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Moraine may also form by the accumulation of sand and gravel deposits from glacial streams emanating from the ice margin. These fan deposits may coalesce to form a long moraine bank marking the ice margin. [11] Several processes may combine to form and rework a single moraine, and most moraines record a continuum of processes.
The Oak Ridges Moraine probably formed in the Late Wisconsin glacial period. Ice melt from the Niagara Escarpment flowed into the western boundaries of the moraine, wherein conduits beneath the ice expanded to form a west-to-east passage between the main Laurentide Ice Sheet and a mass of ice in the Lake Ontario basin.
The name and specific characteristics of a moraine are dependent upon its location relative to the glacial body and the processes that deposited the relevant glacial till. [7] Four overarching types of moraines include lateral, medial, ground, and end. The size of the deposited sediments which form a moraine can range from clay to boulder sized.
Rain and snow melt slowly soak into the moraine, being filtered and purified in its many sand and gravel aquifers. The cool, fresh water is discharged into the headwaters of streams and rivers which eventually flow into Lake Simcoe, Lake Scugog and Lake Ontario. The aquifers are also the water supply for some communities on the Moraine.
A moraine-dammed lake, occurs when the terminal moraine has prevented some meltwater from leaving the valley. When a glacier retreats, there is a space left over between the retreating glacier and the piece that stayed intact which holds leftover debris ( moraine ).
In mountain valleys where glacier movement has formed circular depressions, cirque lakes (or tarns) may form when the water becomes dammed. When damming occurs due to debris from the glacier movement, these lakes are called moraine lakes.
While the terminal moraine consists of a long mound of rock and sediment which forms a structure that appears to be a barrier for water, there are still ways for the water to flow through. Water makes its way through glacial till to form streams and channels. Another landscape feature formed by terminal moraines are kettle lakes.
Tarn—a proglacial lake impounded by the terminal moraine of the retreating Schoolroom Glacier in Grand Teton National Park, Wyoming In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier , a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic ...