The writings of Charles Darwin, Renard, Mellis, Reinisch, and others have already made the salient features of lonely Ascension and St. Helena accessible, if not familiar, to geologists— St. Helena has won the surprised interest of biologists, who have long speculated on the origin of its unique species of plants and animals. From each island collections of rocks have been made. Following Renard's well-known contribution to the petrography of Ascension (“Challenger” Reports, Physics and Chemistry, vol. ii, 1889), Reinisch's paper in the Report of the Deutsche Siidpolar Expedition (1901–3) gives a large number of petrographical. descriptions, including a goodly number of chemical analyses. No adequate geological map of either island has, however, been published, nor, indeed, was this really possible before the British Admiralty had issued the greatly improved chart (No. 1691) of Ascension, in 1910, with corrections added to the year 1921, and the British War Office had issued its excellent contour-map of St. Helena, dated 1904. Each map is on a large scale. Even, though lacking contour lines, the Ascension chart was obviously to be of service to anyone attempting a reconnaisance survey of that island.

During the years 1918–19 we investigated the relations of the beds exposed in a remarkable section at Shenley Hill, north of Leighton Buzzard. Our conclusion that lenticles of limestone of basal varians-age are there overlain by a mass of Upper Gault showing an inverted order of zones provided an interesting glacial problem. This seemed to us of less importance, however, than the discovery that these transported masses had been deposited upon a, floor formed by a basement-bed of transgressive Upper Gault, which there rests immediately upon the local top of the Lower Greensand. The chief interest attaching to this example of glacial disturbance lay in the resulting disposition of particular beds in anomalous zonal relationships. Other striking instances of the glacial transportation of large masses of rock were known to occur in the tract of country to the north-east of this locality. The difference was chiefly one of degree, not of kind. We realized that the detection here of an overlap of the Upper Gault might prove to be a matter of greater moment, possessing, perhaps, a far-reaching stratigraphical significance. A study of the literature dealing with this formation, coupled with the examination of the Gault at a few localities in other counties where an overlap takes place, convinced us that a fuller investigation of the subject would prove fruitful in results.

The lavas which cap the Karroo beds of Southern Africa have general interest as indicating the eruptive activity prevailing at a time of complete quiescence in the European area. The sedimentaries immediately beneath them (Stormberg series) are of Rhætic or even Liassic age, so that the lavas themselves, which are many thousands of feet thick in the Drakensberg range, may confidently be ascribed to the Jurassic period.

The writer has thought it desirable, in the following observations, to embody the results of his examination, last September, of the Arnioceras-bearing beds of Ardnish, near Broadford in Skye. The strata yielded a number of Ammonites of the Upper Coroniceras, gmuentdensis, and Ætomoceras subzones, and belong chiefly to the “Shaly Beds” of division iv of the Broadford Beds of the Survey Memoir on “The Geology of Glenelg, Lochalsh, and the South-East Part of Skye” (1910). They are therein referred, as by Professor Judd in his well-known paper on “The Secondary Rocks of Scotland”, to the bucklandi and semicostatus zones. Judd, the founder of the zone of A. semicostatus, certainly, however, misidentified some of his Ammonites, besides confusing his Lincolnshire A. geometricus with Young and Bird's A. semicostatus of a much higher horizon. Similarly, the Rev. J. E. Cross, in his paper on the “Geology of North-West Lincolnshire” (Q.J.G.S., vol. xxxi, 1875), recorded A. semicostatus from both the lower Gryphcæa incurva beds and the higher Scunthorpe Ironstone, which presents close analogy with the gmuendensis-Ætomoceras-Agassiceras beds of the Harzburg Ironstone. In reality this Ammonite (Arnioceras semicostatum) occurs in a much higher zone than either of these Lincolnshire beds.