The Mauch Chunk sandstones comprise two groups: subgraywacke, forming the dominant group, and protoquartzite. The subgraywacke was deposited on a fluvial and prograding deltaic plain; the dominant current direction was westward, indicating an eastern source in sedimentary clastics and a metamorphic complex. The protoquartzite was deposited in a nearshore marine environment during early Mauch Chunk sedimentation; the source rock was mature and multicycled sediments north and northwest of the study area. The Mauch Chunk, in cross section, is wedge-shaped and thins westward; westward thinning of the terrigenous clastics is accompanied by an increase in the thickness of marine carbonates. The sedimentary model presented for the formation is a molasse basin, an elongate miogeosynclinal basin in which terrigenous deposits thicken toward the source and thin seaward.