Question

What is the material called that is deposited by meltwater beyond the end of a glacier? A) esker B) cirque C) outwash D) moraine

Short answer

The material is called 'outwash' (C).

Step-by-step solution

Understanding the Terminology

First, we need to understand the terms listed in the choices: - **Esker**: A long ridge of gravel and other sediment, typically having a winding course, deposited by meltwater from a retreating glacier or ice sheet. - **Cirque**: A bowl-shaped, steep-walled mountain basin carved by glaciation, often containing a small round lake. - **Outwash**: Sediment deposited by meltwater rivers emanating from a glacier. It is usually well sorted. - **Moraine**: An accumulation of glacial debris (till) carried and deposited by a glacier. By understanding these terms, we can focus on identifying which material is specifically deposited by meltwater beyond the end of a glacier.

Identifying Characteristics of Outwash

Outwash is specifically known for being a deposit made by meltwater rivers flowing from a glacier. When a glacier melts, the water carries sediment away from the glacier and deposits it beyond the glacier's end, creating outwash plains or Outwash fans. This sediment is usually well sorted because of the action of flowing water.

Connecting Description with Choice

The problem specifies that the material is deposited by meltwater beyond the end of a glacier. Given the definitions and understanding from previous steps, 'Outwash' (Choice C) fits this description perfectly, as it is created when meltwater deposits sediments away from a glacier.

Key concepts

Glacial Meltwater

Glacial meltwater plays a crucial role in shaping landscapes as glaciers retreat. As the ice of a glacier melts, it releases this water, which flows away from the glacier. This water is not just any ordinary stream, but it is loaded with sediment. These sediments are picked up by the moving water, creating a dynamic transporter of materials.

The process of meltwater erosion and transportation involves several interesting dynamics:

• Meltwater can carve long valleys, as it carries a significant volume of water and sediment down these paths.
• It sorts and transports sediment, dropping finer materials further away from the glacier and leaving coarser sediments closer.
• The moving meltwater can create unique patterns and landscapes as it shapes the terrain around the receding glaciers.

Understanding how glacial meltwater operates provides insight into the way landscapes are modified in the wake of glaciation.

Outwash Plain

An outwash plain, also known as a sandur, is formed by the deposition of sediments carried by glacial meltwater. These plains typically occur beyond the end of glaciers, where the water slows down, dropping the sediment it carried over long distances.

This geological formation is characterized by its flat and expansive surface. Key features include:

• Well-sorted sediment layering due to the variable speeds of meltwater, which transports lighter grains further than heavier materials.
• Development of braided river patterns, as waterways divide and run simultaneously through the plains.
• A typically broad and low gradient terrain, shaped by the continuous deposition of materials.

The creation of an outwash plain is a clear testament to the powerful influence of meltwater in sculpting and reshaping the earth's geological features.

Glacial Landforms

Glacial landforms are features that are shaped by the powerful movements of glaciers. They include both erosional and depositional features, as glaciers carve and deposit materials across the landscape.

Various types include:

• Cirques: Bowl-like depressions on mountainsides, formed by the glacier's erosive action.
• Eskers: Long, winding ridges of sediment, deposited by streams flowing within or beneath glaciers.
• Moraines: Accumulations of debris and sediment that glaciers deposit, marking former glacial extents.

These features offer insights into past glacial movements, demonstrating the capacity of glaciers to transform vast areas of the Earth's surface. By studying these landforms, scientists gain valuable understanding of historical climate conditions and ecosystem shifts.

Glacial Geology

Glacial geology is a fascinating area within earth sciences that examines how glaciers affect and interact with the earth's crust and surface. It involves studying the deposits, surfaces, and structures left behind by moving ice.

Key focuses include:

• Analyzing the composition of till, which is unsorted glacial debris.
• Understanding the formation process of glacial landforms, such as moraines, drumlins, and outwash plains.
• Examining changes in landscapes due to glacial and meltwater actions.

This field of study not only helps geologists understand past ice ages but also plays a role in predicting future changes in landscapes due to potential future glaciations. Glacial geology not only documents these changes but also helps explain the dynamic processes of Earth’s natural history.