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6. LANDFORMS AND THEIR EVOLUTION

The chapter discusses the various types of landforms, their evolution, and the geomorphic processes responsible for their formation. It covers the roles of running water, glaciers, groundwater, waves, and wind in shaping the Earth's surface through erosion and deposition. The interrelationships among different landforms and their development stages are highlighted, showcasing how climatic conditions and geological activities influence these changes.

Sections

LANDFORMS AND THEIR EVOLUTION

This section explores landforms and their evolution through geomorphic processes such as erosion and deposition.

6 Section Overview

Start current section content and materials

6.1 RUNNING WATER

Running water is a key geomorphic agent that shapes the earth's surface through processes of erosion and deposition, particularly in humid regions.

6.1.1 Is complete reduction of relief of a high land mass possible?

This section explores whether it is possible for high land masses to be completely reduced through geomorphic processes such as erosion and deposition.

6.1.2 Youth

This section discusses the characteristics and evolution of landforms, especially focusing on the primary geomorphic processes involving running water and their stages: youth, maturity, and old age.

6.1.3 Mature

The section discusses the evolution of landforms, emphasizing the mature stage characterized by well-defined streams and valleys.

6.1.4 Old

This section explores the concepts of landforms, particularly focusing on their evolution due to geomorphic processes like erosion and deposition.

6.2 EROSIONAL LANDFORMS

This section explains the processes through which erosional landforms such as valleys, potholes, plunge pools, entrenched meanders, and river terraces are formed.

6.2.1 Valleys

This section discusses the formation and evolution of valleys through the actions of geomorphic agents, highlighting various types of valleys and their characteristics.

6.2.2 Potholes and Plunge Pools

Potholes and plunge pools are significant erosional features formed by the action of flowing water on rocky stream beds.

6.2.3 Incised or Entrenched Meanders

Incised or entrenched meanders are deep, wide bends formed in a river's course typically in steep terrain, highlighting the interplay between erosion and geological changes.

6.2.4 River Terraces

River terraces are remnants of old valley floors created by the process of erosion and deposition, indicating former riverbed levels.

6.3 DEPOSITIONAL LANDFORMS

This section explores the different types of depositional landforms, including alluvial fans, deltas, floodplains, natural levees, point bars, and meanders.

6.3.1 Alluvial Fans

Alluvial fans are landforms created by the deposition of coarse material from streams as they flow from steep slopes to gentler plains.

6.3.2 Deltas

Deltas are landforms formed from the accumulation of sediment where a river meets a larger body of water, exhibiting distinct characteristics such as well-sorted deposits.

6.3.3 Floodplains, Natural Levees and Point Bars

Floodplains are key river depositional landforms that shape the landscape through sediment deposition, featuring natural levees and point bars.

6.3.4 Meanders

This section explains the formation and characteristics of meanders in river systems as a result of erosion and deposition processes.

6.4 GROUND WATER

Groundwater is a crucial geomorphic agent involved in the erosion and evolution of landforms, particularly in limestone regions through chemical processes.

6.5 EROSIONAL LANDFORMS

This section discusses various erosional landforms caused by water movement in limestone regions, focusing on swallow holes, sinkholes, and caves.

6.5.1 Caves

Caves are significant landforms created primarily through the dissolution of limestone by water, leading to unique erosional and depositional features.

6.5.2 Depositional Landforms

Depositional landforms are primarily formed in limestone caves due to the deposition of calcium carbonate.

6.5.3 Stalactites, Stalagmites and Pillars

The section explores the formation and characteristics of stalactites, stalagmites, and pillars in limestone caves, detailing how these unique landforms arise from the deposition of mineral-rich water.

6.6 GLACIERS

This section discusses glaciers as powerful agents of erosion and deposition, detailing the various landforms formed through glacial activity.

6.7 EROSIONAL LANDFORMS

Erosional landforms, primarily shaped by glacial activity, include features such as cirques, horns, and glacial troughs, each representing distinct processes of erosion in mountainous regions.

6.7.1 Cirque

Cirques are key glaciated landforms shaped by glaciers, characterized by deep, trough-like basins often containing lakes.

6.7.2 Horns and Serrated Ridges

This section discusses how horns and serrated ridges form through glacial erosion, highlighting the striking features created by the headward erosion of cirque walls.

6.7.3 Glacial Valleys/Troughs

This section discusses the characteristics, formation, and significance of glacial valleys and troughs in shaping the landscape.

6.7.4 Depositional Landforms

This section covers glacial till and outwash deposits, highlighting their characteristics and formation processes.

6.7.5 Moraines

Moraines are accumulations of glacial till formed by the movement of glaciers, creating ridges of debris along the sides and ends of glacial valleys.

6.7.6 Eskers

Eskers are sinuous ridges formed by glacial meltwater streams that deposit sediments beneath glaciers.

6.7.7 Outwash Plains

Outwash plains are expansive areas formed by glacial meltwater carrying sediments to the plains at the foot of glacial mountains or beyond continental ice sheets.

6.7.8 Drumlins

Drumlins are smooth, oval-shaped ridges formed primarily of glacial till, indicating the direction of glacier movement.

6.8 WAVES AND CURRENTS

This section discusses coastal processes primarily driven by waves and currents, focusing on the erosion and deposition shaping coastal landforms.

6.9 HIGH ROCKY COASTS

High rocky coasts are characterized by steep cliffs, wave-cut platforms, and limited depositional features due to strong erosive forces.

6.10 LOW SEDIMENTARY COASTS

Low sedimentary coasts are characterized by smooth shorelines that exhibit significant deposition, with rivers building coastal plains and forming deltas.

6.11 EROSIONAL LANDFORMS

Erosional landforms like wave-cut cliffs, terraces, sea caves, and sea stacks develop due to the relentless action of waves alongside coastal erosion processes.

6.11.1 Cliffs, Terraces, Caves and Stacks

This section discusses the erosional landforms created by wave actions, including cliffs, terraces, caves, and sea stacks.

6.12 DEPOSITIONAL LANDFORMS

This section explores different types of depositional landforms, specifically focusing on beaches, dunes, bars, barriers, and spits.

6.12.1 Beaches and Dunes

This section describes the formation, characteristics, and significance of beaches and dunes as coastal landforms influenced by erosion and deposition processes.

6.12.2 Bars, Barriers and Spits

This section explores coastal landforms like bars, barriers, and spits, highlighting their formation processes and environmental significance.

6.13 WINDS

Wind is a dominant agent of erosion in hot deserts, impacting landforms through deflation and abrasion.

6.14 EROSIONAL LANDFORMS

This section outlines the processes and formations of erosional landforms such as pediments, playas, deflation hollows, and others primarily in desert environments.

6.14.1 Pediments and Pediplains

This section discusses the formation and evolution of pediments and pediplains, highlighting their significance in the landscape evolution process.

6.14.2 Playas

Playas are shallow lakes in desert basins that temporarily hold water, often covered by salt flats as evaporation occurs.

6.14.3 Deflation Hollows and Caves

Deflation hollows are shallow depressions formed by wind erosion that can lead to the creation of caves over time.

6.14.4 Depositional Landforms

This section explains how wind acts as a sorting agent for sediment particles, influencing the formation of depositional landforms.

6.14.5 Sand Dunes

This section explores the formation, types, and characteristics of sand dunes, highlighting their significance in desert environments.

6.14.6 Mushroom, Table and Pedestal Rocks

This section explores how wind erosion creates distinctive landforms in desert environments, specifically mushroom, table, and pedestal rocks.

6.15 Exercises

This section focuses on various exercises related to landforms and their evolution, emphasizing concepts such as erosional and depositional landforms.

Learning Objectives

  • Landforms are defined as small to medium tracts of the Earth's surface, while landscapes consist of several related landforms.

  • Geomorphic processes such as erosion and deposition significantly alter the surface of the Earth over time.

  • The evolution of landforms involves a sequence of stages comparable to life stages, including youth, maturity, and old age.

Key Concepts

Landform

A small to medium sized part of the Earth's surface characterized by its unique shape and the geomorphic processes that formed it.

Erosion

The process by which surface materials are worn away and transported by natural agents like water, wind, and ice.

Deposition

The accumulation of materials transported by erosion at a new location, leading to the formation of new landforms.

Karst Topography

Landforms that form as a result of the dissolution of soluble rocks such as limestone, characterized by features such as caves, sinkholes, and lapies.

Glacial Erosion

The landform alterations caused by glacial movements, which can significantly reshape valleys and create distinct geological features.

Practice Exercises

Total Questions

3

Estimated Time

6 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting