A boring that was completed in 1921 by Messrs. Pease and Partners, at Roddymoor Colliery, near Crook, Co. Durham, about 5 miles north-west of Bishop Auckland, is of considerable importance. I had the good fortune to be consulted in connexion with the correlation of the strata in the lower part of the section, and was also allowed to make a thorough examination of the whole of the cores. The stratigraphical results are of much interest, and it is mainly with these I propose to deal in this paper. Mr. R. G. Carruthers, of H.M. Geological Survey, also examined the cores, and on his suggestion they were broken up and the fossils in them collected by Mr. Tate, of the Survey. It is hoped that when these are determined, results may be obtained which will aid the zonal classification and correlation of the Lower Carboniferous rocks of the two north-eastern counties.

Although spilite as a rock name has been in use for nearly a hundred years, there are few rocks, probably none of equal importance, so incompletely understood. Introduced in 1827 by Brongniart, “spilite” was first used officially in this country by Flett when describing the pillow-lavas of South Devon (Plymouth and Liskeard Memoir, 1907), and has now completely replaced the indefinite terms “greenstone” and “epidiorite”, by which these lavas were formerly known. It is only quite recently that the importance of spilite has been properly appreciated. The progress of research has shown that at several different geological periods lavas of spilitic type have been almost completely dominant in Britain. Typical spilites and keratophyres were extruded in Pre-Cambrian times over a very extensive area, remnants of the flows being preserved in Argyllshire (Tayvallich and Loch Awe), and in Anglesey, localities which must have been far removed from one another at that time. Throughout Ordovician times the basic lavas were almost without exception spilites or closely allied types. The best known examples of spilites in Britain are those occurring abundantly in the Devonian and lower part of the Carboniferous rocks of South-West England, so ably described by Dewey and Flett, to whom most of our knowledge of these rocks is due. To deny the important rôle of spilite in the history of igneous activity in this country is no mere difference of opinion, but a denial of fact. Yet there are many who, with the American geologists, deny not only the importance, but; even the existences of the rock. The other extreme of opinion is found in those who see in the spilitic rocks a series whose petrogenesis presents problems of more than usual interest and which they have elevated to occupy a position comparable in importance with the better known calcic and alkalic suites.

Calcic and alkaline eruptive rocks representing many varieties have an extensive development along the northern portion of the eastern Rift Zone in the Tanganyika Territory. They are closely similar to those better known to British geologists in Kenya Colony, and in both areas have received a considerable amount of attention from petrologists.1 In Tanganyika Territory the nearest of these occurrences to the Indian Ocean hitherto known, with one exception, to be referred to later, is more than 130 miles from the coast, and the greatest development lies at 170 to about 250 miles inland.

Half a mile above Bredwardine Bridge on the Wye, 11½ miles above Hereford, the river on the right bank runs at the foot of an exposure of drift about 50 feet high, showing the following section: Clayey red sand with sandstone pebbles, subangular; lower 10 feet, more clayey with limestone and claystone pebbles, striated.