Estuary Shales

[Jyonts12]

I was doing some reading today and I found an article that talked about Pennsylvanian brittle stars that can be found in my area in 'estuary shales'. Does anyone know what that means?

[Auspex]

Good question...

An estuary is a partly enclosed, tidally influenced body of water; usually a fluctuating mixture of fresh and salt. My guess is that the term refers to shale that was deposited under such conditions.

[Jyonts12]

Ok thank you. I'll look for the shale within the limestone layers.