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Wednesday, July 2, 2014

Vacation Quest #2: Fossil Hunting

Eastern Oregon has some odd geology. At various times in the past the land has been buried a mile deep, thrust a mile high, turned practically upside down, and buried under water and lava - sometimes at the same time. The rocks have been pushed, pulled, twisted and compressed in about every conceivable manner, and some not so conceivable. That has led directly and indirectly to Arbuckle Mountain in the Umatilla Forest due west of Ukiah, Oregon. At first glance this mountain looks just like every other mountain you've ever seen. But it isn't. During the Eocene it was a tropical archipelago off the ancient Oregon coast. This mountain is noted for its many botanical fossils including avocado, magnolia, and willow. But the real boss of this quest is the giant palm frond, Sabalites Eocenica. That's what I was after here.

[caption id="" align="aligncenter" width="1024"]Arbuckle Mountain 1L Arbuckle Mountain 1L[/caption]

The difficulty of this quest is the palm in question was not all that prolific when compared to all the other botanical specimens of the time. It's actually kind of rare. And it's sort of hard just finding fossils of good quality. Many have low definition because they rotted some before being covered over and deprived of oxygen. That last is critical to good fossil preservation. Oxygen is a consumer of all things, including really nice fossils. So when you wind a really nice fossil with high-definition, even a partial one, you keep it. It helps if it is small and fits in your pocket too, like this one.

[caption id="" align="aligncenter" width="1024"]Partial Leaf Partial Leaf[/caption]

This fossil shows the full base of the leaf and fully two-thirds of the entire thing. The vein structure is very good and it is possible to identify the species from the fossil (I have not done so yet, but I'm thinking it's a magnolia leaf.) That's the mark of a keeper. So I kept it. But unfortunately many are too broken up to be readily identifiable. This is caused by two things. One is fossil hunter error. You can destroy a fossil just by trying to get it out of the ground the wrong way. The second, and more common cause, is the fossil was broken during the uplift process that brought it back to the surface after being buried nearly a mile below the surface. All the sandstone, mudstone and lignite layers are fractured to begin with and many fossils just never stood a chance.

Those that do stand a chance are often small. Here's an example: it's the small fern stem in the lower left corner. At least I think it's a fern. I'm no paleobotanist. Hell, it could also be a Cypress leaf. Half the fun is trying to figure out what it is, no? ;)

[caption id="" align="aligncenter" width="1024"]Small Fern Small Fern[/caption]

Small complete fossils like this are easily missed in the "rush" that always seems to accompany any fossil hunt. What I mean is this. I had a day. Of that day, I had to travel 90 miles to get to the site. Of that 90 miles, the last 20 miles were over forest service roads which a best were gravel and at worst mandated a four-wheel drive capability. Once on location, there were several sites to search. I only found fossils at one of them. Sometimes your search produces nothing. And you always have to keep in mind the long drive home. So you get "rushed." You throw good, cautious digging procedures to the wind and want to just take a pick to the ground. You'll never get good fossils that way, so I leave the pick at home. :P

So you dig carefully. You gingerly pull layers of rock from the ground hoping this one will have that "killer" fossil you were looking for. And you know, sometimes you don't get what you came for, but you certainly get a very nice display piece! :D

[caption id="" align="aligncenter" width="1024"]Forest Floor Forest Floor[/caption]

There are at least three different leaf fossils on this section of  "forest floor." I find it a quite striking piece. It's just over a foot long by a half-foot wide. It will look awesome on my mantle as a display piece.

So what of the "boss" I was looking to best for its fat loot? Well, I had a partial success in that fight - literally. :D

[caption id="" align="aligncenter" width="1024"]Palm Frond Fragment Palm Frond Fragment[/caption]

It's not a bad specimen. It's about the size of the palm of my hand, no pun intended. And the really funny thing about it - it was laying right out on the surface of the road cut. Mother nature had washed it out last winter. Go figure. :roll:

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