Outside the Interzone
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We're looking at a rugged, but more or less flat-lying, marine terrace here. The sedimentary component seems to becoming more sparse, and the basaltic component- both pillows and breccia- more dominant, as compared to earlier exposures farther south along the sidewalk.Photo unmodified. July 10, 2012. FlashEarth location.
This is perhaps one of the nicest exposures along the waterfront sidewalk in Depoe Bay. There's a cleft in the rock, coming right up to the sea wall, near the crosswalk in the middle of town. Looking down onto the rock, you can see individual pillows and clumps of them suspended in a mixture of sandstone and breccia. I presume the latter formed by spalling off the pillows as they formed. Glassy breccia of this sort is pretty standard with pillow basalt, and can be seen in a post from last […]
Some sections of the basalt/sedimentary mixture at Depoe Bay seem at least somewhat stratified- not organized, per se, but not exactly chaotic either. The above shows a disorganized muddle of pillows, breccia and sediment. It's hard to tell the finer breccia material from the sediment at this distance, so I don't have a good sense of how much there really is of the latter here, and how much is purely volcanic in origin.Photo unmodified. July 10, 2012. FlashEarth location.
Taking a break from the basalt and sandstone of the surf area (though you can still see a bit a blue from the bay at the top), this is a close-up of the wall along the sidewalk of the Depoe Bay waterfront. I would describe this as cavernous weathering, with ribs between pits forming in vesicular (bubbly) basalt.Photo unmodified. July 10, 2012. FlashEarth location.
One notable feature of the Depoe Bay basalts is the way the pillows are interbedded with sediments. In some spots, such as this one, the pillows appear to be completely surrounded by, and supported in, the sandstone. My best guess would be that discrete pillows formed on the sea floor, then foundered into the underlying unconsolidated sediment. Alternatively, they might be invasive- that is the pillows may have formed by intrusion of lava into the sediment below- but that seems less likely, to […]
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