Abstract The Sauk megasequence in the far inboard region of the cratonic interior of North America (Minnesota, Wisconsin, and Iowa) is divisible into two packages that fundamentally differ from one another in facies and stratigraphic attributes. A lower Sauk succession package, Marjuman–early Skullrockian in age, is characterized by deposits of the traditional inner detrital belt (IDB) that interfinger hundreds of kilometers seaward with the middle carbonate belt or cratonward margin of the central mid-continent great American carbonate bank (GACB). The IDB contains a typical suite of nearshore siliciclastic facies containing features that document the importance of both wave- and tide-dominated currents in the depositional system. The transitional area between the IDB and the GACB in the Cambrian and earliest Ordovician was a moat, characterized by relatively deep-water deposition, which served as a catchment for mud that was winnowed from landward parts of the shelf and then deposited near the stormwave base. Mixed carbonate and siliciclastic facies in the moat are characterized by condensation features and other attributes indicative of suppressed carbonate productivity and starvation of siliciclastic sand. These facies contrast with shallower water facies that commonly filled available accommodation space in both seaward (central part of the GACB) and landward (cratonic shoreline) directions, the former dominated by typical stacks of oolitic, ribbon-rock, and microbialite lithofacies, and the latter by stacks of nearshore siliciclastic sand-dominated parasequences. Our chronostratigraphic framework provides temporal constraints that support the long-postulated hypothesis that these two depositional systems expanded and contracted in reciprocating fashion: substantial landward migration and expansion of the GACB occurred when siliciclastic input was diminished during the most rapid rates of transgression (marked by maximum flooding intervals in the IDB). Retreat and diminishment in the extent of the GACB corresponded to falls in sea level that led to major progradations of nearshore siliciclastics of the IDB and terrigenous poisoning of the carbonate factory. An overlying upper Sauk succession package records the establishment of a fundamentally different depositional system in the far inboard regions of the cratonic interior beginning in the later Skullrockian. The Prairie du Chien Group and its equivalents represent a major landward migration and perhaps cratonwide distribution of the oolitic, ribbon-rock, and micro-bialite lithofacies that were previously restricted mostly to the GACB of Missouri and adjacent areas. This change was triggered by a pronounced continental-scale flooding event that led to onlap across much, or all, of the cratonic interior. The resultant burial of terrigenous source regions by carbonate strata is in part responsible for this fundamental change in de-positional conditions.

ABSTRACT Red Wing, Minnesota, is located in the upper Mississippi River valley near the northern margin of the Driftless Area, a portion of southeast Minnesota and western Wisconsin that was not glaciated in the late Quaternary characterized by river valleys deeply dissected through a sequence of Paleozoic sediments. River terraces are prominent in the field trip area. These terraces developed in two steps. Glacial outwash filled the valleys in the late Quaternary, followed by at least two pulses of incision associated with meltwater drainage from large glacial lakes to the north, including glacial Lake Agassiz. Following the last pulse of meltwater incision, tributary streams built sediment fans in the valley floor which the post-glacial Mississippi River was not able to erode. As a result, large lakes—including Lake Pepin—developed in the valley bottom. Lake Pepin has subsequently shrunk by delta progradation from the north. Evidence of Native American habitation in the area extends to Paleoindian time (ca. 11 ka B.P. calendar), but there is limited evidence of large, horticultural populations until A.D. 700. This timing coincides with the advance of the Lake Pepin delta front from St. Paul south to the Red Wing area. Large village sites were strategically placed on terraces above the Mississippi. Recent application of LiDAR (light detection and ranging) and resistivity surveys have aided ongoing archaeological investigations in the Red Wing area. Burial mound groups are visible in airborne LiDAR elevation data, and resistivity surveys have revealed evidence of an extensive village at the Silvernale site.

ABSTRACT This field trip guide presents a summary of the Paleozoic bedrock geology of the Twin Cities (Minneapolis and St. Paul) region as well as an introduction to the Quaternary depositional and erosional history of the Twin Cities area, focusing on the carving of the Mississippi River gorge by glacial River Warren. Within this geological context, the philosophy behind a variety of pedagogical techniques is discussed, together with student learning goals, opportunities, and objectives for each locality.

ABSTRACT The Driftless Area is a region of roughly 22,000 km 2 almost entirely in southwestern Wisconsin and adjacent northwestern Illinois that contains no evidence for glaciation during the Quaternary. Both in terms of topography and geomorphic process, it stands in stark contrast to the surrounding glaciated landscapes of the Midwestern United States. The nearly flat-lying Paleozoic sedimentary rocks in the region are deeply incised by the dendritic drainage system of the upper Mississippi and lower Wisconsin Rivers and numerous of their tributaries. Records of geologic processes that predate the Quaternary glaciations are exposed at the near-surface. The landscape is blanketed by loess of the Kieler Formation and was affected by mass wasting and a range of periglacial processes that were pervasive during permafrost conditions that existed between 33 and 14 ka. Post-glacial fluvial systems preserve myriad examples of channel adjustment to changes in sediment supply from the transition of glacial to interglacial conditions, changes in discharge across periods of Holocene climate change, and responses to Euro-American settlement of the landscape.