Underclay deposits of Somerset and eastern Fayette Counties, Pennsylvania

Abstract

The most economically important underclay beds in Somerset, eastern Fayette, and part of eastern Westmoreland Counties, Pa., are in the Allegheny Group of Pennsylvanian age. The beds of local usage, from oldest to youngest, are called the Brookville, Clarion, Lower Kittanning, Upper Kittanning, Lower Freeport, Bolivar, and Upper Freeport. The Clarion, Lower Kittanning, Upper Kittanning, and Bolivar are the best clay beds from a potential economic standpoint. They contain flint and semiflint clay which is used primarily in making high·grade refractory clay products. The underclay beds are probably the result of the leaching of finegrained sediments in an acid swamp.