Unformatted text preview: theory evolved in the 1960s. It explains unified mechanisms such as igneous, sedimentary and metamorphic rocks, distribution of earthquakes and volcanoes, the origin of continents and ocean basins, the distribution of fossil plants and animals, the genesis and destruction of mountain chains, and continental drift. Lithosphere – made of both crust and the upper mantle. It is in motion over the asthenosphere. It bends elastically when loaded. Asthenosphere flows plastically when loaded. 2 types of lithosphere – continental ~150 km thick & oceanic ~7 to 100 km thick. Plate Boundaries – lithosphere is fragmented into ~20 tectonic plates. Plates move continuously at a rate of 1 to 15 cm/yr. Continental Margins – where land meets the ocean. (Margins near plate boundaries are “active”. Margins far from plate boundaries are “passive”.) 3 types of plate boundaries – divergent, convergent, transformed...
View Full Document
- Fall '10
- Plate Tectonics, magnetic anomalies, polar wander