ZOOLOGY 651 Chapter Notes - Chapter 4, 5: Paul J. Crutzen, Graptolithina, Ordovician
16 Sep 2016
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Gubbio, about a hundred miles north of rome. Gola del bottaccione; geologist walter alvarez had discovered the first traces of the giant asteroid that ended the cretaceous period. Alvarez wanted to figure out how, on the basis of plate tectonics, the italian peninsula came into being. Key was a reddish limestone, scaglia rosso. Disappearance of lower layer seemed abrupt although alvarez was a uniformitarianism, gradual processes. Alvarez"s father, luis, came up with idea to test clay using iridium to determine how much time the clay represented. Iridium is more common in meteorites the longer it had taken the clay layer to accumulate, the more cosmic dust would"ve fallen. Clay layer had levels off the charts. Shocked quartz - result of bursts of high pressure that deform the crystal structure grains of shocked quartz were discovered in a layer of clay from the cretaceous-tertiary (k-t) Based on the species preservation potential rarely fossilized preserved more frequently abundant still.
