EOSC 114 Lecture Notes - Lecture 23: Extinction Event, Manicouagan Reservoir, Eugene Merle Shoemaker
20 Apr 2018
School
Department
Course
Professor
Document Summary
Impacts on earth used to be thought as improbable . Moon craters assumed to be extinct volcanoes! Gravitational kicks from : nemesis - companion sun. Red dwarf star - smaller, cooler than our sun. Black hole: is there a planet x beyond neptune, moving thru galactic plane. Can detect stars down to 150 k. Other extinction periodicities also looked @ sometimes discounted entirely. History of impacts - early earth probably suffered multiple impacts. Moon craters used to be asumed to be extinct volcs! Gene shoemaker co-discovered comet shoemaker-levy 9 with his wife carolyn s. Sudden geologic changes arise from asteroid strikes. Asteroid strikes common over geologic time periods. Large circular structures associated w. ejecta, shocked quartz, iridium, etc. Other extinction periodicities also looked at (50 ma, etc), sometimes discounted entirely. Slightly less than a mass extinction event is still a concern.
