Glaciers are powerful agents of erosion and deposition, carving out dramatic landscapes and depositing a variety of landforms as they advance and retreat. The landforms created by glaciers can be classified into two main categories: erosional and depositional landforms.
Erosional Landforms
- Cirques
- Description: A cirque is an amphitheater-like valley formed by glacial erosion at the head of a glacier. It has a characteristic steep, concave, and often bowl-shaped depression.
- Formation: Cirques are formed by the rotational movement of the glacier, which erodes the landscape in a circular manner. Frost action and plucking further deepen the cirque.
- Example:
- Kareri Lake, India: Located in the Dhauladhar range of the Himalayas, Kareri Lake is a cirque lake formed by glacial activity.
- Glendalough, Ireland: The Upper Lake in Glendalough is situated in a classic glacial cirque.
- Arêtes and Horns
- Description: Arêtes are sharp ridges that form between two cirques or glacial valleys, while horns are sharp, pyramid-like peaks formed by the convergence of multiple arêtes.
- Formation: Arêtes are formed by the erosion of glaciers on opposite sides of a ridge. Horns are created when several glaciers erode a mountain from different sides.
- Example:
- The Matterhorn, Switzerland: This iconic mountain is a classic horn formed by the convergence of several glacial cirques.
- The Garden Wall, Glacier National Park, USA: An arête that provides a dramatic view and is a remnant of glacial erosion.
- U-shaped Valleys
- Description: U-shaped valleys, also known as glacial troughs, have a characteristic U-shape with steep sides and a flat bottom.
- Formation: These valleys are carved by the movement of glaciers, which erode the valley floor and sides uniformly, transforming a V-shaped river valley into a U-shaped valley.
- Example:
- Yosemite Valley, USA: Formed by glacial activity, Yosemite Valley is a classic U-shaped valley.
- Kashmir Valley, India: The scenic Kashmir Valley is an example of a U-shaped valley formed by glacial action.
Depositional Landforms
- Moraines
- Description: Moraines are accumulations of glacial debris (till) that have been transported and deposited by a glacier. There are different types of moraines, including terminal, lateral, medial, and ground moraines.
- Formation: Moraines form from the debris that glaciers pick up and carry along their path. When the glacier retreats, it leaves behind these deposits.
- Example:
- Gangotri Glacier, India: The terminal moraine of the Gangotri Glacier is a prominent feature.
- Long Island, USA: Formed by terminal moraines of glaciers from the last Ice Age.
- Drumlins
- Description: Drumlins are streamlined, elongated hills formed by glacial action, often found in groups known as drumlin fields.
- Formation: Drumlins are formed by the reshaping of previously deposited till by the movement of the glacier, creating an asymmetrical shape with a steep stoss side and a gentle lee side.
- Example:
- Central New York, USA: The region is known for its extensive drumlin fields.
- Kangra Valley, India: Drumlins can be found in this region, formed by past glacial activity.
- Eskers
- Description: Eskers are long, winding ridges of sand and gravel deposited by meltwater streams flowing beneath a glacier.
- Formation: As glaciers melt, the subglacial streams deposit sediments along their paths, which remain as ridges when the glacier retreats.
- Example:
- Maine, USA: The state has several prominent eskers formed during the last glacial period.
- Thar Desert, India: Although primarily a desert, some eskers are found in regions that were once glaciated.
- Kettle Lakes
- Description: Kettle lakes are depressions left behind after partially buried ice blocks melt, filling with water to form a lake.
- Formation: Kettle lakes are formed when chunks of ice calve off the front of a retreating glacier and become buried in glacial till. When the ice melts, it leaves behind a depression that fills with water.
- Example:
- Minnesota, USA: Known as the “Land of 10,000 Lakes,” many of which are kettle lakes.
- Tso Kar, India: Located in Ladakh, it is an example of a kettle lake formed by glacial activity.
Summary
Glacial landforms are a testament to the powerful force of glaciers in shaping the Earth’s landscape. Erosional landforms such as cirques, arêtes, horns, and U-shaped valleys are created by the glacier’s ability to carve through rock and soil, while depositional landforms like moraines, drumlins, eskers, and kettle lakes are formed from the sediments transported and deposited by glaciers. Understanding these landforms helps us appreciate the dynamic processes that have sculpted many of the world’s most dramatic and beautiful landscapes.