Clays Ferry Formation

Tim and I spent Saturday in Kentucky with Dr. Stephen Lenhart from Radford University, who was leading a fossil and geode field trip for some of his students. We spent most of the day looking at limestones and shales of the middle Ordovician Clays Ferry Formation. This unit was probably deposited in a very shallow (probably much less that 100 m) tropical sea, and is richly fossiliferous in certain beds. We made three stops in this unit spread over a distance of about 20 miles, and each was distinctly different from the other stops. The first stop had beds made up almost entirely of broken bryozoans:

The second stop had the highest diversity. There were still a lot of bryozoans, but also large numbers of brachiopods and gastropods. Tim found several particularly impressive slabs that we brought back to the museum, including the one below:

There were also a few trilobites, including this half-complete Flexicalymene I found:

Tim also found part of a mold of a nautiloid cephalopod:

Our third stop was again quite different. Note the layer of resistant light-colored blobs in the middle of the section below:

Up close, these turned out to be tabulate corals in life position; an Ordovician patch reef:

There were also small numbers of solitary rugose corals mixed in among the tabulate corals:

We recovered several large coral heads for the museum:

We spent a pleasant if rainy day in Kentucky with the Radford students, and I’d like to thank Dr. Lenhart for inviting us to tag along.

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3 Responses to Clays Ferry Formation

  1. Boesse says:

    Looks like it was cold and damp! Reminds me of TAing geology field camp this summer.

    The patch reef is really cool, especially how you can see it in-situ and the relationship between it and the bedding. I really like looking at invertebrate assemblages in outcrop; aside from being very neat to look at, they can tell you a ton by studying their biostratinomy.

  2. Alton Dooley says:

    My photo doesn’t really do the patch reef justice; it could be traced continuously for at least 100m. It had been raining all day, and the overlying clays had washed down over the reef, obscuring it somewhat.

  3. Alton Dooley says:

    A correction: our last stop was in the late Ordovician Drakes Formation rather than the Clays Ferry.

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