acid clay

acid clay

[′as·əd ′klā]
(geology)
A type of clay that gives off hydrogen ions when it dissolves in water.
References in periodicals archive ?
Lime added to acid clays - clay can be both acid and alkaline depending on the garden's location - causes the particles to cluster but there is no point in this if the soil is already chalky or alkaline.
However, erosion appears to be retarded where there are remnants of thicker acid clays on ridges, often associated with post oak and other trees.