Abstract This paper reviews the hydrology and hydraulics of high energy, particularly proglacial, riverine and deltaic environments, and discusses some of the consequences for resultant patterns of sediment movement and deposition. The hydrology of proglacial rivers is under strong thermal influence and exhibits a singular pattern of flow, both seasonally and diurnally. Moderate flood flows are common. Sediment is frequently entrained and deposited, so that rapid evolution of fluvi u sedimentary features occurs on outwash plains. The possibility exists for extraordinary jokullhlaup floods to occur in front of many glaciers. The hydraulic behavior of proglacial rivers features frequent upper regime flow and rapid adjustment of channel resistance to accommodate the wide variations in discharge and sediment transport. Sediment entrainment is reviewed in sime detail, and theconceptsof “overloose” and “underloose” boundary are introduced. Sediment transport theory is reviewed and recommendations made for assessing total sediment yield. The sediment transport in proglacial rivers is anomalously high by comparison with that in nonglacial environments, because of the large volumes of drift delivered to the glacier margin. Flood deposits on outwash plains and surficial patterns of sediment texture are described. The character of the surface is conditioned by selective deposition of sediment in a simple, aggradational context. Depositional bedforms are classified as small forms (scale controlled by flow depth or lesser flow dimensions) and large forms (scale controlled by channel width). The former reflect purely local flow conditions, whereas the latter are influenced by the total flow pattern of the river. The persistence of bedforms as sedimentary structures in the stratigraphical record is considered. Gravels commonly exhibit only rudimentary plane bedding and imbrication, whereas fine materials commonly feature a wide variety of sedimentary structures. This is a consequence of the vertical distance available for deposition as compared to particle size, and the energy status of the depositional environment. River channels in coarse, noncohesive materials are wide and shallow, so that boundary resistance to flow is high. When large volumes of sediment are being transported in flood, total resistance may become too high to permit passage of the water plus sediment load; deposition and selective scour then produce narrower, deeper channels that are hydraulically more efficient. The morphological result is the occurrence of channel braiding, which is a frequent characteristic on outwash. The long profiles of proglacial rivers and outwash surfaces are concave upward as a consequence of persistent aggradation. Where proglacial rivers enter standing water bodies, classical, high-angle deltas develop. Sediment transported as bed load is deposited on the delta surface, or is deposited on the foreset wedge by avalanching over the delta lip. Turbidity flows (underflows) and slumps move coarse material farther into the water body. Finegrained material is carried in suspension into the standing water and settles to the bottom to form varves. Examples illustrating the application of principles and characteristic conditions are drawn from the literature on glaciofluvial and glaciolacustrine environments.

ABSTRACT Erie Bluffs State Park (Pennsylvania, USA) is a natural classroom that permits the examination of well-preserved Pleistocene landforms as well as exposures of their constituent sediments. These features and their underlying sedimentology and stratigraphy provide a glimpse into part of the landscape evolution of the Lake Erie basin. The landforms examined in this field trip include a Late Pleistocene “Warren” proglacial lacustrine shoreline sequence with eolian dunes, beach ridges, near-shore, and lake plain environments. A distinct fluvial terrace of Elk Creek, a tributary to Lake Erie, is also well exposed. These landforms are intersected by Lake Erie’s eroding, wave-cut bluffs, providing a direct comparison of landform/sediment assemblages, depending on the quality and availability of outcrops, which vary significantly through time due to rapid erosional processes. Outcrops are often sufficient along the lateral extent of the bluffs to piece together stratigraphic relationships and depositional patterns, including the basin-ward progradation of the proglacial shoreline, and incision of Elk Creek due to the base-level controls exerted by post-glacial changes in lake levels within the Lake Erie basin. This field trip examines these landforms and sediments, describes details of the sedimentology of stratigraphic units, and discusses their place in the context of Quaternary landscape evolution of northwestern Pennsylvania.

Abstract A consideration of the interactions between glaciers and permafrost is essential to many environmental studies of cold regions. This paper reviews how concepts, field data and experimental studies from glaciology and geocryology can provide a basis for improved understanding of some of the key glacier-permafrost interactions at scales ranging from continental ice sheets to small proglacial streams. Glacitectonic processes are strongly influenced by water pressures beneath subglacial and proglacial permafrost, and by the amount of unfrozen water within the permafrost. Burial of glacier ice and growth of intra-sedimental ice also occur within sub- and proglacial permafrost, and together they produce a complex assemblage of ground ice in glaciated frozen lowlands. In mountain regions, rock glaciers are associated with the presence of ground ice, and represent a landform that straddles the semantic fence separating glacial features from permafrost features. In proglacial and ice-marginal environments, geomorphological activity reflects the combined effects of glacially- and periglacially-conditioned processes operating synchronously in adjacent areas, or in succession; such activity includes the transport of sediment in glacierized catchments and the calving of glacial ice in ice-marginal lakes. Interaction between permafrost and glacial phenomena depends largely on their proximity: where permafrost occurs close to glaciers, the thermal regime of the active layer is influenced in part by the surface covering of adjacent glacial ice through its effect on albedo and ground heat flux. Glacier-permafrost interactions are particularly important in recently deglaciated terrain, where permafrost may be aggrading. This ‘paraglacial’ zone often shows rapid geomorphological change. Thus, glacier-permafrost interactions are complex and occur over a wide range of temporal and spatial scales.

Abstract This paper describes the key characteristics of a proglacial moraine complex at the Leverett Glacier, western Greenland. The presence of a large stream-cut exposure allowed the examination of its internal structure, as well as its surface geomorphology. It is composed of a variety of ice and sediment facies, including debris-poor ice, ice-rich diamicton and ice-rich gravel. These units are glaciotectonized, with the exposure featuring a major fault and associated drag fold, a planar, erosional unconformity, and a variety of small-scale folds. Various interpretations are considered, including the possibility that the sequence represents a buried basal ice layer. However, it is argued that the structural characteristics are best explained by a two-phase model involving ice advance and proglacial or ice-marginal compression, followed by overriding and subglacial deformation and erosion, tentatively related to ice advance after the Holocene Hypsithermal ( c . 4900–3000 calendar years BP). The polygenetic origin of this ice-marginal, glaciotectonic landform contrasts with the majority of Arctic push-moraines, which are largely considered the result of proglacial deformation and the stacking of imbricate thrust sheets of frozen sediment. This contrast may reflect differences in the thickness and spatial continuity of permafrost within the glacier foreland, and adds to the range of ice-marginal landforms associated with glacier-permafrost interactions.

ABSTRACT Glaciotectonic deformation of glacigenic deposits in southwestern Michigan is described and analyzed to determine the source of stress of these strained sediments, which manifests as overturned folds and other deformation similar to shallow crustal décollements. The succession is exposed in 11 aggregate mining operations along the Valparaiso Upland, in portions of Berrien, Van Buren, and Allegan Counties in southwest Michigan. Observed deformation includes a complex array of folds, faults, and thrust features as much as 5 m below the surface exposure of the pit face, consistent with horizontal compressional stresses that were generally aligned with ice flow. Fabric measurement of elongated clasts in the surficial till indicates ice flow from northwest to southeast across the area and parallel to drumlins in the area. Stratigraphically, the area is dominated by fine, lacustrine deposits with coarse sand and gravel capped by the Saugatuck Till during the last glaciation. Sediment grain size, pore-water pressure fluctuations, and topographic relief are interpreted to be responsible for the deformation observed as the Lake Michigan Lobe overrode a proglacial lake basin, including fans and deltas, as it advanced eastward to the Kalamazoo moraine. The fine texture and fabric of the lacustrine sediment package restricted the flow of subglacial water and caused abrupt local increases of pore-water pressure and concomitant coupling and decoupling of the bed-substrate interface. Advancing ice deformed sediments in two stages: (1) proglacially along a décollement at the ice margin, and then (2) subglacially as ice overrode the sediments.

Abstract The glaciofluvial deposits are by volume and permeability the most important unit in the terrestrial glacial successions, and they are the obvious target for groundwater as well as hydrocarbon reservoir exploration. The dominant glaciofluvial units are related to the proglacial setting in the foreland of an advancing ice margin, which results in a coarsening-upwards sequence with fine-grained beds at the base and glaciofluvial gravel at the top. In a complete sequence a till caps the unit, and at its base a glacitectonite is formed by shearing related to the development of the deformational layer below the ice. The glacial deposits laid down during the same glacial advance represent a glaciodynamic sequence. An important feature added to this is the proglacial glaciotectonic deformation. The glaciotectonic architectural elements comprise thrust faulting, folding of hanging-wall anticlines, thrust-sheet duplexes, hydrodynamic breccias and mud diapirs, the structural style of which define the glaciotectonic complex. The glaciodynamic sequence corresponds to the glaciodynamic event related to one major ice advance. The glaciodynamic processes representing the event comprise deposition as well as deformation, creating a glaciogenic sedimentary succession and a set of glaciotectonic structures. These constitute the elements to be recognized for defining a glaciodynamic sequence.

Abstract This chapter provides an overview and key references of glacial processes and resulting sedimentary products in subglacial, terrestrial proglacial and glaciomarine or glaciolacustrine settings. These settings are characterized by a wide variety of processes ranging from subglacial lodgement and deformation, ice-push and sediment remobilization, which in turn result in a wide range of products such as diamictite, conglomerate, sandstone, siltstone and mudstone. The sedimentary record of proglacial settings exhibits the most lateral and vertical variability due to the dynamic nature of ice margins and the most direct record of climatic fluctuations. Many Neoproterozoic successions, however, preserve glaciomarine deposits that can provide a more continuous and high-resolution (though indirect) record of change. This chapter will enable the reader to identify features that may be used to infer a glacial influence on the formation of ancient deposits. The chapter also outlines some of the important issues that require consideration when evaluating palaeoclimatic models for Neoproterozoic sedimentary successions. These include the equivocal significance of most commonly used proxies such as occurrence of diamictite, outsized clasts in laminated sediments, clast characteristics, lithostratigraphic trends and sequence boundaries. Careful analysis of multiple lines of sedimentary evidence, together with other proxies of climatic changes, can yield meaningful reconstructions and provide a basis for testing palaeoclimate models for this time period. A summary table outlining the characteristics of diamictite with different depositional origins is also included in order to assist with the interpretation of the Neoproterozoic sedimentary record.