The major deglacial-phase deposits of eastern Maine include stratified end moraines, single and amalgamated ice-margin delta complexes, extensive segmented esker systems that link with marine deltas and fans, and a fossiliferous glacial marine mud (the Presumpscot Formation) that is interbedded with, or drapes, the other deposits. Previous work has determined that deposition within the 40-km-wide swath, which is now the modern coastal zone, occurred between 13,500 and 12,500 B.P. Detailed mapping, measurement of stratigraphic sections and paleocurrents, and calculation of drainage basin area and volume of sediment bodies have led to a better understanding of lithofacies assemblages, depositional processes, sediment sources, and regional geometry of these deposits. The “stratified end moraines,” better described as assemblages of marine fans, measure as much as 15 m high, 100 m wide, and 16 km in length, and were deposited along ice lobe fronts. Proximal vertical sequences are dominated by 15- to 30-cm-thick beds of poorly sorted, pebble-to-cobble gravel locally interbedded with gravelly diamict. Well-sorted, matrix-less (“open-work”) pebble/cobble gravel occurs in channel forms that can be traced tens of meters laterally. Distal sequences consist of laminated beds of medium-to-fine sand capped by silt drapes; climbing ripple cross-stratification is uncommon, and some diamict beds are present. Lithofacies of the delta front, prodelta, and esker core (ice-tunnel deposits) are remarkably similar to those of the fans, differing only in greater degree of dip (deltas), and clast size (ice-tunnel deposits). Paleocurrents of fans show a large dispersion, in some instances indicating flow parallel to the inferred ice margin; proximal beds are deformed, indicating an active ice margin. The ice-margin fan and delta complexes have a combined area of 250 km 2 and total volume of nearly 5 billion m 3 , which strongly suggests that the 2,400-km-long ice-tunnel system (including tributaries) was active along its entire length in order to supply needed sediment. Ice-tunnel deposits filled the distal ends of tunnels as the active ice margin retreated. The geometry and volume of deltas, fans, and ice-tunnel deposits, together with the time constraints, indicate deposition into marine waters at the margin of a complex, multi-lobate, grounded, warm-based ice sheet.

Abstract The Scott and Yana outwash fans on the northeastern Gulf of Alaska exhibit a succession of facies from glacier terminus to tidewater that are each characterized by differences of gradient, clast size, bar morphology, and sedimentary structures. The upper fan has steep gradients (as much as 17.6 m/km), large maximum clast size (>10 cm), and longitudinal bars. The midfan has gentler gradients (2 to 6 m/km), clast size ranging from less than 10 cm to sand, and predominantly longitudinal bars. The lower fan, a sand area, has gradients less than 2m/km, longitudinal and linguoid bars in braided reaches, and point and lateral bars in meandering reaches. The longitudinal bars of the upper fan consist mainly of well imbricated, poorly sorted gravel that have clast long-axes oriented transverse to the flow direction. Bars are often covered with transverse ribs, here interpreted as an upper flow regime bedform, and perhaps as relict antidunes. The midfan area is characterized by a decrease in gravel, with a corresponding increase in sand. Sand is deposited as flat upper regime beds interbedded with gravel and as lower regime megaripples in channels forming trough cross-beds. The longitudinal bars of the lower fan show planar cross-beds formed by migration of the bar slipface topped by flat beds on the bar-surface and low-angle ripple-drift cross-lamination. Linguoid bars exhibit large-scale planar to tangential cross-beds topped by ripple-drift cross-lamination. Point and lateral bars are characterized by large-scale planar to trough cross-beds caused by migration of the bar surface and bar slipface. Overbank deposits of silty sand ripple-drift cross-lamination and draped lamination increase in importance downfan. Stream regimen is governed by early summer floodng. Measurements taken during a rising stage and a declining stage indicate gravel movement in channels on the upper fan (bars were mostly emergent), but little gravel movement on the midfan. Megaripple migration in midfan channels and linguoid-bar migration on the lower fan continue at low flow stages.

Abstract Sedimentary structures in distal outwash deposits, in glaciolacustrine deltas, and in lake sediments proximal to glaciolacustrine deltas are similar where the grain-size distributions of the sediment are similar, and where depositon occurs under smilar flow conditions. Draped lamination, a common structure in distal outwash deposit, consists of parallel laminae of sand, silt, and clay deposited from suspension and draped over an underlying bedform. Thickness of the laminae remains essentially unchanged across the underlying bedform, and neither silt nor mica flakes are concentrated anywhere along draped laminae. Overbank deposits in outwash decrease in grain size along the length of the stream, but contain similar sequences of sedimentary structures. Commonly, type A ripple-drift cross-lamination is overlain by low-angle type B, which in turn is overlain by draped lamination. This sequence of sedimentary structures suggests deposition under decreasing flow strength. Ripple-drift sequences in glaciolacustrine deltas are separated in many cases by winter clay layers. The basic sequence begins as a thin unit of draped lamination deposited on a subjacent winter clay. A thin unit of type B ripple-drift cross-lamination follows and is in turn overlain by a relatively thick unit of type A. The type A grades upward into a second unit of type B. As the angle of climb of the type B ripple-drift cross-lamination increases to the vertical, type B grades upward into draped lamination. A superjacent winter clay layer completes the sequence. The basic sequence of sedimentary structures reflects a relatively rapid decrease in the ratio of rates of deposition from suspension to bed-load transport, followed by a gradual increase. Flow strength appears to increase quickly and then decrease. The thin graded beds and rare ripple- drift cross-lamination or isolated ripples observed within lacustrine varved clays are distal equivalents to the sequences observed within glaciolacustrine deltas. Glaciolacustrine deltas are the products of rapid sedimentation into low-energy lake environments and are seldom seriously modified by wave action or currents. Deltas are built into lakes as overlapping lobes of sediment that were deposited from density currents issuing from meltwater distributaries. As distributaries migrate across the delta subaerial plain, lobes move laterally and overlap each other, forming an arcuate delta front.