Saturday, October 13, 2012

Geogalavanting Around Oregon with Dana

Dana came into town on Monday, so I got little reading done on the 8th, 9th and 10th. Then Thursday, Interzone WiFi was down, and OSU visitor was exceptionally weak and difficult to access... I was awfully frustrated. So yesterday morning, I was effectively four days behind in my reading. With this rebuilt machine, though, skimming, skipping and reading is much quicker. I also decided to simply delete all news items older than two days, which means maybe 1500 items skipped- I'm sure I missed some MSM science news I'd like to have read, and I've been pleased at how often (and generally, well) OregonLive covers geology-related news in Oregon and the PNW broadly, so I probably missed 2 or 3 of those as well. Well worth it though, to save myself six or seven hours of browsing time. So I spent eleven hours yesterday, and better than four today, plowing my way back to the beginning of the week. And now I'm caught up. Whew!

In other news, I can say with some degree of excitement and pleasure that our rain has returned with a vengeance. The prediction yesterday was for about 0.1 to 0.25 inches; we got 0.37, and it looks like some serious accumulation tomorrow night through Tuesday morning. Various sites are predicting 2-4 inches in this area. To which I say "Bring it on, baby!" A report that I read this morning, from Cliff Mass Weather Blog, commented, "In the Olympics, north Cascades, and southwest BC terrain (particularly Vancouver Is) amounts reach 5-10 inches, with a few higher values on the windward slopes. Wow." So 2-4 inches sounds about right to me.

On with the show. My goal today is to summarize the geotripping Dana and I did on Monday, Tuesday and Wednesday, along with a few photos. Our original intent was to either hit NW California and the Josephine Ophiolite along route 199, or central/eastern Oregon doing day trips out of Bend- in particular, Dana wants to hit up John Day National Monument, and I've never been to the Painted Hills unit near Mitchel, so I'd like to do that. For various reasons, though, we decided to simply do day trips out of Corvallis. Due to a number of other factors, we did an awful lot of last-minute plan changes, too. But it all worked out well- I don't think there's anything we missed on this trip due to time shortages. Dana and I are both getting better at budgeting our time. And on the plus side, there were a number of things neither of us had anticipated seeing, but did. So overall: good trip!

Monday, we decided to just hang out around town, take in some local parks, and do the architectural walk around the OSU campus that I've done with Ryan and Emily. First stop, Chip Ross Park, north of town. The geology is kind of subtle here, but the views are good, and the interesting component is broadly interpreting the geomorphology visible from the park.
 I love the oaks that line the hill crest, so I took way too many pictures of them...
Old Man's Beard (an epiphytic lichen) and fall foliage on Oregon white oak.
Looking ~west at Marys Peak... didn't think to get photo for annotation [followup, turns out I do have a couple good ones], but Corvallis fault runs just off the left edge of the photo, and has raised basaltic Siletz River Volcanics roughly 2000 feet (guesstimate, based on Marys Peak exposures) against younger, more easily eroded later Neogene turbidites, creating a very visible fault-line scarp.
Looking south, down into my little burg. Growing up in SE Ohio, this quantity of haze should seem trivial, but after 32 years in Oregon, it's painful for me to see the air this awful. Witham Hill in mid-distance along right side, Country Club Hill farther back and out a bit farther from the edge. Both of those hills are composed of Spencer Formation, which is shallow marine sediment (lots of fossils) on top of older Tyee turbidites, and Witham has an Oligocene mafic dike. Avery Park, our next stop, is along the Marys River near its confluence with the Willamette, just to the east (left) of Country Club Hill.
Saprolite (which I learned as 'saprolith,' but I gather is the preferred English geo-usage now) at the base of the hill, as we headed back to the car. The word comes from roots meaning dead or rotten rock.
Gorgeous fall foliage at Avery Park. I was thinking maybe a box elder, but followup says not. So no real clue what kind of tree this is- it has compound leaves that remind me of walnut or pecan, but not quite right for those.
While barely visible at the scale above, the picnic table in the above photo is nearly 86 feet long and cut from a single slab of wood (the benches are not, which make getting sat down less problematic).
Displayed in the Rose Garden, this is one of the first millstones in Oregon... from the plaque on the other side, "This was originally quarried in France, and shipped around the horn from New York in 1850 by sailing vessel." The rock was too stained, warn, and coated with gunk for me to be confident, but I think it might be quartzite. Do you need for me to go off on the importance of geology in day-to-day life again? Okay, I'll wait.

We also did my tour of the OSU campus with a focus on the rocks used in construction, but I took no photos, and ones I've taken previously are not on this computer right now, so I'll just leave that dangle. To make up for it, I'll just let you know that between the two of us, we found complimentary men's and women's rooms that have good examples of fossiliferous stylolitic limestone. The one I've stopped at before is in the Memorial Union, and only the men's room has that rock. It's okay during the summer, when there's no one around, but not good during the regular school year. We also ran into Peter Clarke, Aaron's advisor. I introduced myself to him with, "Hi! My name's Lockwood DeWitt, and there's no reason on earth you should remember me."

Day 2: Up to McKenzie Junction, down the Upper McKenzie River, with stops at Clear Lake, Sahalie Falls, and Koosah Falls, then up over McKenzie Pass to Sisters, dinner, then back to Corvallis, with just enough light to get twilight silhouette of Mt. Washington.
Only a small trickle of water on the Middle Santiam River at Cascadia State Park. Hydrology/hydrogeology emerged as the unexpected theme of this trip- that is, I was certainly aware water would be an aspect of what we would see, but I wasn't expecting the way it came to dominate my attention and thinking. Not in a bad way, of course, but in an interesting way.
A very interesting and puzzling cut-and-fill structure up near Tombstone Pass, which I had never stopped at before. Turns out, there's a spacious pullout area that was much appreciated. (Pretty sure this is the location, in FlashEarth) I'd always assumed the underlying material, with the sort of badlands topography, was an ash tuff. It's not. It shows only modest (if any) rounding, but it's more coarsely lithic and mixed in terms of fragment types than you can see in a drive by. I'm thinking maybe explosive debris, but I'll need to flesh out my reasoning another time.
Three-Fingered Jack looming over McKenzie Juction, fall foliage, a fairly fresh lava flow, and Dana's car. This was beautiful spot to stop, as the viney maple was fiery red, and symbolically very pleasing on flows that cooled quite recently.
A tree trunk, submerged and drowned when Clear Lake was created by a blocking lava flow 3000 years ago. I was terribly shaken by this lake; my balance is weak at best, and I need visual cues to stay upright. The clarity of the lake, combined with weird perspectives and shadows, had vertigo playing havoc with my sense of stability. But it was surreally gorgeous in terms of color. And you think it's wild to see these logs from the dock? You can see them from orbit! This shows a down log underwater, extending under the "Clear Lake" label.
Sahalie Falls. Compare the flow rate here to that of the Santiam at Cascadia: much, much greater. Turns out, there's a very interesting set of reasons for that, which I'll get back to someday.
And finally, for Day 2, a view to the south toward North and Middle Sisters. This is at a viewpoint a few miles west of the Dee Wright Observatory and the interpretive walk, which are right at the pass.

It's getting late, so I'll cover day 3 tomorrow, after I get the Funnies up. Stay tuned... there's more awesome yet to come!

Followup: forgot to drop this in... I was just a little bit into this when Dana posted her summary of her vacation, of which this was about half. And Part 2 of my summary is here.


Anonymous said...

Hi, I've been enjoying your "geogalavanting" series, and was just wondering how the age of that underwater tree trunk was estimated--is the water very acidic so that it's still preserved?

Lockwood said...

At 3ka, the age is perfect for carbon dating. While I'm not certain that's how the age was arrived at, I'd be willing to bet it was. The water is *very* cold, even at the end of a very long summer, and the lake is entirely spring fed, so it's pretty low in oxygen. Not only is decay slowed by temperature, it's also slowed by a lack of a necessary chemical component.