Bruce

from "The Common Rocks and Minerals of Missouri", Keller, UofMO Press, 1945

""Cotton Rock" refers to a white to light grey or buff variety of limestone which has a "soft" some what chalky porous appearance suggestive of cotton. Missouri "cotton rock" is usually dolomitic. Although "cotton rock" has no standing in a technical sense, its fairly wide use indicates that the name has some descriptive value."

Cheers!

John R