Some Points in Sedimentary Petrography

Abstract

For several years prior to 1914 the writer was engaged in the study of the mineral composition of loose detrital sediments with special reference to the rarer minerals and so-called heavy constituents of sands, the principal object of these investigations being an endeavour to ascertain what conclusions, if any, could be drawn as to the source and past history of the material and their bearing on stratigraphical and palæogeographical problems along the lines laid down by Dr. Thomas in his well-known researches on the New Red Sandstone of south-western England. In those days the subject was still in its infancy, and there were no standard books of reference dealing with it, such as are now abundant: it was necessary to evolve methods and to learn the characteristics of the minerals in grains by experimental investigation and by reference to the comparatively few published descriptions then available. This work was carried out chiefly on the Lower Greensand between the borders of Buckinghamshire and the Wash, but a good deal was also done on the superficial deposits of the neighbourhood of Cambridge and elsewhere, and some of the results obtained on the last-named group were published. The study of the Lower Greensand was, however, still incomplete at the end of 1914. After the war, for reasons unnecessary to detail here, it was not possible to continue the investigation of this particular formation on a more extended scale, as had been originally intended, and the results attained up to 1914 were published in the Geological Magazine.