Crystal Mountain Sandstone
The Crystal Mountain Sandstone is an Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. This interval was first described in 1892, but remained unnamed until 1909 as part of a study on the Ouachita Mountains of Arkansas by Albert Homer Purdue. See also List of fossiliferous stratigraphic units in Arkansas Paleontology in Arkansas References Ordovician geology of Oklahoma Ordovician Arkansas Ordovician southern paleotropical deposits