Saturd80's: REM Edition

I read this morning that on April 19th, 1980, REM played their first gig as REM. They'd played for a friend's birthday party on April 5th, but the band was nameless at that time. (This seems to support that contention) So in honor of one of the iconic 80's bands, here's a few clips. Cheers, and thanks for the musical memories!

It's The End Of The World (and I feel fine)

Orange Crush

Stand

Geo 730: April 19, Day 475: Pillows and Beds

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 me at least, to form such nice, round, and normal-looking pillows. It seems quite unlikely that this was a simultaneous deposition of such quantities of both lava and sediment.

This area is not very accessible; we're standing on a sidewalk about 15 or 20 feet above the outcrop, with a vertical wall dropping down to the exposure. But it might be possible to come in from the south, near the passage into the harbor, and walk up to get a closer look at the nature of this deposit. Both of my preferred explanations would require soft sediment deformation, evidence of which might or might not be visible with a closer look. I'd also want to take a closer look at the composition of the finer material, with an eye toward sorting out terrigenous clastics from basaltic breccia fragments, and also to look for evidence of hydrothermal alteration. The latter might support the idea of invasive pillows. Until then, though, the geology from a distance isn't bad.

Photo unmodified. July 10, 2012. FlashEarth location.

Geo 730: April 18, Day 474: Confluence

Somewhere in the OR/WA/ID tri-state area, a spring surfaced in the Miocene. The liquid did as liquids will, and flowed downhill, rushing across the landscape. Gurgling, bubbling, and chortling across the territory later to become known as Oregon, it charged toward its confluence with the great basin of saltwater we now call the Pacific Ocean. When the torrent finally reached that shore, it playfully plunged in.

And froze solid.

Because this was no ordinary, aqueous, spring, but a vast cauldron of molten rock, likely in the range of 1200 degrees Celsius (~2200 F).

The two likely products of a basaltic lava entering water are breccia- shattered fragments- and pillows. Both are evident at Depoe Bay and in this photo. Below, I've highlighted a few of the pillows, balloon-like structures that form as lava enters the water, are quenched on the outer surface, then continue to fill for a bit.

Photo unmodified. July 10, 2012. FlashEarth location.

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.

Geo 730: April 16, Day 472: Depoe Bay, Abridged

Looking south-southwest from under the Depoe Bay Bridge, you can see the narrow notch the fleet must navigate to get into and out of the harbor. As hair-raising a prospect as that sounds to me, the lack of major currents- even those of tides, due to the restricted size of the basin- means that it's probably a less complicated and risky proposition than in larger estuaries. I'm pretty much guessing here, but I've heard stories about "crossing the bar" from several other Oregon locations, especially the Columbia River Bar, and I'd bet for an experienced operator, Depoe Bay presents minimal risk. The basalt forming the sides of the channel are Columbia River Basalt, formerly referred to as the "Basalt of Depoe Bay" (PDF). I guess my concern arises from the fact there's not a lot of room for error, and it doesn't look as if it would be very forgiving to any ship foolish enough to run into it.

Photo unmodified. July 10, 2012. FlashEarth location.

Geo 730: April 15, Day 471: Trolling Depoe Bay

Under the Highway 101 bridge, at the southern end of the Depoe Bay metropolitan area, one can see the narrow neck of the channel into the eponymous bay. I can't tell, at the resolution of the photos I have, what form the basalt is taking here. I suspect it's predominantly breccia, perhaps with some isolated pillows, based on the patchy white spots. The latter are almost certainly composed of zeolites and/or calcite, which are signature accessory/secondary minerals with mafic to intermediate lavas in wet environments.

Photo unmodified. July 10, 2012. FlashEarth location.

Geo 730: April 14, Day 470: Depoe Bay Geology

Not much "geology" to be seen in this photo, aside from a knob of basalt in the lower left. But make no mistake, there's a lot of geology going on here. I had long assumed (due to pillow basalts I'll show in coming days) that in this area, it was Siletz River Volcanics, the basement rock of the Coast Range. However, given the proximity of this area to Otter Rock and the ring dikes there, it should come as no surprise that this is actually Columbia River Basalt, of Miocene rather than Eocene age. There are flows of two distinct ages, separated by an interval of sedimentation referred to as the sandstone of Whale Cove. Up until the 80's, these Miocene basalts were thought to be local eruptions, though that started to look problematic with the development of Plate Tectonic theory, and even at the time, the close chemical affinity to the CRB was recognized. By the mid-late 80's, a number of the more northerly coastal occurrences were confirmed as CRB, and now, the Miocene basalts along the northern coast, down to Seal Rock, are accepted as flows that made it all the way from eastern Oregon to the coast.

The bay itself is something of an oddity: it's quite small, at six acres, with a very tight entry, as we'll see in coming days. It's clear that this was not eroded by wave energy, and there's no major drainage through it, as is the case with most of the larger estuaries on the coast, but only a pair of fairly modest creeks. A key insight for grasping the nature of most of Oregon's harbors is that during the Pleistocene, sea levels were roughly 100 meters (~330 feet) lower than now, as ice sheets covered much of the northern continents. "The shore" would have been miles outboard from its current location. The implication is that erosion by the two creeks- the confluence of which is submerged by the modern bay- could have a steeper gradient and greater competence than one might assume given all the standing water that one sees today. At the end of the last glaciation as ice sheets melted off, the rising sea swamped what I picture as a steep, narrow canyon, creating a small, but very well protected, pocket bay.

There is a publication in The Ore Bin, from 1971 (PDF), that outlines the geology of the area. With the caveat that the "Miocene volcanoes"are now interpreted as flows from hundreds of miles away rather than local eruptions, it looks pretty good today. The following map is on page 14 of that document.

 

Photo unmodified. July 10, 2012. FlashEarth location.

Sunday Funnies: GAH! Edition

Senor Gif

Senor Gif

Skut Farkus

Bad Newspaper

Bizarro

"Me participating in a group project" Tastefully Offensive

Surviving the World

 "1927 was a rough time for donuts." Wil Wheaton

Tastefully Offensive

Are You Talking to Meme?

Funny to Me

Texts From TNG

Very Demotivational

Girls With Slingshots

"This is what happens for real when I can’t find the right words." Six more examples at Funny to Me

Are You Talking to Meme?

The Far Left Side

Satire or Real? Who knows? What Would Jack Do?

Funny to Me

Bad Newspaper

Very Demotivational

Cheezburger

Texts From TNG

Cheezburger

Julia Segal

Funny to Me

Abstruse Goose

Electronic Cerebrectomy

See Mike Draw

Very Demotivational

Little Harley Things

Eric's Comics

1111 Comics

Bits and Pieces

Unearthed Comics

Bizarro

Derpy Cats

Tastefully Offensive

The Far Left Side

Blackadder

Fowl Language Comics

Very Demotivational

Medium Large (Incidentally, if this is all you've heard about this incident, it appears the film misrepresented a number of well-meaning people. KM issued a statement on the misuse of her talent on Facebook.)

Funny to Me

Partially Clips

Cyanide and Happiness

 What Would Jack Do?

Tastefully Offensive

Happy Jar

Tastefully Offensive

Very Demotivational

Texts From TNG

"Get down, Mr. President!" Cheezburger

"One donut to rule them all" Mirach Ravaia

 Savage Chickens

Doghouse Diaries

"Facehugger" Animals Being Dicks

This Modern World

Senor Gif