Not far below Winnisook Lake, the Slide Mountain formation gradually gives way to the Upper Walton Formation,: characterized by gray and greenish-gray fine-grained sandstone with some pebbles like those seen in the stratum above. The Upper Walton soon gives way, by the point the creek receives Giant Ledge Stream, to the Lower Walton, with fine-grained sandstone and some gray shale. This layer remains the Esopus's bedrock all the way to the Bushnellsville Creek confluence.: