Last summer I wrote a post about hiking at Blue Basin, an incredible rock formation in nearby John Day Fossil Beds National Monument. When I was there before, I took the loop trail that circles the whole thing, but recently I went back to check out the shorter trail that takes you into the blue-green canyon itself.
If first guess for what causes the amazing color of the rock is copper, well, you’re not alone; that’s what I would have thought, too. However, it actually comes from the weathering of obscure minerals called celadonite and clinoptilolite, both part of the volcanic ash deposits laid down in this area by ancient volcanoes. (Like I said in my last post: my understanding of the geological history of this region boils down to “volcanoes, woot!”)
If, for some strange reason, you ever find yourself driving Highway 26 through eastern Oregon, the Sheep Rock unit of the John Day Fossil Beds is definitely worth a stop. In addition to Blue Basin, there’s a great visitor center with a lot of interesting fossils on display.
Photos in this post by Evan Heisman.
Photo by Zinneke, via Wikimedia Commons
I have a confession to make: I’m not really a geology person. I understand objectively why some people would consider it fascinating, and I sometimes wish I was one of those people, but whenever I actually try to read a book or watch a presentation about rocks and geologic history my mind starts to wander almost immediately.
Still, occasionally a particular geology concept will lodge itself in my brain anyway, and when that happens I feel very proud of myself for being able to point out some odd rock feature and give it a name. Case in point: columnar basalt. Whenever I’m driving around here and see these odd hexagonal columns of stone, I always think to myself “hey, columnar basalt!” and feel happy.
Basically, these structures form when lava cools relatively rapidly and contracts as a result. From Wikipedia: “While a flow can shrink in the vertical dimension without fracturing, it can’t easily accommodate shrinking in the horizontal direction unless cracks form; the extensive fracture network that develops results in the formation of columns… The size of the columns depends loosely on the rate of cooling; very rapid cooling may result in very small (<1 cm diameter) columns, while slow cooling is more likely to produce large columns.” The fact that these formations are so common around here attests to the area’s volcanic past.
So, to sum up, my entire understanding of the geologic history of eastern Oregon boils down to “volcanoes, woot!” and I’m pretty okay with that. But I really like columnar basalt. Because I know what it is.
If this were less in the middle of nowhere, it would be a pretty popular tourist spot.
Evan, you don’t mind me using the photo you took, right?
Having been to Arches National Park, when I hear “natural arch” I picture red rock desert, not volcanic basalt and pine trees. The idea is the same, though. This is Malheur National Forest’s Arch Rock, the trailhead for which is down a questionably-maintained gravel road and marked with a minimalist sign.
I’m not sure whether or not we were technically breaking the law by hiking on federal land during the government shutdown; there were no signs or barricades at the trailhead or on the road. National forests are so large, and used for so many different things, that it’s impossible to really close them. We passed a number of other people on our way in and out, including a couple cowboys on horseback rounding up a group of cattle.
It was a different story when we drove in the other direction out toward John Day Fossil Beds National Monument. Despite the fact that it’s a unit of the National Park Service, there are no gates or fees and the various overlooks and trailheads are located along a well-traveled state highway, so I thought they might still be accessible. However, each one had literal red tape stretched across the entrance to the parking area.
This thing is going to blow over pretty soon… right?
I spent Monday through Wednesday this week at a training that was being held at a camp in another part of the state. Here’s a satellite image of the area, courtesy of Google Maps:
Green and forested, pretty standard… wait, what’s that gray and white thing to the northeast? Better zoom out a bit.
OH DANG. Yep, I spent the first half of this week near the base of Mount Hood, one of the Pacific Northwest’s many volcanoes, another thing my hold home in the Midwest didn’t have. Mount Hood has been quiet for a long time now, but the USGS website about it doesn’t talk about “if” it will erupt again, but “when.”
The evidence of past volcanic activity is all over the place, even well east of the Cascades where I live, if you know what to look for. Driving around out here you often see outcroppings of odd white soil, which are in fact “Mazama Ash,” deposited by the eruption of Mount Mazama that formed Crater Lake. I don’t have a good photo of one of these ash deposits but you can see what I’m talking about here.
I really enjoyed getting to see another part of the state, and a forest with different vegetation than the pine, fir, and larch that are dominant out here. More to come.
How about some colorful scenery to start your Monday? On Saturday I hiked the Blue Basin Overlook trail, in the Sheep Rock unit of John Day Fossil Beds National Monument. The name comes from the blue-green color of the rock formations, which were originally laid down as volcanic ash. I readily admit to not knowing a lot about geology, but the layers upon layers of white, red, pink, and blue-green rock and soil in this whole region are beautiful.
Once, this was a tropical jungle inhabited by strange prehistoric mammals, whose fossil skulls are now on display at the visitor’s center down the road. How times have changed.
I was impressed last week by how much more rugged the north shore of Lake Superior is than the south shore, which I’m much more familiar with. Imposing rocky cliffs rear up all over the place.
According to a naturalist we talked to, these formations are a very old type of igneous rock called anorthosite. I’m no geologist, so beyond “really old” and “igneous” (formed by cooling magma) I can’t really tell you a whole lot about it. All I can say is that it felt decidedly odd to be looking south across Lake Superior .
One of my favorite places in the Porcupine Mountains is the boardwalk along the Presque Isle River – a short trail runs along the river on its final approach to Lake Superior, and a couple features make this beautiful spot stand out. One is the caramel color of the water as it tumbles over a series of waterfalls and rapids.
This comes from the tannin in the cedars and other plants that line the river and decompose in the water. Tannin also makes the water foamy, creating huge drifts of suds in some places and interesting patterns on the surface in others.
The river has carved through the areas’ layers of shale bedrock and shaped some pretty scenic rock formations. It’s hard to do it justice in photographs.
If you’re ever in the UP, don’t miss the Porkies. They may not be the most mountainous mountains you’ll ever see, but they’re definitely beautiful.