The Hangman Grits of the Quantocks consist of a series of sand-stones, now, in most instances, practically converted into quartzites by the great pressure to which they were subjected during the Armorican movements, and occasional shales, which sometimes show cleavage. There are also beds, never of any great thickness, which bear a strong resemblance to the Keuper Marls. Fossils, other than a few obscure plant-remains, are unknown, except in the beds which are usually regarded as forming the top of the series, where marine fossils occur as casts in what is evidently a decalcified calcareous sandstone.

During the summer of 1933 one of us (B. S.) began work upon the age and correlation of the Culm Measures of North Devon, and the opportunity was taken to collect specimens of the sandstone and of the dune sands of Westward Ho! for a petrological examination. It was felt that a comparison of the mineral content of the Culm rocks with those of similar age in South Wales, upon which work was proceeding at University College, Swansea, might be interesting, and that an examination of the dunes of North Devon might reveal to what extent the Culm had contributed to their mineral composition, and also might confirm some of the conclusions regarding the origin of some of the minerals in the dunes of South Wales (1).

A few miles to the west of, and running approximately parallel to, the main Rhodesian Railway from Kimberley and the Cape, there is a well defined line of hills, which is the eastern edge, and forms the scarp face of, the Kaap Plateau. Between this plateau and the railway is a belt of flat low-lying ground through which the Great Harts River runs southwards to the Vaal. In the vicinity of Taungs Station, between Warrenton and Vryburg, the scarp line is running nearly due north and south, and is only four to five miles distant from the railway; followed southwards it gets farther away from the railway and assumes a more south-westerly course. The Kaap Plateau is formed of dolomite of the Campbell Rand Series of the Transvaal System, corresponding to the dolomite in the Transvaal. The formation dips gently to the west at angles of 2–3°. Along the escarpment the dolomite rests conformably on dolomite shales, the latter frequently forming a series of terraces from the base of the plateau upwards. Lying unconformably against the dolomite to the east are the Lower Karroo Beds, which are largely concealed by secondary limestone and the recent alluvium of the Harts River basin.

In labelling specimens about 1866 from the Menevian of St. David’s, South Wales, Salter used this generic term for Stenotheca cornucopia, which is the genotype.

A long the coast of South Wales is a series of plateaux, mostly at heights up to just over 400 feet above sea-level. They meet the coast in lines of cliffs, varied in character and often of great beauty. The most westerly area, in south and west Pembrokeshire, is the most perfectly developed, its level sky-line having been commented on by numerous writers (Dixon, 1921, p. 2; North, 1929, p. 23). The Gower peninsula, which is detached from the other coastal plateaux by Carmarthen and Swansea Bays, shows similar features, as does also the Vale of Glamorgan which stretches from the shores of Swansea Bay almost to Cardiff.