Late glacial and Holocene history of the Penobscot River in the Penobscot Lowland, Maine

Datos Bibliográficos

ID12266240
AutoresRoger LeB Hooke (School of Earth and Climate Sciences and Climate Change Institute, The University of Maine, USA, autor de correspondencia), Paul R Hanson (0000-0002-8843-9987, University of Nebraska–Lincoln), Daniel F Belknap (School of Earth and Climate Sciences and Climate Change Institute, The University of Maine, USA), Alice R Kelley (0000-0002-8977-1033, School of Earth and Climate Sciences and Climate Change Institute, The University of Maine, USA)
Año2016
Volumen27
Número5
Páginas726-739
Fecha de publicación2016-10-11
Peer ReviewedSí
Open AccessSí
TipoARTICLE
RevistaThe Holocene (JOURNAL)
Identificadores de la revistaISSN: 0959-6836 • E-ISSN: 1477-0911
EditorialSAGE Publishing (PUBLISHER • US)
DOI10.1177/0959683616670474
OpenAlexW2531579401
IdiomaEN
Citas recibidas1
Referencias citadas49

When the Laurentide ice sheet retreated rapidly (~150 m/a) across the Penobscot Lowland between ~16 and ~15 ka, the area was isostatically depressed and became inundated by the sea. Silt and clay were deposited, but no significant moraines or deltas were formed. The Penobscot River was reborn at ~14 ka when ice retreated onto land in the upper reaches of the river’s East Branch. As isostatic rebound exceeded sea level rise from melting ice, the river extended itself southward. Between ~13.4 and 12.8 ka, it established a course across marine clay and underlying glacial till in the Lowland. Its gradient was low as differential rebound had not begun. Discharge, however, was higher and the river transported and deposited outwash gravel. During the cold, dry Younger Dryas, ~11 ka, eolian sand began to accumulate in dunes in the Lowland. Some of this sand, along with fluvial sediment from the headwaters, was redistributed into terraces along gentler stretches of the river and into a paleodelta in Penobscot Bay. Eolian activity continued to ~8 ka and aggradation in terraces until ~6 ka. The climate became wetter and warmer after ~6 ka, the dunes were stabilized by vegetation, the river began to downcut, and braiding became less intense. Pauses in the downcutting are reflected in discontinuous strath terraces. In due course, the river re-encountered the old outwash gravels, marine clay, glacial till, and, in a few places, bedrock. Its profile is now stepped, with gentle, gravel-bedded reaches between bedrock ribs that form rapids

Aggradation · Bedrock · Deglaciation · Fluvial · Geomorphology · Glacial period · Holocene · Ice sheet · Moraine · Outwash plain · River terraces · Silt · Tectonic uplift · Aeolian processes and effects · Geological formations and processes · Geology and Paleoclimatology Research · Geology · Oceanography