Geological Processes: Erosion, Transport, and Sedimentation

Rain Pathways and Surface Water

Rainwater follows three primary paths: evaporation, groundwater infiltration, and surface water runoff. Surface waters act as the primary agents of external geological modeling on terrestrial landscapes. Wild waters refer to surface water that has not yet formed a defined channel.

Geological Activity of Rivers

• Erosion: The action of water breaking down materials through collisions with the sediment load it carries.
• Transport: Materials are moved via solution or suspension, while larger debris is displaced along the riverbed through collision and abrasion.
• Sedimentation: Occurs when transport capacity is reduced due to a decrease in flow or slope gradient.

Fluvial Landforms

Erosion by Waterways:

• Differential Erosion: Occurs where rock resistance varies, creating uneven ground levels.
• Soft Ground Erosion: Water accentuates gullies and ravines.
• V-Shaped Valleys: Formed in mountainous regions where the river deepens its bed.
• Trough Valleys: The river erodes the walls more than the channel floor, widening the valley.
• River Terraces: Former floodplains abandoned at levels above the current water flow.

Glacial Geomorphology

A glacier is a mass of ice that moves across the terrestrial surface.

Types of Glaciers

• Ice Caps: Huge masses of ice covering polar regions.
• Valley Glaciers: Large ice masses located in high mountain areas.

Glacial Zones

• Circus: The highest area where snow transforms into ice.
• Tongue: The mass of ice moving down the valley.
• Terminal Zone: The area where ice melts and deposits materials.

Glacial Processes

• Erosion: Rock fragments embedded in the ice act as abrasives, polishing rocks and creating glacial striations.
• Transport: The ice moves a mass of materials that remain angular because they do not roll.
• Sedimentation: Materials are deposited once the ice melts.

Glacial Landforms

• U-Shaped Valleys: Glaciers excavate valleys with a distinct U-shaped profile.
• Hanging Valleys: Tributary valleys of ancient glaciers located above the main valley floor.
• Glacial Lakes: Formed where the glacier over-excavates the channel.
• Moraines:
  • Frontal Moraine: Deposits at the front of the glacier.
  • Lateral Moraine: Deposits along the sides of the glacial tongue.
  • Central Moraine: Formed by the junction of two lateral moraines from merging glaciers.