Late- and Post-glacial history of the East Branch of the Penobscot River, Maine, USA

Auteurs-es

  • Roger LeBaron Hooke University of Maine http://orcid.org/0000-0002-4403-8698
  • Paul R. Hanson Conservation and Survey Division, School of Natural Resources, University of Nebraska, Lincoln, NE, 8 68583, USA

DOI :

https://doi.org/10.4138/atlgeol.2017.012

Mots-clés :

Maine, Penobscot River, Deltas, Eskers, Late glacial

Résumé

Between ~20 and 15 ka the Laurentide Ice Sheet retreated from the edge of the continental shelf, ἀrst to the Maine coast and then across Maine to the northern reaches of the Penobscot Lowland. The Lowland, being isostatically depressed, was inundated by the sea. As ice then retreated into Maine’s western mountains, valleys through the mountains became estuaries. In the estuary now occupied by the Penobscot River’s East Branch, ten ice-marginal deltas were built during pauses in this part of the retreat. By 14 ka the ice had retreated far enough to expose land in the valley bottom between the ice front and the sea, and the Penobscot River was (re)born. This occurred near the present conᴀuence of the Seboeis River and the East Branch. The river gradually extended itself northward as the ice retreated and southward as relative sea level fell. Braidplains were formed and incised, leaving terraces. High initial discharges eroded the eastern ᴀanks of the esker and deltas, redepositing silt, sand, and gravel all the way to the present head of Penobscot Bay. By ~10 ka the discharge had decreased, the river was adjusting to on-going differential isostatic rebound, and finer sediment was accumulating, forming the present floodplain.

 

Bibliographies de l'auteur-e

Roger LeBaron Hooke, University of Maine

Research Professor

I retired from the University of Minnesota in 1999, but am still actively engaged in research and some teaching.

I copied and pasted my ORCHID number from ORCHID, but you say it is invalid.

Paul R. Hanson, Conservation and Survey Division, School of Natural Resources, University of Nebraska, Lincoln, NE, 8 68583, USA

Assistant Professor and Associate Director,School of Natural Resources.

My main research interests are studying the responses of river, hillslope, and eolian (wind-deposited) systems to climate change. For much of this work, I use optical dating techniques

Publié-e

2017-10-02

Comment citer

Hooke, R. L., & Hanson, P. R. (2017). Late- and Post-glacial history of the East Branch of the Penobscot River, Maine, USA. Atlantic Geoscience, 53, 285–300. https://doi.org/10.4138/atlgeol.2017.012

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