Wednesday, April 27, 2011

Focused Writing: Marys Peak Pillow Basalts

@clasticdetritus asked if anyone was into a 30 minute session of focused writing, which I had never heard of before. When asked, his reply was as follows: "@lockwooddewitt write for 30 minutes with internet friends and then tally up the words -- just a way to motivate each other, it works!"

I've been meaning to get back to my geogalavanting with Dana last fall for some time now, and keep kicking myself that I don't. So I decided to write at least part of the text for the next Marys Peak stop. I have actually covered much of this before in an Accretionary Wedge post, but I wanted to go back and add some site-specific and other details. This does not represent a finished post, but merely what I was able to crank out in 30 minutes. I do most of my proofreading on the fly, which undoubtedly slows me down, but I have a hellacious time editing my own text after the fact. So here is what I wrote, warts and all. I'll try to finish this up, add photos and some maps, and proofread it tomorrow. Incidentally, I have no idea how many words this is, but I'm content with it as the product of 30 minutes of writing.

The Siletz River Volcanics make up the bulk of Marys Peak, from the base to roughly 3000 feet elevation (of 4097 feet total). The unit consisits of primarily submarine volcanics, associated hypabyssal rocks (shallow intrusions), and a small packet of associated sedimentary rocks (the Kings Valley Siltstone Member) derived from subaerial eruptions, and interfingered with the predominant submarine facies.

Given this situation, one might expect that pillow basalts are a primary component to the Tsr, and in fact, that would be correct. These photoa were taken on the Marys Peak trip that Dana took me me on last September, and it is the best outcrop of pillows I believe I've ever seen. It is an old gravel quarry. In much of Western Oregon, despite the lack of population in the more rugged terrain (i.e. the Coast Range and the Cascades) logging is a major and important industry. It's pretty uncommon to be able to find a spot more than a quarter mile or so from a gravel logging road. In fact, one of the major sources of employment in Oregon, both east and west, is the US Forest Service, who holds responsibility for building roads so that Timber companies (who bid for the right to cut designated parcels) have access to the stands to which they have won rights. Thus old quarries like this, sometimes still active at least occasionally, sometimes inactive for decades (such as this one), are among the most common places to be able to see actual rock in this land of 15 meter soil overburdens. Other good spots for geologizing include roadcuts and sream beds.

So what makes pillow basalt distinctive? It's believed to represent underwater eruptions or flows into water from fluid- basaltic- lava. Important characteristics include, first and foremost- and the source of its name- the overall rounded, somewhat flattened toward the horzontal in larger pillows, bulbous shape. Because pillows are rounded, where they contact each other there is an indentation; picture three oranges sitting next to ech other in a triangular arrangement. In the space bewtween them is a similiar indentation. A later pillow flowing into such an indentation will fill it. With good preservation, this infilling is easy to recognize, and provides a rough geopetal structure- that is, one that indicates a sense of stratigraphic "up." in the caase of pillows, as I indicated, this is rough, and not nearly as precise as is the case with many sedimentary geopetal structures.

A second important characteristic is radial jointing. In volcanic rocks, jointing most frequently results from cooling stresses, and forms perpendicualrly to the surfaces of cooling. Since, in pillow basalts, the cooling surfce is either roughly cylindrical or roughly spherical, the joints form from the outer surfaces, then work their way toward either the axis or center of the pillows. There are quite a variety of other ways that roughly spherical rocks can be formed, including sphereoidal weathering and fluvial/mass wasting transport- though the latter is not as efective as the former. However, on the scale that pillow basalts occur- about a third of a meter up to maybe one and a half meters- I know of nothing else that can cause radial jointing. Furthermore, this jointing is frequently discernable, even in rock that has completely weathered to saprolite. For these reason, I consider radial jointing to be the "diagnostic" characteristic of pillow basalts. In other words, if I see it, I'm pretty confident it's pillow basalt. If I don't, I'm leery of making that call.

Cascades Snowfall

(Photograph by Tyson Fisher, submitted to My Shot, from National Geographic)

It's been about five years since I last visited Crater Lake, and it looks like I may get the opportunity to do so again sometime this summer. It's kind of startling to see massive snowbanks persisting into July, but they do. The amounts of snow that fall in the Cascades are difficult to comprehend. Despite the high elevations, summer temperatures can get quite warm, but the sheer amount of snow means that it can take most of the summer to melt off.

We had a good amount of snow coming into the new year, then January and February were dominated by "warm" systems that either didn't add to the snowpack, or, in some cases, actively melted back what was already in place. As a result, at the beginning of March, our snowpack was about 70% of normal for that time. But March and April have been cold, with numerous winter-style storms, and the snowpack is now well above normal (I'm recalling about 120%) throughout the Oregon Cascades. That bodes well for the fire season, for irrigation, for salmon, for hydropower generation... water is important, even in a region that is often perceived to have a surfeit of it.

The news that brought this to mind was this article from The Salem Statesman Journal:
KLAMATH FALLS, Ore. (AP) — The total snowfall at Crater Lake National Park has pushed past 600 inches, with more expected before the end of the season.

The Herald and News reports that 9 inches of fresh snow measured Tuesday increased the total snowfall to 615 inches, well above the 492 inches normally measured by April 26.

Click over to read the rest- I think you'll find the numbers pretty hard to believe. Keep in mind that 615 inches is much greater than the total amount on the ground at a given time, just the total that has fallen over the course of the winter- the total on the ground at park HQ is 12 feet, not 51 feet. But still, picture enough snow to bury a five story building, and tell me if you don't find that kind of breath-taking.

Monday, April 25, 2011

Moonday: Triton

From Wikipedia:
English: original NASA caption: Global color mosaic of Triton, taken in 1989 by Voyager 2 during its flyby of the Neptune system. Color was synthesized by combining high-resolution images taken through orange, violet, and ultraviolet filters; these images were displayed as red, green, and blue images and combined to create this color version. With a radius of 1,350 km (839 mi), about 22% smaller than Earth's moon, Triton is by far the largest satellite of Neptune. It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391 degrees Fahrenheit); it is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator; it may consist of relatively fresh nitrogen frost deposits. The greenish areas includes what is called the cantaloupe terrain, whose origin is unknown, and a set of "cryovolcanic" landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton's interior.
I find cryogeology fascinating; it's not too hard for me to wrap my head around water ice as a rock-forming material, but nitrogen?

Sunday, April 24, 2011

Sunday Funnies

Clay Bennett
Senor Gif... Raawr!
Senor Gif
Hacked IRL
Sober in a Nightclub
Bits and Pieces
Neatorama
Roflrazzi
Very Demotivational
Senor Gif
Bits and Pieces
TYWKIWDBI
What Would Jack Do?
Very Demotivational
Lolcats
Hacked IRL
Senor Gif. How often does looking at an animation make your nose run?
Senor Gif
Loldogs
Sticky Comics
EpicPonyz
Senor Gif... This Alien Vs. Predator film would be better than the other one.
Dork Tower
So Much Pun
Calamities of Nature
xkcd, with the brilliant hovertext addendum, "If you've never had sex, this is what it feels like. Complete with the brief feeling of satisfaction, followed by ennui, followed by getting bored and trying to make it happen again." This is the perfect complement to the classic xkcd, Hell:One in a very funny collection of "keep your eye on the ball" photos at Dark Roasted Blend.
The High Definite
Sticky Comics
Roflrazzi
Tree Lobsters
Totally Looks Like... either that or a peeled potato.
Pundit Kitchen
The High Definite
Dr Boli. Answers in Hesiod, hmm? This NEEDS to happen.
Real life Bert, from Roflrazzi
Hacked IRL
Lolcats
Engrish Funny... mmmm... shnedd ponk... my favorite.
Sober in a Nightclub
Saturday Morning Breakfast Cereal
Totally Looks Like
Bits and Pieces
Very Demotivational
The Daily What:
Guide Goose of the Day: Renata Kursa, a villager from Poland, says she was heartbroken after her dog Baks lost his sight in a recent accident.

But her four-year-old goose Buttons was more than happy to lend her eyes to Baks, leading him with her neck, or directing him with her honks.

“[G]radually Buttons got him up on his feet and starting walking him around,” says Kursa. “They’re inseparable now – they even chase the postman together.”

BizarroBlog
M Thru F
Senor Gif
I met a fairy today that said she would grant me one wish.

“I want to live forever,” I said.

“Sorry,” said the fairy, “I’m not allowed to grant wishes like that!”

“Fine,” I said, “then I want to die after Congress gets their heads out of their asses!”

“You crafty bastard,” said the fairy.
Bits and Pieces
Lolcats
Sober in a Nightclub