HSHM 211 Lecture Notes - Lecture 3: James Dwight Dana, Continental Drift, Oceanic Crust

• School: Yale University
• Department: Hist of Science, Hist of Med
• Course: HSHM 211
• Professor: William Rankin

Document Summary

Plate tectonics: convection currents are the motor, measure motion using gps. Mass extinction: events causing major environmental change, punctuated equilibrium: neo-darwinian. Late 19th through mid-20th centuries: do continents move, same facts explained by different theories, no theories were perfect. Fixism vs. mobilism: fixism (uniformitarianism): ea(cid:396)th"s (cid:272)o(cid:374)ti(cid:374)e(cid:374)ts ha(cid:448)e sta(cid:455)ed i(cid:374) the sa(cid:373)e pla(cid:272)e fo(cid:396)e(cid:448)e(cid:396, cooling earth as theory of continents. James dwight dana (1813-1895): smooth earth with thin ocean that contracted and caused earth to cool, as contraction continued oceans became deeper. Uniformitarianism: edward suess (1831-1914): as earth cools, periodically continents will slump and become oceans, and ocean floors will stay in place and become continents, mobilism (catastrophism): ea(cid:396)th"s (cid:272)o(cid:374)ti(cid:374)e(cid:374)ts ha(cid:448)e (cid:373)o(cid:448)ed o(cid:448)e(cid:396) ti(cid:373)e. Catastrophism: alfred wegener (1880-19): continental drift, 1912, arthur holmes: continent can be split apart by convection currents, 1929. Older rock sitting on top of younger rock. Only explanation: rock layers changed very radically by pressure causing older rock to end up on top of younger rock.