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Difficulty: MediumLandform Development by Wind Action and Glaciation

During glacial retreat, unsorted and unstratified rock debris carried by a glacier is deposited directly by the melting ice to form ridges along the edges and snout of the glacial valley. Which of the following landforms is formed by this process?

  1. A moraineAnswer
  2. B
    An oxbow lake
  3. C
    A scree slope
  4. D
    A river delta

Answer

A moraine is the correct landform formed by the direct deposition of unsorted glacial till during ice retreat.
Moraines are formed when glaciers retreat and deposit unsorted rock fragments and sediment (till) directly onto the landscape. Depending on their position relative to the glacier, they form lateral, medial, or terminal ridges.

Step-by-Step Solution

1
Identify the primary agent of erosion and deposition described in the scenario
The process involves melting ice and glacial retreat, placing the feature under glacial depositional landforms.
Glacial deposition is distinct from running water (fluvial) or gravitational mass wasting processes.
2
Analyze the material characteristics and geometry of the landform
The material is unsorted rock debris (till) forming ridges along the glacial margins and snout.
Glaciers deposit unsorted debris (till) directly, which accumulates into ridges known as terminal, lateral, or medial moraines.
3
Evaluate the options to rule out non-glacial processes
Oxbow lakes and river deltas are formed by running water in river systems, while scree slopes are formed by mechanical weathering and mass wasting under gravity.
Only moraines fit the definition of direct deposition of unsorted till by a glacier.

Key Concept

Glacial Deposition and Till Landforms
Estimated Time:1m 0s
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Topics

Landform Development by Wind Action and Glaciation

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