The 2 great groups of Luvisolic soils are distinguished mainly on the basis of soil temperature. Gray Brown Luvisols have a dark Ah horizon in which organic matter has been mixed with the mineral material (commonly by earthworm activity), a brown, often platy eluvial horizon (Ae) and an illuvial horizon (Bt) in which blocky structure is common.
The 2 primary classifications of Luvisolic soils are primarily distinguished by soil temperature. Gray Brown Luvisols have a dark Ah horizon where organic matter is intermixed with mineral material (typically due to earthworm activity), a brown, often platy eluvial layer (Ae) and an illuvial layer (Bt) that displays blocky structure.