It is nearly a year now since we commenced the systematic investigation of our local soil clays in the North-East of Scotland by the powder method of X-ray analysis. In Aberdeenshire, one of the most wide-spread Soil Associations is the Insch Association, and this is the one I want particularly to talk about to-day. An association consists of soils derived from similar parent material, and the parent material of the Insch Association is till derived from basic igneous rock—mainly hypersthene gabbro, but sometimes with olivine also present.