Tuesday, May 1, 2018

Fossil Beds of Oregon and Idaho


This post is part of my series on the National Park System. One of my goals while the kids are still at home is to visit as many of the National Parks and Monuments in the Western United States as we can.

Last summer, on our epic trip to see the solar eclipse, we saw Great Basin National Park on the way up. We also hit a couple of interesting national monuments related to fossils.

The western United States is well known for its many fossil sites. The reason for this is pretty simple: it is dry. The desert nature of much of the American West has meant that there are large areas without forests, prone to flash flooding and thus erosion. This, combined with the fact that the climate was wetter in the past, has meant that fossils were formed, but are now uncovered and visible. More likely than not, plenty of other places on our planet have fossils that will never be discovered because they are buried too deep for erosion. (At least in anything close to our lifetimes - another billion years, and who knows?) These same factors have made it much easier to study geology: things aren’t buried in forests and sediment.

Once I decided on eastern Oregon for our eclipse viewing, it was pretty easy to see that there were some obvious destinations we could add in. First, Great Basin, since it was pretty much on the way there. If we went through Great Basin, then it would be right on the way to hit Hagerman Fossil Beds - at least a short visit.

Our eclipse site was just a couple hours or so from John Day Fossil Beds, which looked worth a more extended visit. We found a campsite in the mountains to the west of the monument (important during the summer heat), and set aside a couple days to explore it.

Hagerman Fossil Beds National Monument

Hagerman isn’t a bit monument, and you can’t see the fossils in the ground without a dig permit. You can drive through the monument, which is on the west bank of the Snake River east of Boise. The grass-covered bluffs are quite pretty. You can see some of the covered wagon tracks of the Oregon Trail still there over a hundred years later. (Nobody died of dysentery, fortunately…)

Other than these picturesque views, you have to go to the visitor’s center for a short movie on the history. And bones, of course.

Hagerman’s fossils are from the Cenozoic Era - the age of mammals. Specifically, they are from the Pliocene, roughly between two and six million years ago. That’s pretty recent in geological time, but also well before the Pleistocene, with its iconic wooly mammoths and sabertooth cats (fossils from which are preserved at the La Brea Tar Pits in Los Angeles - one of my haunts as a kid.)

The Pliocene had plenty of interesting creatures though. Most notable at Hagerman is the hagerman horse, the first true one-toed horse. It isn’t just the specific creatures, though. It is the fact that Hagerman contains a great variety of fossils, enough to enable fairly good reconstruction of the ecosystem. Also giant otters, which I find cool.

You can see Hagerman in a couple hours easily, and the docents are more than willing to show you around the pictures and bones and reference materials. 

 Hagerman Horse

 Mastodon skull

John Day Fossil Beds

In contrast to Hagerman, which is compact and centralized, John Day Fossil Beds is divided into three units representing just a tiny portion of an absolutely gigantic fossil formation. The formation spreads across much of eastern Oregon, and is bigger than several New England states put together. Some of that is private land, some is BLM and other government holdings. But the three units are specifically protected as a national monument. If you want to see all three units (Clarno, Sheep Rock, and Painted Hills) take roughly two hours of driving just to go between them. Yes, that’s a lot of driving. But it is also extraordinarily beautiful backcountry on twisty, steep roads. We even took the truck on some one-lane gravel roads (which are clearly marked - you won’t get lost) and saw some canyons, hidden valleys with little ranches tucked back there, and more. It’s a beautiful place.

Like Hagerman, John Day Fossil Beds is all about the Cenozoic Era. However, because the elevations are more varied, John Day spans most of the Era, from 66 million to about 3 million years ago. That’s pretty nearly the entire age of Mammals. This was enough time for the climate to change dramatically as the Cascade Mountains rose in the west, blocking the rainfall. It went from jungle to redwood forest to oak forest to grassland, and eventually to its current desert.

The means of fossil preservation varied with time as well. Many of the best preserved fossils are from lahars - lava ash mud flows. Those are pretty nasty in person, clearly, but are fantastic for preserving fossils. Particularly those of the delicate parts plants, which don’t always survive sedimentation well. Leaf fossils abound, and are amazingly preserved - you can see them right there on one of the hikes. Leaf fossils are also preserved at the bottom of ancient ponds - more about those later.

There are also lots mammal fossils, from some pretty big and gnarly bears, to the early ancestors of both cats and dogs, back when they were bearcats. Also brontotheres, early horses and deer, and innumerable rodent-like critters. Also four inch cicadas and other insects, which aren’t always preserved well.

It is kind of interesting to see the progression from the older animals to the younger. There is definitely a progression toward modern species as you go.

The plants are likewise fascinating: you can definitely recognize modern flowering plants and pick out modern “types,” if you will. Oaks, elms, birch, redwoods, ferns, and more. But, they aren’t quite right. There are enough differences that the trained eye can see that they are not the exact same species we have now.

The “Dawn Sequoia” is an interesting example. There are innumerable fossils of this - apparently it was widespread in the area. Dawn sequoias are clearly related to modern redwoods and sequoias, but there is a significant difference: they were deciduous. There is a non-extinct example of this in China, a living relative of the dawn sequoia but not identical, but it has been long gone from North America for quite some time.

I mention this plant not just because I love redwoods and sequoias, but because I now possess some of these fossils. There is a high school in a small town that lets you (for a donation) borrow a hand trowel and dig in the hill behind the school. It is a series of sandstone layers with sediment in between, which makes for easy digging. The layers are from an ancient shallow lake. It was fun to bring out rocks and split the layers to find clear leaf or stick fossils in between. I am so glad the ranger recommended this and that we found time to do it.

The Sheep Rock unit is the one with the visitor’s center, and it is a good place to start, with videos about the formation of the fossils, their discovery, and the human history of the area. It also has a great collection of fossils on display. (Many others are located in museums around the United States - I saw a good one at the Los Angeles Natural History Museum recently - and one from Hagerman too.) This is the place to hike to see some mammal fossils in situ. There is also a preserved ranch that is quite pretty.

The Painted Hills unit is more of a scenic experience than a fossil experience. The titular hills are indeed beautiful. (If not for the ever-present wildfire smoke when we were there, I expect I could have gotten some spectacular pictures.) Created by layers of volcanic ash, they to contain fossils, but none are visible to visitors.

The Clarno unit is the most remote, pretty far from anywhere, and accessible only by a long, twisty, scenic road. Not that this is a bad thing - it is a beautiful drive. We made a loop out of it, cutting through a rarely driven back road. The big attraction at Clarno is the remains of a lahar - a hot, wet ashflow that preserved whole ecosystems of plants. Along the trail, you can see leaf and branch prints, petrified wood, and more. These are fossils you can see without barriers, without plexiglass, and in most cases without labels. You have to keep your eyes open, but they are all around. I imagine someone first saw these and felt like they had walked into Aladdin's cave.

John Day Fossil Beds is a bit out of the way, in a forgotten part of the backcountry. But it is definitely worth a visit. I imagine that last year’s eclipse raised its profile, as it was in the path of totality, but visitation will probably go back to being light this year. 


 Sheep Rock





 Rock formation of the Clarno Unit

 One of the many fossils visible from the trail.

 Petrified logs.

 Fossils I dug up.

The Painted Hills Unit. Sadly, a lot of smoke from the wildfires a hundred miles north.

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