geological Society of America Bulletin
 , v.
97
, p.
162
177
,
Kehew
,
A.E.
Lord
,
M.
Kozlowski
,
A.L.
Fisher
,
T.G.
,
2009
,
Chapter 7. Proglacial megaflooding along the margins of the Laurentide Ice Sheet
,
in
Burr
,
D.
Carling
,
P. A.
Baker
,
V. R.
, eds.,
Megaflooding on Earth and Mars
 :
New York
,
Cambridge University Press
, p.
104
127
.
Kompelian
,
M.G.
Schwert
,
D.P.
1986
,
Paleoenvironmental implications of insect remains from the Seminary site, Cass County, North Dakota
:
Proceedings of the North Dakota Academy of Sciences
 , v.
40
, p.
131
.
Lepper
,
K.
Sager
,
L.
,
2010
,
A revised age determination for the Embden, North Dakota mammoth using optically stimulated luminescence dating
:
Current Research in the Pleistocene
 , v.
27
, p.
171
173
.
Lepper
,
K.
Fisher
,
T.
Hajdas
,
I.
Lowell
,
T.
,
2007
,
Ages for the Big Stone moraine and the oldest beaches of glacial Lake Agassiz: Implications for deglaciation chronology
:
Geology
 , v.
35
, no.
7
, p.
667
670
,
Lepper
,
K.
Gorz
,
K.L.
Fisher
,
T.G.
Lowell
,
T.V.
,
2011
,
Age determinations for Lake Agassiz shorelines west of Fargo, North Dakota, U.S.A
:
Canadian Journal of Earth Sciences
 , v.
48
, p.
1199
1207
,
Leverett
,
F.
,
1932
,
Quaternary geology of Minnesota and parts of adjacent states
:
U.S. Geological Survey Professional Paper
 , v.
161
, p.
149
.
Leverington
,
D.W.
Teller
,
J.T.
,
2003
,
Paleotopographic reconstructions of the eastern outlets of glacial Lake Agassiz
:
Canadian Journal of Earth Sciences
 , v.
40
, p.
1259
1278
,
Lowell
,
T.V.
Fisher
,
T.G.
,
2009
,
Reply to comments by Carlson et al., (2009) on “Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns”
:
Quaternary Science Reviews
 , v.
28
, p.
2548
2550
,
Lowell
,
T. V.
Fisher
,
T. G.
Comer
,
G. C.
Hajdas
,
I.
Waterson
,
N.
Glover
,
K.
Loope
,
H. M.
Schaefer
,
J. M.
Rinterknecht
,
V.
Broecker
,
W. S.
Denton
,
G. H.
Teller
,
J. T.
,
2005
,
Testing the Lake Agassiz Meltwater Trigger for the Younger Dryas
:
Eos
  (
Transactions, American Geophysical Union
), v.
86
, no.
40
, p.
365
,372.
Lowell
,
T.V.
Fisher
,
T.G.
Hajdas
,
I.
Glover
,
K.
Loope
,
H.M.
Henry
,
T.
,
2009
,
Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns
:
Quaternary Science Reviews
 , v.
28
, p.
1597
1607
,
Mann
,
J.D.
Rayburn
,
J.A.
Teller
,
J.T.
,
1997
,
Broken Pipe Lake, Manitoba: A remnant of an Emerson Phase Lake Agassiz lagoon
:
Geological Society of America Abstracts with Programs
 , v.
29
, no.
4
, p.
57
58
.
Matsch
,
C.L.
,
1983
,
River Warren, the southern outlet to glacial Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume 26, Geological Association of Canada Special Paper 26
 , p.
231
244
.
Matsch
,
C.L.
Wright
,
H.E.
,
1967
,
The southern outlet of Lake Agassiz
,
in
Mayer-Oakes
,
W. J.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
121
140
.
Mayer-Oakes
,
W.J.
, ed.,
1967
,
Life, Land and Water
 :
University of Manitoba Press
,
Winnipeg
,
339
pp.
McAndrews
,
J.H.
,
1967
,
Paleoecology of the Seminary and Mirror Pool peat deposits
,
in
Elson
,
J. A.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
253
269
.
Mooers
,
H.D.
Wiele
,
S.
,
1989
,
Glacial Lake Agassiz: glacial surges and large outflow events
,
in
Proceedings Geological Survey of America, annual meeting
 ,
St. Louis, MO
,
1989
, Volume
21
, p.
A54
.
Patterson
,
C.J.
Boerboom
,
T.J.
,
1999
,
The significance of pre-existing, deeply weathered crystalline rock in interpreting the effects of glaciation in the Minnesota River valley, U.S.A
:
Annals of Glaciology
 , v.
28
, p.
53
58
,
Patterson
,
C.J.
Knaeble
,
A.R.
Gran
,
S.E.
Phippen
,
S.
,
1999
,
Regional hydro-geologic assessment of the upper Minnesota River basin
,
St. Paul, Minnesota
:
Minnesota Geological Survey, RHA-4
 ,
Part A, Plate 1, scale 1:100,000.
Rayburn
,
J.A.
,
1997
,
Correlation of the Campbell strandlines along the northwestern margin of Glacial Lake Agassiz
[
M.Sc. thesis
 ]:
University of Manitoba
,
189
p.
Rayburn
,
J.A.
Teller
,
J.T.
,
2007
,
Isostatic rebound in the northwestern part of the Lake Agassiz basin: Isobase changes and overflow
:
Palaeogeography, Palaeoclimatology, Palaeoecology
 , v.
246
, p.
23
30
,
Reimer
,
P.J.
Baillie
,
M.G.L.
Bard
,
E.
Bayliss
,
A.
Beck
,
J.W.
Blackwell
,
P.G.
Ramsey
,
Bronk C.
Buck
,
C.E.
Burr
,
G.S.
Edwards
,
R.L.
Friedrich
,
M.
Grootes
,
P.M.
Guilderson
,
T.P.
Hajdas
,
I.
Heaton
,
T.J.
Hogg
,
A.G.
Hughen
,
K.A.
Kaiser
,
K.F.
Kromer
,
B.
McCormac
,
F.G.
Manning
,
S.W.
Reimer
,
R.W.
Richards
,
D.A.
Southon
,
J.R.
Talamo
,
S.
Turney
,
C.S.M.
van der Plicht
,
J.
Weyhenmeyer
,
C.E.
,
2009
,
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0–50,000 Years cal BP
:
Radiocarbon
 , v.
51
, p.
1111
1150
.
Risberg
,
J.
Matile
,
G.
Teller
,
J.T.
,
1995
,
Lake Agassiz water level changes as recorded by sediments and their diatoms in a core from southeastern Manitoba, Canada
:
Pact
 , v.
50
, p.
85
96
.
Rock
,
J.L.
,
2009
,
Paleoclimatic interpretation of the Moorhead Low Water Phase of Lake Agassiz in the southern basin based on fossil Coleoptera assemblages
[
MS Dissertation
 :
North Dakota State University
,
123
p.
Rosendahl
,
C. O.
,
1948
,
A contribution to the knowledge of the Pleistocene flora of Minnesota
:
Ecology
 , v.
29
, no.
3
, p.
284
315
.
Rubin
,
M.
Alexander
,
C.
,
1958
,
U.S. Geological Survey radiocarbon dates IV
:
Science
 , v.
127
, p.
1476
1487
,
Saarnisto
,
M.
,
1974
,
The deglaciation history of the Lake Superior region and its climatic implications
:
Quaternary Research
 , v.
4
, p.
316
339
,
Shaw
,
J.
,
1989
,
Drumlins, subglacial meltwater floods, and ocean responses
:
Geology
 , v.
17
, p.
853
856
,
Smith
,
D.G.
Fisher
,
T.G.
,
1993
,
Glacial Lake Agassiz: The northwestern outlet and paleoflood
:
Geology
 , v.
21
, p.
9
12
,
Stuiver
,
M.
Reimer
,
P.J.
Braziunas
,
T.F.
,
1998
,
High-precision radiocarbon age calibration for terrestrial and marine samples
:
Radiocarbon
 , v.
40
, no.
3
, p.
1127
1151
.
Teller
,
J.T.
,
2001
,
Formation of large beaches in an area of rapid differential isostatic rebound: the three-outlet control of Lake Agassiz
:
Quaternary Science Reviews
 , v.
20
, p.
1649
1659
,
Teller
,
J.T.
Clayton
,
L.
,
1983
,
Glacial Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz
 , Volume
26
,
The Geological Association of Canada Special Paper
, p.
451
.
Teller
,
J.T.
Thorleifson
,
L.H.
,
1983
,
The Lake Agassiz-Lake Superior connection
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz
 ,
Volume Special Paper
26
,
The Geological Association of Canada
, p.
261
290
.
Teller
,
J.T.
Kehew
,
A.E.
,
1994
,
Introduction to the late glacial history of large proglacial lakes and meltwater runoff along the Laurentide Ice Sheet
:
Quaternary Science Reviews
 , v.
13
, no.
9–10
, p.
795
799
,
Teller
,
J.T.
Leverington
,
D.W.
,
2004
,
Glacial Lake Agassiz: A 5000 yr history of change and its relationship to the 180 record of Greenland
:
Geological Society of America Bulletin
 , v.
116
, no.
5/6
, p.
729
742
,
Teller
,
J.T.
Risberg
,
J.
Matile
,
G.
Zoltai
,
S.
,
2000
,
Postglacial history and paleoecology of Wampum, Manitoba, a former lagoon in the Lake Agassiz basin
:
Geological Society of America Bulletin
 , v.
112
, no.
6
, p.
943
958
,
Teller
,
J.T.
Boyd
,
M.
Yang
,
Z.
Kor
,
P.S.G.
Fard
,
Mokhtari A.
,
2005
,
Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates, paleotopography, and a reevaluation
:
Quaternary Science Reviews
 , v.
24
, p.
1890
1905
,
Thorleifson
,
L.H.
,
1983
,
The eastern outlets of Lake Agassiz [M.Sc.]
 :
University of Manitoba
.
Thorleifson
,
L.H.
,
1996
,
Review of Lake Agassiz history
,
in
Teller
,
J. T.
Thorleifson
,
L. H.
Matile
,
G.
Brisbin
,
W. C.
, eds.,
Sedimentology, Geomorphology and History of the Central Lake Agassiz Basin, Volume Field Trip B2, Geological Association of Canada Field Trip Guidebook for GAC/MAC Joint Annual Meeting
 , p.
55
84
.
Upham
,
W.
,
1895
,
The Glacial Lake Agassiz
 :
U.S. Geological Survey
,
v. Monograph 25
, p.
685
.
Weller
,
M.B.
Fisher
,
T.G.
,
2009
,
Feasibility study of mapping continuous strandlines along the southeast Lake Agassiz basin
:
Journal of Maps
 , v.
2009
, p.
152
165
.
Wiele
,
S.
Mooers
,
H.D.
,
1989
,
Glacial Lake Agassiz: glacial surges and large outflow events, in Proceedings
:
Geological Society of America Abstracts with Programs
 , v.
21
, p.
54
.
Yansa
,
C.H.
Ashworth
,
A.C.
,
2005
,
Late Pleistocene palaeoenvironment of the southern Lake Agassiz Basin, USA
:
Journal of Quaternary Science
 , v.
20
, p.
255
267
,
Yansa
,
C.J.
Ashworth
,
A.C.
Fisher
,
T.G.
,
Early Holocene plant and animal colonization of the southern basin of glacial Lake Agassiz
,
in
Proceedings 45th Conference of the International Association of Great Lake Research
 ,
Winnipeg, Manitoba
,
2002
, p.
46
.
Zoltai
,
S.C.
,
1965
,
Glacial features of the Quetico-Nipigon area, Ontario
:
Canadian Journal of Earth Sciences
 , v.
2
, p.
247
269
,
Zoltai
,
S.C.
,
1967
,
Easter outlets of Lake Agassiz
,
in
Mayer-Oakes
,
W.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
107
120
.

Figures & Tables

Figure 1.

Maximum coverage area of glacial Lake Agassiz during its ∼6000 calendar year history. OEO—older eastern outlets.

Figure 1.

Maximum coverage area of glacial Lake Agassiz during its ∼6000 calendar year history. OEO—older eastern outlets.

Figure 2.

Strandlines traced northward along the southeast corner of Lake Agassiz illustrating upwarping to the north, with older higher beaches experiencing the greatest upwarping. From Weller and Fisher (2009).

Figure 2.

Strandlines traced northward along the southeast corner of Lake Agassiz illustrating upwarping to the north, with older higher beaches experiencing the greatest upwarping. From Weller and Fisher (2009).

Figure 3.

Lake phase diagram for Lake Agassiz at the southern outlet. Modified from Fisher (2005) and Fisher et al. (2008).

Figure 3.

Lake phase diagram for Lake Agassiz at the southern outlet. Modified from Fisher (2005) and Fisher et al. (2008).

Figure 4.

Overview of the southern outlet region. Modified from Fisher (2005). H—Herman, U—Upham, T—Tintah, C—Campbell, N—Norcross, WR—White Rock, North Dakota.

Figure 4.

Overview of the southern outlet region. Modified from Fisher (2005). H—Herman, U—Upham, T—Tintah, C—Campbell, N—Norcross, WR—White Rock, North Dakota.

Figure 5.

Geomorphology of the southern outlet spillway. Modified from Kehew et al. (2009). NWO—northwestern outlet; LIS—Laurentide Ice Sheet; A—Lake Agassiz; EO—eastern outlet; SO—southern outlet; T.L.—Traverse Lake; M.L.—Mud Lake; BdS.R.—Bois de Sioux River.

Figure 5.

Geomorphology of the southern outlet spillway. Modified from Kehew et al. (2009). NWO—northwestern outlet; LIS—Laurentide Ice Sheet; A—Lake Agassiz; EO—eastern outlet; SO—southern outlet; T.L.—Traverse Lake; M.L.—Mud Lake; BdS.R.—Bois de Sioux River.

Figure 6.

LiDAR image of grooves and residual bars in the Mustinka spillway.

Figure 6.

LiDAR image of grooves and residual bars in the Mustinka spillway.

Figure 7.

Lithostratigraphic columns for two cores to bedrock from Big Stone Lake (BSL-00) and Brown’s Valley fan (BVF-99). Accelerator mass spectrometry radiocarbon ages from terrestrial woody material are shown. Modified from Fisher (2003).

Figure 7.

Lithostratigraphic columns for two cores to bedrock from Big Stone Lake (BSL-00) and Brown’s Valley fan (BVF-99). Accelerator mass spectrometry radiocarbon ages from terrestrial woody material are shown. Modified from Fisher (2003).

Figure 8.

Overview of eastern outlet channels. Large dashed arrow in southwest corner indicates original hypothesis of a Kaministikwia (Kam) spillway draining Lake Agassiz eastward. Other than small spillways associated with local lakes that are not shown, a spillway has never been found, thus the eastern outlets now refer to the Kelvin Channels further north. The Nipigon Channels drained water from the Nipigon basin into the Superior basin. Inset photograph illustrates an esker within a channel, requiring that some channels were not active during the last deglaciation, and spillway channels likely develop through repeated deglacial cycles and subglacial flooding activity. Map modified from Teller and Thorleifson (1983).

Figure 8.

Overview of eastern outlet channels. Large dashed arrow in southwest corner indicates original hypothesis of a Kaministikwia (Kam) spillway draining Lake Agassiz eastward. Other than small spillways associated with local lakes that are not shown, a spillway has never been found, thus the eastern outlets now refer to the Kelvin Channels further north. The Nipigon Channels drained water from the Nipigon basin into the Superior basin. Inset photograph illustrates an esker within a channel, requiring that some channels were not active during the last deglaciation, and spillway channels likely develop through repeated deglacial cycles and subglacial flooding activity. Map modified from Teller and Thorleifson (1983).

Figure 9.

Location map of field stops for Friday.

Figure 9.

Location map of field stops for Friday.

Figure A.

Location of Lake Agassiz deposits in North Fargo.

Figure A.

Location of Lake Agassiz deposits in North Fargo.

Figure B.

Contact between the Sherack and Poplar River Formations of Lake Agassiz.

Figure B.

Contact between the Sherack and Poplar River Formations of Lake Agassiz.

Figure 10.

Digital elevation model of strandlines of Lake Agassiz west of Fargo. Modified from Lepper et al. (2011).

Figure 10.

Digital elevation model of strandlines of Lake Agassiz west of Fargo. Modified from Lepper et al. (2011).

Figure 11.

LiDAR digital elevation model of strandlines along the Wheat-land transect. Modified from Lepper et al. (2011).

Figure 11.

LiDAR digital elevation model of strandlines along the Wheat-land transect. Modified from Lepper et al. (2011).

Figure 12.

Northern half of the morning’s field trip route.

Figure 12.

Northern half of the morning’s field trip route.

Figure 13.

LiDAR hillshade of strandlines northwest of the spillway.

Figure 13.

LiDAR hillshade of strandlines northwest of the spillway.

Figure 14.

Cores in and associated with the Upham double spit. Modified from Fisher (2005).

Figure 14.

Cores in and associated with the Upham double spit. Modified from Fisher (2005).

Figure 15.

Historical photograph (1934) from the Wheaton Historical Society of a family having a picnic on the floor of Traverse Lake.

Figure 15.

Historical photograph (1934) from the Wheaton Historical Society of a family having a picnic on the floor of Traverse Lake.

Figure 16.

Residual bars and grooves in the Mustinka Spillway.

Figure 16.

Residual bars and grooves in the Mustinka Spillway.

Figure 17.

Location map for the last three field stops.

Figure 17.

Location map for the last three field stops.

TABLE 1.

NAMED BEACHES AND ELEVATION ADJACENT TO THE SOUTHERN OUTLET

BeachElevation
Milnor1090’ (332 m)
Herman1065’ (325 m)
Norcross1040’(317 m)
Tintah1000’ (305 m)
Campbell980’(299 m)
BeachElevation
Milnor1090’ (332 m)
Herman1065’ (325 m)
Norcross1040’(317 m)
Tintah1000’ (305 m)
Campbell980’(299 m)
TABLE 2.

PUBLISHED OPTICALLY STIMULATED LUMINESCENCE (OSL) AGES FOR AGASSIZ BEACHES

StrandlineField and Lab #Age (ka)Uncertainty(ka)Reference
HermanKL0505, 0506613.9 ± 0.31.3Lepper et al. (2007)
*HermanKG0504 (vfsand)14.3 ± 0.21.3Lepper et al. (2011)
*HermanKG0504 (fsand)14.1 ± 0.21.3Lepper et al. (2011)
HermanKL090114.0 ± 0.31.2Lepper and Sager (2010)
NorcrossKL050713.7 ± 0.31.4Lepper et al. (2007)
*NorcrossKG0503 (vfsand)13.6 ± 0.31.3Lepper et al. (2011)
UphamKL0508, 0601, 060213.5 ± 0.51.4Lepper et al. (2007)
*Upham?KL1004 (vfsand)13.6 ± 0.21.1Lepper et al. (2011)
*Upham?KL1004 (fsand)13.4 ± 0.31.1Lepper et al. (2011)
*CampbellKG0505 (fsand)10.0 ± 0.20.9Lepper et al. (2011)
*CampbellKG0505 (vfsand)10.3 ± 0.20.9Lepper et al. (2011)
**OjataKL060310.9 ± 0.31.2Fisher et al. (2008)
**OjataKL060411.1 ± 0.31.2Fisher et al. (2008)
StrandlineField and Lab #Age (ka)Uncertainty(ka)Reference
HermanKL0505, 0506613.9 ± 0.31.3Lepper et al. (2007)
*HermanKG0504 (vfsand)14.3 ± 0.21.3Lepper et al. (2011)
*HermanKG0504 (fsand)14.1 ± 0.21.3Lepper et al. (2011)
HermanKL090114.0 ± 0.31.2Lepper and Sager (2010)
NorcrossKL050713.7 ± 0.31.4Lepper et al. (2007)
*NorcrossKG0503 (vfsand)13.6 ± 0.31.3Lepper et al. (2011)
UphamKL0508, 0601, 060213.5 ± 0.51.4Lepper et al. (2007)
*Upham?KL1004 (vfsand)13.6 ± 0.21.1Lepper et al. (2011)
*Upham?KL1004 (fsand)13.4 ± 0.31.1Lepper et al. (2011)
*CampbellKG0505 (fsand)10.0 ± 0.20.9Lepper et al. (2011)
*CampbellKG0505 (vfsand)10.3 ± 0.20.9Lepper et al. (2011)
**OjataKL060310.9 ± 0.31.2Fisher et al. (2008)
**OjataKL060411.1 ± 0.31.2Fisher et al. (2008)
*

Wheatland transect.

**

Redwood Loop site (drowned beach).

TABLE 3.

AGES ON MOORHEAD LOW WATER PHASE ORGANICS IN THE FARGO-MOORHEAD AREA

AuthorSite14C ageCalendar ages1Type
Arnold and Libby (1951)Moorhead Water Treatment11298 ± 70012374–14048solid carbon
Rubin and Alexander (1958)Moorhead Water Treatment9930 ± 28011089–11992standard
McAndrews (1967)Seminary9900 ± 40011050–1203standard
Yansa and Ashworth (2005)Trollwood10230 ± 8011802–12090AMS
Yansa and Ashworth (2005)Trollwood10040 ± 12011315–11768AMS
Yansa and Ashworth (2005)Trollwood9920 ± 6011235–11402AMS
Rock (2009)Moorhead 28th Street9737 ± 5311137–11226AMS
Rock (2009)Moorhead 28th Street9911 ± 6811226–11403AMS
Rock (2009)Moorhead 28th Street9872 ± 5611218–11322AMS
Rock (2009)Moorhead 28th Street9952 ± 10411245–11504AMS
Rock (2009)Fargo-UPC9885 ± 9811205–11408AMS
Rock (2009)Fargo-UPC10011 ± 3511392–11505AMS
Rock (2009)Fargo-UPC9953 ± 7211251–11410AMS
Rock (2009)Fargo-UPC9849 ± 5711206–11287AMS
AuthorSite14C ageCalendar ages1Type
Arnold and Libby (1951)Moorhead Water Treatment11298 ± 70012374–14048solid carbon
Rubin and Alexander (1958)Moorhead Water Treatment9930 ± 28011089–11992standard
McAndrews (1967)Seminary9900 ± 40011050–1203standard
Yansa and Ashworth (2005)Trollwood10230 ± 8011802–12090AMS
Yansa and Ashworth (2005)Trollwood10040 ± 12011315–11768AMS
Yansa and Ashworth (2005)Trollwood9920 ± 6011235–11402AMS
Rock (2009)Moorhead 28th Street9737 ± 5311137–11226AMS
Rock (2009)Moorhead 28th Street9911 ± 6811226–11403AMS
Rock (2009)Moorhead 28th Street9872 ± 5611218–11322AMS
Rock (2009)Moorhead 28th Street9952 ± 10411245–11504AMS
Rock (2009)Fargo-UPC9885 ± 9811205–11408AMS
Rock (2009)Fargo-UPC10011 ± 3511392–11505AMS
Rock (2009)Fargo-UPC9953 ± 7211251–11410AMS
Rock (2009)Fargo-UPC9849 ± 5711206–11287AMS
1

Using CALIB 6 Stuiver et al. (1998) and the Reimer et al. (2009) dataset. AMS—accelerator mass spectrometry.

Contents

References

References Cited

Aharon
,
P.
,
2003
,
Meltwater flooding events in the Gulf of Mexico revisted: Implications for rapid climate changes during the last deglaciation
:
Pale-oceanography
 , v.
18
, no.
4
, p.
1079
,
Arndt
,
B.M.
,
1977
,
Stratigraphy of offshore sediment of Lake Agassiz
:
North Dakota Geological Survey Report of Investigations
 , v.
60
, p.
1
58
.
Arnold
,
J.R.
Libby
,
W.F.
,
1951
,
Radiocarbon dates
:
Science
 , v.
113
, p.
111
120
,
Bajc
,
A.F.
Schwert
,
D.P.
Warner
,
B.G.
Williams
,
N.E.
,
2000
,
A reconstruction of Moorhead and Emerson phase environments along the eastern margin of glacial Lake Agassiz, Rainy River basin, northwestern Ontario
:
Canadian Journal of Earth Sciences
 , v.
37
, p.
1335
1353
,
Baker
,
C.H.
,
1966
,
The Milnor channel, an ice-marginal course of the Sheyenne River, North Dakota
:
U.S. Geological Survey Professional Paper
 , v.
550B
, p.
77
79
.
Becker
,
W.M.
,
1995
,
Reconstruction of late glacial discharges in the upper Mississippi Valley
[
Unpublished M.Sc.
 ]:
University of Wisconsin-Madison
.
Björck
,
B.
Keister
,
C.M.
,
1983
,
The Emerson Phase of Lake Agassiz, independently registered in northwestern Minnesota and northwestern Ontario
:
Canadian Journal of Earth Sciences
 , v.
20
, p.
1536
1542
,
Blanchon
,
P.
Shaw
,
J.
,
1995
,
Reef drowning during the last deglaciation: Evidence for catastrophic sea-level rise and ice-sheet collapse
:
Geology
 , v.
23
, no.
1
, p.
4
8
,
Broecker
,
W.S.
Kennett
,
J.
Flower
,
B.
Teller
,
J.
Trumbore
,
S.
Bonani
,
G.
Wolfli
,
W.
,
1989
,
Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode
:
Nature
 , v.
341
, p.
318
321
,
Brophy
,
J.A.
Bluemle
,
J.P.
,
1983
,
The Sheyenne River; Its geological history and effects on Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Geological Association of Canada Special Paper 26
 , p.
173
186
.
Carlson
,
A.E.
Clark
,
P.U.
,
2009
,
Comment: radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns
:
Quaternary Science Reviews
 , v.
28
, p.
2546
2547
,
Clarke
,
G.
Leverington
,
D.
Teller
,
J.
Dyke
,
A.
,
2003
,
Superlakes, mega-floods, and abrupt climate change
:
Science
 , v.
301
, no.
5635
, p.
922
923
,
Elson
,
J.A.
,
1967
,
Geology of Glacial Lake Agassiz
,
in
Mayer-Oakes
,
W. J.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
37
96
.
Elson
,
J.A.
,
1983
,
Lake Agassiz – discovery and a Century of research
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Geological Association of Canada
, p.
21
42
.
Fenton
,
M.M.
Moran
,
S.R.
Teller
,
J.T.
Clayton
,
L.
,
1983
,
Quaternary stratigraphy and history in the southern part of the Lake Agassiz Basin
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Geological Association of Canada
, p.
49
74
.
Fisher
,
T.G.
,
2003
,
Chronology of glacial Lake Agassiz meltwater routed to the Gulf of Mexico
:
Quaternary Research
 , v.
59
, no.
2
, p.
271
276
,
Fisher
,
T.G.
,
2004
,
River Warren boulders: paleoflow indicators in the southern spillway of glacial Lake Agassiz
:
Boreas
 , v.
33
, p.
349
358
,
Fisher
,
T.G.
,
2005
,
Strandline analysis in the southern basin of glacial Lake Agassiz, Minnesota and North and South Dakota, USA
:
Geological Society of America Bulletin
 , v.
117
, no.
11/12
, p.
1481
1496
,
Fisher
,
T.G.
,
2007
,
Abandonment chronology of glacial Lake Agassiz’s northwestern outlet
:
Palaeogeography, Palaeoclimatology, Palaeoecology
 , v.
246
, p.
31
44
,
Fisher
,
T.G.
Lowell
,
T.V.
,
2006
,
Questioning the age of the Moorhead Phase in the glacial Lake Agassiz basin
:
Quaternary Science Reviews
 , v.
25
, p.
2688
2691
,
Fisher
,
T.G.
Smith
,
D.G.
,
1994
,
Glacial Lake Agassiz: its northwest maximum extent and outlet in Saskatchewan (Emerson phase)
:
Quaternary Science Reviews
 , v.
13
, no.
9–10
, p.
845
858
,
Fisher
,
T.G.
Souch
,
C.
,
1998
,
Northwest outlet channels of Lake Agassiz, isostatic tilting and a migrating continental drainage divide, Saskatchewan, Canada
:
Geomorphology
 , v.
25
, no.
1–2
, p.
57
73
,
Fisher
,
T.G.
Whitman
,
R.L.
,
1999
,
Deglacial and lake level fluctuation history recorded in cores, Beaver Lake, Upper Peninsula, Michigan
:
Journal of Great Lakes Research
 , v.
25
, no.
2
, p.
263
274
,
Fisher
,
T.G.
Smith
,
D.G.
Andrews
,
J.T.
,
2002
,
Preboreal oscillation caused by a glacial Lake Agassiz flood
:
Quaternary Science Reviews
 , v.
21
, no.
8–9
, p.
873
878
,
Fisher
,
T.G.
Waterson
,
N.
Lowell
,
T.V.
Hajdas
,
I.
,
2009
,
Deglaciation ages and meltwater routing in the Fort McMurray region, northeastern Alberta and northwestern Saskatchewan, Canada
:
Quaternary Science Reviews
 , v.
28
, p.
1608
1624
,
Fisher
,
T.G.
Yansa
,
C.H.
Lowell
,
T.V.
Lepper
,
K.
Hajdas
,
I.
Ashworth
,
A.C.
,
2008
,
The chronology, climate, and confusion of the Moorhead Phase of Glacial Lake Agassiz: new results from the Ojata Beach, North Dakota, U.S.A
:
Quaternary Science Reviews
 , v.
27
, p.
1124
1135
,
Fricker
,
H.A.
Scambos
,
T.A.
Bindschadler
,
R.A.
Padman
,
L.
,
2007
,
An active sublgacial water system in West Antarctica mapped from space
:
Science
 , v.
315
, p.
1544
1548
,
Gary
,
J.L.
Colman
,
S.M.
Wattrus
,
N.J.
Lewis
,
C.F.M.
,
2011
,
PostMarquette discharge from Glacial Lake Agassiz into the Superior basin
:
Journal of Paleolimnology
 ,
Harington
,
C.R.
Ashworth
,
A.C.
,
1986
,
A mammoth (Mammuthus primigenius) tooth from late Wisconsin deposits near Embden, North Dakota, and comments on the distribution of woolly mammoths south of the Wisconsin ice sheets
:
Canadian Journal of Earth Sciences
 , v.
23
, p.
909
918
,
Harris
,
K.L.
Moran
,
S.R.
Clayton
,
L.
,
1974
,
Late Quaternary stratigraphic nomenclature, Red River Valley, North Dakota and Minnesota
:
North Dakota Geological Survey Miscellaneous Series
 , v.
52
, p.
47
.
Hobbs
,
H.C.
,
1983
,
Drainage relationships of glacial Lake Atikin and Upham and early Lake Agassiz in northeastern Minnesota
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume Special Paper 26
 :
St. John’s, Newfoundland
,
The Geological Association of Canada
, p.
245
260
.
Hudak
,
C.M.
Hajic
,
E.R.
,
2002
,
Appendix E- geomorphology survey profiles, sections, and lists
,
in
Hudak
,
G. J.
Hobbs
,
E.
Brooks
,
A.
Sersland
,
C. A.
Phillips
,
C.
, eds.,
A predictive model of precontact archaeological site location for the state of Minnesota, Final Report
 :
St. Paul, Minnesota Department of Transportation.
Johnson
,
M.D.
Davis
,
D.M.
Pederson
,
J.L.
,
1998
,
Terraces of the Minnesota River Valley and the character of Glacial River Warren downcutting: Contributions to Quaternary studies in Minnesota
:
Minnesota Geological Survey Report of Investigations
 , v.
49
, p.
121
130
.
Johnston
,
W.A.
,
1946
,
Glacial Lake Agassiz, with special reference to the mode of deformation of the beaches
:
Geological Survey of Canada Bulletin
 , v.
7
, p.
20
.
Kehew
,
A.E.
,
1982
,
Catastrophic flood hypothesis for the origin of the Souris spillway, Saskatchewan and North Dakota
:
Geological Society of America Bulletin
 , v.
93
, p.
1051
1058
,
Kehew
,
A.E.
Lord
,
M.L.
,
1986
,
Origin and large-scale erosional features of glacial-lake spillways in the northern Great Plains
:
Geological Society of America Bulletin
 , v.
97
, p.
162
177
,
Kehew
,
A.E.
Lord
,
M.
Kozlowski
,
A.L.
Fisher
,
T.G.
,
2009
,
Chapter 7. Proglacial megaflooding along the margins of the Laurentide Ice Sheet
,
in
Burr
,
D.
Carling
,
P. A.
Baker
,
V. R.
, eds.,
Megaflooding on Earth and Mars
 :
New York
,
Cambridge University Press
, p.
104
127
.
Kompelian
,
M.G.
Schwert
,
D.P.
1986
,
Paleoenvironmental implications of insect remains from the Seminary site, Cass County, North Dakota
:
Proceedings of the North Dakota Academy of Sciences
 , v.
40
, p.
131
.
Lepper
,
K.
Sager
,
L.
,
2010
,
A revised age determination for the Embden, North Dakota mammoth using optically stimulated luminescence dating
:
Current Research in the Pleistocene
 , v.
27
, p.
171
173
.
Lepper
,
K.
Fisher
,
T.
Hajdas
,
I.
Lowell
,
T.
,
2007
,
Ages for the Big Stone moraine and the oldest beaches of glacial Lake Agassiz: Implications for deglaciation chronology
:
Geology
 , v.
35
, no.
7
, p.
667
670
,
Lepper
,
K.
Gorz
,
K.L.
Fisher
,
T.G.
Lowell
,
T.V.
,
2011
,
Age determinations for Lake Agassiz shorelines west of Fargo, North Dakota, U.S.A
:
Canadian Journal of Earth Sciences
 , v.
48
, p.
1199
1207
,
Leverett
,
F.
,
1932
,
Quaternary geology of Minnesota and parts of adjacent states
:
U.S. Geological Survey Professional Paper
 , v.
161
, p.
149
.
Leverington
,
D.W.
Teller
,
J.T.
,
2003
,
Paleotopographic reconstructions of the eastern outlets of glacial Lake Agassiz
:
Canadian Journal of Earth Sciences
 , v.
40
, p.
1259
1278
,
Lowell
,
T.V.
Fisher
,
T.G.
,
2009
,
Reply to comments by Carlson et al., (2009) on “Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns”
:
Quaternary Science Reviews
 , v.
28
, p.
2548
2550
,
Lowell
,
T. V.
Fisher
,
T. G.
Comer
,
G. C.
Hajdas
,
I.
Waterson
,
N.
Glover
,
K.
Loope
,
H. M.
Schaefer
,
J. M.
Rinterknecht
,
V.
Broecker
,
W. S.
Denton
,
G. H.
Teller
,
J. T.
,
2005
,
Testing the Lake Agassiz Meltwater Trigger for the Younger Dryas
:
Eos
  (
Transactions, American Geophysical Union
), v.
86
, no.
40
, p.
365
,372.
Lowell
,
T.V.
Fisher
,
T.G.
Hajdas
,
I.
Glover
,
K.
Loope
,
H.M.
Henry
,
T.
,
2009
,
Radiocarbon deglaciation chronology of the Thunder Bay, Ontario area and implications for ice sheet retreat patterns
:
Quaternary Science Reviews
 , v.
28
, p.
1597
1607
,
Mann
,
J.D.
Rayburn
,
J.A.
Teller
,
J.T.
,
1997
,
Broken Pipe Lake, Manitoba: A remnant of an Emerson Phase Lake Agassiz lagoon
:
Geological Society of America Abstracts with Programs
 , v.
29
, no.
4
, p.
57
58
.
Matsch
,
C.L.
,
1983
,
River Warren, the southern outlet to glacial Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz, Volume 26, Geological Association of Canada Special Paper 26
 , p.
231
244
.
Matsch
,
C.L.
Wright
,
H.E.
,
1967
,
The southern outlet of Lake Agassiz
,
in
Mayer-Oakes
,
W. J.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
121
140
.
Mayer-Oakes
,
W.J.
, ed.,
1967
,
Life, Land and Water
 :
University of Manitoba Press
,
Winnipeg
,
339
pp.
McAndrews
,
J.H.
,
1967
,
Paleoecology of the Seminary and Mirror Pool peat deposits
,
in
Elson
,
J. A.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
253
269
.
Mooers
,
H.D.
Wiele
,
S.
,
1989
,
Glacial Lake Agassiz: glacial surges and large outflow events
,
in
Proceedings Geological Survey of America, annual meeting
 ,
St. Louis, MO
,
1989
, Volume
21
, p.
A54
.
Patterson
,
C.J.
Boerboom
,
T.J.
,
1999
,
The significance of pre-existing, deeply weathered crystalline rock in interpreting the effects of glaciation in the Minnesota River valley, U.S.A
:
Annals of Glaciology
 , v.
28
, p.
53
58
,
Patterson
,
C.J.
Knaeble
,
A.R.
Gran
,
S.E.
Phippen
,
S.
,
1999
,
Regional hydro-geologic assessment of the upper Minnesota River basin
,
St. Paul, Minnesota
:
Minnesota Geological Survey, RHA-4
 ,
Part A, Plate 1, scale 1:100,000.
Rayburn
,
J.A.
,
1997
,
Correlation of the Campbell strandlines along the northwestern margin of Glacial Lake Agassiz
[
M.Sc. thesis
 ]:
University of Manitoba
,
189
p.
Rayburn
,
J.A.
Teller
,
J.T.
,
2007
,
Isostatic rebound in the northwestern part of the Lake Agassiz basin: Isobase changes and overflow
:
Palaeogeography, Palaeoclimatology, Palaeoecology
 , v.
246
, p.
23
30
,
Reimer
,
P.J.
Baillie
,
M.G.L.
Bard
,
E.
Bayliss
,
A.
Beck
,
J.W.
Blackwell
,
P.G.
Ramsey
,
Bronk C.
Buck
,
C.E.
Burr
,
G.S.
Edwards
,
R.L.
Friedrich
,
M.
Grootes
,
P.M.
Guilderson
,
T.P.
Hajdas
,
I.
Heaton
,
T.J.
Hogg
,
A.G.
Hughen
,
K.A.
Kaiser
,
K.F.
Kromer
,
B.
McCormac
,
F.G.
Manning
,
S.W.
Reimer
,
R.W.
Richards
,
D.A.
Southon
,
J.R.
Talamo
,
S.
Turney
,
C.S.M.
van der Plicht
,
J.
Weyhenmeyer
,
C.E.
,
2009
,
IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0–50,000 Years cal BP
:
Radiocarbon
 , v.
51
, p.
1111
1150
.
Risberg
,
J.
Matile
,
G.
Teller
,
J.T.
,
1995
,
Lake Agassiz water level changes as recorded by sediments and their diatoms in a core from southeastern Manitoba, Canada
:
Pact
 , v.
50
, p.
85
96
.
Rock
,
J.L.
,
2009
,
Paleoclimatic interpretation of the Moorhead Low Water Phase of Lake Agassiz in the southern basin based on fossil Coleoptera assemblages
[
MS Dissertation
 :
North Dakota State University
,
123
p.
Rosendahl
,
C. O.
,
1948
,
A contribution to the knowledge of the Pleistocene flora of Minnesota
:
Ecology
 , v.
29
, no.
3
, p.
284
315
.
Rubin
,
M.
Alexander
,
C.
,
1958
,
U.S. Geological Survey radiocarbon dates IV
:
Science
 , v.
127
, p.
1476
1487
,
Saarnisto
,
M.
,
1974
,
The deglaciation history of the Lake Superior region and its climatic implications
:
Quaternary Research
 , v.
4
, p.
316
339
,
Shaw
,
J.
,
1989
,
Drumlins, subglacial meltwater floods, and ocean responses
:
Geology
 , v.
17
, p.
853
856
,
Smith
,
D.G.
Fisher
,
T.G.
,
1993
,
Glacial Lake Agassiz: The northwestern outlet and paleoflood
:
Geology
 , v.
21
, p.
9
12
,
Stuiver
,
M.
Reimer
,
P.J.
Braziunas
,
T.F.
,
1998
,
High-precision radiocarbon age calibration for terrestrial and marine samples
:
Radiocarbon
 , v.
40
, no.
3
, p.
1127
1151
.
Teller
,
J.T.
,
2001
,
Formation of large beaches in an area of rapid differential isostatic rebound: the three-outlet control of Lake Agassiz
:
Quaternary Science Reviews
 , v.
20
, p.
1649
1659
,
Teller
,
J.T.
Clayton
,
L.
,
1983
,
Glacial Lake Agassiz
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz
 , Volume
26
,
The Geological Association of Canada Special Paper
, p.
451
.
Teller
,
J.T.
Thorleifson
,
L.H.
,
1983
,
The Lake Agassiz-Lake Superior connection
,
in
Teller
,
J. T.
Clayton
,
L.
, eds.,
Glacial Lake Agassiz
 ,
Volume Special Paper
26
,
The Geological Association of Canada
, p.
261
290
.
Teller
,
J.T.
Kehew
,
A.E.
,
1994
,
Introduction to the late glacial history of large proglacial lakes and meltwater runoff along the Laurentide Ice Sheet
:
Quaternary Science Reviews
 , v.
13
, no.
9–10
, p.
795
799
,
Teller
,
J.T.
Leverington
,
D.W.
,
2004
,
Glacial Lake Agassiz: A 5000 yr history of change and its relationship to the 180 record of Greenland
:
Geological Society of America Bulletin
 , v.
116
, no.
5/6
, p.
729
742
,
Teller
,
J.T.
Risberg
,
J.
Matile
,
G.
Zoltai
,
S.
,
2000
,
Postglacial history and paleoecology of Wampum, Manitoba, a former lagoon in the Lake Agassiz basin
:
Geological Society of America Bulletin
 , v.
112
, no.
6
, p.
943
958
,
Teller
,
J.T.
Boyd
,
M.
Yang
,
Z.
Kor
,
P.S.G.
Fard
,
Mokhtari A.
,
2005
,
Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates, paleotopography, and a reevaluation
:
Quaternary Science Reviews
 , v.
24
, p.
1890
1905
,
Thorleifson
,
L.H.
,
1983
,
The eastern outlets of Lake Agassiz [M.Sc.]
 :
University of Manitoba
.
Thorleifson
,
L.H.
,
1996
,
Review of Lake Agassiz history
,
in
Teller
,
J. T.
Thorleifson
,
L. H.
Matile
,
G.
Brisbin
,
W. C.
, eds.,
Sedimentology, Geomorphology and History of the Central Lake Agassiz Basin, Volume Field Trip B2, Geological Association of Canada Field Trip Guidebook for GAC/MAC Joint Annual Meeting
 , p.
55
84
.
Upham
,
W.
,
1895
,
The Glacial Lake Agassiz
 :
U.S. Geological Survey
,
v. Monograph 25
, p.
685
.
Weller
,
M.B.
Fisher
,
T.G.
,
2009
,
Feasibility study of mapping continuous strandlines along the southeast Lake Agassiz basin
:
Journal of Maps
 , v.
2009
, p.
152
165
.
Wiele
,
S.
Mooers
,
H.D.
,
1989
,
Glacial Lake Agassiz: glacial surges and large outflow events, in Proceedings
:
Geological Society of America Abstracts with Programs
 , v.
21
, p.
54
.
Yansa
,
C.H.
Ashworth
,
A.C.
,
2005
,
Late Pleistocene palaeoenvironment of the southern Lake Agassiz Basin, USA
:
Journal of Quaternary Science
 , v.
20
, p.
255
267
,
Yansa
,
C.J.
Ashworth
,
A.C.
Fisher
,
T.G.
,
Early Holocene plant and animal colonization of the southern basin of glacial Lake Agassiz
,
in
Proceedings 45th Conference of the International Association of Great Lake Research
 ,
Winnipeg, Manitoba
,
2002
, p.
46
.
Zoltai
,
S.C.
,
1965
,
Glacial features of the Quetico-Nipigon area, Ontario
:
Canadian Journal of Earth Sciences
 , v.
2
, p.
247
269
,
Zoltai
,
S.C.
,
1967
,
Easter outlets of Lake Agassiz
,
in
Mayer-Oakes
,
W.
, ed.,
Life, Land and Water
 :
Winnipeg
,
University of Manitoba Press
, p.
107
120
.

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal