Saturday, March 14, 2015

Geo 1095: March 14, Day 803: No Idea

There is no such thing as a "typical" Klamath Mountain roadcut or outcrop... I suppose this is true for most mountain systems, but with familiarity one can picture a relatively few kinds of scenes one might expect to see in a particular range. With the Coast Range, I expect shallow to deep marine terrigenous sediments, or basalt of one kind or another. With the Cascades, lots of lahar deposits, or basalt to andesite of one kind or another. Oregon's Basin and Range? Cenezoic alluvial to lacustrine sediments... oh, and basalt. Lots and lots of basalt. Columbia River Plateau? Duh. Basalt. You get the picture.

The Klamaths are an utter rats' nest that never ceases to amaze me, and which I will never understand, other than in the most rudimentary, basic sorts of ways. It's a mish-mash of pretty much every kind of rock known to man (though lacking metamorphics of higher grade than schist), squarshed, whirled, blended, folded, spindled, and mutilated, often beyond recognizability. Are there faults in this photo? Almost certainly. Are they where they look as if they might be? Maybe, maybe not. And quite possibly in places where they don't look as if they might be.

I feel a little bad posting this panorama, because, as I pointed out in the title, I have no idea. But upon reflection, I realized that it's a good metaphor for my general understanding of the Klamaths: complicated, fascinating, and humbling, in the sense that they make me painfully aware of how much I don't know, but at the same time, proud that I have clearly learned where that line is, when I get to something that's beyond my ken.

Photo unmodified. May 9, 2013. FlashEarth Location. (Pure guesswork on this one... no idea.)

Friday, March 13, 2015

Geo 1095: March 13, Day 802: Another Fold

Here Dana examines another flopped-over fold on the walk back from Oregon Caves to the parking area. The slightly more prominent and lighter band probably represents a bed with a little more silt and mud, and thus more (resistant) silicates. This is reinforced by the heavy jointing in that bed, which suggests it deformed more brittley than the purer and more plastic carbonates around it.

Photo unmodified. May 9, 2013. FlashEarth Location.

Thursday, March 12, 2015

Geo 1095: March 12, Day 801: Double Dipping with Dana

Here's yesterday's fold again, with Dana for scale. I apparently forgot, when I posted yesterday's shot, there are actually two folds here. Dana's left hand is on the upper limb of the lower one, while her right hand points toward the upper one. The vegetation and irregular surface don't help the clarity here, and frankly, without on-site notes, I'm not 100% certain about that second one. But I'd say 85-90% confident. Here's my annotation of what I think I'm seeing: (The yellow dotted slash is a small fault offset, I think)
Photo unmodified. May 9, 2013. FlashEarth Location.

Wednesday, March 11, 2015

Geo 1095: March 11, Day 800: Overturned Fold

My general approach to visiting Oregon Caves has been to get to the headquarters as quickly as possible in the morning, to get on the first cave tour. This means I've tended to look at surface geology nearby after I've been through the cave. Visitor parking is maybe a third of a mile away from HQ, but an easy, paved, flat walk, so dawdling on the way back to the car is sort of a must-do. There are some very pretty folds. Since carbonates tend to be particularly plastic, deforming easily, and since recrystallization has wiped out fine features that might serve to document stratigraphic "up," I can't say whether this is an anticline or a syncline. Instinct says "anticline," but instinct is too often misleading to count on it being right. A better way of describing my geological instincts, unsupported by evidence, is to call it an "off-the-top-of-my-head guess."

Photo unmodified. May 9, 2013. FlashEarth Location.

Tuesday, March 10, 2015

Geo 1095: March 10, Day 799: A River Runs Through It

I'm not sure if the cave's stream is still called The River Styx at this point, but as I said in the previous post, I really like the effect of bringing it indoors. It's not a steep enough gradient to be a "babbling brook," but enough that I'd call it a "sussurating stream." I didn't think to look out the back to see if they'd done something similarly creative with its re-entry to the outside world.

Photo unmodified. May 9, 2013. FlashEarth Location.

Geo 1095: March 9, Day 798: Indoor Water Feature

So that's where the cave creek goes: inside! The door to the back patio outside the lodge is out of the frame, above and to the left, and the stairs to the upper levels appear in the upper left corner. A culvert carries water from the pool into the ground level of the lodge, where it flows between the restaurant and gift shop. I hadn't been into the lodge before, but the gift shop at the visitors' center hadn't been fully restocked for the season, and I wanted to see if I could find a tee-shirt or hat I liked. Also, I'll typically browse through the books to see what they have. But it turned out, the highlight was this unexpected water feature, which was very pretty, pleasant, and peaceful. The steady flow of water out of the cave means this "creek" runs, without a pump, year-round. It wouldn't surprise me, though, to learn there's another culvert running under the building to accommodate unusually heavy precipitation events, or warm rain on thick snow runoff. Nicely played, architects!

Photo unmodified. May 9, 2013. FlashEarth Location.

Monday, March 9, 2015

Geo 1095: March 8, Day 797: Stygian Cascade

I've posted a picture of this pool and falls before, but here's a different perspective from the patio behind the lodge, near the entry to the restaurant and gift shop. Inside the cave, this stream is called The River Styx, but I'm not sure what (if anything different) it's called after it exits the cave. The human entrance and hydrological exit to/from the cave is on the hillside just off the right edge of this photo. It passes under the road in a culvert, cascades down over the rocks seen here, enters the pool... and vanishes again.

To reinforce a point I made recently, if water evaporation was the major cause of calcite precipitation, I'd expect to see travertine all over those rocks. No, I don't see any, either.

Photo unmodified. May 9, 2013. FlashEarth Location.

Geo 1095: March 7, Day 796: Oregon Caves Lodge

This shot was taken from the pavilion between the Park Headquarters and the cave entrance, where tour groups gather prior to their spelunkage. This and yesterday's building aren't geology proper, but keep in mind, like Timberline Lodge at the beginning of the year (and most explicitly discussed in this post), they wouldn't exist but for the geology this area has to offer. In the lower right, you can see the doors into the restaurant and gift shop, where the next few photos were taken.

Photo unmodified. May 9, 2013. FlashEarth Location.

Sunday, March 8, 2015

Geo 1095: March 6, Day 795: Oregon Caves HQ

This is Oregon Caves National Monument Headquarters. Like so many buildings in the western National Parks and Monuments, it's a gorgeous example of rustic architecture. The Klamath-Siskyou Mountains are much higher and more rugged than can be readily appreciated traveling through or near the area on major roads. This means the rain shadow off the Pacific is quite sharp and extreme. Summers here are long and very, very dry. The scary thing in this photo is easy to miss: those dead trees on the ridge behind the building were killed by a major fire just a few years before our visit. It would be truly tragic to lose a gem like this. In the FlashEarth image, you can see that the fire got terrifyingly close.

Photo unmodified. May 9, 2013. FlashEarth Location.

Geo 1095: March 5, Day 794: Barely Seen Bear

This is, unfortunately, a really crappy photo of a really neat find; I was torn as to whether I should even bother with it. Those dim white forms, behind the plexiglass and condensation, are black bear bones, dated to 3000 years ago. Just how they got here is an interesting question; we're quite some distance from any known natural entrances. We're close to an artificial exit tunnel, blasted in the early 1930s, but the bear clearly didn't use that. It's possible that another entrance has since collapsed or otherwise been hidden, and it isn't really impossible that the bear wandered here, lost in utter darkness. Whatever the means of the bear's demise, these bones were only discovered in 1998, meaning that I didn't see them during my first few visits to this monument. See page 24 of the photographic tour for a better shot.

Photo unmodified. May 9, 2013. FlashEarth Location. (Since we're underground, I have only a vague idea where this is with respect to the surface.)

Geo 1095: March 4, Day 793: Translucent Needles

Geologists use the term "acicular" to mean "needle-like," and here we see a nice example of acicular crystals of calcite. It looks to me as if this represents two periods of growth of this speleothem, the first very slow, with the initial crystals acting as seed sites for further growth. Water flowing over this surface deposited more calcite in a crystallographically consistent manner. You can see vague concentric color bands; those bands represent small variations in impurities during different times. However, you can also see that individual crystals extend through most or all of the bands, indicating that they grew over long periods. The outermost few millimeters, with the brownish crust, is much finer-grained, and I'm inclined to say chaotic-looking. But I can't make out individual crystals or their relationships to each other, so describing them as "chaotic" is beyond what I can actually observe. On the other hand, there was definitely some kind of environmental change between the deposition of the inner acicular crystals and the outer, finer-grained crust.

Photo unmodified. May 9, 2013. FlashEarth Location. (Since we're underground, I have only a vague idea where this is with respect to the surface.)