On the road again

Interstate 64 from Lexington, VA to Charleston, WV is one of the most stunning routes in the eastern US from a geological standpoint. Immediately after crossing the state line into West Virginia you can see this rock exposure (above) on the south side of the highway, with sedimentary rock layers tilted about 70 degrees from horizontal. The surfaces of some of these layers are covered with ripple marks, visible from across the highway:

I believe these are from the Late Devonian Chemung Formation, which may represent delta deposits in this area.

As you continue west on I-64, the road cuts across the Appalachians and eventually begins to follow the Kanawha River valley towards Charleston (the New River in Virginia is a tributary of the Kanawha). This leads you through a series of spectacular, towering roadcuts, that were mostly hidden from us on Wednesday due to snow. But every now and then the weather would clear enough to see things like this:

These are classic Pennsylvanian Period coal and sandstone deposits. The dark coal beds are formed from highly compressed fossil plants that were probably living in the flood plains or deltas of rivers. The light-colored sandstones most likely represent deposits within the river channels as they migrated back and forth across the flood plain. The curves in the beds could be a result of the shape of the channel, tectonic deformation from the formation of the Appalachian Mountains (which occurred after these rocks were deposited), different amounts of compression in the various rocks, or all three of these things.

After passing through West Virginia, I-64 takes you through more flat-lying and much older Ordovician Period sedimentary rocks. Once again, the winter weather obscured much of the geology:

We stopped at Owingsville, KY to see an outcrop where I’ve collected in the past. On my previous visits it has looked like this:

but in February it’s a little different:

But not even giant icicles like the one below can deter us from finding fossils:

A few minutes of digging through the snow revealed several different species of brachiopods and bryozoans, both of which were common filter-feeding invertebrates during the Ordovician Period.

Tomorrow (actually, later this morning), we continue on to Lincoln.

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7 Responses to On the road again

  1. Doug says:

    If you think taht’s beutiful, you should see the rocks out at Montana de Oro (well, if you’re ever in CA).

  2. Alton Dooley says:

    I’d love too…all in good time.

  3. Doug says:

    I have some pictures on my flickr page you can look through.

  4. Alton Dooley says:

    Cool photos. Looks like there are some nice gentle folds there, a some interesting wave erosion features.

  5. Doug says:

    thanks. There’s also some interesting looking lava rocks out at Avila.

  6. Alton Dooley says:

    Nice! They appear to be pillow structures; you get them when volcanoes erupt underwater, causing the lava to cool very rapidly.

  7. Doug says:

    Oh yeah, this whole area used to be underwater and a lot of the local geology speaks of lots of volcanic activity, most prominently of which would be the Seven Sisters, a chain of Miocene volcanic peaks.

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