Abstract The Maltese Islands lie in the middle of the tsunamigenic Mediterranean domain, around whose margins and islands evidence of historical tsunami landfall has been increasingly recognized in recent years. Critical review of historical evidence of events in 1693 and 1908 indicates extremely modest tsunami impacts. In marked contrast, though, recently discovered geomorphological evidence summarized herein suggests that Malta’s coastlines have been overwashed up to elevations of >20 m above sea level by an exceptional event. A new perspective is provided by a review of the central Mediterranean context within which the Maltese evidence is located. Recent advances in understanding the Holocene sequence forming the floor of the Mediterranean Sea present a new stratigraphic and temporal framework within which to elucidate tsunami history. Within 100 km of Malta, terrestrial stratigraphy on Sicily also provides supporting evidence of tsunami impact. Review of these advances suggests that the exceptional event required to emplace the most extreme sedimentary and geomorphological signatures on and around Malta is likely to have had a far-field origin. The currently available circumstantial evidence points strongly towards a probability that the AD 365 earthquake and tsunami were responsible. This, in turn, enables critical reassessment of the exposure of Malta to tsunami hazard.

Abstract Detailed geologic mapping and new SHRIMP (sensitive high-resolution ion microprobe) U-Pb zircon, Ar/Ar, Lu-Hf, 14 C, luminescence (optically stimulated), thermochronology (fission-track), and palynology reveal the complex Mesoproterozoic to Quaternary geology along the ~350 km length of the Blue Ridge Parkway in Virginia. Traversing the boundary of the central and southern Appalachians, rocks along the parkway showcase the transition from the para-autochthonous Blue Ridge anticlinorium of northern and central Virginia to the allochthonous eastern Blue Ridge in southern Virginia. From mile post (MP) 0 near Waynesboro, Virginia, to ~MP 124 at Roanoke, the parkway crosses the unconformable to faulted boundary between Mesoproterozoic basement in the core of the Blue Ridge anticlinorium and Neoproterozoic to Cambrian metasedimentary and metavolcanic cover rocks on the western limb of the structure. Mesoproterozoic basement rocks comprise two groups based on SHRIMP U-Pb zircon geochronology: Group I rocks (1.2-1.14 Ga) are strongly foliated orthogneisses, and Group II rocks (1.08-1.00 Ga) are granitoids that mostly lack obvious Mesoproterozoic deformational features. Neoproterozoic to Cambrian cover rocks on the west limb of the anticlinorium include the Swift Run and Catoctin Formations, and constituent formations of the Chilhowee Group. These rocks unconformably overlie basement, or abut basement along steep reverse faults. Rocks of the Chilhowee Group are juxtaposed against Cambrian rocks of the Valley and Ridge province along southeast- and northwest-dipping, high-angle reverse faults. South of the James River (MP 64), Chilhowee Group and basement rocks occupy the hanging wall of the nearly flat-lying Blue Ridge thrust fault and associated splays. South of the Red Valley high-strain zone (MP 144.5), the parkway crosses into the wholly allochthonous eastern Blue Ridge, comprising metasedimentary and meta-igneous rocks assigned to the Wills Ridge, Ashe, and Alligator Back Formations. These rocks are bound by numerous faults, including the Rock Castle Creek fault that separates Ashe Formation rocks from Alligator Back Formation rocks in the core of the Ararat River synclinorium. The lack of unequivocal paleontologic or geochronologic ages for any of these rock sequences, combined with fundamental and conflicting differences in tectonogenetic models, compound the problem of regional correlation with Blue Ridge cover rocks to the north. The geologic transition from the central to southern Appalachians is also marked by a profound change in landscape and surficial deposits. In central Virginia, the Blue Ridge consists of narrow ridges that are held up by resistant but contrasting basement and cover lithologies. These ridges have shed eroded material from their crests to the base of the mountain fronts in the form of talus slopes, debris flows, and alluvial-colluvial fans for perhaps 10 m.y. South of Roanoke, however, ridges transition into a broad hilly plateau, flanked on the east by the Blue Ridge escarpment and the eastern Continental Divide. Here, deposits of rounded pebbles, cobbles, and boulders preserve remnants of ancestral west-flowing drainage systems. Both bedrock and surficial geologic processes provide an array of economic deposits along the length of the Blue Ridge Parkway corridor in Virginia, including base and precious metals and industrial minerals. However, common stone was the most important commodity for creating the Blue Ridge Parkway, which yielded building stone for overlooks and tunnels, or crushed stone for road base and pavement.

Abstract The siege of Petersburg and Richmond during the American Civil War in 1864–1865 provides a stellar example of how geology can affect military operations and thus the course of history. During the Union drive to take the Confederate capital, they used Virginia’s broad tidal rivers on the Atlantic Coastal Plain as supply lines for their huge army. During the siege, both sides took advantage of the unconsolidated Cenozoic sediments of the Coastal Plain to create a new style of combat—trench warfare—which would be taken to horrifying extremes in World War I. This trip visits seven sites of both historic and geological significance in the Petersburg area.

ABSTRACT Seattle’s geologic record begins with Eocene deposition of fluvial arkosic sandstone and associated volcanic rocks of the Puget Group, perhaps during a time of regional strike-slip faulting, followed by late Eocene and Oligocene marine deposition of the Blakeley Formation in the Cascadia forearc. Older Quaternary deposits are locally exposed. Most of the city is underlain by up to 100 m of glacial drift deposited during the Vashon stade of Fraser glaciation, 18–15 cal k.y. B.P. Vashon Drift includes lacustrine clay and silt of the Lawton Clay, lacustrine and fluvial sand of the Esperance Sand, and concrete-like Vashon till. Mappable till is absent over much of the area of the Vashon Drift. Peak local ice thickness was 900 m. Isostatic response to this brief ice loading was significant. Upon deglaciation, global ice-equivalent sea level was about −100 m and local RSL (relative sea level) was 15–20 m, suggesting a total isostatic depression of ~115–120 m at Seattle. Subsequent rapid rebound outstripped global sea-level rise to result in a newly recognized marine low-stand shoreline at −50 m. The Seattle fault is a north-verging thrust or reverse fault with ~7.5 km of throw. Conglomeratic Miocene strata may record initiation of shortening. Field relations indicate that fault geometry has evolved through three phases. At present, the north-verging master fault is blind, whereas several surface-rupturing faults above the master fault are south verging. The 900–930 A.D. Restoration Point earthquake raised a 5 km × 35 km (or larger) area as much as 7 m. The marine low-stand shoreline is offset by a similar amount, thus there has been only one such earthquake in the last ~11 k.y. Geomorphology is largely glacial: an outwash plain decorated with ice-molded flutes and large, anastomosing tunnel valleys carved by water flowing beneath the ice sheet. Euro-Americans initially settled here because of landscape features formed by uplift in the Restoration Point earthquake. But steep slopes and tide flats were not conducive to commerce: starting in the 1890s and ending in the 1920s, extensive regrading removed hills, decreased slopes, and filled low areas. In steep slopes the glacial stratigraphy is prone to landslides when saturated by unusually wet winters. Seismic hazards comprise moderately large (M 7) earthquakes in the Benioff zone 50 km and more beneath the city, demi-millennial M 9 events on the subduction zone to the west, and infrequent local crustal earthquakes (M 7) that are likely to be devastating because of their proximity. Seismic shaking and consequent liquefaction are of particular concern in Pioneer Square, SoDo, and lower Duwamish neighborhoods, which are largely built on unengineered fill that was placed over estuarine mud. Debris from past Mount Rainier lahars has reached the lower Duwamish valley and a future large lahar could pose a sedimentation hazard.

Out-of-sequence thrust faulting in the Himalaya poses a great challenge to our understanding of the slip distribution on faults, in particular those that are active. The Kashmir Basin in the NW Himalaya is a classic example of out-of-sequence faulting where the geomorphic analysis of tectonic landforms was possible because of a variety of readily available satellite data, including Shuttle Radar Topography, Google Maps, Global Earth, and Global Multi-Resolution Topography. This was augmented with geologic, seismologic, geodetic, and historical earthquake and flood data. The results show the NW extension of the previously mapped SE-dipping Kashmir Basin fault, where newly mapped discontinuous fault traces are freshly broken and back-tilted, and they preserve warped fluvial surfaces in the Quaternary to Holocene succession. The morphology of the basin suggests that it is rising along an active NE-dipping thrust fault. Importantly, two traces of this fault system cut through the course of the Jhelum River, the only river that drains the Kashmir Basin, and movement on the fault has modified its path. Recent movement on the fault potentially caused damming of this river that resulted in flooding of the Kashmir valley during major earthquakes around A.D. 1505 and/or 1886. Such movement likely caused historical drainage reversals, impoundments, and SE tilting, which were previously attributed to some unknown structures under the Pir Panjal Ranges.

Abstract The Channeled Scabland of east-central Washington comprises a complex of anastomosing fluvial channels that were eroded by Pleistocene megaflooding into the basalt bedrock and overlying sediments of the Columbia Plateau and Columbia Basin regions of eastern Washington State, U.S.A. The cataclysmic flooding produced huge coulees (dry river courses), cataracts, streamlined loess hills, rock basins, butte-and-basin scabland, potholes, inner channels, broad gravel deposits, and immense gravel bars. Giant current ripples (fluvial dunes) developed in the coarse gravel bedload. In the 1920s, J Harlen Bretz established the cataclysmic flooding origin for the Channeled Scabland, and Joseph Thomas Pardee subsequently demonstrated that the megaflooding derived from the margins of the Cordilleran Ice Sheet, notably from ice-dammed glacial Lake Missoula, which had formed in western Montana and northern Idaho. More recent research, to be discussed on this field trip, has revealed the complexity of megaflooding and the details of its history. To understand the scabland one has to throw away textbook treatments of river work. —J. Hoover Mackin, as quoted in Bretz et al. (1956, p. 960)

Abstract The western Snake River Plain (SRP) is a southeast-northwest–trending complex graben bounded on the SW by the Owyhee Front. This graben, which merges with the central SRP at its southeast end near Bruneau Canyon, is a subsidiary tectonic feature that resulted from southwest-northeast extension as the main SRP–Yellowstone hotspot trend evolved. Silicic volcanism during the late Miocene along the Owyhee Front and in the central SRP resulted in large welded-tuff and rhyolite lava flows being erupted; these are well exposed southwest of the western Snake River Plain (WSRP) and in the western Mount Bennett Hills, northeast of where the western and central SRP merge. As the WSRP graben developed, it held a large lake, into which some of the rhyolite units flowed. At various stops described in this field guide, the characteristics of rhyolite lavas versus rheomorphically deformed welded tuffs, and of subaerially deposited versus subaqueously deposited rhyolite units, are displayed. During Pliocene and Pleistocene time, basaltic volcanism partially filled the WSRP graben and developed a basalt plateau across much of the central SRP. At various stops described in this field guide, the characteristics of subaerial versus subaqueous basalt flows, and of phreatomagmatic vent complexes, are displayed. Altogether, the stops described provide a guide to the wide variety of rhyolitic and basaltic volcanism phenomena in the western SRP, Owhyee Front, western Mount Bennett Hills, and Bruneau Canyon areas.

Abstract The surficial geology of the Baraboo area is very important because it includes the transition from a glaciated region to the Driftless Area. The eastern portion of this area was glaciated as part of the Green Bay lobe of the ice sheet in this area. The terminal moraine is present and is characterized by sandy till. No valid information that substantiates glacial activity exists west of the city of Baraboo. The Driftless Area includes a site of the earliest Wisconsin habitation.

Abstract This road log is different than most in a variety of ways. It is similar in that the stops are numbered in a certain order. That is because each stop must have some identification and numbers are the simplest and easiest to follow. Mileage is provided between stops, not in a cumulative fashion. This makes it easy to arrange the stops to suit the specific leader(s) and students. Those who use this field guide can choose to visit the stops in any order that they wish. The complete trip is designed to take two full field days, but stops can be visited in any fashion that suits the wishes and schedule of the group. There are a few alternate stops that may be used in addition to or in lieu of some of the regular stops. The estimated time necessary to spend at each stop is indicated in the log to help in organizing your trip. The total estimated time of the combined stops is ~12–14 hours. This does not include any travel time or lunch stops so that leaders can develop their own plans. Unless indicated in the figure caption, all figures herein are those of the co-authors. The trip starts at the intersection of Wisconsin Highway 33 with Interstates I-90 and I-94 (Appendix Figure A1.) Enjoy!

Caves were and continue to be highly charged and sacred places for the Maya of Mexico and northern Central America. Viewed as the homes of gods, spirits, and ancestors as well as living beings themselves, they were the sites of regular ritual activities including the burning and caching of offerings. Caves defined and even at times provided the names for communities. They were often incorporated into the layout of cities, and the ancient elite associated themselves with caves through proximity, as well as representations in iconography and architecture in order to reinforce their political power. Archaeologists, historians, and ethnographers conduct research in caves for a variety of reasons. They are essential places for the study of Maya ritual and religion, but the paraphernalia left behind from ceremonial events can also be used to answer questions related to the economy, changing political systems, land tenure, and responses to drought and other environmental changes. Nevertheless, they continue to be important places for the contemporary inhabitants of the region, and, therefore, it is necessary to collaborate with neighboring groups when planning and conducting speleological research.

Poljes are distinctive features of Mediterranean karst landscapes, but their Pleistocene sedimentary fills have not been widely investigated. Most previous research has focused on their formation and hydrology. Many Mediterranean poljes are situated downstream of high mountains that were glaciated during the cold stages of the Pleistocene, so that meltwater streams delivered glacially derived sediment into these basins. This study examines the Pleistocene alluvial records in karst poljes surrounding Mount Orjen in western Montenegro and explores their wider significance. There is a record of at least four glaciations preserved on Mount Orjen—two from the Middle Pleistocene (marine isotope stages [MIS] 12 and 6) and two from the last cold stage (MIS 5d-2), including the Younger Dryas. Detailed sedimentological analysis and uranium-series dating indicate that the Orjen poljes were filled with thick deposits of coarse- and fine-grained alluvium prior to 350 ka, during the major glacial phase of MIS 12. During the cold stages that followed MIS 12, ice was less extensive and limited to the Orjen plateau, and there is little evidence of outwash deposition during these later glaciations. Surface runoff and sediment supply were greatly reduced after MIS 12 and largely channeled into the subterranean karst network. The poljes around Orjen contain some of the best-preserved records of Middle Pleistocene glacial outwash in the Mediterranean, representing an important legacy of an extensive Middle Pleistocene glaciation for which wider impacts have not been fully appreciated.

Abstract Glacial Lake Missoula was repeatedly dammed by the Purcell Trench Lobe of the Cordilleran ice sheet during the last glaciation to maximum altitudes near 4200 ft (1280 m). Studies from outside of the lake basin suggest that the lake filled and drained multiple times in the late Pleistocene. Deposits and landforms within the former glacial lake basin provide evidence for a complex lake-level history that is not well understood for this famous impoundment. At least two general lake phases are evident in the stratigraphy: an earlier phase of catastrophic drainage that was responsible for large-scale dramatic erosional and depositional features, and a later, less-catastrophic, phase responsible for the preservation of fine-grained glaciolacustrine sediments. Features of the earlier lake phase include giant gravel dunes and openwork gravel with anomalously large clasts (erratics). Deposits from the later phase are mostly low-energy glaciolacustrine sediments that record a history of lake-bottom sedimentation and repeated lake-floor exposure. A focus of this field trip is to look at evidence for the two lake phases as well as evaluate the record of exposure surfaces, and therefore lake-level lowerings, during the second phase at multiple locations in the lake basin. One of the second phase sites is close to a highstand, full basin position in the lake (near Garden Gulch), representing a maximum water depth at this site of ~100 m, whereas others (Rail line and Ninemile) are at lower altitudes in regions that may have been under as much as 300 m of water. Fine-grained glaciolacustrine sediments are rippled very fine sandy silt and fining-upward sequences of laminated silt and clayey silt of glaciolacustrine origin. Periglacial features, contorted bedding, desiccation, and paleosols in outcrop provide clear evidence of multiple exposure surfaces; each represent a lake-lowering event. Optically stimulated luminescence (OSL or “optical dating”) ages on quartz from the three sections (Ninemile, Rail line, and Garden Gulch) allow for preliminary correlations that suggest approximately the same phase of glacial Lake Missoula sedimentation. The exposure surfaces suggest that the glacial-lake level rose and fell at least 8–12 times to elevations above and below the sections (936–1180 m), filling to within 100 m of full pool (1280 m). Optical dating shows that this occurred after 20 ka and the last inundation of the lake before 13.5 ka. Correlation of specific exposure surfaces throughout the basin will be required to develop a lake-level history.

Abstract This one-day field trip through Metro Vancouver, British Columbia, illustrates the breadth of societal contributions afforded by urban geology. In addition to the classic geotechnical needs and concerns about geological hazard mitigation, interest is growing in the heritage and educational values of geological sites, and their potential roles in fostering a sense of place. As urban populations become increasingly diverse, they cannot be united by shared history; therefore, the shared environment can emerge as a strong element of shared identity. With more than 50% of the global population now living in urban centers, it becomes too easy for them to become alienated from geology as a “science of the hinterland,” devoted more to resource exploration and development than to matters of shared heritage. A surprising amount of geological information can be studied and appreciated in an urban area, despite development. There is a need for ongoing urban geological surveys, supported by educational institutions linked to urban administrations and provincial and/or state and national agencies. The surveys would have rapid-response capability to allow optimal recovery of fine-scale information from the temporary exposures that daily come to light. Metro Vancouver’s exposed (in-place) bedrock and surficial deposits represent over 100 million years of Earth history. It is a history of continuous mountain building and collapse as recorded by granitic batholiths with cross-cutting dikes and sills, Mesozoic and Cenozoic clastic sedimentary rocks, volcanic features, and Quaternary glacial and nonglacial deposits. Several of its landforms have cultural significance for both aboriginal and settler populations, reflected in their names and associated stories. Both information and meanings reside in the urban geological landscape and beg to be interpreted, providing excellent educational and research opportunities even as they also contribute to cultural continuity.

Abstract This field guide examines Quaternary volcanism in the Canadian Cascade arc informally known as the Garibaldi Volcanic Belt. During the first day, the trip proceeds along the Sea-to-Sky Highway corridor from Vancouver to Pemberton and focuses on Quaternary glaciovolcanic deposits and lavas. Interactions between volcanoes and ice in the Garibaldi Volcanic Belt have been common during the past two million years, which has resulted in a diverse array of landforms, including subglacial domes, tuyas, impounded lava masses, and sinuous lavas that exploited within-ice drainage systems. On Days 2 and 3, the trip heads northwest of Pemberton, British Columbia, along logging roads to see deposits from the 2360 yr B.P. eruption of the Mount Meager volcanic complex. The eruption began Plinian-style, generating pyroclastic fall and density current deposits (Day 2) and ended with the production of welded and nonwelded block and ash flows by explosive (Vulcanian) collapse of a lava (Day 3). The guide will examine the deposits of the temporary lake impounded by a block and ash flow deposit dam, and the evidence of the catastrophic failure of the dam and the generation of a huge outburst flood and lahar. Many of the traits of the deposits seen on this three-day trip are a reflection of both the style of eruption and the nature of the surrounding landscape. In this regard, the trip provides a spectacular window into the nature and hazards of effusive and explosive volcanism occurring in mountainous terrains and the role of water and ice.

Following the middle of the twentieth century, Earth scientists increasingly became aware of the significant role played by the incorporation of dust in the formation of soils. Dust plays an especially important role in the development of aridland soils, given the usually abundant supply of dust and generally limited magnitude of chemical weathering that characterizes aridland soils. The recognition that virtually all calcium in pedogenic carbonate is derived from calcium-bearing dust that primarily accumulates in a very common horizon of aridland soils, the calcic horizon, was critical in convincing scientists that soil formation in aridlands differs in fundamental respects from that in more humid settings. Research conducted by Leland Gile and his colleagues in the Desert Soil Geomorphology Project in southern New Mexico produced one of the most important bodies of published research in the 1960s to the early 1980s, that demonstrated both the significant impact of dust on aridland soils and their geomorphic significance. Subsequent research in the Cima volcanic field of the Mojave Desert, southwestern United States, showed that the nature of soil development associated with the formation and evolution of desert pavements is markedly different from that proscribed by the “canonical” A/B/C model of soil profile development described by V. Dokuchaev, the profile model most familiar to the majority of Earth scientists. The soils that develop beneath desert pavements form in parent materials increasingly composed of entrapped dust that is subsequently translocated below the pavement. Vesicular horizons, the key surface horizon of desert pavement soils, and subjacent, thickening clay and calcium carbonate–enriched B horizons form mainly through accretionary and inflationary profile (AIP) development, a type of cumulative soil development associated with rising desert pavements. The “upward growth” model of desert pavement formation profoundly contrasts with the “deflation” model. The behavior of the vesicular A horizon is important in maintaining a balance between rates of dust entrapment and translocation that enables continued AIP, while maintaining desert pavement at the surface. Soil chronosequence studies show that AIP and desert pavement formation are favored on other landforms (e.g., alluvial fans), providing that a weathering-resistant rock type is available to form a persistent pavement. Once desert pavements and soils have formed, most have likely survived exposure to “glacial” periods, despite effectively greater precipitation and locally significant changes in the nature of biotic communities that are characteristic of such periods. AIP is also an important mode of soil profile development in semiarid regions where desert pavements cannot form and vesicular horizons are weakly developed or absent. Increased plant density continues to favor the dust entrapment rates necessary to maintain AIP, as well as to provide a surface stabilizing function. Given the ecologically limiting role of water in aridlands, the nature of and time-dependent changes in soils forming by AIP strongly influence patterns of recruitment and composition of plants in aridland landscapes and their response to environmental change. The hillslopes of aridland hills and mountains are excellent dust traps, and in favorable circumstances, weathering and dust entrapment promotes the development of thick, vegetated and smooth soil-mantled hillslopes. Toposequence studies in selected areas of the southwestern United States indicate that the presence of dust-entrapping colluvium is probably necessary to maintain AIP on hillslopes over long periods of time. Vegetation also promotes entrapment of dust, but vegetation on hillslopes is highly sensitive to episodic drought and/or fires that temporarily eliminate or drastically reduce vegetation cover. Episodically increased erosion potential prevents sustained AIP, and accumulated dust in soils is quickly transported from the hillslopes. Certain types of bedrock in aridland hillslopes weather rapidly and favor the development of soil-mantled, transport-limited hillslopes, but the typically thin, weakly developed soils are prone to rapid erosion, especially when subject to a combination of extreme drought followed by large increases in rainfall. Glacial-to-interglacial changes in climate also cause substantial changes in biotic communities, rates and processes of weathering, and soil development that influence the behavior of aridland hillslopes. Models that employ the soil production function have been developed recently to enable calculation of rates of soil production on soil- and vegetation-mantled upland hillslopes. The results of a half century of soil geomorphological research in aridlands, relying largely on the “CLORPT”-based approach, complemented by studies of the behavior of biotic communities in aridlands, suggest that maintaining the necessary conditions fundamental in the application of soil production functions in studies of hillslopes (transport solely by diffusive processes maintaining steady-state soil thickness and a spatially and temporally constant diffusion coefficient) for thousands to tens of thousands of years is highly unlikely in aridlands. Changing the word soil , in the term soil production function to the term mobile regolith will reduce confusion concerning the actual meanings of these different terms and facilitate a greater degree of integration of very different approaches in the study of soil landscape evolution.

Abstract Research in recently burned mountainous watersheds in California, Colorado, and Utah shows that most postfire debris flows are initiated by runoff and erosion and grow in size through erosion and scour in channels. Most commonly, postfire debris flows occur within two years after a fire. This paper describes a field trip to three such occurrences in the southeastern Sierra Nevada as well as debris flows in the arid Inyo Mountains. On 12 July 2008, tropical moisture moved across the American Southwest and stalled against the eastern Sierra. Local convective cells simultaneously produced brief periods of intense rainfall on steep-sloped, burned watersheds near the towns of Lake Isabella and Independence, about 155 km to the north. Both communities sustained significant damage and infrastructure disruption. On 10 August 2010, intense rain fell on the Haiwee Creek drainage that was burned in 2008, producing a debris flow that swept a semi tractor trailer off of Highway 395, caused overnight traffic delays, and damaged infrastructure.

ABSTRACT The Great Lakes coast contains numerous unstable bluffs underlain by heterogeneous glacial materials consisting of till, sand, and gravel layers, and lacustrine clays. Many of the bluffs are steeper than their equilibrium angles and typically move as slow earth slides or occasional rapid slumps. Such movements develop largely where interlayered sand and clay contain perched groundwater that acts to reduce effective stress during winter months when perched potentiometric surface elevations rise because water cannot discharge through frozen soil. Aerial photograph records dating back to 1938 show that bluffs recede in amphitheater-like depressions followed by "catch up" where headlands between amphitheaters are attacked by other forms of erosion. This bluff recession is particularly pronounced during stages of high lake levels. The erosion control experiment described herein has been designed to determine the manner in which groundwater activity influences the causes and mechanisms of mass wasting on the Great Lakes coasts. Three dewatering demonstration sites were selected, monitored electronically for virtually all movement and cause relationships, and dewatered to demonstrate a potential mitigation strategy other than construction of wave barriers. Erosion activity and dewatering effects were carefully monitored for three seasonal cycles. Results show that (1) dewatering greatly reduces ground displacements during winter months, and (2) bluff movements are almost perfectly timed to, or lag slightly after, the hours when potentiometric surfaces near the bluff face reach their highest elevations during freezing (greatest soil pore pressure) or their greatest rates of surficial discharge (soon after thaw). This field guide project was supported by grants from the U.S. Army Research Office, Terrestrial Sciences Program (Grant 3467-GS) from 1996 to 1999 and the U.S. Army Engineer Research and Development Center (ERDC) from 2000 to 2007, and 2012, through U.S. Senate Bill 227 (National Shoreline Erosion Control Development and Demonstration Program), with support from Western Michigan University (WMU). Additional personnel involved were Alan E. Kehew, Co-PIand, WMU graduate students William Montgomery, Rennie Kaunda, Mark Worrall, Gregory Young, William Bush, and Amanda Brotz. Well and monitoring instrument positions were chosen by R. Chase and designed by Ronald L. Erickson and James P. Selegean, U.S. Army Engineer District, Detroit, Michigan. Well constructions and instrument installations were done by STS Consultants, Chicago, Illinois. This huge project was very smoothly administered by M. Eileen Glynn and William R. Curtis, ERDC, Vicksburg, Mississippi.