They formed in residuum that is affected by soil creep in the upper part, and weathered from high-grade metamorphic rocks high in mica content such as mica gneiss, mica schist, and pegmatite . Near the type location mean annual air temperature is about 56 degrees, and mean annual precipitation is about 64 inches. Solum thickness ranges from 20 to 40 inches. Depth to bedrock is more than 60 inches . Content of rock fragments ranges from 0 to 35 percent in the A horizon and 0 to 25 percent in the Bw horizon.
Fragments are dominantly gravel in most pedons, but cobbles or stones are dominant in some pedons.
Reaction is extremely acid to moderately acid. Flakes of mica range from few to many in the surface layer and are many in the Bw and C horizons. The A1 or Ap horizon has hue of 10YR or 7.5YR, value of 2 to 5, and chroma of 0 to 4. Where value is 3 or less, this horizon is less than 7 inches thick. Some pedons have A2 horizons that have slightly higher value and chroma than the A1 or Ap horizon.