One Year From Today

The blue line across the middle represents the mid-line of the August 21, 2017 total solar eclipse. The shaded area around that line represents the area of totality, where the sun's disk will be completely obscured for a period of time as the moon passes in front of it. The closer an observer is to the mid-line, the longer the sun will be obscured.

I've been excited about this for years; I've never seen a total solar eclipse. I've seen partials that were total or annular elsewhere, but I've never been in the path of totality. For viewing, all I really need to do is be awake and standing in view of the sun, but I'd like to get to a decent elevation. I understand that if you're in a spot with a good east-west vista, you can see the shadow of the moon approaching and receding before and after totality. In Corvallis, the umbral speed will be 1.310 km/sec, or 2929 miles per hour-- which is to say, the fastest predictable thing I will ever see. This interactive map (from which the above screen shot was taken) is the best resource I've found for planning, with extensive details about the event. Simply click the crosshairs on a point of interest, and a table of data will pop up, telling you everything you could want to know about the eclipse at that position.

I have some ideas about where to watch it, but I hope to have opportunities to do some scouting between now and then. It may be that I can get up to the Santiam Pass area and do geology for much of the remainder of the day. In the end, I suspect I'll play it by ear. This time of year, fires and smoke can muddle an otherwise glorious view. However, the chance of rain- or even heavy clouds- in mid-late August is next to nil.

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 730: July 21, Day 567: Sidewalk, Redux

Okay, it's a pretty lousy photo, and the shadows from the fence when I was out taking pictures don't help at all, but here's the same stretch of sidewalk I featured five years (!) and a month ago. I've annotated just two of the more distinctive pebbles, but you can see the full deal here. That photo seems to have a big impact in presentations I've done over the past few years. In a field trip a month ago, participants found quite a few nice agates at our first stop, and were somewhat distracted from the geology we wanted to point out. No great loss, though. If they take away the importance of geological materials in construction, I can concede distraction from other rocks.

Photo unmodified. July 18, 2014. FlashEarth location.

Geo 730: July 20, Day 566: 9 to 5, and Nighttime, Too

Interzone's sundial is marked from nine AM to five PM, and oddly, "Night" is marked, too. How does that work? When the sun goes down, the street light comes on, and casts a shadow along the marked path. We're on a spnning ball of rock, which means the sun appears to move through the sky, but the lamp spins with it, so it appears fixed.

Photo unmodified. July 18, 2014. FlashEarth location.

Geo 730: July 19, Day 565: Lavender Garnished with River Gravel and a Bonus Butterfly

Prior to chalking in the sundial in yesterday's photo, Tim and his son removed the cheatgrass that normally dominates the base of the pole, brought in some good soil, and planted a number of lavender starts. Then they tiled the bare areas with some river gravel. It's a refreshing change from the nasty invasive. A passing butterfly appears to agree.

While the angle of the shadow with respect to 16th and Monroe is not evident in this photo, I'll first admit, I threw out a bit of a deceptive comment yesterday when I described 16th as running "roughly north-south." The original street grid in Corvallis was laid out parallel to the riverfront, and runs about 20 degrees east of north. At Kings Avenue, a block west of my current location, the street grid snaps to N/S-E/W, or truly compass oriented (See the FlashEarth location). Second, due to modern horological conventions, we're currently on daylight savings time, which means the clock gets to noon about an hour earlier than the sun reaches "true noon," at its greatest height in the sky and directly to the south. Put those two factors together, and you can see why the two o'clock mark is the one that's almost parallel to 16th street, not the 12 o'clock mark.

Understanding these sorts of seemingly unrelated tidbits to make sense of the world around us is all part and parcel of "thinking like a geologist." I commented, "we're looking at an intersection of geology, geography, horology, and human history." When solving geological puzzles, one needs to be able to draw from a great many disciplines, even if the puzzle is as trivial as, "Why isn't the shadow falling where we'd expect it to?"

Photo unmodified. July 18, 2014. FlashEarth location.

Geo 730: July 18, Day 564: High Noon at Interzone

I'll be taking a few days' break from Quartzville to enjoy a spontaneous bit of art that happened at Interzone starting on Tuesday. Every hour, on the hour, IZ denizen Tim snapped a chalk line on the left edge of the shadow cast by the street lamp/telephone/power pole on the northeast corner of 16th and Monroe. Then the lines were bolded and times colored in with sidewalk chalk by Heidi and Erin. Shea drew a silhouette on the two o'clock line, which is the one most parallel to the street. This was shot within a minute of noon; for the time being, it's surprisingly accurate.

Where's the geology in this? If you've followed this blog at all, you know my attitude is that it's all geology, and this is no exception. Under the "12" is asphalt, a mixture of petroleum products, sand and gravel. Under my shadow and in the upper right is concrete, made of lime (CaO) (which in turn is limestone (CaCO3) heated to drive off the CO2) mixed with clay, to which water, sand and gravel are added and allowed to set. The chalk itself is either the same composition as limestone (true chalk) or gypsum (which is softer and easier to work with). These materials are normally powdered, some clay added for a higher degree of consistency and hardness, then pigment and binder added. The result is then molded into the cylindrical form in which we are accustomed to using it.

At a more esoteric level, we're looking at an intersection of geology, geography, horology, and human history. I'll get back to this tomorrow, but I'll leave with a comment and a couple questions: the streets in this area run roughly north-south. Why is the sun at noon casting a shadow so far to the west? Wouldn't you expect the shadow to be falling northwards, roughly parallel to the street, rather than across it?

Photo unmodified. July 18, 2014. FlashEarth location.

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It's been a crazy period of my life... I got evicted with no reason given, Corvallis has been completely overrun by  predatory property management companies, and I've been having a heluva time finding a reasonable place to live. But I found a good one yesterday, signed paperwork and paid initial move-in costs today, and will move in over the next few days. Even got an okay for Bif. It's a nice older place with real character, and the owner/landlord, who lives downstairs, is a construction contractor, so not only is everything in good shape, but if something goes wrong, he's right there to get on it.

So the blog hiatus is not due to ill health or anything on my part, just too busy with other stuff to fuss with that too. Posting will be light to nil through the weekend, but I will get caught up with the Geo 365 series next week at latest. Sunday Funnies may be AWOL until next Sunday. I have to be out of my current apartment by Sunday night, so hopefully Monday, life will settle back into a more normal routine. Until then, wish me luck.

Geo 730: Feb. 9, Day 405: Outside the Interzone

Okay, one more of these self-indulgent meteorological mineralogy photos: this is my home-away-from-home, the Interzone. The snow started melting yesterday, with a fairly steady, but light, just above-freezing rain. The roads are now rutted slush, and especially for low-clearance vehicles, driving looks as treacherous as it's been over the last few days. Improvement is on the way, but conditions for the time being are not good.

Photo unmodified. February 7, 2014. FlashEarth Location.

Geo 730: Feb. 8, Day 404: Ground Not Found

I saw "404," and thought, "what couldn't be found?" Well, obviously. Many people have been skiing and snowboarding around town the last couple days, thanks to our 18 inch coating of white mineral grains, and as I commented to @GeoHols earlier, "It's gone beyond troublesome to obscene to freaking hilarious. Not a huge fan of snow, but have to admit I'm enjoying this." The very best was Thursday morning, when a guy on skis was being towed by his dog. He was passing the vehicular traffic.

Photo unmodified. February 7, 2014. FlashEarth Location.

Geo 730: Feb. 7, Day 403: Meteorminerology and Geology

 Technically, snow is simply a pile of mineral grains. A mineral is "a naturally occurring, inorganic, crystalline solid with a fixed composition, or a composition that varies within a fixed range." Snow (and ice of any kind) meets each criterion of that definition; it is a mineral. And man, oh man, have we a pile of mineral grains in Corvallis right now. I'm guessing about 15-16 inches, rivalling the deepest snow I've ever seen here. As sort of a meta-treat, we're looking at the back side of Wilkinson Hall, the Geosciences building on the Oregon State University Campus. Beyond that is Burt Hall, the Oceanography and Atmospheric Sciences Building. Together, the two house much of CEOAS, OSU's College of Earth, Oceanographic, and Atmospheric Sciences.  (I'll head back to SE Oregon in a day or few, but this snow is pretty amazing, and I can't pass it up.)

Photo unmodified. February 7, 2014. FlashEarth Location.

Geo 365: June 26, Day 177: Jefferson and Three Sisters

A view similar to Monday's panorama, but a single shot. Mount Jefferson is visible in the gap in the trees to the left, and Three Sisters, somewhat obscured in low clouds, can be seen near the center. I suspect there are viewpoints less obscured by trees farther up the summit trail, but we were time constrained on Saturday, and I no longer have the stamina to tackle even a portion of that trail lightly. Unless the viewing is excellent, I'm not going to wear myself out trying.

Photo unmodified. June 22, 2013. FlashEarth location.

Geo 365: June 25, Day 176: These Are Some Features in My Neighborhood

Looking east out over the Willamette Valley from the top of Marys Peak, the fault marking the boundary between the valley floor (forearc basin) and the Coast Range (forearc ridge) is pretty obvious. The fault itself actually sits about 1 1/2 km (1 mile) in front (east) of the prominent ridge. This sort of landform, where the escarpment runs parallel to the fault, but not on the fault- typically because erosion has beveled the ridge back- is called a fault line scarp. This differentiates it from a fault scarp, which is taken to mean that the ridge accurately marks the location of movement.

The Corvallis Fault is stitched by gabbroic/diabasic intrusions of Oligocene age, contemporaneous with and similar to the Marys Peak Sill. These intrusions have not been broken tectonically, providing good evidence that our neighborhood fault has not been active for roughly 30 million years. Despite its proximity to town, it's not one we need to worry about with respect to seismic hazards.

1st photo unmodified; in 2nd, contrast ramped up and annotated in Paint.net. June 22, 2013. FlashEarth location.

Geo 365: June 24, Day 175: The View Across the Valley

The view on Saturday looking out over the Willamette Valley (forearc basin) to the Cascade volcanic arc. Mount Jefferson on the left (north), Three Sisters on the right (south). We're standing on Marys Peak, the highest point in the Oregon Coast Range, the forearc ridge. It's difficult to describe how profound this view is to me; we're looking at a fundamental component of the earth's engine.

Photo stitched in Hugin, otherwise unmodified. June 22, 2013. FlashEarth location.

Marys Peak Geology Roadlog

Saturday, I'm doing another Willamette Valley Geology Workshop for the Oregon Master Naturalist Program, and yesterday Bob Lillie and I went over the schedule, outlines of presentations, and scouted out the Marys Peak Geology field trip we'll be doing to top the whole thing off. I've posted various bits of stops up Marys Peak in the past, but never really brought the whole thing together in one cohesive guide before, so I hope this is useful to people who are interested in exploring the area on their own.

Imagine Coffee is at 53rd and Philomath Boulevard (Route 20/34) between Corvallis and Philomath. I had never been in there before yesterday, but based on my visit, it's a nice relaxing space, with good coffee, tasty breakfast sandwiches, and a nice selection of pastries. I'm sure they wouldn't mind your business, but if you're in a rush, just zero your odometer as you go through the intersection with 53rd Street.

Why Marys Peak? I know my Oregon Central Coast Range geology pretty well, and there is no place that gives an as complete or well-exposed transect as the drive up Marys Peak. It shows a tale of ocean floor eruptions, building to Hawaiian-style subareal eruptions, with associated erosion and deposition of volcanoclastic sediments on the flanks of that(those) island(s). This was followed by subsidence, accretion to North America, and pretty much at the same time, burial under a voluminous Eocene sediment source in the form of an apparent river drainage coming out of the Idaho Batholith. I've seen speculation that the headwaters of this drainage lay in the lake environment that created the Green River Formation in the UT/WY/CO tri-state area, but I don't know whether that was ever confirmed. While the coarser deltaic facies of the Tyee Formation now lie to the south, in the Roseburg area, in the central coast range, this unit forms well-defined couplets of sandstone-silt/mudstone turbidites. Finally, about 30 million years ago, as the reactivated (after stepping back and reinitiating following the above-mentioned accretion) Cascadia subduction zone got going, a series of Oligocene intrusives invaded the Coast Range. The thousand-foot-thick Marys Peak Sill is an outstanding example of one of these, and its resistance to weathering and erosion make it a capstone protecting the softer underlying rocks, explaining why Marys Peak is the highest in the Coast Range.

Even if you aren't into geology, the drive to the top is replete with wonderful scenery and a parade of ecological change as you drive through ever higher elevations and frequent changes in aspect, leading to large variations in sun and moisture availability. The views from the summit area are to die for. And for geologists, the ability to walk from one side of a parking lot to the other, and see from pretty much directly over the subduction zone, under the ocean horizon to the west, the forearc ridge (where the peak stands), the forearc basin (the Willamette Valley), to the volcanic arc (the Cascades), is utterly mind blowing. You can, from one spot, see a cross section of one of the major features resulting from the plate tectonic activity of our planet.

0.0              Start (Intersection of 53rd and Philomath Blvd-Route 20/34)
0.4              View to north of hills on N side of Corvallis Fault- Siletz River Volcanics
3.7              Turn Left on Route 34, to SW, toward Alsea & Waldport
10 .0           Switchbacks up to Alsea Pass
11.1            (pull off on left; caution crossing opposite lane) Stop 1: Steeply dipping beds of Tyee Formation turbidites.

12.7             Turn right onto Marys Peak Road
14.8             (Optional stop- not easy to get more than one or two vehicles off the road here, not recommended for larger groups) Hyalocalstite below (on the right, if you're facing upslope), crudely columnar jointed basalt sill above (left). In between,  a few inches of Kings Valley Siltstone, the result of erosion and deposition of Siletz River Volcanics that erupted subareally. This is the lowest (stratigraphically) spot in which I've found it.

15.9             (Optional stop) Pullout on left. Across the road is a nice set of columnar joints that roll over along the outcrop, so you can see them both from the side and on end. They rest over some oddly and very heavily weathered sphereoids of (possibly) a pre-existing flow. I'm not certain how to interpret this contact, but I've been considering that it might be a stream channel that was filled by a later subaereal flow. I want to emphasize that that idea is highly speculative, but I haven't been able to come up with an explanation I like better.

16.4             Large parking area on left, pull out and regroup for walk to Stop 2, Pillow Basalts (+lunch) See further discussion here. Hand sledge for scale on lower left of outcrop.

18.2             Harlan Road to left (Optional side trip) Drive about a mile down a very rough, pot-holed gravel road to the outcrop just past where the power line crosses the road- there's room to get off the road on the downhill side at the lower end of this outcrop. This is the best exposure I know of of the Kings Valley Siltstone, though it's weathered pretty badly over the years. See this for a detailed discussion of the unit. Another feature here are some ashy layers. It was suggested in the early 80s that these might be derived from the Challis Volcanics (PDF), and with the clearer picture of the Coast Range block migration that emerged in the mid to late 80s, that seems to make even better sense.

Continue down the road another 1/2-3/4 mile (We didn't do this spur on our scouting trip yesterday, so I don't have good mileages), to where the road turns well into the hillside to contour into a significant drainage, Parker Creek. There a very obvious parking area, a fire ring and a number of large, beautiful cedars. I particularly like this spot due to the gorgeous riparian habitat, with ferns everywhere, and the gigantic trees. Geologically, though, we've gone downhill, but up section- the bedrock is Tyee Formation, which overlies the Siletz River Volcanics and its associated Kings Valley Siltstone member. So we can infer a significant fault somewhere between the previous stop and this one. Return to the main road, and turn left.

19.2             Pull out to left as far as possible, walk back to Stop 3, Tyee Fm, Kings Valley Siltstone, fault and landslide

(Click here for a selection of sizes at Flicker; right click on that image for a list of size choices. Alternatively, right click on the photo above and open image in a new window.) To the left, you can see the horizontally bedded Tyee Formation, with its well-defined sand-mud couplets. On the right, the poorly bedded and more chaotic Kings Valley Siltstone stands out mostly because it's so much darker- almost black- than the Tyee. Again, we can infer a fault between these two exposures. Another point of interest is that you can see the base of the Tyee above the Kings Valley on the right side (though it doesn't really show up in the above photo)- the only place I think I've ever seen the base of that unit. On the left-most side of the photo, you can see a temporary Jersey Barrier, and the edge of the road has collapsed. This has been repaired, and the barrier replaced with a hefty guardrail, but this failure was very likely due to the fault, which shattered the rock, and allowed easier access for water and air to weather the zone out more quickly and easily than elsewhere.

19.6             Parking area to right for Stop 4, Parker Creek Falls, Marys Peak Sill (Gabbro) This is a terrbly tough, resistant rock that intruded into the base of the Tyee about 30 million years ago. It has acted as a protective capstone, about a thousand feet thick, over the softer, more weathering and erosion-prone rocks below it. That, in combination with uplift between the Corvallis and Kings Valley faults, explains why Marys Peak is nearly 1000 feet higher than the highest of the other Coast Range Peaks.

21.2             (Optional stop) Meadow Pullout on right. Due to elevation, with subsequent harsh winter weather- deep snow pack, powerful winds, bitter cold, and comparatively short growing seasons- along with parched, dry summers- this is the first place along the road where we see the mountain meadows that dominate the crests and south sides of the Coast Range's tallest peaks. Flower season runs from early May into July, with a long cast of characters that's constantly changing. Take a moment to consider how the stack of geology we've seen so far has created the environment that supports this botanical wonder, then walk east up the road and look for the rocks in the road cut. This type of rock is called hornfels, and it was created by contact metamorphism when the sill below cooked overlying Tyee sandstones and silts. See Dana's post for more information being explained by me in video format.
22.3             Summit Parking area, Stop 5: views of subduction zone, forearc ridge, forearc basin, and volcanic arc. I can't say enough about this spot. There must be other places in the world where you can basically see from the location of the subduction zone to the associated volcanic arc, but this is the one I know. And it blows my mind every time I get up there on a clear day. Again, here's what Dana had to say about it. Below is a view to the west from near the summit parking area; the dim blue line is the horizon above the Pacific Ocean, and a bit of trigonometry suggests that the horizon is about 75 miles distant- very close to the location of the decollement fault where the Juan de Fuca plate begins its dive under North America!

One final optional side trip, if you want a bit more petrologic goodness. At the northeast corner of the parking area, a trail descends the mountain side after following the summit ridge a ways. Walk a few hundred yards/quarter mile or so down the trail, and keep an eye out for cobbles of Marys Peak Sill weathered out onto the surface.

Enjoy your geotripping!

Geo 365: May 11, Day 131: May 10 Teasers

We had hoped to get a good view of the Cascade Crest from the summit parking lot at Marys Peak, but we've already had a month of summery weather with little rain. Additionally, the humidity was headed up; as a result, the haze was nearly as bad as during our visit last summer. I could make out Hood and, barely, Jefferson, but photos were right out. So yesterday ended up being more bio than geo, but still, a good day.

Sphereoidal weathering in the Marys Peak Sill, a bit above Parker Creek Falls. We saw only one other vehicle on the road up the mountain yesterday, and it was headed to the top as we headed down. It was a good day for pulling off in areas with a narrow berm- places I've walked out, but rarely had the chance to stop with others.

The view from the summit parking area (which is about 500 feet below the actual summit). Philomath lies at the mouth of the valley that runs from lower right toward the middle, and Corvallis is roughly behind the taller of the two trees to the left.

A lilly in the meadow near the parking lot. At ~3700 feet, there was still snow standing in sheltered, mostly shaded areas, and the grasses were still pressed and felted flat. This is likely the equivalent of mid-March in terms of seasons up here.

A bird that is not uncommon to see in streams in western Oregon, but is rarely cooperative in terms of being photographed, a water ouzel, or American dipper. This guy was hanging out along a stretch of stream at Alsea Falls, and while he moved around quite a bit, he wasn't leaving that stretch at all. I watched him for half an hour or more, mesmerized. Dana got some really nice video clips of his bobbing and feeding.

Photos unmodified. May 10, 2013. Locations will be specified when I post on these spots in more detail.

313... And Counting

Today is the 313th anniversary of the last Great Cascadia Earthquake, and I have a number of items to commemorate it. First, a couple of days ago, The Pacific Northwest Seismic Network had a truly outstanding post on what happened,  where we are, and what we know now. Very much recommended.

Second, a news article from The Oregonian online, "Opponents say Riverbend Landfill's mega-quake analysis falls short." Long story short, a Portland area landfill has filed for an expansion permit, and are required to do a seismic analysis as part of that process. One was done, but it assumed a maximum magnitude of 8.5. Now the range I typically mention is "9 plus or minus 0.5." That may be a bit much on the high end, but not too much. So the number they use would cover the vast majority of quakes that affect the area, but liquifaction and slumping in the event of a truly great quake can't be discounted. And especially in view of the landfill's proximity to the Yamhill River, that is of real concern.

A related personal anecdote: last May, the house next my apartment, a student rental, started to undergo an enormous restoration. I found it quite irritating, as work started at 7 each morning, and often continued until 10 or 11 at night- this was right outside my bedroom window. Then suddenly, in mid-September everything came to a halt- and work was clearly not complete. Only a couple of weeks remained before fall term began, and I had assumed the owner wanted it back on the rental market for 2012-13 school year.

As I walked in to the Interzone one morning shortly afterward, I noticed a big sign posted near the door. I don't remember the exact wording, but in effect it was this: "DO NOT ENTER. The Corvallis City Inspector has found this building is unsafe to occupy. The structural integrity of this building renders it unfit for human occupation at any time." Within a couple more days, hurricane fencing had been installed around the entire property. It sat abandoned for nearly a month, then work resumed.

I felt kind of bad for the owner. My assumption was that he/she/they had hired unlicensed contractors who had cut corners- so either the building would be demolished, or four months of work would have to be, at least in part, redone.

However, in early November, again as I was heading out in the morning, a worker was just pulling up to start the day. After peering at the recently poured concrete/rebar foundation, with about 8 inches of rebar sticking up every 18 inches or so, I walked over to him, explained I was a next door neighbor, and was curious about the situation. It turned out, he was the owner, and he'd been doing a lot of the work himself, with daily hires, or specialized operators as needed. The house dated to 1890, he explained, and the wooden piles on which it rested had never been updated. He'd inspected it during the spring, and realized they were completely rotten. So he'd found satisfactory arrangements for last year's tenants, who were forced to move just a month before OSU concluded its spring term, and started work immediately.

He had jacked the house up, removed the old pilings, then leveled the entire house on a series of jacks intended for that purpose. In his words, "I was just replacing something that was really bad with something I thought was good."

However, unknown to both of us, new seismic restrictions have gone into effect in Corvallis. While I didn't pin down the details, my supposition is that any work done on a building that involves its structural and/or foundational integrity must be brought up to the new code. In this case, it involved digging and pouring a foundation for the entire building that, in his words, "could stand up to a nuclear blast." And from what I'd seen of its construction, for anything but a direct hit, that's not an exaggeration. He explained that at first they said they going to require what I can only describe as "flying buttresses" on each corner, which I agreed was overkill- it's a one-story, wooden-framed house. As long as it stays on its foundation, it's almost certainly not going to have problems. And remember those steel bits protruding above the foundation? Once the house was lowered onto those and bolted down, it ain't going nowhere.

I was quite pleased I'd had the chance to chat with him... what I had presumed was laziness and/or cutting corners actually revealed our own ignorance- both his and mine- of pertinent changes in building codes.

Now, I have regularly complained that Oregon is not moving as decisively or as speedily as I might like with respect to seismic preparedness. But the previous two stories illustrate a point that makes me feel good (or at least better): regulations- regarding dumps and housing construction, for example- are not really high on my radar profile, nor those of journalists. However, they can quietly pass at the city, county, or state level, and have enormous effect. Do I wish things were moving faster? Sure. But that house next door is going to be one safe dwelling- I'd willingly pay a premium for a structure like that, whether for rent or as the price of the property. One dwelling down isn't much in a city of fifty thousand, but over time, between new buildings and retrofitting, the effects will accumulate.

So it's not all gloom and doom.

Finally, when Dana and I were down on the south-central coast last March, we saw some spectacular stumps at Sunset Bay that are carbon-dated to about a thousand years ago, apparently victims of coastal subsidence, in another great quake. The nice thing about these is that they're readily accessible, just a short walk, rather than out in the middle of a salt marsh. The first photo is on the same side of Big Creek as the parking lot.

There are quite a few of them. This was after we had crossed the creek. If there's too much water to simply wade across, a short walk upstream, near the picnic shelter, there's a bridge and a trail back to the south shore.

Photos taken March 12, 2012. FlashEarth Location.

Also, as a reminder, or if you missed it, Tuesday I posted some links and information regarding earthquake preparedness. And as I said in that post, the best time to be prepared for an earthquake, or whatever sort of disaster your locale is prone to, is right now.

Stay safe, all!

Whole Lotta Shaking

I was just checking on the date of the 1700 Cascadia Earthquake; it was, as I thought I remembered, January 26. I'll try to find something appropriate to post for Saturday, but in the meantime, I found the Wikipedia entry informative and interesting.

Also, I checked the "Great Oregon Shakeout" page. I'm pretty sure that used to be on Jan 26, to commemorate that last great quake, but it appears to have been moved to 10:17 AM, October 17. My sense is that this is to better align with other "Shakeout" drills nationally and globally, though off the top of my head, I don't know if this commemorates the anniversary of some other quake. But in the end, it doesn't matter. The best time to be prepared for an earthquake- or any disaster, for that matter- is right now.

The following text was lifted without permission from the shakeout page (PDF Link)- note that it is copyrighted, and if I'm asked to remove it, I most certainly will. But it seems to me that the nature of this information is such that it needs to be shared and read by as many as possible.

Recommended Earthquake Safety Actions

© 9/15/12 Earthquake Country Alliance


Federal, State, and local emergency management experts and other official preparedness organizations all agree that “Drop, Cover, and Hold On” is the appropriate action to reduce injury and death during earthquakes.  Great ShakeOut earthquake drills (www.shakeout.org) are opportunities to practice how to protect ourselves during earthquakes.

You cannot tell from the initial shaking if an earthquake will suddenly become intense…so always Drop, Cover, and Hold On immediately!
•    DROP to the ground (before the earthquake drops you!),
•    Take COVER by getting under a sturdy desk or table, and
•    HOLD ON to your shelter and be prepared to move with it until the shaking stops.

If there is no table or desk near you, drop to the ground and then if possible move to an inside corner of the room. Be in a crawling position to protect your vital organs and be ready to move if necessary, and cover your head and neck with your hands and arms.

Do not move to another location or outside.  Earthquakes occur without any warning and may be so violent that you cannot run or crawl. You are more likely to be injured if you try to move around during strong shaking. Also, you will never know if the initial jolt will turn out to be start of the big one…and that’s why you should always Drop, Cover, and Hold On immediately!

These are guidelines for most situations. Read below to learn how to protect yourself in other situations and locations, or visit www.dropcoverholdon.org.

If you are unable to Drop, Cover, and Hold On: If you have difficulty getting safely to the floor on your own, get as low as possible, protect our head and neck, and move away from windows or other items that can fall on you.

In a wheelchair: Lock your wheels and remain seated until the shaking stops. Always protect your head and neck with your arms, a pillow, a book, or whatever is available.

In bed:  If you are in bed, hold on and stay there, protecting your head with a pillow.  You are less likely to be injured staying where you are.  Broken glass on the floor has caused injury to those who have rolled to the floor or tried to get to doorways.

In a high-rise:  Drop, Cover, and Hold On.  Avoid windows and other hazards.  Do not use elevators.  Do not be surprised if sprinkler systems or fire alarms activate.

In a store: When Shaking starts, Drop Cover and Hold On.  A shopping cart or getting inside clothing racks can provide some protection. If you must move to get away from heavy items on high shelves, drop to the ground first and crawl only the shortest distance necessary. Whenever you enter any retail store, take a moment to look around:  What is above and around you that could move or fall during an earthquake?  Then use your best judgment to stay safe.

Outdoors:  Move to a clear area if you can safely do so; avoid power lines, trees, signs, buildings, vehicles, and other hazards. 

Driving:  Pull over to the side of the road, stop, and set the parking brake.  Avoid overpasses, bridges, power lines, signs and other hazards.  Stay inside the vehicle until the shaking is over.  If a power line falls on the car, stay inside until a trained person removes the wire.

In a stadium or theater:  Stay at your seat or drop to the floor between rows and protect your head and neck with your arms.  Don’t try to leave until the shaking is over.  Then walk out slowly watching for anything that could fall in the aftershocks.

Near the shore:  Drop, Cover, and Hold On until the shaking stops. If severe shaking lasts twenty seconds or more, immediately evacuate to high ground as a Tsunami might have been generated by the earthquake.  Move inland two miles or to land that is at least 100 feet above sea level immediately.  Don’t wait for officials to issue a warning.  Walk quickly, rather than drive, to avoid traffic, debris and other hazards.

Below a dam:  Dams can fail during a major earthquake.  Catastrophic failure is unlikely, but if you live downstream from a dam, you should know flood-zone information and have prepared an evacuation plan.

More information: 
www.shakeout.org/dropcoverholdon      
www.dropcoverholdon.org
www.earthquakecountry.org/dropcoverholdon