1. Ch. 2 Earth Materials & Processes

2. Earth Materials & Processes Focus: Geologic materials and processes most important to the study of the environment Objectives: –Acquire a basic understanding of the geologic cycle and its subcycles (tectonic, rock, hydrologic, biogeochemical) –Review of some of the important mineral and rock types and their environmental significance –Appreciation/significance of geologic structures –Appreciation of the landforms, deposits, and environmental problems resulting from wind and glacial processes

3. Earth Materials & Processes 1.Geologic cycles & processes (espec. Tectonics) 2.Rocks & Rock Materials –General properties –Types/classification (general) –Geologic structures 3.Surficial Processes: Ice & Wind

4. Earth (Geologic) Processes Combinations of Internal and Surficial Processes affect and shape the environment: –Mountain Building Processes (Internal processes) Volcanism Faulting Folding –Erosional/Depositional Processes (Surficial: driven by solar energy): Water/Rivers Glaciers Wind Landslides

5. Geologic (Earth) Cycles Tectonic (plate tectonics) Rock Cycle Hydrologic Cycle Biogeochemical Cycles –Carbon, Nitrogen, Phosphorous, etc.

6. Tectonic Cycle Tectonic = Large-scale internally driven dynamic earth processes Shape and deform the earth’s crust (landforms) –Mountain building –Continents –Basins

7. The earth is a differentiated planet with dynamic internally-driven processes

8. Essentially all parts are in motion, producing: “Plate” motions in the lithosphere: Plate Tectonics

9. Continuous cycling of “lithospheric” material through: Formation of new “oceanic” crust at “spreading centers” Destruction of older “oceanic” crust at “subduction” zones “Islands” of thick, relatively stable, “continental” crust These “zones” define plate boundaries

10. Surface/Crustal Manifestation of Plate Tectonics

11. Observations/Correlations: Types and spatial distribution of plate boundaries Correlation between plate boundaries and volcanoes (+ earthquakes)

12. Two Types of Crust/Lithosphere: Oceanic Crust (O) Continental Crust (C)  = 2.8  = 2.9  = 4.5 Core  = 10.7

13. Two Types of Crust/Lithosphere: Oceanic (O): forms 70% of earth’s crust constitutes sea-floor bedrock; ~30 km thick made of primary volcanic “basalt”; density=2.7-3.0 Young; No old oceanic crust Continental (C): Thicker (~100 km) Composition: Less dense sediment/granite “floats” on denser mantle material Older Mantle –Primary material (from which basalts are derived) –Underlies crust

14. Plate Boundaries Most major tectonic activity (volcanoes, earthquakes, etc.), and major topographic features occur (or were formed) at plate boundaries

15. Main Types of Plate Boundaries Divergent (splitting apart) Convergent (colliding) Third Type = Transform (e.g., lateral offset)

16. Types Plate Motion, Plate Boundaries, and Examples of Associated Landforms/Features Divergent (separating): O-O sea-floor spreading/mid-ocean ridges C-C Continental “rifts”: Red Sea, Rio Grande & Mississippi river valleys, E. African (Kenyan) Rift Valley Convergent (colliding): O-O Island arc Subduction; Japan, Aleutians O-C Continental margin Subduction; Cascades, Andes C-C Continental collision; Himalayas, Alps, Appalachians Others: Obduction; Accreted terrain

17. Divergent Plate Boundaries (splitting) Oceanic Rifts/Ridges Continental Rifts: –Red Sea; E. Africa –Flood lavas (basalts)

18. Convergent Plate Boundaries (Colliding)

19. Continent-Contintent Convergence Himalayas Alps Urals Appalacians

21. Other Types of Convergence & Convergent Features Oman Obduction Coast Ranges Klammath Mtns. Oman Newfoundland Accreted Terrain: Olympic Mtns. Etc.

22. Lateral offset of divergent boundaries – Offsets of mid-ocean ridges – San Andreas fault Transform Boundaries

23. Other Important Types/Features Hot Spots: –Hawaiian Islands –Yellowstone, Snake River Plain, Columbia River Plateau Flood Basalt Provinces (within continents) –Columbia River Basalts –India, S. Africa, Greenland, Brazil, Germany, etc.

24. Hawaiian Hot Spot

25. Also correlated with distribution of volcanoes and earthquakes (see book)

26. Plate Tectonics of the Western US Major tectonic activity (volcanoes, earthquakes, etc.), and geographical features occur at plate boundaries and/or hot spots.

27. Hydrologic Cycle

28. Carbon Cycle

29. Rock Cycle Stay Tuned

30. Summary Earth is differentiated and dynamic Manifestation of dynamic earth processes in lithosphere = plate tectonics Two types of crust: oceanic & continental Centers/Zones where crust is formed (spreading) or destroyed (subducted) or accreted define plate boundaries Two types of plate boundaries: –Divergent (splitting/spreading) –Convergent

31. Summary con’t Major “tectonic”/topographic features/events are localized at plate boundaries (volcanoes, earthquakes, mountains, trenches, hydrothermal vents) Other related features: –Transform boundaries (faults) –Hot Spots (oceanic & continental) Hydrologic Cycle: Water transport & storage system Biogeochemical Cycles: Counterpart for chemicals ± biologic systems/storage