The entire ridge was glaciated during the last Wisconsin glaciation, which scoured the ridges, left pockets of till, and dumped talus (blocks of rock) off the east side of the ridge. On top of the ridge, the soils are generally thin, highly acidic, low in nutrients, and droughty, but in depressions and other areas where water is trapped by the bedrock or till, there are interspersed lakes and wetland areas. Soils on top of shale are thicker, less acidic, and more fertile. Topography on the top of the northern Shawangunks is irregular due to a series of faults that form secondary plateaus and escarpments.