Introduction

What is a Landform?

The chapter opens by recalling that weathering acts on earth materials, and then the geomorphic agents — running water, groundwater, wind, glaciers, and waves — perform erosion. Erosion changes the earth's surface, and deposition follows erosion, bringing further changes. So both erosion and deposition shape the surface.

A landform is, in simple words, a small to medium tract or parcel of the earth's surface. Think of it as an individual feature — a hill, a valley, a delta, a sand dune. Each landform has its own physical shape, size, and materials, and it is the result of the action of certain geomorphic processes and agents.

Landform vs Landscape

If a landform is a small to medium part of the surface, then a landscape is the larger picture. Several related landforms together make up a landscape — large tracts of the earth's surface. So a landscape is a collection of connected landforms, not a single feature.

How Landforms Develop

The actions of most geomorphic processes and agents are slow, so the results take a long time to take shape. Every landform has a beginning. Once formed, a landform may change in its shape, size, and nature — slowly or fast — due to the continued action of geomorphic processes and agents.

Changes in climatic conditions and vertical or horizontal movements of landmasses can alter the intensity of processes, or even change the processes themselves. This leads to new modifications in landforms.

What Evolution Means

Evolution here implies stages of transformation — either of a part of the earth's surface from one landform into another, or of individual landforms after they are once formed. In other words, every landform has a history of development and changes through time.

A landmass passes through stages of development somewhat comparable to the stages of life — youth, mature, and old age.

Two Important Aspects of Evolution

The book poses the question: what are the two important aspects of the evolution of landforms? These are:

1. Transformation of a part of the earth's surface from one landform into another — the surface itself changes form over time.
2. Transformation of individual landforms after they are once formed — a single landform continues to change after its initial creation.

Both aspects together capture the full meaning of evolution — landforms are not static; they have a beginning, a history, and a sequence of changes through time, much like living organisms passing through youth, maturity, and old age.