In the course of field work in North-East Yorkshire on the Dogger and associated rocks, in which we have now been engaged for some years, we have found several occurrences of a rock which we may call Black Oolite. In order to prevent any misunderstanding it will be well to say at once that this is not the magnetite-oolite of Rosedale, so often mentioned in the literature and no longer exposed, but quite a different type, which does not appear to have been described by any writer, though well worthy of special investigation. This is the more remarkable in that all the sections known to us where it occurs are referred to in nearly all the standard works. Incidentally we should like to remark that over and over again we have been amazed at the inadequacy and often the entire incorrectness of the petrographical descriptions given in the literature of numerous admirable exposures throughout the district. Not seldom we have found it impossible to reconcile with these descriptions our measurements and petrographical determinations of such sections, although there can be no doubt of their identity; it should also be remarked that sixty or seventy years ago many of these sections, especially in alum works, must have yielded even fresher and more easily determinable material than they do to-day.

The “Tarskavaig-Moine” schists occupy a small area in the Sleat district of Skye, extending southwards from Tarskavaig to the Point of Sleat, a distance of about seven miles, with a maximum width of outcrop of two and a half miles between the coast on the west and structurally overlying formations on the east. Their tectonic relationships and petrographic characters were first described in detail by C. T. Clough in the Geological Survey Memoir on the North-West Highlands of Scotland (1, pp. 589–594, and pp. 618–621). The northern part of the outcrop falls in Sheet 71 of the one-inch geological maps, and is described in the accompanying memoir (2); the southern part falls in the unpublished Sheet 61. Later publications summarize these earlier discussions (3, p. 171; 4, p. 309; 5, p. 23); the last named includes a map of the whole outcrop, on a scale of two miles to an inch, simplified from manuscript maps by Clough. A summary of the tectonics and metamorphism has recently been published by Dr. E. B. Bailey (6).

Two publications by Grabau, which will be treated in the following pages, have led to the ensuing considerations.

In his opinion world-wide advance and retreat of the sea are simply explained by vertical movements of the sea-level. About the possible cause of these movements he makes some very brief remarks, as we shall see later. It is, however, quite possible that the explanation must be sought in simultaneous but opposed movement of continents and sea-level. In trying to obtain an insight into the cause of these movements, rhythms of an entirely different sort come up for discussion, viz. phases of diastrophism and magmatic cycles. And then a further question presents itself: can these different phenomena be connected, and thus give an insight into certain rhythmical processes in the deeper parts of the earth ? I, personally, am convinced that we must answer this question in the affirmative. Stille, Joly, Holmes, and Bucher have reached a similar conclusion by different ways. Meanwhile, the following pages are only intended to shed some light on the different aspects of the problem, and I shall restrict myself to outlining the questions that demand further study.

In our earlier paper on the Petrography of the Blea Wyke Series (1) we stated our intention of describing the Blea Wyke Beds as developed alongside the Peak Fault, or as near to it as possible. This section has never been described, while the brief references to it in the Geological Survey Memoirs (2, 3) are not altogether correct. Here it is stated that “all the beds become thinner in the steep cliffs to the northwards of Blea Wyke, so that below Peak Hall, where they are again accessible, there are not more than 15 feet of the ‘Grey Beds’ and 20 feet of the ‘Yellow Beds’”.

The western peninsula of Cyprus, which is known as Akama or Akamas, is somewhat inaccessible and its geological features little known. It was not visited by the present writer in 1929, but Mr. C. P. Manglis, mining engineer of Nicosia, has recently traversed it and collected specimens of a fossiliferous Miocene limestone with interesting characters in places where no fossils had previously been found, and he informs me that a ridge of the Trypanian Series outcrops along the central part of the peninsula (though this is not indicated on Bellamy's map), and that there is also an abundant effusion of andesitic lavas. The limestones are white in colour and mostly hard, compact, or semicrystalline; they contain massive compound corals, generally in a poor state of preservation, their internal structure being often largely obliterated. Apart from corals, the rocks have only yielded a few large boring Lithodomi and some indeterminable small fragmentary impressions or casts of small gasteropods and lamellibranchs. It is to be remarked that Gaudry recorded' from the Miocene of Cyprus only one species of coral, Astraea [Orbicella] guettardi Defr., and that was from another part of the island. But limestones containing corals similar to those collected by Mr. Manglis occur in various parts of the Mediterranean basin, and we may especially compare those species described by Felix, Daus, Schaffer, Oppenheim, Blanckenhorn, Gregory, and Kühn from the Miocene of Asia Minor, Syria, Persia, Egypt, and Cyrenaica. The Miocene corals of Cilicia appear to be in, many cases identical with those in this collection, and bearing in mind the proved tectonic relations of Cyprus with the mainland, this is what we should expect. The literature on these Miocene corals is very extensive, and Kiihn has recently (Palaeontographica, lxxix, Abt. A, 1933) given a useful list of references which have been consulted in identifying the specimens in this collection.

The investigation of the possibility of late-glacial sea-levels at 190 feet (58 m.) and 140 feet (42 m.) has entailed the reading of a vast quantity of literature dealing with glacial observations. The following is an account of some facts gathered and some ideas arising from these readings.

The purpose of this paper is to discuss methods by which the data of sedimentary petrology (mineralogical composition, grainsizes, etc.) may be most usefully recorded upon a map. The ultimate aim which the writer had in mind when commencing this work was to learn something of the palaeogeography of North-East Yorkshire during Middle Jurassic times.1 It soon became evident, however, that a map upon which the data have been registered may be a record not only of the conditions at the time of deposition but also of the subsequent mineralogical changes in the rocks themselves and, what was less expected, of the tectonic development of the region as a whole.

The sub-genus Lycophoria was founded by Lahusen (1886, p. 221), and referred to the Strophomenidae, the only species described, Lycophoria nucella (Dalman, 1828, p. 130) being the genotype. Part of the original diagnosis runs: “Klappen convex; Rückenklappe stärker gewölbt, am Stirnrande ein breiter flacher Sinus. In der Bauchklappe eine kleine dreiseitige Area mit dreieckiger offener Deltidialspalte. Schlosszähne von zwei divergirenden Zahnplatten gestützt, die in ihrer Fortsetzung am Grunde der Schale eine längliche, durch eine kurze Mittelleiste getheilte Muskelgrube umgrenzen. In der Rückenklappe ein starker, hakenförmiger Cruralfortsatz, innen durch eine Längsfurche getheilt und auf der Rückseite mit einem kleinen, zahnartigen Schlossfortsatz verbunden” (Lahusen, 1886, p. 221). Lycophoria has also been discussed by Hall and Clarke (1894, p. 230), by Kozlowski (1929, p. 131), who placed it with the Porambonitidae in the Telotremata, and by Schuchert and Cooper (1932, pp. 105–6), who regarded it as the sole representative of a new family of the Orthacea. The close external similarity to Porambonites and the fact that Lycophoria had also been referred to the Pentameracea, led the writer to investigate Lahusen's genus in a search for possible ancestors of the pentamerids.

The Lower Palaeozoic rocks of Britain afford the most complete succession of graptolite faunas as yet known, but these successions are not always of uniform type, since they are controlled by different factors.

In the search for oil on asymmetrical anticlinal structures it is of prime importance to know the position of the axial “plane” of the fold, for it is never safe, even where asymmetry is only moderate, to drill a test well across the axial “plane” and so penetrate the steep flank. Where such a thing has happened, the evidence in regard to the oil prospects of the area can generally be ruled out as inconclusive, and in that way much money and effort have been wasted.

The genus Proetus is present at three horizons in the Girvan district. The first appearance is at Balclatchie in the highest beds of the Barr Series of Lapworth (Bala); next it occurs in the Drummuck Trinucleus Shales (Ashgillian), now usually referred to as the Drummuck Group; and its final occurrence is at Newlands in the Saughhill Group (Mid-Valentian).

As shown by his paper on “The Age of the Rocks and Topography of Middle Northern Iceland” (Geol. Mag., LXXV, 1938, 289–296), Dr. Hawkes realizes the great change of view concerning fundamental features of Icelandic geology necessitated by my discoveries in North Iceland of Pleistocene metamorphic glacial deposits. In fact, the changes involved seem to him so great that he finds the whole thing incredible, and he rejects what he terms my hypothesis. In this incredulity, I think, is to be found the reason for his being unable to repeat for himself some observations I made on the eastern side of Fnjóskadal. That I should have been mistaken is, I think, out of the question; a typical “striated pavement” is something a geologist of some experience cannot be mistaken about. In Skridugil I exposed a surface which quite definitely exhibited traces of glacial action. That “similar deposits” to those overlying the pavement “are found at various horizons in the older Tertiary Series of Iceland” (Hawkes, op. cit., p. 293) is unknown to me. The name “Skridugil” was given to me by a man who may not have understood to which locality I was referring.

Plates VII and VIII show four photographs of U-shaped markings in fallen blocks on the foreshore at Kedcliff, between Redcliff Point and Bowleaze Cove, near Weymouth. They were first noticed by members of the Sedgwick Club during an excursion in March, 1939, and further examination has revealed abundant markings which show interesting features worth putting on record. They do not seem to have been previously recorded from the Corallian Beds, perhaps owing to the abundance of “fucoid” and other strange markings in all the sandstones and oolites of the formation. The examples here illustrated occur in the hard doggers of finegrained calcareous sandstone in the Bencliff Grit, and some occur also on the same horizon between Bran Point and Osmingtoh Mills, two miles to the east.

The Devil's Frying Pan is a well-known feature of the coast scenery of The Lizard. It is a deep cavity in the cliffs connected with the open sea by a very fine natural arch; and unlike the Lion's Den, near the Bumble Rock, it has not been spoiled by being used as a rubbish-bin. It is clearly marked on the 6-in. Ordnance Survey Sheet lxxxiv S.E., just south of Cadgwith. Shaped like a funnel, its dimensions are as follows. The beach at the bottom of the funnel is triangular with the apex of the triangle pointing through the natural arch towards the S.E. The sides of the triangle are: a cliff on the S.W. of the beach trending E.S.E. and W.N.W. and about 132 feet long; a cliff on the N.W. of the beach trending N.E. and S.W. and about 115 feet long; a cliff on the E. of the beach trending S.S.E. and N.N.W. and about 148 feet long. On the panorama-sketch shown in Text-fig. 1 these cliffs extend between the following bearings approximately: S.W. cliff, between 160° and 300°; N.W. cliff, between 300° and 10°; E. cliff, between 10° and 130°. The top of the funnel touches the 200-ft. contour-line near White Feather Bungalow and the maximum diameter of the top of the funnel is about 460 feet from E. to W.

In my publication On the Mechanism of the Geological Undulation Phenomena, etc.1 I discussed on pp. 69–73 the different characteristics of flat-dipping compaction folds and of folds caused by folding during sedimentation.