Final answer:
An esker is a long ridge of gravel and sand, deposited by a river flowing within a glacier. This feature of glaciation deposition is left behind after the glacier retreats, indicating the path of the ancient meltwater flow.
Step-by-step explanation:
Glaciation Deposition is a geological process where material transported by glaciers is eventually laid down when the ice melts. Features of deposition such as eskers, moraines and drumlins are formed by this glacial activity.
Esker
An esker is a feature of glaciation deposition that can be characterized as:
- A long ridge of gravel and sand.
An esker forms within the channel of a glacier and is left behind as a long, winding ridge after the glacier retreats and the sediment carried by meltwater is deposited. Eskers can often be seen snaking across the landscape marking the paths of ancient subglacial rivers.
Other features commonly associated with glaciation deposition include:
- Circular depressions left by melting blocks of ice, known as kettles.
- Hills of debris called moraines, which accumulate at the sides or terminus of a glacier.
- Erratics, which are large boulders transported and deposited by glacial ice far from their source.