How Natural Forces Shape Earth’s Landscapes

Posted on Feb 25, 2025 in Geology

Weathering and Erosion

Weathering is the process that breaks down rocks and minerals into smaller pieces due to atmospheric agents. Two key factors in this process are:

Temperature: High temperatures facilitate chemical reactions that disintegrate rocks.
Humidity: Humidity facilitates chemical reactions and produces weathering.

Chemical Weathering: The decomposition of rocks through chemical reactions, altering their mineral composition. Rainwater, being slightly acidic, reacts with rocks, causing them to break down.
Biological Weathering: The breakdown of rocks by living organisms. For example, plant roots exert pressure, causing rocks to fracture.
Mechanical Weathering: The breakdown of rocks into smaller pieces due to physical forces like temperature changes, wind, and rain. Freeze-thaw weathering, caused by fluctuating temperatures around freezing point, is a prime example.

Water, wind, ice, and ocean movements are the primary agents shaping Earth’s landscapes. Key processes include:

Erosion: The movement of weathered rock fragments.
Transportation: The movement of eroded rock material.
Deposition: The settling of rock materials when the transporting force weakens.

Wind erodes, transports, and deposits rock materials through eolian processes, particularly effective during strong winds.

Glaciers, masses of moving ice found in alpine and polar regions, carve distinctive landforms.

Glacial Valleys: U-shaped valleys carved by glacial movement.
Glacial Cirques: Rounded depressions where snow accumulates and transforms into ice.

Glacial tongues carry and deposit rock material known as moraine.

Rivers erode, transport, and deposit materials. The dominant process depends on water velocity.

Upper Course: Fast flow, erosion and transportation dominate, creating narrow, deep valleys.
Middle Course: Slower flow, transportation dominates, meanders form, and valleys widen.
Lower Course: Slowest flow, deposition dominates, and valleys flatten.

Rainwater is highly erosive, especially in arid climates, forming gullies, ravines, and gorges.

Alluvial Fans: Fan-shaped sediment deposits left by slowing streams entering flat valleys.
Fairy Chimneys: Tall, conical rock formations sculpted by erosion.

Karst landscapes are formed by the dissolving action of water on rock.

Slightly acidic water, containing dissolved carbon dioxide, dissolves calcium carbonate in limestone. Dripping water within caves creates deposits:

Sinkholes are depressions formed by the collapse of underground cavities.