Wednesday, October 1, 2014

Geo 730: October 1, Day 639: Over the Sea Wall

This is an odd perspective, but we're looking directly over the edge of the sea wall in downtown Depoe Bay. You can see a bit of the wall along the upper right edge of the photo. This is a fairly wide-angle shot, so in the bottom right, we're looking almost straight down; up and to the left, we're looking progressively closer to horizontal. But what are we looking at? These are pillows of Columbia River Basalt, from flows that made it all the way across the state, to the edge of the Pacific Ocean, which was close to the same position at the time (Miocene) as it is now. As I commented, back in April, my suspicion is that these pillows formed, then sank into unconsolidated sediments of the Astoria Formation. I can imagine pillows forming invasively, that is, basalt forming pillow structures as it intrudes into soft sediment, but it seems like it would necessarily have a more chaotic result than we see here. The pillows are quite regular.

Photo unmodified. July 15, 2014. FlashEarth Location.

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