During the last six or seven years a series of valuable papers bearing on the origin of laterite has appeared in the Geological Magazine. The conclusions arrived at have been somewhat diverse and contradictory. Dr. Fermor, on the one hand, regarded the laterites of India as residual in character, and believed that they represented the insoluble residues left in the process of rock weathering after the soluble constituents had been removed in solution. Mr. Simpson, at the other extreme, suggested that they represented the soluble material, leached out of the subjacent rocks during weathering under peculiar conditions, and deposited as a chemically-formed rock by precipitation at the surface of the earth.

In the June issue of the Geological Magazine for 1917 there appears an article by Mr. C. T. Trechmann, D.Sc., F.G.S., on “The Glaciation Controversy in New Zealand”, in which he traverses my views as to the extent of the Pleistocene glaciation of this Dominion. I regret that my recent journeys to the Isle of Pines and Cape Yorke Peninsula and the irregularity of the oversea mails arising from the war conditions have prevented an earlier reply. Mr. Trechmann deals first with the glaciation of the North Island. He says it seems to him that the question of the glaciation of the North Island stands or falls with the origin of the striations on the large andesitic boulder lying near Mangaweka in the Rangitikei Valley (see Plate XIV). He selects these striations as the sole criterion of former glaciation, and argues that “if the scratches are not glacial the boulder is not glacial, and if this boulder is not glacial none of the others are glacial, and the chief evidence for a glaciation of the North Island fails”. As a matter of fact this great striated boulder was not discovered by me till 1915, or some five years after the close of the glaciation controversy between Dr. P. Marshall and myself. Its existence was unknown in 1909. At that time I relied on other evidences of glaciation that Mr. Trechmann passes over with little or no comment.

We will now try and picture to ourselves how the circulation of the water was affected by the breach in the land bridge. We have seen in the earlier part of these papers that one of its effects was that the southern and western part of the Baltic became rapidly richer in marine forms. This is because the Straits between Gjedserodde in the island of Falster and Darrserort on the mainland of Mecklenburg form a great barrier to the eastern migration of the marine mollusca, whose species increase greatly in numbers when we pass westward of them. This seems to again point to the fact that the inflow of salt waters into the Baltic from the North Sea passes chiefly through the deeper Belts and not through the shallower Sound, which is the chief outlet of the more brackish Baltic water. On the other hand, the Swedish side of the sea remains poor in fauna until we reach the latitude of the island of Saltholm, due partly to its greater shallowness, which only allows a smaller proportion of the incoming North Sea water to pass.

In an interesting paper lately published my friend Mr. R. B. Newton has expressed the opinion that the Coralline Crag should be grouped with the Diestien and Anversien of Belgium as Upper Miocene, the fauna of the Suffolk boxstones being regarded by him as Middle Miocene. The recent researches of Mr. Alfred Bell have led me to agree with Mr. Newton that the latter is pre-Pliocene, but I regret I cannot accept his view as to the age of the Coralline Crag, which I consider to be more nearly related to the Waltonian horizon of the Red Crag than to the Belgian Miocene.

A recent attempt by the writer to utilize the information at present available with a view to gaining some notion of the dominant characteristics of the denudation suffered by the Chalk of the London Basin prior to the deposition of the Eocenes yielded results of sufficient interest to encourage him to apply the same method of analysis to the East Anglian area.