What is "mudstones"

Usage examples of "mudstones".

Henry knew that the mudstones had been dumped from icebergs, floating on the surface of the polar ocean that had once covered this land, an ocean four hundred million years gone.

It sweeps away any fine-grained material, including, in time, the solid rock of sandstones and mudstones, but it can’t move the bigger material, like chunks of bone.

Here and there he saw sandbars strewn with black or brown boulders mudstones and shales, said McCann, laid down in ancient swamps.