Ridge-like accumulations of drift deposited
at the farthest point of travel of a glacier’s terminus. Terminal
moraines may be found as depositional landforms at the
bases of mountain or valley glaciers marking the locations of
the farthest advance of that particular glacier, or they may be
more regional in extent, marking the farthest advance of a continental
ice sheet. There are several different categories of terminal
moraines, some related to the farthest advance during a
particular glacial stage, and others referring to the farthest
advance of a group of, or all, glacial stages in a region. Continental
terminal moraines are typically succeeded poleward by
a series of recessional moraines marking temporary stops in
the glacial retreat or even short advances during the retreat.
They may also mark the boundary between glacial outwash
terrain toward the equator, and knob and kettle or hummocky
terrain toward the pole from the moraine. The knob and kettle
terrain is characterized by knobs of outwash gravels and sand
separated by depressions filled with finer material. Many of
these kettle holes were formed when large blocks of ice were
left by the retreating glacier, and the ice blocks melted later
leaving large pits where the ice once was. Kettle holes are typically
filled with lakes, and many regions characterized by
many small lakes have a recessional kettle hole origin.
See also GLACIER.
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