The geology of South Africa is once again being brought to the notice of European geologists in the able papers by Dr. Voit in the Zeitschrift für praktische Geologie. In the first instalment Dr. Voit follows Drs. Hatch & Corstorphine in correlating the Waterberg Sandstone with the Table Mountain Sandstone, which is a small matter perhaps, but as it would in Europe be equivalent to correlating the Old Red Sandstone with the Torridon Sandstone, it is necessary to state the objections to this correlation and enable geologists to judge for themselves whether it is right or wrong.

A Critic of my paper on “The Winding of Rivers” writes to me that I and others “do not take into account the nature of the soil traversed by a stream,” which “must materially affect its course.” Let me call attention to the two figures (117 and 118) on p. 499, vol. i, of Sir A. Geikie's Text Book of Geology, ed. 1903. The one is entitled “ Meandering course of a Brook,” and resembles that which is often seen in meadows. The other represents the “Winding of the Gorge of the Mozelle above Cochem.” There is no essential difference between them. Without knowledge of the scale I could not say that either had been formed in alluvium and not in hard rock. Both are based on the same principle; each is an adaptation, evolved from a more extended network of streams, formed to meet the requirements of the area to be drained. Lateral streams, even though they do not now exist—the growth of turf or of timber may have rendered them unnecessary—have united with that line in the network best adapted both for the longitudinal and the lateral drainage. In detail this may differ; in principle it is always the same.

Most geologists who have had anything to do with the ironstone nodules in the Coal-measures have been struck by their perverse and refractory behaviour under the hammer. How one nodule will refuse to break under the most well-directed blows, and another, though breaking easily, will exhibit to the disappointed collector a clean bright surface of clay-ironstone, without a trace of that organism that he hoped, and almost had a right to expect, was there. It seems therefore necessary to find some other and perhaps less violent method of breaking them.

Taking into consideration the apparently hopeless tangle in which the ripplemark and submarine erosion questions had become involved, I submitted to the Devonshire Association in July last a paper entitled “The Ripplemark Controversy,” in which I attempted to bequeath the subject to posterity in such a form that anyone interested in the enquiry could pick it up where it had been dropped. It was, at any rate, my own farewell, or was so intended to be.

Of all the animuls of the Stormberg Beds the Theriodonts are the most interesting, as they bear strong resemblances to mammals. Dr. Broom, of Stellenbosch, says they have practically solved the problem of the origin of mammals. Of these Theriodonts only two are said to have come from Basutoland, both of small size, viz. Galesaurus and Tritylodon. They are only known from their skulls. I have not been able to discover whether they came from Molteno Red Beds or Cave Sandstone, but I imagine most likely from the first. Tritylodon has a small and decidedly mammalian-like skull, and is said to have been found at Thaba Tsuen, a mountain 16 miles south-west of Morija. It was brought to England by Dr. Exton, Curator of the Bloemfontein Museum, and described by Sir Richard Owen at a meeting of the Geological Society in 1884. Dr. Broom, who has recently discussed the affinities of the skull, inclines to the view that it is a mammal.

From the point K northward to the stile leading to the road on to the Towan Head the killas comes to the top, but just short of the stile there is a section of another hill-wash-dune showing about 5 feet, but not exposing the base. Land shells are abundant towards the top, especially at 1 ft. 3 in. and 2 feet from the surface, but the lower portion contains very few. The Helix nemoralis zone lies just below. This section yielded the flint flake found by Mr. Warren.

The separation of the weakly magnetic minerals of crushed rocks, sands, etc., is best effected by using an electromagnet, which, if suitably constructed, is, for any given size, much stronger than a permanent magnet. The electromagnet exerts no attractive force when the current is shut off, and for this reason the process of separation is made easy, as the grains which have been attracted to the poles drop when the current is switched off.

The Swedish Magellanic Expedition spent some time in the Falkland Islands before proceeding to Tierra del Fuego, where important work is being carried on. The writer utilised his stay in the Falklands to study the geology and collect fossils. The following is a brief note of the work there.

In attempts to unravel some of the weightier problems of geology it has lately been assumed that certain discordances of stratification are due to the thrusting of old rocks over those of a later geological age. Without in any way suggesting that the geology has in any particular instance been misread, I should like to point out the difficulties in accepting the explanation looked at from a dynamical point of view when applied on a scale that seems to ignore mechanical probabilities. Some of the enormous overthrusts postulated are estimated at figures approaching 100 miles. Have the authors considered that this means the movement of a solid block of rock or rocks of unknown length and thickness 100 miles over the underlying complex of newer rocks? If such a movement has ever taken place, would it not require an incalculable force to thrust the upper block over the lower, even with a clean fractured bed to move upon? Assuming that the block to be moved is the same length as the overthrust, the fracture-plane would in area be 100 × 100 = 10,000 miles. I venture to think that no force applied in any of the mechanical ways known to us in Nature would move such a mass, be it ever so adjusted in thickness to the purpose, even if supplemented with a lubricant generously applied to the thrust-plane. These are the thoughts that naturally occur to me, but as my mind is quite open to receive new ideas I shall be glad to know in what way the reasoning can be met by other thinkers.

In view of the interest which charriages and extensive overthrusts of low inclination are exciting in various parts of the world, an interest which has steadily increased since Nicol first put forward his explanation of the anomalous position of the Moine gneisses, it may be worth while to place before readers of the Geological Magazine a brief account of a remarkable structure in the Pyrenees, which has been noticed by various geologists, but only recently explained, by Bresson, as another example of overthrusting, and named by him the “nappe de recouvrement de Gèdre-Gavarnie,” after two villages in the neighbourhood. I have the less hesitation in doing this because the phenomena, considering their importance and their setting amidst the magnificent scenery of the lofty central parts of the range, appear to have received less attention from English geologists than they deserve. For these reasons also, other questions in Pyrenean geology are afterwards discussed in the light of some recent observations.

Towards the end of January last the inhabitants of Lyme Regis were somewhat alarmed by the announcement that a portion of the cliffs on the eastern side of the town, towards Black Ven, was “on fire”; a “Full Report of the Volcanic Eruption” was soon afterwards published in the Bridport News for January 24. It was then stated that on Sunday, January 19, “dense vapour appeared at intervals to rise from a mound on the edge of the cliffs, about half-way between Lyme and Charmouth,” and that the burning portion “consisted of a large fallen mass of the cliff which had some time since slipped away from the body of the cliff.” Mr. A. C. G. Cameron, who was at the time resident at Lyme Regis, explained that the case was one of spontaneous combustion, due to the decomposition of iron pyrites and the consequent generation of heat sufficient to ignite the bituminous shales of the Lower Lias.

Botanists who study the tissues of Living plants, or those palæobotanists who deal with actual petrifactions, have scarcely any idea of the difficulties that meet the worker on carbonised plantremains, especially when the material is so limited that the research cannot be repeated in the event of damage to a single preparation. Moreover, the research can be conducted only on those portions of the tissue that are cutinised, since all the rest have been carbonised or destroyed in the course of fossilisation, and no longer appear after the preparations have been bleached. The student of Mesozoic plants is in the further unhappy position that, with a few notable exceptions, he rarely finds portions of the plant that show any structure; he in particular must direct his attention to the cutinised membranes, and above all to the cuticle of the leaves and stems and, in the case of Pteridophyta, to the spores.