In a recent paper Professor Shand put forward a pleafor the more careful consideration, in rock classification, of the saturated or unsaturated state of the constitnent minerals. The criterion of saturation which is assumed is the capability of co-existence with some form of free silica, as shown by the “observed facts of distribution”. By means of this criterion, the rock-forming minerals are divided into two groups—the saturated minerals and the unsaturated ones. The former group includes the felspars, amphiboles,pyroxenes, micas, and most of the so-called accessory minerals, as well as those of pneumatolytic origin; while the latter group comprises the felspathoids, olivine, the spinels, corundum, and the garnets (except spessartite, which is put into the first class). Rocks are divided into three classes, according as they are made up wholly of saturated minerals, partly of saturated and partly of unsaturated ones, or wholly of unsaturated ones.

The presence of cordierite does not seem to have been often recorded from the granite of Dartmoor, in spite of the abundance of that mineral amongst the contact-altered sediments surrounding the igneous mass. The recently published Survey memoirs on Dartmoor and Ivybridge cover nearly the whole area of the granite, and I can only find references to two specimens in which cordierite, or rather pinite pseudomorphs representing that mineral, have been detected microscopically. Within the limits of the granite proper the mineral does not appear to have been observed at all in an unaltered condition, at least so I infer from the absence of any record of it in the above-mentioned memoirs, as I must confess to a somewhat scanty knowledge of West of England geological literature. Having recently done a certain amount of geologising along the northern margin of Dartmoor, which has not been investigated by the Survey since the introduction of modern petrographical methods, and having obtained some rather interesting results, of which I hope to publish shortly a detailed account, I was glad to take advantage of an opportunity presented by a visit to the South of Devon to make some comparisons with the contact and other phenomena described by the Survey.

I Claim to have now shown that the zone of O. pilula as established in 1912 for Hants and the Salisbury area holds good in its broad features also for Sussex, the Isle of Wight, and Dorset, and that it is almost equally constant in some of its minor features, especially the way in which it ends in a bed 2 ft. 6 in. to 3 feet thick with a flint seam in the middle of it and enclosed by two marl seams. I am only prevented by a single section in Hants from setting this up as the universal rule in all sections I have seen. In The Stratigraphy I assigned pits Nos. 1065, 1066, and 1067, the last of which will be more readily recognized as Mottisfont Whiting Pit, to the zone of A. quadratus, because on examining them for the purposes of that work for the first time since 1892 I had failed to find evidence of more than a seam of O. pilula without any others of the associated fossils of the zone. At the time of that examination all the pits were in a most unfavourable condition. Since then I have been keeping regular watch on the Whiting Pit (No. 1067), and I soon found that the subzone of abundantO. pilula must be represented at its base, and then that the upper belt of O. pilula in that subzone must be exposed: but it was only this spring that I was able to fix the absolute position of the boundary between the zones of O. pilula and A. quadratus in the Whiting Pit, and at the same time, owing to developments in the other two pits, to identify the cinctus belt in the old face and the lower belt of O. pilula in the new workings (and probably also at the lowest point of the old face) of Pit No. 1066, and the lower belt of O. pilula at the base of Pit No. 1065.

In the Cairo Scientific Journal the first chapter of Professor Walther's new edition of Das Gosetz der Wüstenbildung was considered in some detail. His second chapter, “Die Abtragung in der Wüste” (pp. 111–218), is no less stimulating to thought and replete in observation. He opens this section of his work with a statement of the facts which point to great climatic stability in Egypt during historical times. Two of these are specially mentioned. First, the presence of a small sack of salt in a grave of the Eighteenth Dynasty, the analysis of which agreed absolutely with that of the salt at present obtained from the lakes of the Wadi Natrun. This occurrence, according to him, proves that the same salt mixtures were being formed at periods 3,500 years apart. A statement as to the nature of the resemblances which lead to so wide a conclusion would have been of interest. Secondly, attention is also called to the total absence of water in the Tombs of the Kings since they were first excavated, pointing to the underground water having stood for many thousands of years at more than 50 metres below present valley level.

The zone of offaster pilula is probably exposed on the coast in West Sussex on the foreshore near Bognor, but the nearest cliff exposures to those of East Sussex are those of the Isle of Wight, at Culver Cliff and Scratchells Bay. In both of these the Chalk is so highly inclined that only a very small area of each bed can be reached; and the condition of the accessible surface is such as to make it most improbable that anything beyond the broad outlines of the subzone of abundant O. pilula, which is the key and pith of the zone of O. pilula, will be detected.

In 1866 I communicated a paper to the Geological Society of London on the Pleistocene Succession in the Trent Basin. The boulderclays and outwash deposits of this district are of two distinct kinds, the one containing rocks from the west and north-west, and the other boulders etc., from the east or north-east of the district. In all cases, except where they have been ploughed up and re-arranged by the ice itself, the drifts containing westerly rocks only are the lowest, and the drifts with easterly rocks have been spread over them. We thus have two distinct ice-flows to deal with.