Monday, October 20, 2014

Geo 730: October 20, Day 658: Looking Back

This is the view from Devils Punchbowl, looking back north to the site of yesterday's photo, Otter Crest. That headland and the next one beyond are composed of Columbia River Basalt. The yellow to gray tilted beds in the middle promontory are Astoria Formation, which was deposited but not yet lithified when the basalt arrived. Those beds, in turn, were beveled off to create a flat marine terrace, upon which the much lighter, flat-lying sands were deposited. The the whole kit and kaboodle was uplifted by, presumably, Cascadia earthquakes or deformation caused by subduction. Though you can't see it here, the headland from which I shot this is essentially the same sequence as we see in the mid-distance.

Photo unmodified. July 15, 2014. FlashEarth Location.

No comments: