Pondering Petrified Wood

Human beings are funny creatures. When we see something, we immediately want to categorize it.  For a birder, identifying and tallying species is a huge part of the hobby. For my work as a scientist working with satellite imagery, my task is to categorize the types of land cover (cropland, urban, deciduous forest, etc.) on the earth’s surface.  For a rockhound?  I’m struggling with identification as a rockhound newbie, just as I did 20 years ago when I was a birding newbie.

Petrified wood is one category of material I thought was easy to identify. When I’m out on the Buffalo Gap National Grasslands, there is a LOT of petrified wood lying around. By that, I mean there’s a lot of easily identifiable pieces that look exactly LIKE wood, with obvious grain patterns.  But as with anything in life, it’s not that easy.  Below are some of the obvious, and not so obvious pieces I’ve found on the Grasslands. Thoughts? Are all of these petrified wood?

Petrified Wood - Buffalo Gap National Grasslands, South Dakota

First, an obvious piece of petrified wood. This is what I find the most of…gray exterior pieces with clear grain patterns, some of which are so detailed they look like fresh pieces of wood.

Petrified Wood - Buffalo Gap National Grasslands, South Dakota

Another obvious one. Both of these first two pieces have also been tumble polished to a nice shine.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

And this piece? This is the most colorful piece I’ve found, for something that’s possibly petrified wood. You certainly see a linear “grain” running throughout. Petrified wood? Perhaps an agatized petrified wood?

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

Same piece as above, except on the flip side. Again, you see the grain pattern throughout.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

A less obvious one. The photo doesn’t show it as clearly as what you see through a loupe, but there are rough “grain” patterns. They’re more little streaky nodules all oriented the same direction. I know there’s petrified palm that can be found in this area, but I don’t know what exactly the palm looks like from this area.

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

A similar one, with little linear nodules lined up in the same orientation like a wood grain (again, a bit hard to see in this photo).

Potential Petrified Wood - Buffalo Gap National Grasslands, South Dakota

The photo of this piece does a better job showing the type of “grain” seen in the previous two pieces as well. Obvious, and all oriented in the same direction.

What are your thoughts? Comment here!

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