Upper Devonian marginal-marine deposits exposed at Ashcraft Quarry, northern-most Pennsylvania, are unusual in that they contain limestone in addition to the sandstone and shale which is prevalent in the Catskill clastic wedge. A 3 m. thick lower unit is a lateral-accretion deposit, composed mainly of planar and cross-stratified sandstones with subordinate wavy-flaser bedding. Erosion surfaces beneath sandstones are overlain by intraformational breccias containing transported crinoid, brachiopod, bivalve and plant remains. Paleocurrents are unidirectional westward, but current ripples rarely indicate bidirectional paleoflow.

The 3.5–5.5 m. limestone unit, comprising skeletal grainstone interbedded with calcareous sandstone, fines up or coarsens up from an...