THE HYDROSPHERE AND GRADATIONAL PROCESSES UNIT III THE HYDROSPHERE AND GRADATIONAL PROCESSES

the origin and development of landform the origin and development of landform features is attributed to the work of wind, waves, ice Geomorphology: formal scientific study of landforms, the study of form or shape of Earth’s surface Landforms (landscape features) are a product of interaction among three primary factors: 1. Structure 2. Process 3. Development

1. Structure Geological Structure arrangement of rock components acquired during process of formation or deformation (e.g. folds and faults) gradation occurs along zones of weakness

b) Rock Type (Lithology) Dolomite physical, chemical properties of Earth’s materials different rock types exhibit varying degrees of susceptibility to weathering and erosion E.g. granite/rhyolite/ dolomite are more resistant than limestone/ sandstone/shales Limestone

2. Process there are three principal agents of landscape formation or agents of change: WATER, ICE, and WIND of these, by far the most important in terms of the amount of gradation achieved and the proportion of Earth’s land surface area is WATER (even in glacial and desert environments)

Landscape reduction is accomplished by three processes: Weathering the mechanical and chemical break-up of Earth’s materials into smaller particles. Also, there is Biological weathering. Erosion involves the pick-up and transportation of weathered materials from one location to another Weathering Erosion

c) Deposition involves the accumulation of transported earth materials (debris) in localities where energy is no longer available for work and transport occurs on level surfaces, still water bodies or surfaces of zero potential energy – known as base level of erosion

3. Stage of Development the type and rate of geomorphological evolution is also a function of the nature and intensity of the stresses imposed by various agents of weathering and erosion, as well as, the length of time Geographical Cycle: theory of landscape evolution which says landscapes tend to evolve through three distinct stages of development from the time they are first subjected to the time they are totally consumed by agents of weathering and erosion

Stage 1: Youth V-Shaped Valley

Stage 2: Maturity Integrated system of streams, and valleys, sharp divides

Stage 3: Old Age Characterized by the development of a plain of subdued relief

Homework Read Chapter 7, “Wearing Down the Land fro Above” pp. 102- 108. Answer question 1 on p. 114. Explain the difference between mechanical and chemical weathering. Be sure to be able to provide examples. Answer question 3 on p. 114.