Before proceeding to describe the more common porphyrites, I wish to return to the subject of the true andesites, referred to in my last paper, and their relation to Tertiary and recent rocks of a similar chemical and mineralogical composition. On referring to the note appended to that paper, it will be seen that my description of the pyroxenic constituents of these rocks was very imperfect, not to say inaccurate. The number of elongated sections which extinguished parallel with the vibration-planes of the crossed Nicols attracted my attention when first I examined the rock, but seeing that the same feature occurred in the so-called augite-andesites of Hungary and Santorin, and seeing further that as regards cleavage and crystalline form the pyroxenic constituents of the Cheviot rock resembled those of the augite-andesites above mentioned, I came to the conclusion that the prevailing pyroxene in both cases was the same, and also that it was augite. In the former conclusion I still think I was right, but in the latter I was unquestionably wrong.

The series of fossil plants from the Tertiary strata of New South Wales and Tasmania, to which these remarks relate, were sent to Mr. R. Etheridge, jun., at the British Museum, for examination partly by Prof. Liversidge, of Sydney University, and by Mr. C. S. Wilkinson, F.G.S., Government Geologist for New South Wales, whilst the remainder already formed a portion of the National Collection.

Brockenhurst fossils were found as long ago as 1858 by Mr. Keeping on Cutwalk Hill, Lyndhurst. He had been lately excavating in the railway cutting near Brockenhurst, at the time that the line was being converted to a double one, and he was anxious to prove the presence of this bed, which just then was attracting much attention at Lyndhurst.

As recent events in Switzerland have called the attention of the world to these startling phenomena, perhaps a short summary of what is known of them may be of some service to the readers of the Geological Magazine. In the text-books in use in this country they generally receive little more consideration than the comparatively small scale, on which ‘landslips’ occur in England, would seem to claim for them; and these for the most part occur on the sea-coast. Examples familiar to most of us are such as those of the Isle of Wight, where the Upper Cretaceous strata are known from time to time to slide over the Gault, which is locally known as the “blue slipper,” and that between Seaton and Lyme Regis. On the west coast of South America, in Ecuador, they have been known to occur on a much more gigantic scale in recent years. The tertiary strata of the district of more than 400 feet in thickness consist of sandstones interbedded with clays, and dip towards the coast. The erosive action of the sea eating away the base of the cliffs, and the clays getting softened by water, an enormous portion of the upper strata descended into the sea during the years 1870 and 1871. The landslip of Naina Tal is also fresh in the recollection of most of us. It is however in connexion with the Alps that I propose here to treat of phenomena of this class. The worn-down stumps of ancient mountain-systems which these islands furnish give us only a faint idea of the importance of Bergstürze in relation to the physiography of the Alps, which are of comparatively recent elevation.

The Lias in the vicinity of Lincoln is well exposed in the several brick-pits that lie at the foot of the “cliff” or in the steep slope beneath the escarpment of the Northampton Sand and Lincolnshire Oolite which go to form the cliff; the exposures however show us nothing below the Ammonites capricornus zone of the Lower Lias, the limestones and lower beds of this division lying several miles away to the west. The whole of the series, Upper, Middle, and Lower, is almost purely argillaceous, the usual sandy beds of the Middle and Lower Lias being entirely absent or only very feebly represented. The following is a description of the beds. Zone of:—

Having resided for some years past on Long Island, the terminal moraine of the Great American continental glacier, and having given considerable attention to the drift phenomena, I am convinced that no oscillation of the continent has taken place subsequent to the Glacial period; and that the river kames, with their assorted gravel, etc., can be accounted for, without resorting to any such doubtful interpretations. I am aware that the presence of shells in the Boulder-clay argues in its favour; but that shells become mixed with the drift while the glacier is in motion is evident from what Prof. Geikie saw in Scandinavia. I will now try in a brief way to give your readers the result of my observations; and, though the sketch may be somewhat crude and imperfect, it may serve to throw a little light on this difficult problem.