Having made a general study of the Devonian-Carboniferous junction in North-West Europe and a more detailed one of special areas, the author discusses here the correlation of the Pilton Beds of North Devonshire and the “K beds” of the Bristol and Forest of Dean areas with the Etroeungtian and other horizons near the Devonian-Carboniferous boundary on the Continent.

If the term “laterite” is restricted to apply only to hydrates of iron, aluminium, or in special cases manganese, formed by katamorphic processes, then obviously a great deal of what we commonly term “laterite” is incorrectly named. I am assuming that laterite is the end or apical product of a process of rock degradation which may stop short at the formation of the hydrated silicates—clays or lithomarges—or continue right on to hydrate according to chemical and physical environment and nature of the parent rock. Harrison’s studies of deposits in British Guiana show that lithomarge and bauxite are associated with each other in all possible proportions, with or without the hydrates of iron (which does not appear to pass through a secondary hydrated silicate or “kaolin” stage), and free silica, which on one occasion has been recorded in the form of tridymite. These substances are mixed in all degrees, and can only be distinguished by laboratory tests. The point which decides whether one of such rocks should be classed as a laterite or a lithomarge seems to be quite arbitrary, unless it is agreed that a laterite should contain an excess of hydrates over hydrated silicates.

(1) The Elsworth Rock of Elsworth and St. Ives is a condensed deposit belonging to the plicatilis zone.

(2) There is no evidence that it contains any ammonites derived from earlier zones. Statements that it does are based on misidentifications.

(3) The Elsworth Rock at Elsworth overlies at least 8½ feet of ironshot clays with thin bands and nodules of limestone, the clays containing abundant ammonites of the cordatus zone and no others.

(4) The so-called Elsworth Rock at Upware is the equivalent of the ironshot cordatus zone developed below the Elsworth Rock at Elsworth.

(5) The true Elsworth Rock (plicatilis zone) is represented at Upware by the Coralline Oolite and Lower Coral Rag.

(6) For convenience in stratigraphical nomenclature it is desirable to group together the condensed ironshot cordatus and plicatilis beds of Elsworth as the Elsworth Series.

(7) The Elsworth Series, as defined in 6, corresponds with the Oolithe ferrugineuse and the greater part of the Oolithe de Trouville on the Normandy coast. At Trouville the plicatilis zone to some extent combines the developments at Elsworth and Upware.

(8) The ironshot cordatus zone was proved in the Upware well to rest directly upon normal clays of the mariae zone, and the same zone was proved in the vale below Elsworth in the Fen Stanton brewery boring.

I am greatly indebted to Mr. E. E. L. Dixon and Mr. A. G. Brighton for criticisms and suggestions, and especially to Mr. Brighton for the trouble he has taken in sending me all the fossils on loan and supplying the relevant information.

Recent work in the Glen Falloch area has revealed that certain small masses shown as diorite on 1 inch Sheet 46 of the Geological Survey (Scotland) contain rocks belonging to the kentallenite and appinite suites. As these intrusions have not been previously mentioned in geological literature it has been considered worth while placing a short description on record.

Sandstone “dykes” have not previously been noted in Tanganyika Territory. Those described below were observed by the writer while engaged in regional mapping in the Dodoma district during 1936.