1. THE HYDROSPHERE AND GRADATIONAL PROCESSES
UNIT III
THE HYDROSPHERE
AND
GRADATIONAL PROCESSES

2. 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

3. 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

4. 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

5. 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)

7. 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

8. 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

9. 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

10. Stage 1: Youth
V-Shaped Valley

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

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

13. Homework
Read Chapter 7, “Wearing Down the Land fro Above” pp
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.