Match The Glacial Features With Their Descriptions.

Match the Glacial Features with Their Descriptions: A Comprehensive Guide

Glaciers, majestic rivers of ice, sculpt the Earth's landscape in breathtaking and powerful ways. Their movement carves valleys, transports sediment, and leaves behind a unique array of landforms. Understanding these glacial features is key to appreciating the power of these icy giants and the geological history they reveal. This comprehensive guide will delve into various glacial features, matching them with their descriptions to enhance your understanding of glacial geomorphology.

Types of Glacial Features: A Categorization

Before we dive into the specifics, it’s helpful to categorize glacial features based on their formation:

1. Erosional Features: These are landforms created by the abrasive and plucking action of glaciers as they move. The glacier acts like a giant bulldozer, scraping away at the underlying rock and soil.

2. Depositional Features: These are landforms created by the deposit of sediment carried and transported by glaciers. As glaciers melt, they release the vast amounts of rock, gravel, sand, and silt they've accumulated.

Let's now explore some of the most prominent glacial features, categorized for clarity:

Erosional Glacial Features: Sculpting the Landscape

1. Cirque: A Hollowed-Out Amphitheater

Description: A cirque is a bowl-shaped depression carved into a mountainside by a glacier. It's often found at the head of a glacial valley and is characterized by steep, often near-vertical, walls and a relatively flat floor. The formation of a cirque involves freeze-thaw weathering, where water seeps into cracks in the rock, freezes, and expands, causing the rock to fracture and break away. This debris is then plucked and transported by the glacier, deepening and widening the hollow.

Keywords: Cirque, glacial erosion, freeze-thaw weathering, bowl-shaped depression, mountainside, head of glacial valley

2. Arête: A Knife-Edge Ridge

Description: An arête is a sharp, narrow ridge separating two adjacent cirques or glacial valleys. It's formed by the erosional action of two glaciers eroding away the rock between them, leaving behind a thin, jagged ridge. The process is often enhanced by freeze-thaw weathering and plucking.

Keywords: Arête, sharp ridge, glacial erosion, two cirques, glacial valleys, freeze-thaw weathering, plucking

3. Horn: A Pyramidal Peak

Description: A horn is a pointed, pyramidal peak formed when three or more cirques erode into a mountain from different directions. The converging erosion leaves behind a steep, isolated peak. The Matterhorn in the Swiss Alps is a classic example of a horn.

Keywords: Horn, pyramidal peak, glacial erosion, three or more cirques, converging erosion, isolated peak

4. U-Shaped Valley: A Glacial Carving

Description: A U-shaped valley is a valley with a characteristic U-shaped cross-section, formed by glacial erosion. Unlike V-shaped valleys carved by rivers, U-shaped valleys have steep, straight sides and a flat, wide floor. The glacier's immense weight and erosive power widen and deepen the valley, creating its distinctive shape.

Keywords: U-shaped valley, glacial erosion, U-shaped cross-section, steep sides, flat floor, V-shaped valley, river erosion

5. Hanging Valley: A Tributary Valley

Description: A hanging valley is a tributary valley that enters a main glacial valley at a significantly higher elevation. This is because the smaller glacier that carved the tributary valley eroded less deeply than the larger glacier that carved the main valley. The result is a valley that appears to "hang" above the main valley, often resulting in waterfalls where the tributary stream plunges into the main valley.

Keywords: Hanging valley, tributary valley, glacial erosion, higher elevation, waterfall, main valley, smaller glacier

6. Roche Moutonnée: A Sheep-Backed Rock

Description: A roche moutonnée (meaning "sheep back" in French) is a rock formation sculpted by glacial erosion. It has a smooth, gently sloping stoss side (facing the direction of ice flow) and a steep, rugged lee side (facing away from the ice flow). The stoss side is smoothed by abrasion, while the lee side is fractured and plucked by the glacier.

Keywords: Roche moutonnée, glacial erosion, stoss side, lee side, abrasion, plucking, smoothed surface, rugged surface

7. Striations: Scratches on the Rock

Description: Striations are parallel scratches or grooves carved into bedrock by glacial movement. They are formed by rocks embedded in the base of the glacier acting as abrasives, scraping against the underlying rock surface. The direction of striations indicates the direction of ice flow.

Keywords: Striations, glacial erosion, parallel scratches, grooves, bedrock, abrasion, ice flow direction

Depositional Glacial Features: The Legacy of Ice

1. Moraine: Glacial Debris Deposits

Description: A moraine is a landform composed of glacial till—unsorted sediment deposited by a glacier. There are several types of moraines:

• Lateral Moraine: Runs along the sides of a glacier.
• Medial Moraine: Forms in the middle of a glacier where two lateral moraines meet.
• Terminal Moraine: Marks the furthest extent of a glacier's advance.
• Recessional Moraine: A series of moraines formed as a glacier retreats.
• Ground Moraine: A sheet-like deposit of till left behind by a melting glacier.

Keywords: Moraine, glacial till, unsorted sediment, lateral moraine, medial moraine, terminal moraine, recessional moraine, ground moraine

2. Drumlin: An Elongated Hill

Description: A drumlin is an elongated hill composed of glacial till. It's typically oval or egg-shaped, with its long axis parallel to the direction of ice flow. The formation of drumlins is not fully understood, but it is believed to involve the deposition and reshaping of till by a moving glacier.

Keywords: Drumlin, glacial till, elongated hill, oval shape, ice flow direction, deposition, reshaping

3. Esker: A Winding Ridge

Description: An esker is a long, winding ridge composed of stratified sand and gravel. Eskers are formed by meltwater streams flowing within or beneath a glacier. As the glacier melts, the sediment carried by the streams is deposited, creating a long, sinuous ridge.

Keywords: Esker, stratified sand and gravel, meltwater streams, glacier, deposition, sinuous ridge

4. Kame: A Hill of Sand and Gravel

Description: A kame is a hill or mound of stratified sand and gravel deposited by meltwater streams within or at the edge of a glacier. Kames are often found in groups and can vary significantly in size and shape.

Keywords: Kame, stratified sand and gravel, meltwater streams, glacier, deposition, hill, mound

5. Kettle Lake: A Glacial Depression

Description: A kettle lake (also known as a kettle hole) is a depression in the ground formed by the melting of a large block of ice buried in glacial deposits. As the ice melts, it leaves behind a hole that often fills with water, forming a lake.

Keywords: Kettle lake, kettle hole, glacial deposits, melting ice, depression, lake

6. Outwash Plain: A Flat, Sandy Plain

Description: An outwash plain is a flat, gently sloping plain formed by the deposition of sediment carried by meltwater streams flowing away from a glacier. The sediment is typically sorted by size, with coarser material deposited closer to the glacier and finer material further away.

Keywords: Outwash plain, meltwater streams, glacier, deposition, sorted sediment, flat plain, gently sloping

Conclusion: Understanding the Glacial Legacy

This exploration of glacial features highlights the immense power of glaciers to shape the Earth's surface. By understanding the processes of erosion and deposition, we can better interpret the landscapes they leave behind and appreciate the intricate history etched into the land by these magnificent icy rivers. Remember, continued study and observation are key to further enhancing your knowledge of these fascinating geological formations. Further research into specific glacial environments and their unique features will provide an even deeper understanding of glacial geomorphology.