{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


Why do we care about the patterns of extinction

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: kground level, straddling a geological boundary. Why do we care about the patterns of extinction? Possible causes of mass extinctions: sea level fall —> temp drop, development of ice caps Sea level change sea level rise —> high carbon shales form; anoxia Oceanic circulation change uplift decreases greenhouse effect and cause global cooling —> high weather reactions Tectonic activity absorb co2 Volcanic activity adds ash and other aerosols to stratosphere = short term cooling; adds co2 and other greenhouse gases to atmosphere = warming Extraterrestrial impact Examples: three different episodes of mass extinction: 1. end-Permian episode - severe and protracted; not very selective largest extinction in earth history 57% of families; 84% of genera; ~80-96% of species become extinct loss of cambrian fauna and decimation of Paleozoic fauna; severe at low latitudes (tropics) Cause? drop in sea level Extensive marine regression Major drop in ratio of 13C to 12C in ocean reservoirs Overturn of oceans high co2...
View Full Document

{[ snackBarMessage ]}