It must inevitably happen sometimes that an author does not quite convey to his readers the whole of his own conception of a subject. It may be perhaps that certain objects in his mental picture are to him so obvious as to be unworthy of emphasis, and he is apt to forget that to his readers no part of the picture is, in the first instance, obvious. From the recent paper by Messrs. A. K. Wells and S. W. Wooldridge (“The Mechanism of Sedimentation Cycles”, Geol. Mag., Vol. LX, December, 1923, pp. 545–50), it is evident that I have failed to convey, to them at least, the whole of my conception of the Anglo-Franco-Belgian Basin. I apologize, therefore, to readers of my Introduction to Stratigraphy for any lack of clarity, and I should like to thank Mr. Wells and Mr. Wooldridge for bringing the matter into the light of day and allowing me an opportunity of stating very simply my ideas, all of them already published, on the geography of the Anglo-Franco-Belgian Basin in Eocene times. Perhaps had my critics, before rushing into print, read pages 278–9 of my book as well as page 267, the occasion would never have occurred.

1. The comparatively shallow Chalk Seas of the Northern Hemisphere owed much of their clarity to their situation in a geographical belt where matured desert figured as the typical associated continental form.

1. A belt of gneiss of dioritic composition lies along the west side of the Togo Range, and is exposed at intervals practically all the way from Pode to Atakpame.

2. Associated with it are hornblende- and mica-schists, garnet-amphibolites, and hypersthene-gneisses resembling rocks of the charnockite series. These last form the greater part of Agu Mountain, and also occur at several places along the foot of the Togo scarp.

3. The valley of the Dsawoë River appears to be in large part underlain by gabbro and dolerite types of rock, with associated dyke rocks.

4. A tract of garnetiferous biotite-gneiss, partly granitic in composition, occupies that part of the basin of the Amu River due south of Atakpame. It is associated with schists similar to those accompanying the dioritic gneiss.

5. Basic intrusions occur in the gneisses, e.g. serpentine at Djeti and pyroxenite north of Pode. A pyroxenite north of Akata is intrusive in rocks of the Togo series. No granitic intrusions were found.

6. The rocks described form a basement upon which the rocks of the Togo series and other younger ones rest.