The Holyoke series consists of shallow, well drained and somewhat excessively drained soils formed in a thin mantle of till derived mainly from basalt and red sandstone, conglomerate, and shale. They are nearly level to very steep soils on bedrock controlled ridges and hills. Slope ranges from 0 to 50 percent.
Permeability is moderate.
Depth to hard bedrock ranges from 10 to 20 inches. Mean annual temperature is about 50 degrees F., and mean annual precipitation is about 43 inches. Holyoke silt loam - forested, very stony with a 2 inch layer of undecomposed forest litter on the surface. USGS Avon topographic quadrangle, latitude 41 degrees 47 minutes 44 seconds N., longitude 72 degrees 47 minutes 55 seconds W., NAD 27. Thickness of the solum and depth to bedrock range from 10 to 20 inches.