1. Minerals vs. Rocks Common silicate minerals: Olivine- independent tetrahedra joined by Fe or Mg Pyroxene- single chains of linked tetrahedra Amphibole- double chains of linked tetrahedra Micas and Clays- 2-D sheets of linked tetrahedra Quartz- 3-D framework of fully polymerized tetrahedra Feldspar- also a 3-D framework, but Al, Na, Ca, or K can substitute

2. Minerals vs. Rocks Common non-silicate minerals: Calcite- CaCO 3 a carbonate Dolomite- CaMg(CO 3 ) 2 Apatite- Calcium phosphate (PO 4 ) Halite- NaCl Gypsum- hydrated CaSO 4

3. Rock Types l Igneous

4. Rock Types l Igneous Polished slab of granite 10 cm across Thin section of basalt 4 mm across

5. Rock Types l Sedimentary l Metamorphic

6. 2) The Earth’s Interior

7. General Geological Principles: 1) Geologic Time

9. Geologic Time l Relative dating by superposition, cross-cutting relationships, fossils and evolution

10. Geologic Time l Relative dating by superposition, cross-cutting relationships, fossils and evolution l Absolute dating by radioactive decay (igneous) # parent atoms time  1½¼

11. Isostasy Water density 1.0 Wood density 0.5 2 g 3 g 5 g 8 g Water density 1.0 0.5 0.3 0.2 density = 0.1 Each block weighs 2 g

12. Isostasy

13. Isostasy

14. 3) Plate Tectonics

15. Divergent and Transform Plate Boundaries

16. Continental Rifting

17. Continental Rifting the East African Rift

18. Convergent Plate Boundaries

19. “Andean-type” orogenesis l Crust thickens by addition of magma l Compression due to plate convergence

20. Convergent Plate Boundaries The Origin of the Himalayas

21. “Himalayan-type” orogenesis Begins as Andean-type

22. “Himalayan-type” orogenesis How do you locate the “suture zone” today? How can you determine the “polarity” of subduction?

23. Slivers of oceanic crust and upper mantle (ophiolites) become incorporated into the “mélange” in the accretionary wedge of deformed sediments The “suture zone” is marked by the mélange and particularly by the occurrence of ultramafic rocks composing the mantle portion of the ocean lithosphere

24. Chain of ultramafic bodies in Vermont indicating a suture zone of the Ordovician Taconic Orogeny. The ultramafics mark a closed oceanic basin between North American rocks and an accreted island arc terrane. From Chidester, (1968) in Zen et al., Studies in Appalachian Geology, Northern and Maritime. Wiley Interscience.

25. Appalachian History Can “accrete” island arc terranes as well as continents

26. Accreted Terranes of the Western Cordillera

27. Hot Spots

28. The Plate Tectonic Regime of the Western USA

29. Earthquakes and Plate Tectonics

30. General Geological Principles: 4) The Rock Cycle

31. Plate Tectonics and the Rock Cycle

32. Examples of Other Cycles: the Hydrologic Cycle

33. Examples of Other Cycles: the Carbon Cycle

34. Population

35. Population

36. Population Impacts: l Resources l Waste Disposal l Pollution l Hazards/Disasters l Farmland and Food/Soil l Disruption of Natural Systems