The Jefferson series consists of deep, well-drained soils on mountain sides and foot slopes. They formed in colluvium from soils formed in residuum of acid sandstone, shale, and siltstone.
Permeability is moderately rapid.
The average annual precipitation is about 49 inches, and the average annual temperature is about 57 degrees F. Slopes range from 2 to 75 percent. Thickness of the solum is more than 40 inches. Content of rock fragments of sandstone range from 5 to 35 percent to a depth of about 40 inches, and below 40 inches from 20 to 80 percent. Some areas are stony to extremely stony. The soil ranges from stronly to very strongly acid, excep the A horizons which range from very strongly acid to neutral.