Jump to content

Recommended Posts

Posted

Here's a strange one.
I found plentiful piles of what I thought were casts and internal molds in the iron-rich St. Mary's clay of Virginia last year. Loose clam fossils riddled blocks of talus. I was able to wiggle some out of their ancient resting places without s much as scratching the matrix. Generally that's because the shell disintegrated, leaving a void between the mold and the cast. If you look closely, however, what looks here like an internal mold isn't. The sculpture on the surface is clearly the outside of the shell. If it were the inside, you would see round protrusions where the ligament attached to a depression in the shell, not concentric ridges. Shown here is the most distinct of my specimens, but not the only one. Any thoughts?
Mercenaria campechiensis, Miocene, VIrginiaUntitled1.jpg.3afacb657cfeaa7494bd92e5458afd68.jpgIMG_8532.jpg.4fa7879b0a5f1e42dd44e6beb4f87dea.jpg

  • I found this Informative 1

I refuse to give up my childish wonder at the world.

Posted

pseudomorph. Cavity of dissolved shell filled with precipitated calcite or some such.

  • I found this Informative 1
Posted
3 hours ago, Plax said:

pseudomorph. Cavity of dissolved shell filled with precipitated calcite or some such.

If it were a pseudo morph, would there be gaps between the fossil and the surrounding matrix?

I refuse to give up my childish wonder at the world.

Posted

most of the time I'd say no. Some times you get a sort of shrunken pseudomorph of the original. Not sure of the mechanism of this.

  • I found this Informative 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...