Saturday, August 10, 2013

Geo 365: August 10, Day 222: Scenic Shore

I'm unsure of the exact location of this photo, but it's somewhere in the Sunset Bay/Shore Acres/Cape Arago parks area. The plane of the uplifted terrace in this region is clear, as is the modern terrace at approximately sea level. We were headed to Sunset Bay for the low tide, and this trip was chosen to coincide with a series of negative tides, so this is getting close to maximum exposure of the modern terrace. It may look as if we're looking at a syncline in the cliff in the mid-distance, but that's an illusion. Along the right portion of the cliff, we're looking more or less along strike, so the beds appear mostly horizontal. About the middle of the photo, the cliff changes orientation to almost perpendicular to strike, so the dip of the beds becomes clear. So you're not seeing a fold, but almost uniform tilted beds from two different perspectives.

Photos of Sunset Bay can be seen in the week of February 11 through 17 in the Geo365 series.

Photo unmodified. March 8, 2012. Location uncertain; somewhere in the vicinity of Cape Arago/Shore Acres/Sunset Bay State Parks, Oregon.

Friday, August 9, 2013

Geo 365: August 9, Day 221: The Modern Terrace

I'm not really sure where these next two were actually shot. We looped through Cape Arago State Park after the sea lion viewpoint, and stopped at a cove south of Sunset Bay briefly, so the above may have either been taken at the viewpoint or the latter stop. Either way, it shows a good view of the development of a modern marine terrace (as opposed to an uplifted, prehistoric, terrace). This is also a good illustration of strike, the compass orientation of a series of beds' intersection with a normally imaginary horizontal plane. In most cases, a geologist has to use a level- often, the bubble level in a Brunton Compass- to determine precisely where "horizontal" is. In this case, at least to a good approximation, the rocks are beveled horizontally flat, so the lineations of the bedding planes show up as lines. The compass orientations of those lines would be strike.

Photo unmodified. March 8, 2012. Location uncertain; somewhere in the vicinity of Cape Arago/Shore Acres/Sunset Bay State Parks, Oregon.

Thursday, August 8, 2013

Collapsing Schools

The Eugene Weekly is a free "alt" newspaper that comes out of Eugene, Oregon every Thursday. "Collapsing Schools" is the cover story this week.
Photo by Trask Bedortha
I occasionally pick up a copy to read "This Modern World" and "Red Meat" or to browse through when I've finished reading the internet. My take on the article? It has a very definite Eugene focus- which is to be expected- but change the names and locations to any other west side PNW district, and it's pretty representative of the problems those districts face. Rebuilding and/or remodeling/retrofitting is awfully expensive, and too often, keeping up with new building code is simply impossible. But the closing comments in the final paragraph are too important to ignore:
For engineers like Wang, it’s all about protecting Oregon’s infrastructure and, more importantly, its people.  “The goal is to get something done slowly but surely so it’s not that painful when we divert a small percentage of our funds to improve things,” Wang says of the statewide mission to prepare Oregon schools for a major earthquake. “After it happens, we will definitely wish that we did more. I’ve seen it all around the world. No one ever expects it; it’s always a surprise. But those who prepare well recover more quickly.”
Yes, I think we should be working more quickly. But it's reassuring, as always, to know that even when I'm not aware of it, progress is being made.

Geo 365: August 8, Day 220: Simpson Reef

An oblique view of Simpson Reef, between Shore Acres and Cape Arago State Parks, near Charleston, Oregon. I had recalled this as a plunging anticline/syncline pair, and it more or less is. But as is so often the case, it's a little more complicated than I thought- there's a substantial fault cutting through as well. I've just spent an inexcusable amount of time tracking down the article (3.9 Mb pdf) that first clarified for me to the geology of the area. We visited and mapped the north cove of Cape Arago, visible in the aerial photo below, in our structural geology class, with Bob Yeats, lo these many years past. I found the Ore Bin Piece shortly afterward, and things kinda sorta started making sense. The following two illustrations are from the article linked above.
 The vantage point from which the leading photo was taken is labeled "Sealion Viewpoint" on the sketch map below, which also clarifies the structure. The viewpoint is indeed a good place to watch pinnepeds during calving season- late June through early August. Hint: bring binoculars. But when I stop here, it's more often to look at the geology.
Photo unmodified. March 8, 2012. FlashEarth location.

Wednesday, August 7, 2013

Geo 365: August 7, Day 219: More Soft Sediment Deformation

In the same area as yesterday's photo, this one shown quite a number of small flame structures (you'll need to enlarge to full size to see some of them), and some odd bleaching around the crack in the upper middle.

Photo unmodified. March 8, 2012. FlashEarth location.

Tuesday, August 6, 2013

Geo 365: August 6, Day 218: Soft Sediment Deformation

Looking down-dip, some deformed sediments in the Coaledo Formation in the eroded terrace at Shore Acres State Park. There's a large ball-and-pillow structure below and around the lens cap, and a flame structure- albeit not very well developed- on the right side of  that feature. On the left, a thin dark bed has been broken and lifted up. And above, tilted strata have been eroded off then re-covered with new layers, and the whole package deformed into undulating waves. The lens cap is 52 mm in diameter.

Photo unmodified. March 8, 2012. FlashEarth location.

Monday, August 5, 2013

Geo 365: August 5, Day 217: North Cove at Shore Acres

Looking down from the tafoni-riddled platform of the past week to the north, a number of small faults can be seen running across the cove to the north. I've seen people walking around down there, and finally realized they were clambering down the inclined bedding plane on the far side from this view. Sorry, nope, not gonna happen.

Photo unmodified. March 8, 2012. FlashEarth location.