GEO 330 Lecture Notes - Lecture 5: Impact Crater, Zodiacal Light, Eugene Merle Shoemaker
6 Feb 2018
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Document Summary
Cratering as a geologic process: age dating of surfaces, properties of target material. Water (volatiles: crater shapes are "known" Deduce post-impact tectonics: post-impact erosion/deposition processes, sub-surface layering, simple to complex cratering -> "lithosphere-scale layering, atmospheric properties. Shoemaker: meteor crater first feature on earth widely recognized as impact crater - evidence used was: Meteorite fragments found (only for small craters) Presence of glass as a cementing agent of ejecta fragments - not volcanic but due to shock pressure: ~180 impact craters now known on earth. Available data: size and number of craters (size frequency distribution (sfd), depth/diameter ratio, different terrains, shape (simple, complex, peaks, rings, pits, etc. ) Crater sfd and crater-forming objects: sfd of the craters on a planetary body is a function of the sfd of the objects in the solar system. N = number of craters with a diameter larger than d. B varies between 2 and 5 according to diameter d, but average value for objects larger than.
