GEO 103 Lecture 32: Cenozoic Life
28 Apr 2017
School
Department
Course
Professor
Document Summary
Climatic events having durations of centuries such as little ice age, too short to be accounted for by plate tectonics or milankovitch cycles. Variations in solar energy due to changes in sun itself. Passage of solar system through interstellar dust/gas clouds reflecting solar radiation into space. Volcanism injecting ash and gas into the atmosphere, reflecting solar radiation. This is not known to decrease temperatures over hundreds of years, but rather only a couple of years such as the cases that had happened in the last few hundred years. Sulfur gases from volcanism also known to have cooling effect on climate. Although cooling effects of volcanic eruptions well documented, no established correlation with short-term climate cycles. Not surprisingly, cenozoic fossil record is relatively complete compared to mesozoic, paleozoic, and precambrian. By the cenozoic, earth taking on present-day appearance - eg. mammals clearly differentiated from ancestors and highly diversified. Contrary to common perception, evolutionary processes do not lead to increasingly complex organisms.
