The Presumpscot formation is a late

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

glacial deposit image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

of predominantly submarine clays, located along the

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

and

New Hampshire New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...

coast and inland along their major river valleys. It consists of primarily silt- and clay-sized particles formed from the glacial abrasion of the

feldspar Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagiocl ...

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

, and

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...

s of the region, carried by glacial meltwater and deposited below sea level before subsequent crust rising (

isostatic rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound ...

) elevated the deposits up to more than . It is named after the

Presumpscot River The Presumpscot River () is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed June 30, 2011 river located in Cumberland County, Maine, United States. It is the main outlet of Sebago ...

where large amounts of the characteristic blue-gray clay are found.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

ized remains of marine organisms are found interspersed among the deposits. It was a historically significant resource for the production of brick, though little of that industry remains.

Pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

found in the clays near

Portland, Maine Portland is the List of municipalities in Maine, most populous city in the U.S. state of Maine and the county seat, seat of Cumberland County, Maine, Cumberland County. Portland's population was 68,408 at the 2020 census. The Portland metropolit ...

, indicate spruce forests, with low proportions of pines, about 11500 BP.''Terrestrial Fossils in the Marine Presumpscot Formation: implication for late Wiconsinan paleoenvironments and isostatic rebound along the coast of Maine.'' Anderson, Miller, Davis, Nelson; 1990.

References

{{Reflist *Barker, 2011, ''Glacial-marine deposits of southern Maine''. *Thompson, W., and H. Borns,. 1985. "Surficial geologic map of Maine." Augusta, ME: Maine Geological Survey, 1:500,000.

External links

Maine Geological Survey
Geologic formations of Maine Geologic formations of New Hampshire