Lake Merrimack was a
glacial lake
A glacial lake is a body of water with origins from glacier activity. They are formed when a glacier erodes the land and then melts, filling the depression created by the glacier.
Formation
Near the end of the last glacial period, roughly 10,0 ...
that formed during the late
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch. After the
Laurentide Ice Sheet
The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years a ...
retreated, glacial ice melt accumulated at the terminal
moraine
A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...
and blocked up the
Merrimack River
The Merrimack River (or Merrimac River, an occasional earlier spelling) is a river in the northeastern United States. It rises at the confluence of the Pemigewasset and Winnipesaukee rivers in Franklin, New Hampshire, flows southward into Mas ...
, creating the narrow lake. The lake extended from
Manchester
Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...
to
Plymouth, New Hampshire
Plymouth is a rural New England town, town in Grafton County, New Hampshire, Grafton County, New Hampshire, United States, in the White Mountains Region. It has a unique role as the economic, medical, commercial, and cultural center for the predom ...
. It is unknown when the lake was drained.
Lake Hitchcock is an important part of the
geology of New Hampshire
The geology of New Hampshire is similar to that of the rest of New England in comprising a series of metamorphosed sedimentary and volcanic rocks of Late Proterozoic to Devonian age, intruded by many plutons and dikes ranging in age from Late ...
. It experienced annual layering of sediments, or
varve
A varve is an annual layer of sediment or sedimentary rock.
The word 'varve' derives from the Swedish word ''varv'' whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as ''Hvarfig lera'' (var ...
s: silt and sand in the summertime (due to glacial meltwater) and clay in the wintertime (as the lake froze).
See also
*
Lake Winnipesaukee
Lake Winnipesaukee () is the largest lake in the U.S. state of New Hampshire, located in the Lakes Region at the foothills of the White Mountains. It is approximately long (northwest-southeast) and from wide (northeast-southwest), covering & ...
*
Champlain Sea
The Champlain Sea (french: Mer de Champlain) was a prehistoric inlet of the Atlantic Ocean into the North American continent, created by the retreating ice sheets during the closure of the last glacial period. The inlet once included lands in ...
*
Lake Albany Glacial Lake Albany was a prehistoric North American proglacial lake that formed during the end of the Wisconsinan glaciation. It existed between 15,000 and 12,600 years ago and was created when meltwater from a retreating glacier, along with water ...
*
Lake Hitchcock
Lake Hitchcock was a glacial lake that formed approximately 15,000 years ago in the late Pleistocene epoch. After the Laurentide Ice Sheet retreated, glacial ice melt accumulated at the terminal moraine and blocked up the Connecticut River, cre ...
*
Lake Stowe
References
External links
Information on the Pemigewasset River
{{DEFAULTSORT:Merrimack
Former lakes of the United States
Merrimack River
Lakes of New Hampshire
Proglacial lakes
Geology of New Hampshire
Glacial lakes of the United States