Saturday, September 27, 2014

Geo 730: September 27, Day 635: Bedded Breccia

While the rocky island to the left shows columns, suggesting basalt that cooled relatively slowly from a melt (but not slowly enough to form large crystals), the headland to the back right shows clear bedding. This likely represents water-cooled basalt spalling off the advancing front of the flow. The small white rectangle in the lower right is a sign that prohibits going past that promontory, so even if the back head is physically accessible at low tide (this was near high tide), it's a protected area. Without a permit, one is not going to get close enough to determine what textural or compositional differences create the marked bedding. This is a situation where trying to identify the broad rock class is a rather pointless exercise, in my opinion. Is it sedimentary or volcanic/igneous? Yes.

Photo unaltered. July 15, 2014. FlashEarth Location.

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