GEOL 101 Lecture 15: Geo 101 Lecture 15
Document Summary
Crust and mantle: earth"s crust and uppermost mantle are solid, somewhat brittle, elastic, outermost solid layer is the lithosphere. Thinnest under the oceans, averaging 50 km thick (30 miles) Under the continents can be up to 100 km thick (60 miles: layer below the lithosphere is asthenosphere (depth of 300 km) Rock not rigid and can ow plastically due to high temperatures and moderate pressure. Allows isostatic, up and down movement, maybe other movement. Fossil record: revealed geology and paleontology matched on opposite sides of the atlantic, matching fossils records that span across all continents. Continental drift: proposed by prominent german meteorologist and geologist alfred wegener in. 1912: concept is that large scale horizontal movements of the earth"s continents, super continent was pangaea, early triassic 237 ma, rejection. No proof they move- no actual measurement. No driving mechanism that could move continents: suggested tidal forces forced continents through ocean crust but was rejected for the force being too small.
