1. OBJECTIVES: At the end of the presentation, you should be able to know about the following: • Definition of Diastrophism • Theories explaining Diastrophism • Stress and Strain • Faults and Folds
2. Defining DIASTROPHISM:Tectonismdeformation of Earth’s crust by natural processes (movements)leads to the formation of continents and ocean basins, mountain systems, plateaus, rift valleys, and other features.
3. TRIVIA:Do you know that?Due to Earth’s gravity it is impossiblefor mountains to be higher than49, 000 feet (15,000 metres).
4. How does Diastrophism occur?
5. 1.) Isostasy Theory state of gravitational equilibrium between the Earths lithosphere and asthenosphere tectonic plates "float" at an elevation which depends on their thickness and density.
6. Simple Analogy:
7. Example:North Greenland fjord cliffs
8. TRIVIA: Thegeneral term isostasy was coined in 1889 by the American geologist Clarence Edward Dutton.
9. 2.) Contraction TheoryEarth is SHRINKING.Gravity draws the crust inward causing it to bend, buckle and trench.
10.  Shrinking resulted in a reduction in the Earth’s diameter while the circumference remained unchanged due to folding and buckling of the crust
11. 3.) Convection Current Theory convection within the Earths mantle pushes the plates movement of a fluid, caused by differences in temperature
12. According to this theory: Theplate is the cooled surface layer of a convection current in upper mantle.
13. 4.) Continental Drift Theory Continents were joined in a super-continent, called Pangaea (all lands). Over a vast period of time, the continents drifted apart to their current locations.
14. Some Evidences: The jigsaw fit of the outline of the continental margins.
16.  Numerous geological similarities between South America and Africa.
17. TRIVIA: Continental Drift theory was first presented by Alfred Wegener who died two days after his 50th birthday.
18. 5.) Expansion Theory Earth is physically expanding in diameter, mass, or both.
19. 6.) Plate Tectonics Theory Earths outer layer is fragmented into plates that are in constant motion.
20. Plate Boundaries and Their Motions Divergent Convergent Transform/ Thrust
21. Major Earth Movements Uplift Subsidence
22. TRIVIA:Do you knowthat?On everycontinentthere is a citycalled Rome.
23. STRESS AND STRAIN3 main concepts about stress and strain:rocks deform,stress causes strain and strain results in structures,different physical conditions create different structures
24. STRESS is a Force acting on some areas