Saturday, September 27, 2014

Saturd80's: Here Comes the Rain Again Edition

Summers in Western Oregon are glorious: seemingly endless clear, sunny days, and nice cool nights. This summer, though, was trying. By all accounts, it was the hottest summer on record- we had no days I recall that broke 100 degrees, but it was just consistently hot. We get very little rain from early July to (generally) sometime in September to early October, but even on that count, we set a new record for dryness. Now I enjoy all kinds of weather, but I want change fairly regularly. A week ago today, it was 89 or 90, then it cooled Sunday and Monday.

Then Tuesday night it poured.

To say I was ecstatic would be the understatement of the season. I spent an obscene amount of time Tuesday watching the radar, tracking the incoming storm. Here's a Tweet I posted that afternoon. And when I opened that link, it reminded me of a couple of other Eurythmics songs I don't think I've posted before.

Who's That Girl

Love is a Stranger

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.

Friday, September 26, 2014

Geo 730: September 26, Day 634: Creating Cobbles

When I first glanced at the diagram in the lower left, my reaction was "No, no, that's spheroidal weathering." But while the two processes are different- erosional rounding is physical, and spheroidal weathering is predominantly chemical- the overall result is quite similar, just as the diagram shows. If you enlarge the photo to full size, you can read the text over to the right side, where it's cut off. With one minor exception, it's pretty good and accurate for a lay audience. And that minor exception really is pretty trivial: I don't think palagonite is really a mineral, it's more a mixture of microcrystalline minerals and amorphous materials. However, that's a picky technicality.

Photo unaltered. July 15, 2014. FlashEarth Location.

Thursday, September 25, 2014

Geo 730: September 25, Day 633: The Other Rocks

The rocky island from two days ago is to the left in this photo, and you can see a larger one in the foreground and a third in the back right. The foreground rock is also covered with nesting birds, which commenter Bob P. identified yesterday as predominantly common murres (I think there are some cormorants in there too, the black ones in the second crop in yesterday's post). Whodathunk, when this Columbia River Basalt erupted some 16 to 18 million years ago, that it would later be infested with marine-dwelling dinosaurs?

Photo unaltered. July 15, 2014. FlashEarth Location.

Wednesday, September 24, 2014

Geo 730: September 24, Day 632: The Birds

The sheer number of birds nesting on this rock was overwhelming. People were grumbling about the stench, but I hardly noticed it in my awe of the density of living things in front of me. I'm not going to try to guess what species are here; I don't know my birds very well. The full-size panorama is 6148 by 1331 pixels, so even expanding this image to full size, given blogger's size constraints, results in a tremendous loss of resolution. Below are some crops to illustrate:
 Near the middle.
 To the right.
To the left. Stunning!

Photo unaltered. July 15, 2014. FlashEarth Location.

Tuesday, September 23, 2014

Geo 730: September 23, Day 631: The Rock

Not Alcatraz, of course, but a rocky island of Columbia River Basalt south of Yaquina Head. Newport, Oregon is in the distance. You can't really tell at this scale, but that rock is literally covered with wall-to-wall nesting seabirds (Open the photo for full size; they're much more apparent in a larger version). The only thing remotely similar I've seen is penguin colonies in Antarctica. There- my vision wasn't good enough to tell, here- the spacing is determined by how far the birds can crane out and peck while sitting in their nests. The nests will be far enough apart that any two that are occupied will be far enough apart that their residents can't quite reach each other. This is a great example of how differential weathering and erosion- physical processes- have a profound influence on and benefit to biological processes.

Photo unaltered. July 15, 2014. FlashEarth Location.

Monday, September 22, 2014

Geo 730: September 22, Day 630: Dana Makes Contact

Jumping ahead a bit in covering our July trip this year, I realized that in the two previous anniversary posts, I should have included at least one photo of Dana. And since this is one of my favorite photos from our recent trip, here you go. Why favorite? Because she's so obviously happy to be here, pointing at the contact above her head, like Vanna White doing a show called "Wheel of Earth History."

But there's some very pleasing geology here, too. Regular readers may remember that in last year's series, I posted a couple of photos of Elephant Rock, at Seal Rock State Park. I was initially frustrated in trying to explain vertical jointing in a vertically tabular sheet of basalt, but I finally generated an idea of how that could happen: it wasn't a dike, as I'd long thought, but an eroded mass that was originally horizontally cylindrical. I couldn't support that with evidence, but it was plausible, and explained those vertical columns.

Now I have evidence! Dana is standing in front of (Miocene) Astoria Formation, and above and to the left of where she's pointing, you can see the lower contact of a Columbia River Basalt flow. AND... it's tilted just as one would expect if that invasive episode was originally cylindrical! (There are also some nice cross-beds in the lower right, but I have better photos of those for later.)

So not only did this make Dana happy, it made me happy, too.

Photo unaltered. July 15, 2014. FlashEarth Location.

Sunday, September 21, 2014

Geo 730: September 21, Day 629: Anniversary Beach

Here we're at Sutton Beach/Creek, a recreation area on Siuslaw National Forest land. We're looking north to the headlands between Florence and Yachats, which are composed of Yachats Basalt, about 35-30 million years old. I've just realized, looking through these photos, that I haven't included many of them from this area on this trip, although I did thoroughly cover a later stop at Cape Perpetua (April 8 to 28 in the Geo 365 Series), about 15 miles north of here. So there's geology in the background, but is there any in the foreground? Yes, though you'd need a bit more context to see that. I chose this photo because I like the dramatically windswept tree, but if I had turned 90 degrees to the left, you'd see a stream and open beach; this area has only been colonized by plants within the past couple of centuries. There's no higher ground between here and the ocean, thus nothing protecting the vegetation from fierce storm winds, which are frequent and persistent in the winter. If you're unfamiliar with the area, this isn't necessarily evident from this photo, but if you have spent any time along the Oregon Coast, this sort of setting has clear implications for the geologic context where it's found. If you want to get a sense of what the solid earth materials are doing, you have to have a strong understanding of what the other earth components- living, liquid and gaseous- are doing, too.

Photo run through's AutoLevel routine for contrast and saturation. September 20, 2010. FlashEarth Location.