 Soils in the Pennsylvania State Game Lands Number 207 , in the Solomon Creek watershed , include the Arnot Rock outcrop complex . On hills with a grade higher than 25 % , the steep variety of this soil appears . It is a dark brown silt loam with a bedrock depth of 12 inches ( 30 cm ) . It has fast runoff and 3 % to 40 % of the surface is covered with boulders . The regular variety of this soil , which occurs on slopes with a grade of 8 % to 25 % , is the same , but has a bedrock depth of 18 inches ( 46 cm ) and slower runoff . 
