In a discussion of this kind it is advisable to be as concise as possible, eliminating minor details, so as to give prominence to the main outlines of any theory one holds. This communication, which the Council of the Ninth International Congress of Geography have honoured me by asking me to address to you, I propose to put into the form of a ‘credo’. To this I shall add a few fundamental facts upon which, my reasoning was based, leaving minor ones for discussion at greater leisure elsewhere. For convenience I propose to divide my theory into two sections. In the first I shall review what may be conveniently called deep volcanic action, and in the second that group of phenomena that occur when igneous matter nearly reaches the surface or actually finds an exit thereon. Unfortunately, in the first case I am obliged to rely on hypotheses and deductions, whereas in the second section, that of superficial volcanic action, there are a number of fundamental facts and observations upon which to base speculation, and to which. I propose to draw your attention.

The two Cephalopods—an Ammonoid and a Belemnoid—referred to in the present note were obtained in the summer of 1907 by Dr. A. P. Young from the Tarntaler Köpfe, an isolated mountain-mass in Tyrol, to the north of the Tuxer Alps, and about 20 kilometres south-east of Innsbruck. The Ammonoid was found “at a height of nearly 2500 metres above sea-level, on the surface of a scree-cone which has accumulated under the high hanging valley known as the Lower Tarntal”, and the Belemnoid was found “somewhat lower on the slope of the same cone”. They are the fossils referred to by Dr. A. P. Young on p. 342 of his paper on the Structure and Physiography of the Tarntal Mass, published in the August number of this Magazine (pp. 339–346), where a photograph of the scree-cone is given (Pl XVII, Fig. 5), and now form part of the National Collection.

A period of nearly forty years has now elapsed since several bands of Spirorbis-limestone were met with in the so-called Lower Permian rocks of the South Staffordshire Coal-field during the sinking of the Sandwell Park and Hamstead pits in the neighbourhood of West Bromwich. From the published accounts of those sinkings, in the first case by Mr. Henry Johnson, and in the second by Messrs. Meachem and Insley and Dr. Robert Kidston, Spirorbis-limestones appear to have been found at 206 feet above the base of the ‘Permian’ at Sandwell, and at 329 and 795 feet respectively at Hamstead.

Just over three years ago I described the field relations, chemical composition, and petrographical characteristics of the Old, and also of the Newer, Red Granite of the Transvaal. As then, so now, I cannot do better than introduce this subject with the words of the late Charles Darwin — “Granite to the geologist is classic ground; from its widespread limits, and its beautiful and compact texture, few rocks have been more anciently recognized. Granite has given rise, perhaps, to more discussion concerning its origin than any other formation. We generally see it constituting the fundamental rock; and, however formed, we know it is the deepest layer in the crust of this globe to which man has penetrated”. South and Central Africa furnish no exception. Their granites, which are of astonishingly widespread occurrence, of varying and often characteristic texture, have been classic ground to geologists, as the numerous papers concerning them and their mode of origin and relative geological age well testify.

In the Geological Magazine, 1904, Dec. V, Vol. I, p. 403, I criticized the view put forward by Dr. Parkinson that the Culm beds in the neighbourhood of Marburg were of Lower Carboniferous or Tournaisian age. Last summer I had the advantage of being taken over the ground by Professor Kayser, of Marburg, and also of seeing his valuable and extensive collections from the Culm of various parts of Germany.