The Smithsonian has a collection for a geologist named Henry Nettelroth (1835-1887) and they have some reports I found on-line. I think they are from the mid to late 1800s when a lot of the fossils in the Louisville area were named. Nettelroth refers to the Silver Creek formation as "hydraulic limestone". Also he refers to Clark County as Clarke County. I have also seen Speed, Indiana USA referred to as Speeds, Indiana in older texts.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9B_lxjflK5KqZ3nmfHK6-n54Mdd5QomGIE4v1ycULr6Ztn26gEr7G2DnI4xzEsPbOYQYAGlJDFOOozbwvYhPGXDiHgTc7J3Pv67Yp2qs6bdL0cMAbND2eem07Rbvr-Ki6vbWxbPl_dpay/s400/para3.jpg)
UPDATE: This entry has been modified with a picture of another clam fossil. As of August 2010, this fossil was on display at the Smithsonian Museum of Natural History. It list it was found in Kentucky.