Glacial depositional features Flashcards
What is a Lateral moraine and how is it formed?
As glaciers flow down a valley, they erode material away from the valley sides. Eroded sediment builds up between the glacier and valley side. When the glacier melts. material is deposited parallel to where the glacier once existed in two narrow ridges, one on each side of the valley.
What is a Medial moraine and how is it formed?
When two glaciers meet, the lateral moraine from the two glaciers come together in the centre of one large glacier. This sediment is observed on the glacier surface, but is not observed after the glaciers have melted.
What is a Terminal moraine and how is it formed?
Glacial till deposited at the end (snout) of the glacier. This moraine stretches the width of the valley floor. It marks the location of the furthest ice advance during the last glacial period
What is a drumlin and how is it formed?
A low, oval mound/small hill insisting of compacted boulder clay, moulded by glacial actions.
Formed by glaciers that re-shape the ground beneath them. They point in the direction the glacier flowed.
What is an erratic and how is it formed?
Glacier-transported rock fragment that differs from the local bedrock.
Formed when large rocks are carried by glaciers and are deposited far from their origins, standing out in their landscape.
What is boulder clay and how is it formed?
The clay, sand, stone, or boulders left by melting ice sheets/glaciers
Formed when a glacier melts, creating a varied landscape.
Hummocky moraine
Formed in the dying days of a glacier, when all the sediment being carried by the glacier is dumped randomly across the valley floor. This creates lumps and bumps on the surface of the landscape.
Recessional moraine
Glaciers retreat during the summer when the temperatures are warmer. Glaciers advance during the winter when the temperatures are cooler. Parallel lines of glacial till are deposited across the width of the valley, as the glacier responds to changes in climate.
