Why, Hello, There!

Apologies for the two-week hiatus. If you follow me on Twitter, you know we had about five days over that interval that were hot enough to knock me down and out- hot weather destroys my appetite, so poor nutrition was likely a factor too. I finished the Upper McKenzie stretch of the Geo series, and I just lost motivation- coinciding with the first of the hot days. Then my co-presenter for the Oregon Master Naturalist Willamette Valley Geology workshop had to cancel, so instead of planning half of that day, I'm planning all of it. And I got called for jury duty tomorrow (Update: Yay!). And on and on. I make no promises either way on the continuation of the Geo series, though I have hatched an idea that could allow for a quick catch-up with minimal work. On the "maybe not" side, Dana is also suffering from a series of set-backs (pitch in if you can), I haven't been out in the field since October, and I don't have a whole lot more trips to choose from in terms of photo series.

And yes, I am still tagging stuff for Sunday Funnies. Both the last two Sundays have been beastly, and finishing this up today means I won't have time this Sunday either. But never fear, they'll be back. Sigh... okay, here's a good one:

A Comik

On the flip side, I did do a scouting trip for next Saturday's field trip (too busy taking notes to take photos, though) so here's the result. For those doing this trip on their own, it would likely be easiest to reverse stops 1 and 2, starting in the parking area, then going two to three tenth miles back to the Tyee soil, then subtract 4.9 miles from the mileage at each subsequent stop. (In other words, no need to start at OSU, just start at Chip Ross Park.)

Marys Peak Field Trip Route and Stops

Players in the story, oldest to youngest:

·                     Siletz River Volcanics- sea-floor and Hawiian-island type basalt, about 60 to 50 million years old (Ma = "mega-annum," or million years.)

·                     Kings Valley Siltstone- formed from erosion and marine redeposition from one or more islands of SRV. Toward the end of same span as SRV.

·                     Tyee Formation- Turbidites, vast underwater "sand and dust storms" that settled out in distinctive sand->mustone couplets, from erosion of granite to the east, in or near the Idaho Batholith. About 48 to 38 Ma.

·                     Corvallis Fault- A fracture in the earth's crust creating the boundary between the Willamette Valley floor and Coast Range foothills in the Corvallis area. Probably active around 35 Ma for a few million years, but does not appear to have been active since the following intrusive activity.

·                     Marys Peak sill (along with numerous similar intrusions of about the same age and composition in central Coast Range)- Gabbro, similar in composition to basalt, but slower cooling, so larger mineral grain size. Quite resisitant to weathering and erosion. 30 Ma.

We will be walking along the roadside at several stops. Be alert for traffic, and make safety your first priority.

Mileage Location/Stop Number/Feature

0.0 Depart Richardson Hall. Zero odometer as you turn onto 30th Street northward.

-At intersection with Harrison Blvd., turn right, and jog over a block to 29th.

-At 29th, turn left and continue north to Walnut Blvd.

-At Walnut, turn right, and continue east to Highland Dr.

-At Highland, turn left and wind up the hill to the ridge crest.

-Just before Highland descends into Crescent Valley, turn left on Lester Avenue. There's a small brown sign pointing to Chip Ross Park on the right (Correction: left- this is an unusual case where I really did recall right, rather than making a sloppy mistake) berm.

-We didn't get accurate mileages until noted, so the first two stop mileages are estimates from Google Maps

4.6 Stop 1 Lester Ave. Roadcut. Soil developed from Tyee Formation- note light yellow color. The Corvallis Fault cuts across the lower saddle between here and the Chip Ross parking area. As we move from stop 1 to stop 2, look for nice views to the southwest of Marys Peak and Alsea Pass, where this same fault cuts across the Coast Range crest.

4.9 Stop 2 Chip Ross Park Parking lot. Soil developed from Siletz River Volcanics- Note dark red color. Why are we going up Marys Peak to look at the geology of the "Willamette Valley?"

-Return to Highland, and turn right.

-At Walnut, turn right.

-Follow Walnut roughly 5.5 miles to Philomath Boulevard. The line of hills to the north and west of this drive is more resistant Siletz River Volcanics, uplifted by offset along the Corvallis Fault. The less resistant Tyee (and overlying Spencer) Formation form, at most, low hills to the south and east.

11.8 -(At this intersection, we figured out how to get tenth-mile accuracy on our exploratory vehicle.) At Philomath Boulevard, turn right and procede through Philomath.

15.6 - Route 20/34 split. Turn left, and follow route 34 to Alsea Pass.

24.5- Marys Peak Road- turn right, and drive to the Marys Peak Summit Parking area.

34.0- Stop 3 Marys Peak Summit Parking area. Lunch. Depending on interest, some of the group may choose to hike to the summit. (We budgeted about an hour here.) This, to me, is one of the most profound viewpoints in Oregon. There are quite a number that are more scenic, but I can think of few that have such a mental wallop. We're standing on the Coast Range crest, the divide of the Cascadia forearc ridge. To the east, if we have decent visibility, a few to many of the Cascade Peaks are visible. Normally, Mount Jefferson and Three Sisters can be seen, and Mount Hood can be picked out more often than not. On rare days with near perfect conditions, one can see from Mount Rainier in the north to the vicinity of Crater Lake to the south. To the west, the Pacific Ocean can be seen, taking on different appearances as the light changes through the day. With help from trigonometry, you can calculate that the distance to the horizon is about 75 miles, which is close to where the Juan de Fuca Plate begins its long slide into the earth's interior. It's that slide that has created the forearc ridge of the Coast Range, the more-or-less vertically stationary forearc basin of the Willamette Valley, and water "sweating" off the subduction slab causes melting in the upper mantle, creating the magma that produces volcanism in the Cascades. My favorite metaphor to describe what we're seeing is that here, we have an overview of one piston in the engine that drives earth's plate tectonic activity!

Before departing, be sure to make use of the sanitary facilities at the south end of the parking lot. There will be no further opportunities for actual restrooms until we return to Richardson Hall.

35.1 Stop 4 (Possible, depending on how time looks) This meadow provides a long parade of wildflowers from mid-spring into mid-summer, but in terms of rocks, a short walk up the road to the closest cut will reveal a metamorphic rock called hornfels, created when heat from the underlying Marys Peak Sill baked the overlying Tyee formation. This is similar in nature and effect to what happens when you fire a raw clay pot in a kiln; it becomes harder, stronger, and more dense.

36.7 Stop 5 Parker Creek Falls. This is the dense, tough, and extremely resistant to weathering and erosion Mary's Peak Sill, a rock called gabbro, and a good illustration of how Marys Peak sits about a thousand feet higher than any other Coast Range mountain. Note that most of the weathered, and lichen/algae coated cut face looks like basalt. But if you look carefully, a more recently broken surface will show a typical "salt-and-pepper" appearance. Those light and dark grains are the minerals making up the rock. Individual mineral grains are not visible to the naked eye in "typical" basalt. (There are exceptions beyond the scope of this workshop.)

37.1 Stop 6 We'll pull off a bit up the road from the outcrop, as there isn't safe space at the spot itself, and walk down the road to a nice outcrop of horizontally-bedded Tyee Formation. Note the abundant mica flakes and fragments of plant material- these two features can help distinguish this rock unit from others. A bit farther on, there is a fairly chaotic outcrop of Kings Valley Siltstone, which is derived from erosion of Siletz River Volcanics. As we saw at Chip Ross Park, the color difference between these two units is striking. Given that the Tyee is horizontal, there must be a fault between these two exposures, even though we can't see it. Walking across the road to the guard rail, we see another effect of the hidden fault: a fairly large landslide. The fault created a zone where the rock was broken up, and water and air had better access to the rock, speeding weathering and further weakening it.

39.9 Stop 7 Parking lot. Park here and walk back about a quarter mile or so to a quarry exposing spectacular pillow basalts of the Siletz River Volcanics. Keep in mind, these were erupted on the ocean floor. Here, they've been uplifted to thousands of feet above sea level.

40.5 Stop 8 (Possible, depending on how time looks) Columnar basalt is common in Oregon, which is no surprise, given how much of the state is covered with that rock. These are the best examples I know of on Marys Peak.

40.7 (In passing; we'll try to slow down a bit to get a look, but we won't be stopping.) Slickensides. The vertical scratches, or striations, you see on this wall were created as a fault ground the two opposing surfaces. The orientation of the "slicks" gives you two possible directions for fault offset: up or down, parallel to the scratches. Continue back to Route 34, and turn left (east) back toward Philomath and Corvallis.

45.1 Stop 9 We will not be crossing the road here. Both we and oncoming traffic have very poor visibility. Tilted beds of the Tyee Formation. Unlike the flat-lying beds of Tyee we saw near the top of the peak, these are steeply tilted. Now off the Siletz River Volcanics, we've crossed the Corvallis Fault again, but it's very close by, probably crossing through the clear cut up the valley. Deformation and folding near major faults is common, and explains why these beds are tipped over to such a degree.

58.3 Return to Richardson Hall.

Postscript: The sequence we've seen here, ocean floor volcanics, overlain by marine sediments, and modified by later events, such as magma intrusions and faulting, varies in details from place to place in the Willamette Valley and the Coast Range, but as a general outline, is consistent across the region. In other words, if you were to drill a hole on the Willamette Valley floor, you would go through a few to a few hundred feet of  Missoula Flood and Willamette River sediment, then you'd hit marine sedimentary rock of one formation name or another. (From the Albany-Salem area north to Portland, you'd also encounter Columbia River Basalt interfingered with the uppermost marine sedimentary rock.) Eventually you'd go through the Tyee, which is the lowermost of those sedimentary units, and pretty much ubiquitous in the region. Finally, you'd hit basalts of the Siletz River Volcanics. Those basalts are not continuously exposed on the surface, so they have different names in different areas (Roseburg Volcanics and Crescent Volcanics, for example), but they were all formed the same way in a geologically short period of time, and they are believed to be all the same unit, connected underground where we can't see it. Climbing nearly four thousand feet off the valley floor has allowed us to see rocks that lie thousands of feet below it. Furthermore, as we saw at the first two stops, due the the milder climate of the lower elevations, rock that is exposed in the valley is often too weathered to get much information from.

Geo 1095: May 30, Day 880: Spring Surprises

Here's a final shot from the Upper McKenzie drainage, for now, another from "Lost Springs," as I informally named it in the previous post. The best story that Anne told us about her dissertation work up here was that in the first few years of the 2000s, someone had done a project similar to hers, working out the volumes and characterizing springs forming the headwaters of the Metolius River in central Oregon. One aspect of that work was comparing the annual rate/volume of water flow, from the springs, out of the presumed hydrological basin, extending from those springs to the Cascade crest, to the modeled annual volume of water equivalent precipitation. When all was said and done, the conclusion was that there was an excess of spring flow amounting to 12 cubic meters per second! In other words, 12 cubic meters (~424 cubic feet, a bit short of 3200 gallons) of water per second more than could be explained by precipitation was flowing out of the east side springs. Needless to say, over the course of a year, some 31.5 million seconds, that's quite a bit of water.

Now I don't know how that scientist, or the committee, reacted to that result. I would have been frantically puzzled, wondering where I'd messed up, or where the incorrect assumption(s) was/were, or whether the precipitation model was anything approaching realistic. I would have not been a happy camper, because that really is an awful lot of unexplained water.

Then Anne did her dissertation work in the latter part of the same decade, and did a similar estimate of precipitation input versus spring output. The result? The west side springs appeared to have a 12 cubic meters per second deficit with respect to the amount of water equivalent precipitation it receives.

Those balancing numbers delight me. What it suggests is that the Cascade hydrological divide in the central portion of Oregon is, at least in some areas, well to the west of the topographic divide. Given the extensive covering of this portion of the High Cascades by young lava flows, cinder cones, and other tephra, that's certainly plausible. And I'm not going to fault the east side for hijacking "our" water. They need it much more than we do.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 29, Day 879: Lost Springs

I don't know if this system of springs has a name, but the outflow drains down Lost Creek to the McKenzie River, so it seems reasonable to call it "Lost Springs." They're easy to find, but from the road, there's no clue to what most people sail past on their way to or from the pass. So perhaps a better name would be "Missed Springs." In person you can see fish- I'd guess trout; I'm not a fish person, so that is a guess- swimming languidly in the crystal-clear water, but they're not easy to pick out in these photos. I think I'm seeing a few over the lighter sand, and under the long pole across the middle of this shot:

Dana got some video of the fish swimming, but I don't know if she ever posted it.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 28, Day 878: Where the Water Goes

As we left Proxy Falls during our July 2013 (my first) visit, I asked Anne if she knew where the water came back out. She grinned and nodded "yes." I don't know if she had intended to stop at this spot or not, but it's gorgeous, and I'm awfully glad we did. This is merely the edge of a vast area where water reemerges as springs and pools, so it's not just where the water from Proxy Falls comes back to the surface, but likely the main set of springs for this entire drainage, up onto the western portion of the High Cascades Platform. To find it (It's maybe 6 or 7 miles down the road from the Proxy parking area.), look for a large field on the north side of the road, with a large Douglas fir standing out from the rest of the forest toward the back. There's a dirt road across that field, which circles the tree. The path to the springs is pretty much directly opposite the tree from the highway, and it's a very short and easy walk from the field to the pools. The FlashEarth view should make it pretty clear, and drag the view to the WNW to get a sense of the extent of these springs.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 27, Day 877: Simple Contact, or Channel?

Down in those vine maples, you can see the contact between the edge of the Collier Cone Lava Flow (right) and the older, glacially carved, volcanic rock of the valley floor (left). The question is, has this contact been modified by rare to occasional burst floods from above the valley? It seems clear to me that there has been no such activity recently; the thick-bedded moss would not be so consistent. Likewise, there's some down logs in pretty advanced states of decay near the center of the photo. Any recent (past decade or so) would have left both of those features more chewed up. The contact seems rounded, which might indicate erosional modification... but look at all that living and dead plant material! Surely that might be the explanation for the apparent rounding.

In the end, as is so often the case, the answer is, "I don't know; I need more information." I'm okay with that. It means I have a reason to go look again.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 26, Day 876: Upper Proxy Notch

Looking back down the path from Upper Proxy Falls (i.e., the falls are behind us in this view), The Collier Flow is on the right, and the southern edge of the valley is on the left. Has this notch been reworked by running water? It's not clear, but it seems possible. It would certainly fit with the idea of burst floods contributing soil components (clastic sediment and plant debris) to the surface of the lava flow, and fostering an environment for rapid recolonization and reforestation. I have a few more photos of this notch, and I'll post at least one more, but looking over them, I see nothing convincing either way. Next time I get back here, I should see if I can spot rounded gravel farther down the notch- it drops quickly just past that saddle.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 25, Day 875: Collier Flow Berm

My camera's flash has a tendency to go off at times I think it's unnecessary, but it can lead to some interesting shots, such as this one. One has to clamber over the root system of this Doug fir to get at the rubbly hillside- the south edge of the Collier Cone Lava Flow- where you can see Anne and Chris in the upper left corner. It might be interesting to come up here with a couple bottles of food coloring to see if you can actually find the area(s) where the water is leaving the pool. It's shallow, and the volume is fairly small compared to the rate of flow from Upper Proxy Falls into it, so I'd bet the residence time of water in this pool is in the range of ten minutes or less.

Photo unmodified. July 6, 2013. FlashEarth location.

Geo 1095: May 24, Day 874: Upper Proxy Runout

Sitting up on the berm of the Collier Cone Lava Flow, looking down to the runout of Upper Proxy Falls is a peaceful experience. I love the little Doug fir that has managed to get established on a tiny island in the pool... I think I'll call it The Little Prince. As I mentioned in the previous post, this pool has no outlet. However, looking at the shape of the gap between this little cove and the lower valley, where the trail leads to this spot, I'm pretty confident this stream does overflow its basin from time to time. This may be related to the burst floods that (rarely) make it into channels up on the flow behind us here.

Photo unmodified. July 6, 2013. FlashEarth location.

Geo 1095: May 23, Day 873: Upper Proxy Plunge Pool

This is far from an ideal panorama; the left photo has too much motion blur, the center one is fine, and the right photo is overexposed in comparison to the other two. Nevertheless, it's the best I have to capture the "rather unique twist" I mentioned in yesterday's post. That photo was facing toward the falls; this one is taken standing a bit to the west, looking back toward the base of the falls. You can see the run-out coming in from the right side, flowing into the pool at the base. Given the amount of talus and downed logs at the bottom of the falls, this isn't technically a "plunge pool," but for the title, I liked the alliteration. The trees and their roots on the left pretty well obscure the fact that the slope there is the southern margin of the Collier Cone Lava Flow. Can you spot what's missing?

There's no outlet to this pool. This stream emerges from springs at the top of the glacially-carved valley, tumbles off the edge as a hanging valley waterfall, then promptly goes right back underground, into the side of the lava flow. Neato!

Photo stitched in HugIn, otherwise unmodified. July 6, 2013. FlashEarth location.

Geo 1095: May 22, Day 872: Upper Proxy Falls

Upper Proxy Falls is smaller than Lower Proxy (shown in yesterday's post), both in terms of height, about a hundred feet shorter, and flow rate. This one appears to be two streams converging in a waterfall, while the other appears to be a single stream splitting in a fall; in that sense, they're kind of opposites of each other. This one, though, has a rather unique twist to it, which I'll get to tomorrow.

Photo stitched in HugIn, otherwise unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 21, Day 871: Lower Proxy Falls

This is actually a single photo, which I don't think is as good as the very similar-looking panorama I posted shortly after our visit last October. Comparing the two, I think the higher top of this one includes brighter light, and it looks as if that has caused the entire photo to have poorer saturation than the panorama. However, for the sake of completeness during this segment, I'm including another shot of Lower Proxy Falls, which, on our trip with Anne the previous summer, we skipped. It probably wasn't really necessary to skip it; this waterfall is no more than a hundred yards from the junction, so to this viewpoint, it's an easy walk. Dana and B. walked down to near the base, but as is often the case with me in recent years, I didn't want to earn "back uphill" points. I just sat here until they came back up the hill, dazed by the beauty of this spot.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 20, Day 870: Hard Evidence

Can you spot the hard (pardon the pun) evidence of running water in this photo? And we're not talking about a minor trickle, but a fairly competent flow. If not, take a look at the crop below. The Douglas fir cones scattered around are typically 2-3 inches long, for a sense of scale.

Look how rounded that gravel is! This is very clearly not simply a lava gutter, though it may have started out as one. I don't know if water has ever been actually witnessed flowing through this channel, but clearly it has at some point. Eyeballing the woody debris, and its generally not-too-decomposed state, I'd bet it hasn't been very long, maybe in the range of a decade or so. During the winter season, the road to this trail is closed. People do visit during the winter season, but it's a fair trek in from the gate (~7 miles round trip), so the number is limited. Take into account that the kind of weather that I'd guess is responsible for burst floods that might behave like this is heavy warm rain on a heavy snow pack, it seems likely that even those venturous folk might hesitate to visit on days when this might happen.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 19, Day 869: Channel Conveyor?

If Anne hadn't pointed these channels on our trip the previous summer, I would've either not noticed them, or I would've assumed they were probably lava gutters (here are a couple of examples of lava gutters). However, these may actually be water carved channels, or possibly water-modified lava gutters. I'm relying on a short discussion a couple of years ago, and I'm not sure how clearly I remember it. But look at how verdant the vegetation is here! There are rhododendrons in the upper left, a young cedar on the center left, and another in the lower right. This does not look at all like an extremely young lava flow; it looks more like a late-stage second growth conifer forest. The general idea, as I understand it, is that rare burst floods from the slopes above this glacially carved valley may be responsible for carving or modifying channels like this one, and provide a potential explanation for how portions of the Collier Cone Flow in this area have been so rapidly reforested. Such floods may have provided sediment and plant debris, allowing a jump start to soil formation. Otherwise, the slow breakdown and colonization of fresh lava would taken several times as long. Similar flows with similar climatic and environmental conditions nearby are nowhere near as heavily vegetated.  As I pointed out in the previous post, the distribution of heavily tree covered areas on this flow is patchy. Here, close to this channel, we're in lush, mature forest.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 18, Day 868: Pretty Pathway

The geology here is redundant and relatively trivial with respect to the High Cascades: blocky basaltic andesite. But I really like this photo. It's pretty, and just screams "PNW autumn!" If you look at the FlashEarth link, you can see that the tree cover is highly variable on this flow. The outline of the lava lobe ir easy to pick out, but the tree distribution is very uneven. It's pretty clear that some areas are more hospitable to colonization than others.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 17, Day 867: Big Doug(s)

I think, but I'm not sure, that these two shots are of the same Douglas fir, at a nice viewpoint along the Proxy Falls trail. A couple years ago, I posted a panorama to show the glacial aspects of the north side of the valley the day after we visited the area. Those shots were taken in between these two, so I had moved to a different perspective between, and Chris and Anne got into the frame for scale in the second.

One of the features that can help accelerate the colonization of barren rock is abundant organic material. You can see there's plenty of it on the ground here, but I suspect most of what we're seeing has fallen off the big tree(s) in the photos. Vegetable debris, such as fallen leaves, needles, and slowly rotting woody material, are very effective at retaining moisture and providing nutrients. These are two of the most lacking environmental conditions on newly repaved volcanic landscapes. However, what we're seeing here likely can't be used to explain how this ground was colonized so quickly, as it post-dates the establishment of the trees we're seeing.

However, unexpected additions of organic matter may provide at least a partial solution to the problem I described in yesterday's post.

Photos unmodified. July 6, 2013. FlashEarth location.

Geo 1095: May 16, Day 866: Conifer Confusion

If you look back at some of the photos from late March and early April of this year, on lava flows almost double the age of this one (~3000 years versus ~1600 years), you can see the trees near McKenzie Junction are scattered and stressed. That's not to say some of them aren't large and healthy, but the fresh surface to the east are clearly difficult for the conifers to flourish upon. We see a similar situation here. However, given that this flow is roughly half the age of the flows near the junction, it's a bit of a puzzle how these ones are doing as well, and are as mature, as they are. This area is perhaps more sheltered from strong winds (though I'm guessing; the valley could act as a funnel, and strengthen them), and being higher elevation, may get more annual precipitation. On the flip side, higher elevation means cooler, shorter growing seasons. The short version is that it's difficult to imagine even scattered trees growing to the sort of maturity we see here, from barren, sterile lava, in only 1600 years.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 15, Day 865: Blocky Basaltic Andesite

This is pretty typical of the landscape of the Collier Cone Lava Flow's surface on the Proxy Falls Trail loop. There's not much here for a firm sense of scale, but those vine maples (with the bright fall colors) are probably a bit less to a bit more than person-height. If I was standing in the middle of this photo, most of their foliage would be lower than the top of my head, but a few of the taller stems might be a foot or two over it. When you take that scale into account, you can see what an unpleasant, and, bluntly, treacherous landscape this would be to attempt to cross or do fieldwork upon. If you didn't click through to the research paper I linked yesterday (mostly paywalled, but you can get the gist from the abstract), it's about using LIDAR on this flow to thoroughly map it, and using that data to elucidate how the morphology of the flow was created by its emplacement conditions.

Photo unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 14, Day 864: Not What It Looks Like

After our brief stop up in the Lost Creek Cirque, we continued back down to the west until we got to the Proxy Falls trail head. The area south of Route 242 and the parking lot (FlashEarth location) is dominated by a steep berm of the Collier Cone Lava Flow. Most of the walk (maybe a mile or a bit more)  is upon that flow, the most recent in the area, at about 1600 years. The blocky Collier flow is basaltic andesite, with an oddly smooth, glass-like (but definitely not glassy) texture and feel to it. Given that it came from a cinder cone, there were certainly portions of the eruption that were gassy, but whether this was a later, less gas-rich portion of the original magma, or perhaps in this distal portion of the flow, the lava had almost entirely lost its volatile components, the result is rock almost if not entirely free of gas bubbles (in geologese, "non-vesicular.")

So I was sort of surprised to see what looked like breadcrust texture on this block. The first of those two links describes what "breadcrust texture" means, how it forms, and therefore what it implies. With little exsolving gas, breadcrust texture shouldn't form. As it turns out, it didn't. This is actually a coating of moss and lichen, nearly an inch thick, that I'd guess has shrunk with dessication at the end of a long dry summer. In the case of breadcrust texture, the crackles are the result of an expanding interior breaking up a solid surface. This is a case of a shrinking exterior breaking up over a solid interior. It pays to look twice.

Photos unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 13, Day 863: Precipice Perspective

As I illustrated with a crop from a topographic map a few days ago, this section of road is on an extremely steep headwall of a cirque at the head of (what I presume would be called) Lost Creek Canyon. I'll bet your eye was caught pretty quickly, as was mine, by the warning/speed limit sign in the upper left side. I'll also bet you didn't notice the similar one for traffic coming uphill, in the lower right.

Yep. There's a road down there.

Generally, I only post one photo per daily piece, and occasionally two to help clarify or extend an idea or feel of a location. I think this is the first time I've posted three, with the exception of a few "teaser posts," where I'm trying to capture a few highlights of a particular day's stops. In this case, I think these work well together, but the second and third wouldn't really be noteworthy on their own.

Photos unmodified. October 9, 2014. FlashEarth location.

Geo 1095: May 12, Day 862: More Sloping Lava and The Husband(?)

Walking down the road toward the lower switchback (note sign in lower right), there are more steeply tilted emplaced lava flows in the road cut. This would have been quite a show to see from nearby, but this particular location would have been an unpleasant spot from which to watch it. The issue likely wouldn't have been the lava itself, at least at first. Even runny lava doesn't tend to advance that fast. But on  this slope, hot boulders breaking and rolling off the flow would have heralded the advancing front. And even if you managed to avoid getting brained by one of those, they probably would have been setting numerous fires as they bounded merrily down the mountainside.

While the above is simply an exercise of my imagination, it's neither empty nor pointless; similar events will, with almost complete certaintly, occur in the future. The portion of the Cascades between North Sister and Route 20 has been highly active during the Holocene, and with the exception of the high peaks standing above the High Cascades platform, has been almost entirely repaved with fresh young mafic flows during the past 10,000 years. This road's existence will be quite short in geologic terms. It may not be destroyed in the lifetime of anyone reading this, in fact, it most likely won't be. It might be centuries, but it might be only months... this drive will almost certainly be buried under fresh basalt.

As I indicated in the title, I think the peak on the horizon in the left middle is The Husband, a large peak to the west of The Three Sisters, though of lower prominance than any of them. I'm not certain, though, thus the parenthetical question mark.

Photo unmodified. October 9, 2014. FlashEarth location.