GEOG 441 Lecture Notes - Lecture 3: Geochemistry, Silicate Minerals, Tharsis
Document Summary
Noachian surfaces on mars are intensely cratered: craters on top of craters to the point that it becomes challenging to pick out which ones are superposed on which others. Noachian surfaces also show a great diversity of crater sizes, with some big craters mixed in with medium and small ones. Noachian craters, too, show a lot of geomorphic reworking: Very distinctive softening of the rims, as though they"d sagged and spread out. Hardened ejecta blankets with that "wet splat" look, sometimes with two or more layers of flowing ejecta, sometimes with the kinds of striations produced by very rapid and fluidized movement, often ending in a rampart edge. There was quite a bit of this geological work back in noachian times: Valley networks are found almost exclusively on noachian surfaces, showing fluvial action by what is more and more accepted as water, even precipitation-fed channelization.
