1. Till:
* Definition: Till is unsorted, unstratified glacial sediment deposited directly by the ice. It contains a wide range of particle sizes, from clay to boulders, and often shows angular shapes due to minimal weathering during transport.
* Types of Till:
* Ground moraine: This is the most common type of till, deposited beneath the glacier as it moves. It forms a relatively flat, undulating plain with low relief.
* Lateral moraine: Accumulates along the sides of the glacier. It forms a ridge parallel to the valley walls.
* Medial moraine: Occurs within the glacier, formed by the merging of lateral moraines from tributary glaciers. It appears as a dark band within the ice.
* Terminal moraine: Forms at the furthest point reached by the glacier. It marks the ice front at the time of maximum glacial advance.
* Recessional moraine: Forms as the glacier retreats, leaving behind a series of moraines that mark the position of the ice front at different times.
2. Stratified Drift:
* Definition: Stratified drift is sorted and layered glacial sediment deposited by meltwater. It is typically finer-grained than till, with a greater proportion of sand and gravel.
* Types of Stratified Drift:
* Outwash plain: A broad, gently sloping plain formed by meltwater flowing away from the glacier. It is characterized by well-sorted sediments, often with a braided stream pattern.
* Kame: A steep-sided hill of stratified drift formed by meltwater deposits in a depression on the glacier's surface.
* Esker: A long, winding ridge of stratified drift deposited in a meltwater channel beneath the glacier.
* Kettle: A depression in the landscape formed when a block of ice left behind by a retreating glacier melts. It is often filled with water, forming a kettle lake.
* Drumlin: An elongated, streamlined hill of till formed by glacial erosion and deposition. They are often found in clusters, with the blunt end pointing in the direction of ice movement.
Other Depositional Features:
* Glacial Lake Deposits: As glaciers melt, they can form lakes, which deposit fine-grained sediments such as clay and silt. These deposits often form layers that can be used to study past glacial activity.
* Loess: Fine-grained, wind-blown silt deposited by the wind after glacial meltwater deposits have dried. It forms thick deposits in areas downwind from glacial regions.
These various types of glacial deposition contribute to the diverse landscapes we see in glaciated regions worldwide. Understanding the different forms of deposition helps us interpret the history of glaciers and their impact on the environment.
