Weathering

1. Weathering GPH 111

2. Weathering Game Plan: • What is WEATHERING and how does it fit within gemorphology? • Major TYPES of weathering • How does climate affect weathering?

3. What is Weathering? • The collective processes that lead to the surface and sub-surface disintegration and dissolution of rock. The major types include physical, chemical, and biological weathering.

4. Weathering within Geomorphology Sierra Estrella Mountains and the Gila River

5. Weathering Processes • Salt Weathering • Sheeting • Solution • Frost Action • Oxidation • Hydration • Hydrolysis • Thermal Expansion

6. Weathering Processes • Chemical _________ - Minerals chemically combine with water _________ - Mineral breakdown through contact with Oxygen (Rust) _________ - Mineral absorption of water causes swelling and stress _________ - Mineral dissolution by water Examples:Spheroidal Weathering, Karst Topography, Gnamma Pits • Physical _________ - Water freezing induced expansion _________- Mineral crystal growth induced expansion _________ - Pressure released expansion through unloading _________ - Rapid heating from lightning and fires Examples - Exfoliation Domes and talus slopes • Extra

7. Weathering Processes • Chemical Hydrolysis - Minerals chemically combine with water Oxidation - Mineral breakdown through contact with Oxygen (Rust) Hydration - Mineral absorption of water causes swelling and stress Solution - Mineral dissolution by water into their ionic form Examples:Spheroidal Weathering, Karst Topography, Gnamma Pits • Physical Frost Action - Water freezing induced expansion Crystallization - Mineral crystal growth induced expansion Sheeting - Pressure released expansion through unloading Thermal Expansion - Rapid heating from lightning and fires Examples - Exfoliation Domes and talus slopes • Extra

8. Chemical Weathering Processes • Weathering Processes Hydrolysis Oxidation Hydration Solution • Associated Weathering Landforms Spheriodal Weathering Karst Topography Gnama Pits

9. Chemical Weathering This process removes CO2 from the atmosphere, counteracting global warming • Hydrolysis Minerals chemically combine with water, substituting silica for hydrogen and weathering individual mineral grains Feldspar (K, Al, Si, O) + carbonic acid and water residual clays (Kaolinite) + dissolved minerals + Si

10. Chemical Weathering Iron bearing minerals (like biotite) combine with Oxygen to generate oxides and softer clay minerals. • Oxidation Rusted railway car; that has undergone oxidation

11. Chemical Weathering • Oxidation The Wave, Southern Utah Wupatki, Northern Arizona

12. Chemical Weathering • Hydration - Clay minerals absorb moisture along their cleavage planes, dramatically increasing in volume.

13. Chemical Weathering Water is the universal solvent, capable of dissolving at least 57 of the natural elements Minerals can dissolve into ions with water, like dissolving sugar in coffee • Solution

14. Weathering Landform • Karst Topography - generated through solution mostly into limestone bedrock

15. Weathering Landform Caves and Caverns

16. Sinkholes • Karst Topography Can Be Associated with Extensive Damage (Sink Holes)

17. Weathering Landform • Spheroidal Weathering - Chemical weathering attacks all surface areas, rounding sharp edges into spheroid shapes.

18. Weathering Landform

21. Weathering Landform • Gnamma Pits - How do you think these guys form, what chemical weathering processes could affect their growth?

23. Physical Weathering Processes • Weathering Processes Frost Action Salt Weathering Sheeting Thermal Expansion • Associated Weathering Landforms Talus Slopes Exfoliation Domes

24. Physical Weathering • Frost Action - Where water seeps into rock weaknesses during day, then freezes and expands at night--breaking the rock apart.

25. Physical Weathering

27. Weathering Landform • Chemical weathering rounds rocks--physical weathering generates angular rocks. • Talus Slope - A pile of angular rock fragments

28. Physical Weathering • Crystallization -Where mineral rich water seeps into rock, evaporates, and allows the dissolved solids to crystallize, breaking the rock apart.

29. Only non-water related process Physical Weathering • Sheeting - Buried rocks are under tremendous pressure and once uncovered, pressure drop sharply and the rocks rebound. Sandstone Granite

30. Half Dome, CA Weathering Landform • Exfoliation Dome - Develop after extensive unloading and sheeting. Enchanted Rock, Texas

31. Physical Weathering • Thermal Expansion - Rocks dramatically heated by forest fires can explode when water absorbed in the rock flashes to steam.

32. Physical Weathering • Thermal Expansion - Rocks dramatically heated by lightning can explode when water absorbed in the rock flashes to steam.

33. Physical Weathering • Thermal Expansion - Different rates of mineral expansion and water absorption throughout numerous day and night cycles.

34. Extra Weathering • Root Growth - Root growth extends into rock fractures, expand and bust the rock apart

36. Where do you think the different weathering processes dominate on the planet? • In the Amazon (Tropical Rainforest) • Serengeti of Africa (Savanna) • Death Valley (Arid) • Minnesota (Humid Continental) • The Sierras (High Alpine) • Alabama (Humid subtropical) Make a list for each one!!!

37. Importance of Surface Area • What will weather quicker, one huge boulder or a huge boulder broken down into a bunch of smaller boulders? Why?

38. What does Weathering DO? • The in situ disintegration of rock supplied by tectonic (and isostatic) rock input!

39. Things to Know: • What is weathering • Chemical processes round edges, physical processes generate angles • Types of chemical weathering and associated landforms • Types of physical weathering and associated landforms • Importance of SURFACE AREA Need Help: WM