The following remarks were written for the Settle Caves Exploration Committee in the spring of 1871. They were subsequently submitted to the British Association in 1872, and are, with additions embodying the result of the latest explorations, offered to the scientific public. First, I propose briefly to describe the beds with which we have become acquainted in the course of the explorations, their apparent range and superposition. Secondly, I will endeavour to show to what natural causes they probably owe their origin.

At the meeting of the British Association in Nottingham,inAugust of last year, a joint discussion on “Coral Reefs” was held by the sections of Zoology and Geology. Prof. Sollas,inopening the discussion, referred to the “ Dolomites of South Tyrol” as a country affording brilliant examples of Fossil Coral Reefs. He demonstrated this by sections taken from the wellknown work of Mojsisovics, and showed several photographs of some of the more imposing dolomite mountains—Schlern, Langkofl, and Sella—which had been explained as reefs of Triassic age. in the course of the discussion, Dr. Hickson said he believed there were no corals in these so-called fossil reefs. Dr. Rothpletz corrected this statement, saying briefly that there were corals in the dolomite and limestone rock, along with other groups of marine animals, but that many of the sections shown by Prof. Sollas were incorrect. Prof. Bonney emphasized the ample evidence of Coral life in many parts of the district which he had visited.

THE features of the Glacial deposits and associated phenomena just discussed are in general so clear that most observers would arrive at the same conclusion regarding them, but there are some other features about which, either due to their controversial nature or the conflicting character of the evidence, there is not yet such general agreement. These are (a) the evidence for interglacial Periods in the Drift of these counties, (b) the raised beaches of East Durham, (c) the origin of the leafy clays, (d) the explanation of the distribution of fragments of certain rocks —Flint, Chalk, Magnesian Limestone—in the Superficial Deposits.

During the year 1873, it was my good fortune to be one of a party who, in the course of an exploration of the Andaman and Nicobar Islands, were enabled to spend a few hours on the detached volcanic islands of the Bay of Bengal, which are known respectively as Barren Island and Narkondam. The time at our disposal did not admit of our making as thorough an examination as we should have wished, but there was sufficient opportunity for testing the accuracy of the statements regarding the islands which had been previously published, and also for making a few original observations.

Mr. Ami's interesting discovery has already been announced in a letter addressed to Mr. A. H. Foord, F.G.S., published in this Magazine (October, 1888). Mr. Ami now supplies a “Note” on the precise geological position of the beds in which the Turrilepas was found. Want of space, however, precludes us from giving the whole of his detailed observations, which are accompanied by a sketch section, here reproduced:—

The following is a summary of Mr. Ami's “Note.”

The Turrilepas was found in a band of bituminous limestone cropping out on the right bank of the Rideau River, at the Rifle Range, near Ottawa. The precise position of the beds (Lower Utica = about the lower part of the Bala Series), was ascertained by means of their fossil contents, which include an interesting Brachiopod—Siphonotreta Scotica, identified and named by the late Dr. T. Davidson, F.R.S.

In 1863 the skull and a portion of the skeleton of a large extinct species of Ox (B. primigenius), which had been found in the peat of the Cambridgeshire Fens, and which apparently had been killed by a celt, was placed in the Woodwardian Museum at Cambridge. At the time of its deposition there a portion of the flint remained firmly fixed in a fracture in the frontal bone, being partially retained in sitû by a mass of peat: as, however, this peat gradually dried, it crumbled away, and the celt became loosened and displaced; moreover, some small fragments of bone fell away from the margin of the wound, so that in its present condition the specimen merely exhibits an irregular fracture in the forehead, in which a fragment of a flint implement lies loosely; but it no longer furnishes conclusive and positive evidence to prove that the fracture was actually caused by the celt which occupies it.

THE Lower Cambrian genus Salterella, Billings, has lately received a good deal of attention in connection with the problem of the origin of the Cephalopoda. The genus, it may be remembered, was first described by its author as undoubtedly allied to Serpulites i.e. a worm-tube, but it was soon transferred by Billings himself to the pteropods. Barrande and Walcott also considered Salterella to be related to Tentaculites and Hyolithes. Clark (1925), who revised the genus, came to the conclusion that Salterella was a cephalopod, and not by any means a primitive type, but it did not seem to him to be ancestral to any subsequent form. Poulsen (1927) accepted this view, stating that the cephalopod characters were very conspicuous, but his later (1932) restoration of an East Greenland form, identified with S. rugosa from Labrador, is no more convincing than was Clark's restoration of S. conulata. Unfortunately, the genotype species of Salterella (S. rugosa Billings) is still incompletely known and I agree with Teichert (1935) that further investigation is needed before the real nature of Salterella can be held to be established. If the “septal necks” are still a doubtful feature and if the very existence of a “siphuncle” is open to question, as Teichert rightly says, it is clearly as premature to visualize Salterella as a possible forerunner of the holochoanites (Schuchert, in Schindewolf, 1929) as it is to connect the equally doubtful Volborthella with either holochoanites (Teichert and Kobayashi) or orthochoanites (Schindewolf, 1934).

A regional Tertiary basaltic dyke swarm intensifies within a Caledonian granite at Barnesmore, Co. Donegal. Rapid heating along the contact of one (possible feeder) dyke resulted in disequilibrium partial melting of granite wall-rock and the generation of a range in melt composition by the in situ melting of feldspar. The compositional variability of the melt is preserved in a glass containing feldspar spherulites and other quench phases which suggest rapid cooling. During partial melting the trace elements, Rb, Sr, and Ba were mobile and have been concentrated in glassy melted granite close to the contact of one dyke. The textures, mineralogy and geochemistry of dolerite in two dykes indicate localized bulk contamination and mixing with melted granite. This had a particularly marked effect on the crystallization of pyroxene and resulted in a wide range in mineral composition reflecting the degree of contamination. The intensification of a regional dyke swarm in well-jointed granite might control the siting of some major intrusive centres. Granite melted and mixed with basaltic magma may contribute to the evolution of granites in such centres.

The gravel beds of Finchley, which belong to the Drift or Boulder-clay series, have yielded to the researches of Mr. N. T. Wetherell, of Highgrate, many specimens of Flints, containing fossils of the Chalk formation,—of these, the genera Inoceramus and Pecten are most abundant, associated with which are casts of Ammonites, and specimens of Terebratula, Rhynchonella, Dianchora, Lima Hoperi, Spondylus spinosus, and many Echinoderms, as Micraster, Cardiaster, (similar to one from Northfleet,) two or three species of Cidaris, Cyphosoma, Ananchytes, Galerites, but with these it is important to notice there are sometimes found silicified specimens of Venericardia planicosta, a condition in which these shells are rarely found in their original Eocene beds.

Almost due west of Mozambique Island, at a distance of about forty-two miles from the sea, the military road from Mosuril to Nampula crosses the Ampwihi River, an important tributary of the Monapo. During the dry season the stream is reduced to a string of stagnant pools, separated by long reaches of sand and gravel that here and there are interrupted by outcrops of the underlying formations. Throughout the greater part of its course the Ampwihi flows through a region in which gneisses persist with monotonous regularity, the only variation being that due to occasional intrusions of granite and of still later pegmatite dykes. At the point where the military road crosses the narrow channel a welcome diversion is introduced by the presence of a dark compact dyke about 10 feet in thickness. The dyke appears on the right-hand bank and crosses obliquely to the other side, taking a N.N.W.–S.S.E. course across the strike of the older rocks. Upstream, about seventy yards to the south-east, the Ampwihi bends to the south-west, so that it returns towards the dyke, which is again exposed across its sandy floor. The dyke was traced by Mr. E. J. Wayland in July, 1911, for a distance of altogether 200 yards, and was examined by Mr. D. Alex. Wray and later by myself during the same year. It is clearly the latest rock of the district, and is intruded along a line of fault, for in two cases pegmatite dykes seen on the eastern side are broken across and reappear on the western side with a well-marked northerly displacement.

The Whidborne Collection of Devonian fossils from Devon and Cornwall now in the Sedgwick Museum, Cambridge, contains the majority of the specimens and nearly all the types described and figured by him in his memoir published by the Palaeontographical Society, vols. xlii-lii, between the years 1889–1898. The following notes have been made on a re-examination of certain of his Upper Devonian specimens in the light of more recent work and other material, though unfortunately many of the fossils are too imperfectly preserved for a satisfactory determination. A comparison of several of the species with those of Sowerby's types described and figured in 1840 has been of much value. Those specimens in the Whidborne collection which require no further remarks or are so poor that a correct identification is deemed at present impossible are omitted.

The Duobagou Permian–Triassic granites of the Dunhuang orogenic belt are of great importance in understanding the tectonic evolution of the southernmost Central Asian Orogenic Belt. LA-ICP-MS U–Pb zircon ages indicate that Permian–Triassic granitic intrusions from the Duobagou area formed at 276–274 Ma and 246 ± 1 Ma. These granites have high SiO2, Na2O and K2O, but low Al2O3, CaO and MgO contents and belong mainly to the high-K calc-alkaline I-type granite series. Based on whole-rock geochemistry and Sr–Nd and zircon Hf isotopes, the Duobagou Permian–Triassic granites were dominantly derived from the partial melting of lower continental crust formed during late Palaeoproterozoic to Mesoproterozoic times in a post-collisional extensional setting. Permian granites with zircon ϵHf(t) values of −5.4 to +3.1 and Hf model ages of TDM2 = 1.14–1.70 Ga indicate the involvement of a mantle component in their petrogenesis. Triassic granites with higher zircon ϵHf(t) values (+0.5 to +3.8) and TDM2 = 1.08–1.31 Ga suggest more juvenile sources caused by a greater contribution of mantle-derived melts, indicating a significant crustal growth. Regional extension from lithospheric delamination and heating from asthenospheric upwelling were proposed to have triggered the partial melting of lower crust, resulting in the generation of the Permian–Triassic magmatism. This may have been the mechanism for the significant crustal growth during Permian and Triassic times in the southernmost Central Asian Orogenic Belt.

The Yarmouk River gorge extends along the Israel–Jordan–Syria border junction. It marks the southern bound of the Irbid–Azraq rift and Harrat Ash Shaam volcanic field at their intersection with the younger Dead Sea Transform plate boundary. During the last ∼13 Ma, the gorge has repeatedly accumulated basaltic units, chronologically named the Lower, Cover, Yarmouk and Raqqad Basalt formations. We examined their origin and distribution through aerial photos, and geological and geophysical evidence. Our results define a southern Golan magmatic province, which includes exposed Miocene (∼13 Ma) basalts, gabbro–diabase intrusions below the gorge and the adjacent Dead Sea Transform valley, and numerous Pliocene–Pleistocene volcanic sources along the gorge. Cover Basalt (∼5.0–4.3 Ma) eruptions formed two adjacent 0–100 m thick plateaus on the transform shoulder before flowing downslope to fill the topographically lower Dead Sea Transform valley with ∼700 m thick basalts. Later incision of the Yarmouk River and displacement along its associated fault divided the plateaus and formed the gorge. The younger Yarmouk (0.8–0.6 Ma) and Raqqad (0.2–0.1 Ma) basalts erupted in the upper part of the gorge from volcanos reported here, and flowed downstream toward the Dead Sea Transform valley. Consequently, eruptions from six phreatic volcanic vents altered the Yarmouk River morphology from sinuous to meandering. Our results associate the ∼13 Ma long southern Golan volcanism with the proposed SW-trending extensional Yarmouk Fault, located east of the Dead Sea Transform. Hence, the Yarmouk volcanism is associated with the ongoing Harrat Ash Shaam activity, which is not directly linked to the displacement along the Dead Sea Transform.

The Franconian Platform of SE Germany and the underlying Permian and Triassic rocks that developed from latest Permian to Triassic time were affected by multiple compressional and extensional events that created a complex fracture, fault and stylolite network. We reconstructed the spatio-temporal variations of post-Triassic palaeostress fields in the Franconian Platform and Triassic strata using fault-slip and tectonic stylolite inversion. Our highly resolved stress inversion enables us to demonstrate a cyclic stress evolution from the stress regime of normal faulting to thrusting, strike-slip and back to normal faulting. Five main stress fields correlating with two stress cycles are determined for Late Jurassic to Cenozoic time. The first cycle consists of: (SF1) an initially NE–SW-directed horizontal extension during Late Jurassic to Early Cretaceous time; (SF2) NNE–SSW-directed horizontal compression with an early set of tectonic stylolites prior to the development of reverse and thrust faults; and (SF3) a strike-slip-dominated setting with (N)NE–(S)SW horizontal compression representing a first relaxation. The second cycle comprises (SF4) NW–SE-directed horizontal extension during Oligocene–Miocene time; and (SF5) a second strike-slip-dominated regime with WNW–ESE to NW–SE horizontal compression during the Alpine shortening, creating the youngest set of tectonic stylolites. In addition, we consider the transitional stages between thrusting and a strike-slip regime as a snapshot in the process of intraplate tectonics.