Thursday, April 17, 2014

Geo 730: April 17, Day 473: Whale Cove Sandstone

Looking more or less north from the southern end of the city of Depoe Bay, in the foreground we see the basalt of Depoe Bay. The buff cliffs under the buildings in the distance are composed of sandstone, referred to as the sandstone of Whale Cove (a small cove just to the south), and the darker rocks out on the point are made of Cape Foulweather basalt. Overall, this represents a pair of Columbia River Basalt flows separated by an interval of sedimentation. It wouldn't surprise me to find that work done in the 40+ years since the geological sketch map I posted Monday has reorganized current understanding and nomenclature of these rocks. For example, the sandstone could have logically been demoted to "member" status in the larger and more extensive Astoria Formation. It's source and environment are probably very similar to the latter formation, with the only real distinction being that it was deposited after a basalt flow reached the area.

Photo unmodified. July 10, 2012. FlashEarth location.

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