The C V Jeans collection of x-ray diffraction films and x-ray diffractograms form the basis of my investigations into the clay minerals stratigraphy of the Cretaceous, Jurassis, Permo-Triassic and Old Red Sandstone strata of the British Isles. It covers the period from 1965 to 2006 and involved both my own private research as well as investigations carried out for clients