1 May 2013

Graptolites!

Posted by Callan

Following a tip from my colleague Pete Berquist (Thomas Nelson Community College), I did some graptolite collecting this weekend. Our family went down to Waynesboro, Virginia, so my wife could run a half-marathon, and on the way back home, we spent some time geolgizing.

One site we visited was Mint Spring, Virginia, in the parking lot of the Days Inn.

Here, at the contact between the Lincolnshire Formation and the overlying Edinburg Formation, there are some papery shales exposed:

They include bulky graptolite fossils preserved as carbon films:

Graptolites were (are?) colonial animals, and each of the little “sawteeth” you see on either side of these long, dark shapes (technically called “stipes”) is a “theca,” a  little cup that held a small graptolite animal.

I love the contrast of the dark graptolites against the light-colored background of shale.

My experience with graptolites is limited, but these were easily the best I’ve ever seen.