Understanding Geomorphic Processes and Its Impact on Earth's Surface

1. WELCOME[[ Lets try to learn

2. Exogenous Geomorphic Processes: Submited by: Md: Rubaet Bin Abedin Md: Jaber Bin Abdul Bari Md: Ahsan Ullah Md: Abu Yousuf Mst:Israt Mehejabin Mst:Nusrat Jahan Ishita

3. Geomorphic Processes: • Physical processes which create and modify landformson the surface of the earth • Endogenous (Endogenic) vs.Exogenous (Exogenic) Processes • Rock Cycle 

4. Also calledGradational Processes, they comprise degradation and aggradation– they modifyrelief • a continuum of processes – Weathering  Mass Wasting  Erosion  Transportation  Deposition • these processes are carried through by Geomorphic Agents: gravity, flowing water (rivers), moving ice (glaciers), waves and tides (oceans and lakes), wind, plants, organisms, animals and humans • 1. Degradation Processes Also called Denudation Processes • a. Weathering , b. Mass Wasting and c. Erosion and Transportation • Aggradation Processes • a. Deposition – fluvial, eolian, glacial, coastal B. Exogenous Processes

5. Degradation Processes:Weathering, Mass Wasting,Erosion and Transportation

6. Clasify exogenous process.

7. Relationship: Weathering Mass Wasting Erosion and Transportation Together, these processes are responsible for Denudation of Earth’s surface

8. WEATHERING Weathering is disintegration and decomposition of rocks insitu – no transportation involved  produces regolith • More precisely, it involves the mechanical or physical disintegration and/or chemical decomposition that fragments rock masses into smaller components that amass on-site, before being moved by gravity or transported by other agents • The processes begin inmicroscopic spaces, cracks, joints, faults, fractures, lava vesicles and other rock cavities • Types of Weathering: 1) Physical or Mechanical Weathering, 2) Chemical Weathering, and 3) Biological Weathering

9. Physical or Mechanical Weathering • Disintegration and decay of rocks via weather elements: high temperatures, extreme cold and freeze-thaw cycles • No change in chemical composition of rocks • Exfoliation– due to thermal expansion/contraction and/or release of pressure when buried rocks are uplifted and exposed • e.g., Exfoliation Dome (Stone Mountain, GA) and Exfoliation Sheets (Sierra Nevada) • Frost Wedging • Salt Wedging

10. Chemical Weathering •  decomposes rocks through a chemical change in its minerals Oxidation – important in iron-rich rocks – reddish coloration like rust Hydrolysis – igneous rocks have much silica which readily combines with water Carbonation and Solution – carbon dioxide dissolved in water reacts with carbonate rocks to create a soluble product (calcium bicarbonate)

11. Biological Weathering – plants and animals contribute to weathering. • Roots physically break or wedge rock • Lichens (algae and fungi living as single unit), remove minerals and weaken rock by releasing acids • Burrowing animals can increase weathering. Lichens

12. Some important questions: • How is weathering differ from erosion? • How is mechanical weathering differ from chemical weathering? • Why water considered “the most important cause” of withering? • What Cause acid rain? • How does mechanical weathering make it easier for a rock to be chemically weathered? • How does chemical weathering make it easy for a rock to be mechanical weathered?

13. Erosion • What is erosion? • The process by which the earth surface is warm away by the action of glacier,wind, wave etc.

14. What is the driving fources of erosion? • Water • Wind • Ice • Climate • Othet factors

15. What are the types of erosion? • Physical erosion • Chemical erosion • How erosion occure? • Why erosion happen faster in tropical rigion? • How erosion affect sedimentation?

16. How coastal erosion affect the coast line? • What are the difference between weathering and erosion? • What are the affect of erosion? • How erosion impact on human? • How to control erosion?

17. What is transportation? • Movement of earth material sources by water, ice or gravity. • Example: pabbles roled along a river.

18. What is the process of river transportation? • Solution • Suspension • Saltation • Traction

19. EROSION and TRANSPORTATION – Various Geomorphic Agents, associated Processes, and resultingErosional Features • Flowing Water –Fluvial Morphology Humid regions: Perennial streams and entrenched channels, rapids, waterfalls, plunge pools, potholes, meandering streams, bank erosion, oxbow lakes, etc.

20. What is deposition? • Deposition is a process of geological aggradation which involves deposited of rock sediments.

21. – Various geomorphic agents, associated processes and resulting Depositional Features • Fluvial – Humid regions: Braided streams, sand bars, floodplains (alluvium deposits), natural levees, distributaries, deltas Arid regions: Alluvial fans, bajadas, piedmont alluvial plains, playas, playa lakes, Salinas (salt flats) • Eolian – Sand dunes (Barchans, Parabolic, Transverse, Longitudinal, Star), and sand sheets • Coastal –Sea beaches and coral reefs • Glacial – Alpine:Glacial drifts, tills, moraines (lateral, medial, end, terminal, recessional, and ground) Continental: Till plains, outwash plains, drumlins, eskers, kames, erratic DEPOSITION

22. What are the agent of deposition? • Moving water • Wind • Gravity • Ice wear

23. Clasify deposition. • Glacier deposite • Coastal deposite • River how does deposition occur?

24. Thank you all