The Trevlac series consists of moderately deep, well drained soils formed in residuum weathered from interbedded siltstone, sandstone and shale bedrock.
Permeability is moderate.
Slopes range from 6 to 70 percent. The solum is dominantly 28 to 40 inches thick but ranges from 20 to 40 inches, and corresponds to the depth of bedrock. The size of the coarse fragments is dominantly less than 3 inches but a few fragments range up to 6 inches. The A horizon has hue of 10YR, value of 3 or 4, and chroma of 2 or 3. Where present, the Ap has hue of 10YR, value of 4 or 5, and chroma of 2 to 4.