The material, in which this felspar occurs, was collected by Dr Hans Meyer during his visit in 1887 to the East-African “snowmountain,” the Kilimandscharo, and kindly entrusted to me for description by Prof. F. Zirkel of Leipzig, to whom I desire to express my indebtedness for assistance and advice supplied me whilst working in his laboratory.

The rocks which possess this mineral as felspathic constituent are Nepheline- and Leucite-basanites, and were found in sitû on the south and south-east flanks of the Kibo peak. As rock-constituent this felspar is presumably confined to the outflows from the higher peak—the Kibo4—as no trace of it is to be found in the large series of rock-specimens, which represent the materials of which the other and lower peak—the Kimawenzi—is formed.

Since 1857, the occurrence of a gigantic species of the Selachian family Rhinobatidæ in the Lithographic Stone of Bavaria has been well known, and three fine specimens are exhibited in the Munich Museum. No figure, however, appeared until 1887, when Dr. K. A. von Zittel published the illustration he has kindly allowed to be reproduced here; and the only detailed description is that of Wagner, written about thirty years ago. Quite recently, the British Museum has acquired the counterpart of one of the fossils in the Munich collection—a female individual in a remarkable state of preservation; and this is now exhibited in the form of a slab upon the west wall of the Gallery of Fossil Fishes.

In the present communication I call attention to a Reptilian vertebra which does not appear to have received the notice it deserves, and also give a preliminary diagnosis of certain forms which I hope to describe more fully later on.

On the extreme north-west flank of the Lower Palæozoic region of the Southern Uplands of Scotland there occurs a remarkable coastal area of stratified, igneous and altered rocks, known to geologists as the “Ballantrae Rocks,” from the little fishing town of Ballantrae, which is built upon them. They range along the shores of the Firth of Clyde for a distance of about 12 miles, and are well displayed in section in a series of rugged cliffs cut through by the picturesque coast road between Ballantrae and Girvan. The area they occupy nowhere exceeds five miles in width, and is limited inland by the smoother regions floored by the barren greywackés of the Uplands and the fossiliferous strata of the Girvan district, but this inland boundary is everywhere curiously broken and irregular.

In a short paper on the nomenclature of the Old Red Sandstone Fishes published in this Magazine for November, 1888, I expressed the opinion “that the scattered teeth and fragments of jaws known as Dendrodus and Lamnodus belong to fishes at present known to us by their scales as species of Holoptychius and Glyptolepis.” The family terms “Holoptychiidæ” and “Dendrodontidæ” I consider absolutely synonymous. On the other hand, the Rhizodontidæ (Gyroptychius, Tristichopterus, Rhizodus, etc.) present a somewhat different form of tooth-structure, and one which is, in the main, identical with that which, in so many Stegocephalous Amphibia, is called “labyrinthodont.”

In his “Geology of North Wales” (p. 102, 2nd ed.), Sir A. Ramsay figures a vertical cross-section of a greenstone dyke, which he describes as running along the cleavage-planes of the slate in the Ffestiniog quarries, and alternately “bulging and thinning off in a rapid succession of oval-shaped masses of 3 or 4 feet in length.” He seems to imply that this is one of the dykes posterior to the disturbance which produced the cleavage of the district. The ordinary post-Carboniferous dykes of North Wales, however, strike nearly at right angles to the cleavage; and further it is not easy to imagine any circumstances attending the intrusion of this one that would account for the phenomenon of alternate thickening and attenuation described. A precisely similar peculiarity is to be seen in ‘Dew's quarry’ at Pen-y-bryn, Nantlle.

Last summer I had the pleasure of passing a fortnight in the Channel Islands under the guidance of my friend the Rev. E. Hill, who has done so much to elucidate their geology. During our short visit to Sark we spent some hours in the beautiful little cove called Port du Moulin, examining the interesting sections of the hornblende-schist and underlying gneissic rocks. I was wandering on the beach looking at the wave-worn boulders which afford most interesting studies of the structure of this crystalline series, when my eye was attracted by one which differed much from the rest, and resembled a dark-coloured serpentine of a slightly exceptional character. With some difficulty, owing to its form, I detached a tolerable specimen, and on examining the fresher surface, felt convinced that I had found a rock composed chiefly of an altered olivine and a silvery talc-like mineral.

1. The object of this paper is to show how the soilcap, or its upper portion, may creep down an inclined surface through the action of frost. The subject has also been discussed by Mr. W. C. Kerr in a valuable memoir, “On the action of frost in the arrangement of superficial earthy material,” published in May, 1881. I reproduce here one of the figures given by Mr. Kerr, as I cannot better describe the nature of the phenomenon which it is the aim of this paper to consider.

The Wicklow greenstones occur in sheets and dykes intrusive in the Lower Silurian slates (the equivalent of the Bala beds of Wales) that lie to the east of the main chain of the Leinster granite. Like the Welsh greenstones, they are associated with acid lavas (felsites and keratophyres) and felspathie tuffs, although of slightly later origin than these.

More than one kind of rock, as we learn from Dr. H. Hicks and other writers, occurs in the conglomerate which forms a well-marked base to the Cambrian system at St. Davids. Sometimes the pebbles are mainly vein quartz, sometimes felstone predominates, but occasionally, as in the neighbourhood of Nun's Chapel Bay, quartzites (using the term rather generally) are not uncommon. At one place, not far from a quartz-felsite dyke, these are rather large, occasionally about a foot in diameter. From this locality, while spending a few days at St. Davids in 1882, I brought away specimens of three of the most marked varieties of quartzite, of which I had slices prepared, thinking that as examples of rocks which were probably far from modern at the beginning of the Cambrian age, their structures might be instructive.

On the western flanks of the Malverns, the Upper Silurians are folded in several great anticlinals and synclinals, formed parallel to the axis of the Hill itself. To the west of Ledbury and again near Woolhope these contorted strata dip beneath the Old Red Sandstone, which, as computed by Phillips, has a maximum thickness of 8000 feet, that of the Upper Silurians being 2690 feet.

The thickness of the strata of which the Longmynd is formed has been estimated by the Government Surveyors at not less than 26,000 feet, as exposed in their highly inclined edges; the beds dipping at an average inclination of 60° to the W.N.W. They thus appear as if they had been tilted by pressure against the more ancient rocks of the Caer Caradoc Range.

Some three years ago the writer communicated to this Magazine a “ Note on the Genus Stenotheca ” of Hicks, stating that from the appearance of the species, which on this (western) side of the Atlantic had been referred to it, it did not seem to belong to the Pteropoda, but more probably to the Gasteropoda. I also stated that there were two distinct types of shells which had been referred to Stenotheca, one of which by its internal muscular scar and position of the umbo might be compared to Parmophorus, etc.; while the other, represented by a number of minute species, appeared to correspond to the original Stenotheca of Dr. Hicks.

So little is as yet known of the Palæozoic Ophiuroidea, that the discovery of some specimens that represent a new species of Protaster in the Upper Silurian rocks of Victoria is of interest. Some of the specimens were forwarded to Dr. Woodward by Mr. Frederick McKnight, of 60, Hawke Street, West, Melbourne, Victoria, some time ago, but they were too fragmentary to be of much service; several better examples having been received from the same source, Dr. Woodward has kindly entrusted them to me for description.

In the winter of 1886–7 a boring was made at Bletchley Junction for the London and North-Western Railway Company, and acquired importance from the report that, after passing through the Oxford Clay, it had entered a mass of granitic rock. Probably many readers of this Magazine wondered why no detailed account of the boring was published after this announcement; but the reason was, that when inquiries came to be made, some uncertainty was found to exist as to the position and mode of occurrence of the granitic rock. My attention was recently called to the boring by learning that the water obtained from it was salt. I then obtained all the information I could with regard to the rocks passed through, and think the results are of sufficient importance for publication.

The sample of Gault, of which the analysis is given below, was obtained from the Clay Pits at Dunton Green, which I visited with the “London Geological Field Class” during June last. At this place the Gault rests upon a bed of reddish yellow sand (Lower Greensand), which is mixed in certain proportions with the Gault clay to form bricks. This sand, of which I also give an analysis, is very moist when first taken from the bed, but very rapidly becomes dry, upon exposure to the air, so that it afterwards loses very little more water at 100°C. The Gault, as taken from the pit, contained 26·68 per cent of moisture, but upon ignition of the dried substance, in a muffle furnace, it becomes so hard that it will scratch glass easily.

In an Appendix to the Explanatory Memoir on Sheets 138 and 139 of the Map of the Geological Survey of Ireland (Dublin, 1888), I have given some notes on the petrographical characters of the igneous rocks of Co. Wicklow. One or two of the facts elicited by an examination of these rocks are sufficiently interesting to deserve a wider circulation.

Abundant as the remains of the Mammoth and its associated group of Pleistocene Mammalia are in the adjacent valleys of the Medway and the Cray, none have been yet recorded in the valley of the Darent, to which the Mammoth no doubt commonly resorted at the same time. One reason may be that this valley is very bare of Drift, and between Dartford and Otford there is not a single pit in the little drift-gravel that is met with.

In a recent paper on the volcanic rocks of Kilimandjaro I referred to the presence in the basaltic lavas of olivine crystals, which appeared to possess zonal structure. Although actual proof was wanting, still the symmetrical arrangement of the inclusions, as also the mode of alteration of the crystals, rendered the occurrence of such a structure highly probable. The olivines, being rich in iron, were altered into ferric oxide or ferric hydrate; and the line of division between the fresh and decomposed portions was mostly parallel to the crystallographic outlines. There was, however, no break in the optical continuity, such as the presence of zonal structure would demand.

Among instances of the bodily deformation of rocks by lateral pressure, the case of the phyllade aimantifère of Monthermé is well known. By its strong cleavage this rock gives evidence of considerable lateral compression. Professor Renard has shown that prior to this compression the magnetite crystals already existed in the rock, and were surrounded by a coating of chlorite. The crystals yielded to the pressure much less readily than their matrix, and the latter, having already a firm consistence, became separated from the crystals, carrying the chlorite with it, and was displaced along the planes which are now cleavage-planes, that is, in a direction at right angles to that of the pressure.