TY - JOUR T1 - Glacioisostasy and lake-level change at Moosehead lake, Maine JF - Quaternary Research Y1 - 1998 A1 - Balco, G. A1 - Belknap, D. F. A1 - Kelley, J. T. AB - Reconstructions of glacioisostatic rebound based on relative sea level in Maine and adjacent Canada do not agree well with existing geophysical models. In order to understand these discrepancies better, we investigated the lake-level history of 40-km-long Moosehead Lake in northwestern Maine. Glacioisostasy has affected the level of Moosehead Lake since deglaciation ca. 12,500 C-14 yr B.P. Lowstand features at the southeastern end and an abandoned outlet at the northwestern end of the lake indicate that the lake basin was tilted down to the northwest, toward the retreating ice sheet, by 0.7 m/km at 10,000 C-14 yr B.P. Water level then rose rapidly in the southeastern end of the lake, and the northwestern outlet was abandoned, indicating rapid relaxation of landscape tilt. Lowstand features at the northwestern end of the lake suggest that the lake basin was tilted to the southeast at ca. 8750 C-14 yr B.P., possibly as the result of a migrating isostatic forebulge. After 8000 C-14 yr B.P., water level at the southeastern end was again below present lake level and rose gradually thereafter. We found no evidence suggesting that postglacial climate change significantly affected lake level. The rebound history inferred from lake-level data is consistent with previous interpretations of nearby relative sealevel data, which indicate a significantly steeper and faster-moving ice-proximal depression and ice-distal forebulge than geophysical models predict. (C) 1998 University of Washington. VL - 49 IS - 2 N1 - Zm315Times Cited:9Cited References Count:46 JO - Glacioisostasy and lake-level change at Moosehead lake, Maine ER - TY - JOUR T1 - Paleoclimatic implications of Holocene lake-level fluctuations, Owasco Lake, New York: Comment JF - Geology Y1 - 1997 A1 - Balco, G. A1 - Belknap, D. F. A1 - Kelley, J. T. VL - 25 IS - 4 N1 - Wu319Times Cited:0Cited References Count:7 JO - Paleoclimatic implications of Holocene lake-level fluctuations, Owasco Lake, New York: Comment ER - TY - JOUR T1 - Stratigraphic evolution of the inner continental shelf in response to late Quaternary relative sea-level change, northwestern Gulf of Maine JF - Geological Society of America Bulletin Y1 - 1997 A1 - Barnhardt, W. A. A1 - Belknap, D. F. A1 - Kelley, J. T. AB - Accumulations of deltaic and littoral sediments on the inner continental shelf of Maine, Gulf of Maine, preserve a record of postglacial sea-level changes and shoreline migrations, The depositional response of coastal environments to a cycle of regression, lowstand, and transgression was examined with seismic-reflection profiles, vibracores, and radiocarbon dates collected from sediments at the mouths of the Kennebec and Penobscot Rivers, Sequence-stratigraphic analysis of these data reveals two distinctly different successions of late Quaternary deposits that represent end members in an evolutionary model for this glaciated coast. Seaward of the Kennebec River, coarse-grained shorelines with foreset beds occur at depths of 20-60 m and outline the lobate margin of the Kennebec River paleodelta, a complex, rock-framed accumulation of glaciomarine and deltaic sediments capped by estuarine and marine deposits, Sand derived from this system today supports large barrier spits and extensive salt marshes, In contrast, the mouth of the Penobscot River is characterized by thick deposits of glaciomarine mud overlain by marine mud of Holocene age, including gas-charged zones that have locally evolved into fields of pockmarks, The distinct lark of sand and gravel seaward of the Penobscot River and its abundance seaward of the Kennebec River probably reflect differences in sediment som ces and the physiography of the two watersheds, The contrasting stratigraphic framework of the se systems demonstrates the importance of understanding local and regional differences in sediment supply, sea-level change, bedrock structure, and exposure to waves and tides in older to model river-mouth deposition on glaciated coasts.Evolution of shelf deposits was largely controlled by relative sea level, which locally fell from a highstand (+60 to +70 m at 14 ka) contemporary with deglaciation to a lowstand (-55 m at 10.8 ka), The sea-level lowering was accompanied by fluvial incision of older deposits, producing a regressive, basal unconformity, Major rivers deposited abundant sediment over this surface, Sea level then rose at varying rates, extensively reworking formerly emergent parts of the shelf and producing a shoreface ravinement surface in areas exposed to waves, A tidal ravinement surface has developed in sheltered embayments where erosion is due mainly to tidal currents. Incised valleys in both settings preserve transgressive estuarine deposits that contain lagoonal bivalves and salt-marsh foraminifera at depths of 15-30 m, These deposits accumulated ca, 9.2-7.3 ka, locally a period of relatively slow sea-level rise. VL - 109 IS - 5 N1 - Wy671Times Cited:38Cited References Count:65 JO - Stratigraphic evolution of the inner continental shelf in response to late Quaternary relative sea-level change, northwestern Gulf of Maine ER - TY - JOUR T1 - Late Quaternary Relative Sea-Level Change in the Western Gulf of Maine - Evidence for a Migrating Glacial Forebulge JF - Geology Y1 - 1995 A1 - Barnhardt, W. A. A1 - Gehrels, W. R. A1 - Belknap, D. F. A1 - Kelley, J. T. AB - New radiocarbon-dated cores obtained by Vibracorers in the western Gulf of Maine confirm that a short-lived, relative sea-level lowstand of similar to-55 m occurred at 11-10.5 ka. These cores and younger salt-marsh data also reveal that rates of transgression varied throughout the Holocene, probably due to local variations in glacial isostasy. The isostatic component is resolved by subtracting published approximations of eustatic sea level from our well-determined observations of local relative sea level. A large peek in the isostatic curve coincides with the lowstand and is interpreted as a forebulge 20-25 m in amplitude. Forebulge migration is estimated at 7-11 km/100 yr, based on the timing of lowstands across the region. VL - 23 IS - 4 N1 - Qr847Times Cited:69Cited References Count:32 JO - Late Quaternary Relative Sea-Level Change in the Western Gulf of Maine - Evidence for a Migrating Glacial Forebulge ER -