[C1. 41], Sedgwick Collection, from near the top of Bwlch Mawr, is a rock of greenish-grey colour, with rather fewer felspars than the last. In the microscope the ground is seen to be largely occupied by squarish crystals of felspar, between which is some crypto-crystal-line matter. The larger felspars seem all plagioclase, but they are all much decomposed, some of the smaller ones are perhaps ortho-clase. There is no pyroxenic mineral preserved; calcite aggregations result, and also viridite extinguishing in no position. There are many minute quartz grains in the ground, which have the appearance of being secondary. Apatite is abundant; there are also black and brown crystals of iron oxides (ilmenite). A few crystals of epidote have been formed. No hornblende is to be found, and amorphous matter in the ground is uncertain, yet the rock may most conveniently be placed among the porphyrites. It has not, however, the andesitic structure of the Carn Boduan rock. The dark colour would be due to the chloritic matter and iron oxide scattered through the ground.

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.

Reference is sometimes made, in the course of the active discussion of the Glacial age in the Geological Magazine, to the Pleistocene of Canada, a country which, perhaps, as much as any other, in its great extent from the Atlantic to the Pacific, and from latitude 45° to the Arctic Sea, affords opportunities for the study of the deposits of this period. It has occurred to me, in connexion with this, that it might be useful to your readers to present to them a short summary of Canadian facts, as I think I have established them in publications on this subject, which are, perhaps, better known in this country than in England.

In a previous paper of this series I endeavoured to show that the so-called Marine Drifts found at high levels, on both sides of the Irish Sea and elsewhere, are proved by their testaceous contents to have had no connection with the Glacial Age; while the mode of their distribution shows that ice in no form can have distributed them as we find them, nor yet are they consistent with the sub-mergence of the land for any considerable time beneath the sea; and I concluded that the only power known to us capable of distributing them is a wide-spread flood of water. I now propose to carry my argument considerably further, but before doing so, as it is so easy to be misunderstood, I must guard myself against the supposition that in what I have said or mean to say I am minimizing the Great Glacial Age.

The country between Market Weighton and the Humber is characterized geologically by the reappearance of the Oolites along an outcrop of ten or a dozen miles, after having disappeared under the Cretaceous beds further north at Acklam Brow, near Malton.

Having published in the Palæontographical Society’s Volume for the current year the first part of my Monograph on the Trilobites of the Carboniferous Limestone, it occurred to me that a brief account of the species described might prove useful to some of the readers of the Geological Magazine.

In 1879 Mr. Sorby in his Presidential Address to the Geological Society published the result of his investigations into the question of the extent to which the mineralogical constitution of shells, etc., influenced their preservation as fossils.

What is the burden of all these facts? Why, assuredly that the shells found in our higher marine drifts, or at least in nearly all of them, far from bespeaking conditions of climate such as can alone be fairly described as Glacial, on the contrary, speak to us of a time when the general temperature was perhaps somewhat lower than it is now, but when the North Sea and North Atlantic were filled with open water, and bathed a land where the Mammoth and the Rhinoceros could find abundant food, where the Oak and the Pine flourished, and where the rivers could sustain such molluscs as the Cyrena fluminalis. This conclusion destroys at once the basis of those who have argued that our high-level marine drifts were left where they are found by ice—either by floating bergs or a creeping ice-foot. But apart from the general conclusion which the particular collocation of shells enables us to make, quite a number of facts may be collected going to show the impossibility of ice having been the motive power which deposited such beds as those at Moel Tryfaen.

Striking a radius of 40 miles from Southport, the line will be seen to intersect the sea-coast near the Silurian districts of Ulverstone in North Lancashire, and Colwyn Bay in North Wales. The succession in both cases is very similar, Denbighshire Grits and Flags of the one area corresponding in time to the Coniston Grits and Flags of the other; and just as the Silurians of the Lake District are overlaid by a fringe of Carboniferous Limestone, so the Silurians of Diganwy are overlaid by the Carboniferous Limestone of the Great and Little Ormes Head. Laid upon a floor of Silurian rocks, the Carboniferous Limestone may be regarded as extending continuously under the Irish Sea, and underlying the various Carboniferous and Triassic rocks now occupying Lancashire.

In recent discussions upon the classification of the Archæan, great importance has naturally been attached to the occurrence of beds of fragmental origin. In the distinctly volcanic beds these are numerous; in the older or more highly metamorphosed portion of the group they are less frequent and their character and origin are more obscure.

It frequently happens that in questioning the occurrence of remains in any deposit, we have to point out that they may have been derivative from older beds, or, on the other hand, may have been introduced at some later date into that in which they are actually found. In such cases various hypothetical explanations are offered with a view to proving that sources of error still remain, which must be investigated before the unexpected association of remains can be accepted as a fact. Such difficulties frequently meet us in investigating the contents of caves, beds of gravel and sand, etc., more frequently in connexion with the history of the newer formations, and especially in criticizing the evidence for the association of human relics with the remains of extinct forms of life. It becomes of importance therefore to place on record any well-authenticated case in which objects in the same deposit and in the same state of preservation can be shown to belong to totally different times.

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:—

My remarks will have to be limited to Norfolk; because personally I know very little of the Red Chalk of Yorkshire, and nothing of that of Lincolnshire. Of course the subject would be better treated as a whole; but Norfolk geologists will forgive me for not waiting until that time (perhaps never to come) when I may know all the English Red Chalk. Perfection may be devoutly prayed for; but to wait for it would be to do nothing.

Let us move on again. The rolled gravels of Central and Southern England are divisible into two well-marked varieties, which were well discriminated, as Professor Phillips says, as long ago as 1815 by Dr. Kidd, and separated by him into a hill group and a valley group.

The author of a paper on the above subject read before the Anthropological Section of the British Association at Southport having made the startling assertion that, “In immediate proximity (to where the skull was found) were numerous bones of the Irish Elk and Reindeer,” I feel it incumbent on me to relate the facts of the case. Unfortunately I was not at the meeting when the paper was read, so could not contradict the statement on the spot.

These difficulties are assuredly most embarrassing for those who conclude that the shell-beds point to the positions where they are found having once been the sea-bottom, and especially for those who argue that its submergence and re-emergence were the result of causes operating for thousands of years. We must remember that if Sir Charles Lyell's calculations are of any value, they understate the problem, for many of the shells found in these beds are not littoral, but deep-water shells, and the land must not only have sunk to the level of the sea, but much below, to render it a fit habitat for them. We are to believe, then, that a whole continent, which was submerged for ages in this way, has nothing left to show the fact save these shreds left at different levels and always near the present coast-lines. In regard to the differing levels at which they occur, my acute friend, Mr. Darbishire, well says:—

The specimens selected for illustration of the shell-structure of this species of Chonetes were found in a bed of shale in the Lower Carboniferous Limestone series at Capelrig old quarry, in the parish of East Kilbride, Lanarkshire. The fossils in this shale have their structure generally well preserved, there being less change, through crystallization of the lime present in the shells of the various organisms, than is found in those obtained from most of the other fossiliferous localities in Western Scotland.

Like many other geologists at the present time, I have been engaged in reading Mr. Clement Reid's Memoir on the Geology of the Country around Cromer—reading it, I may say, with mingled feelings of pleasure and pain;—pleasure, at the amount of interesting and valuable matter which he has assiduously unearthed; and dissatisfaction at his attempts to destroy one of the cherished convictions of childhood—faith in the Cromer Forest Bed! Mr. Reid evidently does not believe in the Cromer Forest Bed; but then what would a Manual of Geology be without it? This either he or his superior officers have felt, and the name “Forest Bed” has therefore been retained for a bed which, according to his own confession, “least deserves the name.” This course, though illogical, is no doubt a concession to popular geological prejudice.