Some pedons have thin horizons of fine sandy loam. It has granular structure or subangular blocky, or it is massive or single grain. Reaction is moderately acid to extremely acid. The BC horizon has hue of 5YR to 2.5Y, value of 3 to 6, and chroma of 2 to 6. Texture is coarse sand, sand, loamy coarse sand, loamy sand, or loamy fine sand in the fine-earth fraction.
Reaction is extremely acid to moderately acid.
The C horizon has hue of 7.5YR to 5Y, value of 3 to 7, and chroma of 2 to 6. It is composed of gravel, cobbles, or stones with coarse sand, loamy coarse sand, loamy sand, or sand in the interstices and has varying degrees of stratification. Reaction is very strongly acid to slightly acid. Grotto soils have a xeric moisture regime. Guardlake soils have a thinner solum and higher reaction in the substratum.