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What is a Terminal Moraine?

With their movement, glaciers can produce new land formations, including moraines. Primarily made from soil and rock, moraines erect from the squeezing, pushing, and dumping of earth material and the melting of glaciers. 

Terminal moraines, which are formed from the glaciers’ movement throughout numerous centuries, emerge at the end of a glacier. Long Island houses two terminal moraines, originating from a glacier’s advance in the Pleistocene Epoch. 

An Introduction to Moraines

Glaciers are only familiar to some people as the primary cause of the titanic’s sinking. Although they’re not wrong, glaciers are much more than a massive floating chunk of ice. Glaciers can also create new landforms with their movements.

A long-spanning accumulation of sediment, rock, crystalline ice, and water from land, forms glaciers. Glaciers emerge from areas where annual average temperatures are near the freezing point and where precipitation from winter creates heaps of snow. They need lengthy periods to convert from snow to glacier ice as they require numerous decades to accumulate a sufficient snow pile. Glaciers can also form landscapes in a process called glaciation. Glaciation impacts the rocks, the land, and the water of a location. (Source: USGS

The movement of glaciers throughout the years constructs different types of moraines. Mainly composed of soil and rock, the dirt and boulders moved by glaciers form moraines. With that said, only areas of the Earth with glaciers, either in the past or currently, can have moraines. Moraines are significant subjects studied by experts to research past environments.

There are four common categories of moraines namely, lateral moraines, medial moraines, supraglacial moraines, and terminal moraines. These classifications depend on where the moraines have formed on a glacier. Lateral moraines form on the lateral sides of the glacier, while medial moraines are inside and on an existing glacier. Following that, supraglacial moraines emerge on a glacier’s surface, and terminal moraines materialize at the end of a glacier. (Source: National Geographic

The Terminal Moraines of Long Island

In a recently posted web article on Antarctic Glaciers, Jacob Bendle describes the significant role of terminal moraines in the studies of past environments, specifically ice sheets, and glaciers.

Terminal moraines, for example, mark the maximum extent of a glacier advance and are used by glaciologists to reconstruct the former size of glaciers and ice sheets that have now shrunk or disappeared entirely.

Jacob Bendle, Antarctic Glaciers

(Source: Antarctic Glaciers)

Known for having two terminal moraines, Long Island is the home to both the Ronkonkoma Moraine and the Harbor Hill Moraine. Regarded to as the spine of Long Island, the Ronkonkoma Moraine starts from the Greenwood Cemetery to Forest Park, continuing onto Cunningham, Nassau, and into Suffolk County. Meanwhile, the Harbor Hill Moraine extends eastward and intersects with the Ronkonkoma Moraine at Lake Success. (Source: Forgotten New York

These terminal moraines reach the highest altitude of nearly 400 feet above sea level. The Ronkonkoma Moraine and the Harbor Hill Moraine come from an enormous continental glacier’s advance during the Wisconsin glaciation of the Pleistocene Epoch. (Source: Garvies Point Museum & Preserve

Long Island not only contains the Ronkonkoma and the Harbor Hill Moraines, but they also have numerous smaller glacial land qualities. (Source: Garvies Point Museum & Preserve

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