Sunday Funnies: Not Going to Let Tragedy Get in My Way Edition

What Would Jack Do?

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Sober in a Nightclub: Scariest fortune ever.

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Badtux the Snarky Penguin

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Sofa Pizza. Follow the link for additional fun facts on Romney, Bachmann and Gingrich.

Sofa Pizza

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Sofa Pizza

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Wil Wheaton's Tumblr, available for sale at Nowhere Bad

Dr Boli

Clay Bennett

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Buttersafe... Disaster!

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Meanwhile, in Australia... epic4chan

Wil Wheaton's Tumblr

Dr. Boli

Some Guy With a Website

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Criggo

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SMBC

Tree Lobsters, "Dr. Hugh"

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Sober in a Nightclub

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Sober in a Nightclub

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Volcanic Ramblings Part 3: Salt Creek Falls

In Memoriam: Harold "Sharkey" Enlows

There's not too much of note to see on the drive down I-5 from the Corvallis exit to Route 58 just south of Eugene... at least little I'm not jaded to. So with an exception I'll tack on at the end, our first stop was at Salt Creek Falls. As the second tallest waterfall in Oregon, it's an enjoyable, lovely stop for anyone, even non-geotypes. I must say, Dana and Cujo359 got an earful of my griping about the $5 day-use fee for what used to be a nice, free roadside rest.

Dana has focused mostly on the glacial aspect of this spot in her post- and that is indeed an important part of the story- so I'll look more carefully at the bedrock geology. The Cascade Volcanic arc has an interesting evolutionary history. I have no idea if the pattern is unusual, but it youngs and narrows toward its eastern margin. In other words, when volcanism initiated about 35 mybp, following the docking of Siletzia (the Coast Range block), and subduction started outboard of that newly accreted terrane, it spread from the eastern side of the Willamette Valley to central Oregon. As time passed, though, the axis of active volcanism narrowed to what is now a fairly confined band along the eastern margin of what was originally a wide swath of activity. So the arc- at least in Oregon- can be divided into two portions: the Western (older) Cascades, and the High (younger) Cascades. The Western Cascades were more explosive overall, and produced a huge pile of pyroclastic rocks, volcanoclastic sediments and debris flows/lahars. They were also the ash source for the John Day formation in central to northeastern Oregon, famous for its preservation of Cenozoic mammals and other organisms.

According to a conceptual model developed by Ed Taylor, and apparently largely accepted on the basis of subsequent work by him, his students, and others, the origin of the modern Cascades began with the foundering of the ancestral "Plio-Cascades" 4-5 mybp into what is referred to as the "High Cascade Graben," as shown schematically above. The image that understandably comes to mind when one pictures these mountains are the big stratovolcanoes, but they are the exceptions, not the rule. Most of the High Cascade arc actually consists of a low ridge of basalt, andestic basalt, and basaltic andesite.

So what does all this have to do with Salt Creek Falls? When we stopped here with Sharkey, it was not for the pretty water feature, but because it was the boundary between the Western and High Cascades. The lower layer of rock, of Western Cascade affinity, is one I have not had an opportunity to look at closely, but judging from its fragmentary nature at a distance, I feel safe saying it's probably either lahar deposits or pyroclastic rocks of some kind- dark in color, so probably fairly mafic in composition. Overlying the fragmented rock is a thick intracanyon High Cascade mafic flow- Dana has found a source saying it's andesite, and I have no reason to say differently. I never could distinguish the mafic lavas without a petrological scope. So in a nutshell, we have a thick, competent, vertically-jointed rock overlying a soft, easily weathered and eroded rock.

This is a classic set-up for a waterfall.

Water erodes the softer rock and undercuts the overlying hard rock, which, because of its vertical jointing, slabs off to form a vertical face. While in most cases, erosion would incise and smooth the streambed, in this case, the physical arrangement of components acts to maintain a shear face. There are certainly other ways waterfalls can form, but I think of the "hard-over-soft" scenario as being the most common.

Well, isn't that sweet. Blooger has decided it controls the vertical and horizontal again. Sorry, I'm tired of fighting with this for now... maybe I can figure out how to fix it later.

Looking downstream, ~west, from the top of the falls.

This is perhaps not the best possible view to show it, but the landscape is pretty clearly the product of two distinct phases of erosion: a broad, glacially carved valley, followed by Holocene incision by Salt Creek.

The falls from the north rim...

...and from halfway down the trail.

Lovely columns.

Sunday Funnies: Missing "A" Edition

The death of a computer is a horrible thing to watch. Two keys on my dementia-afflicted electronical difference engine no longer work: the "a" and the scroll down arrow. So how is it I have all the "a's" in these sentences? I copy one into the buffer, then paste it with the "Ctrl-V" command. It's convoluted, but it works, and one actually does get used to typing it that way. But god help me if another letter goes belly-up. Now, I find blooger has gone and "upgraded" its composition format- that is, taken a simple function that worked perfectly well and fixed it so that using it requires an advanced degree, and even then won't do what you want it to. Sigh. If my life didn't revolve around this fucking machine, I would take great joy in devising a fitting demise for it.

Sober in a Nightclub

Savage Chickens

Sober in a Nightclub... "Why we have eyebrows."

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SMBC

Cyanide and Happiness

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Abstruse Goose

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Sober in a Nightclub

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What Would Jack Do?

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What Would Jack Do?

Sofa Pizza

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Fake Science

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Darius Whiteplume's Tumblr... two other hysterical historical markers at the link.

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Criggo

Criggo

Slowpoke

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Sober in a Nightclub

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Woot! Photo Shout-Out From NASA!

A photo I took on our recent Volcanic Ramble has received a complimentary treatment from Robert Simmon, along with a structural interpretation by Callan Bentley (@callanbentley ) And to make sure all involved parties get appropriate credit, that's Dana Hunter's hammer (currently on sabbatical with Bif and me), held by none other than the lovely @Dhunterauthor herself. Boo-Yah! Teamwork!

BTW, I've been repeatedly distracted from my efforts on Salt Creek Falls this afternoon, but I'm hoping to have that up before I go home.

Volcanic Ramblings Part 2: A Dedication

I'd like to start off the more methodical portion of this "Volcanic Ramblings" series with a heart-felt dedication to Harold "Sharkey" Enlows, who first showed me many of the stops we made on this trip on the 1984 Petrology series spring excursion. Enlows could be curt and abrasive, but in his way, he was a very caring Teacher. He wasn't affectionate, but he simply wouldn't accept less than what he believed a student was capable of. His nickname arose not from fear, but from the respect and fondness his students felt toward him.

One example: I was not the most responsible student in the history of studenting (I've always said, "I'm an excellent learner, but I'm a terrible student."), and frequently missed early morning classes. The petrology/petrography series lectures fell into that category. So when the test for metapet rolled around, and I was confronted, on the first page, with the question, "Describe the mono-mineralogical problem with respect to metamorphic rocks," I mentally shrugged and skipped it. Sharkey typically sat in his office and did other paperwork while classes took tests, and when we finished, we took our tests to him and dropped them off. He glanced up when I dropped mine off. I turned to go, but he brought me to a sharp stop with "Hold it, DeWitt!" I knew that tone. I turned, and he had his finger on the hole where an answer should have been. I muttered, "I think I must have missed that day," to which he responded, "You did. But you can figure this out. Take this (he shoved the paper back at me) and go sit down until you do."

I had it sussed even before I got back to my seat. If you have only one mineral phase in a nice clean metamorphic rock- like a quartzite or marble- it's nearly impossible to say anything quantitative about the T & P history it's been through. Metapet depends on finding how differing elemental components have been partitioned into differing mineral phases; only one phase, no partitioning. So within a couple minutes I was back in his office, waiting, embarrassed, while he made a great show of reading my answer, then flipping through the rest of the pages to make sure there were no other blanks. He rolled his eyes at me and said, "Good. You're sharp. Don't let lazy get in the way."

Word.

When I graduated, some years later, I made a point to visit most of my profs to explicitly thank them for the effort they'd put into my education. I do believe most of them were close to teary-eyed (I know I was); too few students make that small effort of their own. But I didn't make that happy trip to Sharkey's office. Why? Because unbeknownst to us undergrads, he had been diagnosed with and in treatment for cancer for the entire year we'd had him as a teacher. In summer of 1984, just a month or so after we finished his class, and less than two after he took us on what remains to this day one of the best field trips of my life, the disease took him. One of my biggest regrets is that I never had a chance to express my respect, thanks, and admiration to his face. He wasn't my "favorite" prof, but he's the one who made me work the hardest, and from whom I learned the most.

And that's no small compliment.

So for each of the stops we made on our Volcanic Ramblings that I saw first under Sharkey's tutelage, I'll just skip over the long-winded intro, but preface the post with a dignified "In Memoriam: Harold "Sharkey" Enlows." It feels like the least I owe him.

I was going to write up our first official stop, Salt Creek Falls, but it occurs to me I've forgotten to eat today, and I need to blow my nose and dry my eyes. Dana will have Salt Creek Falls covered for you in the near future. Here's a spur-of-the-moment photo I took when we stopped for gas out near I-5, on our way out of town, looking back over Corvallis to the iconic profile of Marys Peak.

Marys Peak, Oregon: a fore-arc uplift of seafloor basalt overprinted with oceanic plateau basalt, topped with a frosting of deep-water turbidites, then intruded and capped with a gabbroic sill.