bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on the Tiree Marble, with Notes on others from Iona
Authors: Coomáraswámy Ananda K.
Published: October 2009

I. Introduction.

Although so well known, and represented in many mineralogical collections, the Tiree Marble has never been described in detail. Macculloch says that the Tiree flesh-coloured marble

‘resembles the greater number of the primary limestones found in gneiss and mica-slate, and may be considered as a large nodule ... The nodule of limestone ... appears to be an irregular mass of about 100 feet in diameter, and is surrounded on all sides by gneiss.’ [The marble] ‘occasionally contains imbedded lumps of granite or gneiss, similar to those which occur in the limestone of Glen Tilt. These are always visible at the surface, from their superior power of resisting the action of the atmosphere.’

He also describes the exposures of limestone in a field south-east of Balephetrish Hill. He says that

‘it is possible that the masses of limestone thus found in gneiss have once been stratified, and that they have suffered some posterior changes by which the appearances of this disposition have been obliterated.’

Prof. Bonney has given a valuable description of the dynamic phenomena so well illustrated in thin sections of the Tiree Marble.

Prof. Cole & Prof. Sollas have suggested that the Tiree Marble may originally have been a wind-blown coral-sand rock, with abundant rounded crystals of detrital augite, etc., such as was found on the east side of Mér, one of the Murray Islands. This theory appears untenable; for it is impossible to imagine a volcanic origin for the majority of the accessory minerals, which, with
The Granite and Greisen of Cligga Head (Western Cornwall)
Authors: Scrivenor John Brooke
Published: October 2009

The small mass of granite known as Cligga Head, forming a bold promontory between St. Agnes and Perranporth on the northern coast of Western Cornwall, has long been known, not only to the geologists of that county, but also to others from farther afield.

Conybeare, in 1817, from notes by Buckland, described a small formation at Cligga Point which would ‘probably be considered by the Wernerian school as the newer granite,’ and remarked on tho stratification and the fact that it was worked for tin. A sketch also is given of the headland (
op. cit.
pl. xxiii), which does not, however, show the leading features exactly as they occur.

In 1818, Joseph Carne spoke of granite at Cligga Head, apparently stratified obliquely, but proving, on a nearer view, to be traversed by small veins of ‘blackish quartz, whose contemporaneous formation can scarcely be doubted.’ In a footnote the same author wrote:—

‘The granite at Cligga Point (if it is not a large elvan-coarse) might be called secondary or transition granite, without affecting the age of the granite of other parts of Cornwall, as it is far from the large granite-chain’ (
op. cit.
pp. 74–75).

In 1820 Sedgwick gave a description of the granite, as resembling the common granite of the country, except the ‘intermediate parts,’ which exhibited varied modes of aggregation: the strong folding of the parallel ‘beds’ in the granite was also noticed.

Œynhausen & Dechen, in 1829, noted the ‘numberless veins of granite which interest the granite itself,’
Note on the Occurrence of Keisley Limestone-Pebbles in the Red Sandstone-Rocks of Peel (Isle of Man)
Authors: Gill E. Leonard
Published: October 2009

In his recent paper on ‘The Red Sandstone-Rocks of Peel,’ Prof. Boyd Dawkins mentions a rock which occurs in a derived form in one of the conglomerates of the Peel Series, and has been identified with the Keisley Limestone. When Prof. Boyd Dawkins was preparing the paper quoted above, he entrusted to me the examination of the pebbles of the rock in question; and as the resulting identification possesses an interest apart from the main issues of his own work, he has kindly offered me the opportunity of giving a separate account of it. The following notes, therefore, contain a brief description of the rock and its fossil contents, with the grounds for believing it to be identical with the Keisley Limestone.

The pebbles which formed the material for the investigation were collected by Prof. Boyd Dawkins from the conglomerates forming the coast-line at Whitestrand, near Peel (Isle of Man). They are composed of a coarsely-crystalline limestone, greyish-white in ground-colour, and as a rule thickly mottled with pink : agreeing, in fact, very closely with those beds of the Keisley Limestone which Mr. F. R. Cowper Reed, M.A., F.G.S., speaking of their lithology in his exhaustive paper on that group, :~ describes as Type 3. The amount of this limestone available for examination was not great; and at first, as no fossils more distinctive than ostracods and some small and indefinite braehiopods had been met with, it was thought, on the strength of other fragments with which it was associated
An Experiment in Mountain-Building
Authors: Avebury
Published: October 2009

Many years ago Sir James Hall illustrated the formation of folded mountains by placing layers of cloth under a weight, and then compressing two of the sides so that the cloth was thrown into folds. Since then, other and more complete experiments of the same kind have been made by Favre, Cadell, Daubrée, Willis, and Ruskin.

In these experiments the compression was from two sides. If, however, folded mountains are caused by compression due to the contraction of the earth, the compression must take place in two directions at right angles one to the other.

With the view of illustrating this I consulted Mr. Horace Darwin, and he constructed for me an apparatus consisting of four square beams of wood, resting on a floor, which by means of screws could be moved nearer to, or farther from, each other. The beams left between them a space 2 feet across and 9 inches in depth.

In the square central space I placed some pieces of carpet-baize and layers of sand, each about 1½ inches deep. About an inch above the upper layer of sand I placed a piece of plate-glass and some weights. The machine was then set in motion, causing the beams of wood to approach one another. The sand rose in the centre, until it reached the glass, when it was flattened out.

On removing the upper layer of sand, the top-piece of cloth was as shown in fig. 1 (p. 350), which is a photographic reproduction of a
On a Shelly Boulder-Clay in the so-called ‘Palagonite-Formation’ of Iceland
Authors: Pjetursson Helgi
Published: October 2009

It is a fact well worthy of note that, while the basalt-formation of Iceland bears, geologically, a very close resemblance to the basalt-plateaux of the British Isles, the Tertiary volcanic phenomena of this latter region present nothing strictly analogous to the great tuff- and breccia- or so-called ‘palagonite-formation’ of Iceland. For it is obvious that the fragmental materials of the British volcanic region, which are intercalated with the basaltic lavas and only of ‘trifling thickness,’ cannot have their geological equivalent in the great palagonite-formation of Iceland, which covers thousands of square miles, and in isolated patches is met with over a greater part of the total area of the island.The palagonite-formation has been in several respects a puzzle to the geologists who have visited Iceland: some have been of the opinion that the tuffs and breccias are contemporaneous with the plateau-basalts or even older; but the more systematic investigations of Prof. Th. Thoroddsen have shown that in reality the fragmental masses are younger than the basalt-formation. Prof. Thoroddsen thinks that towards the close of Tertiary time the central parts of Iceland were buried under a continuous covering of fragmental volcanic materials 3000 to 4000 feet thick, which formation was broken up into single mountain-masses and isolated fells before and during the Glacial Period.

In the summer of 1899 it was observed that very considerable masses of ground-moraine are intercalated with the breccias which constitute hills rising out of, or bordering, the southern lowlands of Iceland; and in subsequent years observations
On Primary and Secondary Devitrification in Glassy Igneous Rocks
Authors: Bonney T. G. , Parkinson John
Published: October 2009

A few prefatory words are needed in explanation of the form of this paper. The authors have frequently discussed its subject, the elder of them having kept it in view since 1877; while the younger has enjoyed favourable opportunities of studying large spherulites, especially those in the obsidian of the Yellowstone, which the other knows only from hand-specimens. When they had agreed upon a joint paper, each wrote a draft, one of them having undertaken to fuse them together. But he found this impracticable; for, while their conclusions were practically identical, the paths followed were very different, so the papers, after substituting cross-references for some passages common to both, are now presented as separate chapters.

Part I.—By John Parkinson, Esq., B.A., F.G.S.

The excellent account and figures published in the Memoirs of the United States Geological Survey by Prof. J. P. Iddings render superfluous any general description of the well-known spherulites of Obsidian Cliff in the Yellowstone Park. Nevertheless some mention, however brief, must be made of a few facts, as these are closely connected with the general problem of devitrification.

Excluding microliths, the first-formed crystallizations are the ‘granophyre-groups’ of Prof. Iddings. These are intergrowths of felspar and quartz built with extreme delicacy, two or more crystals of felspar entering into the composition and forming rectangular or rudely spherical outlines. The greater the number of felspar-individuals the closer is the approximation obtained to a spherical form. As Prof. Iddings states, it is clear that these microscopic ‘granophyre-groups,’ together with the
Metamorphism in the Loch-Lomond District
Authors: Cunningham-Craig E. Hubert
Published: October 2009

I. Introduction.

This communication has been written, not so much with the idea of describing any phase of metamorphism specially interesting in itself, as of contributing to our knowledge of what metamorphism is, and of distinguishing between different kinds of metamorphism.

The term ‘metamorphism,’ or even ‘progressive metamorphism,’ has so often been used in a somewhat vague sense, without any distinct specification as to whether dynamic, thermal, hydrothermal, or contact-metamorphism, or a combination of two or more of these, is meant, that a study of an area where each of these types can be readily distinguished by its effects and considered separately, may prove of interest, as indicating the nature of those problems which workers among the Highland rocks have to investigate.

In the ‘Loch-Lomond District’ I include all the Highland rocks on both sides of the loch, as well as the area lying to the eastward, including the Trossachs-—in fact that part of the Highlands which is embraced by Sheet 38 of the Ordnance-Survey map. The material for this paper was collected two years ago, after four years of work in the district, and the main conclusions will appear in the ‘Explanation of Sheet 38’ by the Geological Survey of Scotland.

It is well-known that, in passing north-westward from the Highland Boundary-Fault, the metamorphism is seen to increase in degree. The progressive metamorphism in the Loch-Lomond district can be considered under two heads—dynamic, and what, for want of a better word, I call ‘constructive’ metamorphism. These processes have in
The Caernarvon Earthquake of June 19th, 1903, and its Accessory Shocks
Authors: Davison Charles
Published: October 2009

During the nineteenth century, the county of Caernarvon was visited by at least fourteen earthquakes. Seven, if not more, of these disturbances arrived from distant centres, situated near Pembroke, Hereford, etc.; but three or four were probably of local origin, their epicentres being either within or not far from the boundaries of Caernarvonshire. All of these local shocks, however, were of slight intensity; and, indeed, within the last five centuries, there does not seem to have been a single indigenous earthquake that can be compared either in intensity or in extent of disturbed area with that which, on June 19th, 1903, was felt over nearly the whole of Wales, the North-West of England, the Isle of Man, and several of the eastern counties of Ireland.

In the investigation of this earthquake, I have, as usual, been assisted by a large number of correspondents, to whom my best thanks are due. In various ways, I have also received timely aid from Mr. Edward Greenly, F.G.S., Mr. J. D. Macdonogh of Bettws-y-Coed, Mr. W. T. Davies of Nantlle, and Mr. W. A. Thomas of Llanfair-pwllgwyngyll. For lists of after-shocks, the value of which it would be difficult to overestimate, I am indebted to Mr. F. C. Carey of Bethesda, Mr. E. Davies of Bodfeirig, Mr. W. T. Davies of Nantlle, Mr. W. Hughes of Gaerwen, Mr. W. W. Hughes of Penygroes, and Mr. R. R. Jones of Clynnog.

The total number of earthquakes belonging to the recent series may amount to 15
The Discovery of Human Remains under the Stalagmite-Floor of Gough's Cavern, Cheddar
Authors: Davies Henry Nathaniel
Published: October 2009

Gough's Cavern is an extensive and much-branching subterranean waterway, which opens at the base of the cliffs on the south side of a picturesque gorge in the Carboniferous Limestone of the Mendips,near the village of Cheddar. For many years the proprietor,Mr. R. C. Gough, has worked the cavern, clearing out without much

method the accumulation of ages, in order to make a comfortable and easy access for visitors to the principal chambers; and quite recently the grandeur of the vaulting and the beautiful stalactites in the more inaccessible parts have been revealed by the introduction of the electric light.

In carrying out these necessary improvements, beds of stalagmite and cave-earth, blocks of limestone, pebbles and sand have been removed from the entrance and passages ; and the bones and teeth of extinct and existing animals, with human relics (prehistoric and historic) have been brought to light, and are now to be found crowded together in a small museum near the entrance. The objects prove that the caves were the alternate resort of extinct animals and man. The cases contain jawbones and teeth of the cave-hyaena, cave-bear, cave-lion, woolly rhinoceros, boar, horse, deer, Irish elk, etc., which have at various times been taken out of the cave-earth during the excavations ; but they were never found in large numbers, while flint-flakes, knives, scrapers, borers, and chips were plentiful, and bone and horn-borers, needles, and pins were some-times met with. From the takus at the base of the cliffs, which rose high
On a small

Plesiosaurus

-Skeleton from the White Lias of Westbury-on-Severn
Authors: Gwinnell Wintour Frederick
Published: October 2009

[Abstract.]

The remains described were found on the Severn beach at Easter 1904, and had evidently fallen recently from the cliff above, which is there made up of the Upper Rhaetic Beds, including the
Estheria
- Bed and the White Lias Limestone. The matrix of the specimen corresponds with the White Lias ill colour, texture, and material,and it is similarly traversed by fissures often coated with dendrites.The remains are in excellent preservation, neither pyritized nor appreciably carbonized, as is so usual in 'Bone-Bed' specimens. They include more than twenty small dorsal vertebrae, with spinous and transverse processes, lying in natural sequence. Pseudomorphs in calcite of the spinal cord and intervertebral cartilages occur also in relative position. Several slender ribs, and indications of other bones (probably from the pectoral or pelvic arches), also occur in the slab, but are not yet worked out. Hitherto only single vertebrae or fragmentary bones of
Plesiosaurus
have been recorded from the Rhaetics in Britain, and these only from the bone-beds below the White Lias. At present, it has not been found possible to assign the fossil to any existing species, but the characters most nearly approach those of
Plesiosaurus bibractensis
.

The specimen has been presented to, and accepted by, the British Museum (Natural History).
On some Quartzite-Dykes in Mountain-Limestone near Snelston, Derbyshire
Authors: Arnold-Bemrose Henry Howe
Published: October 2009

I.
DESCRIPTION OF THE QUARRY AND THE DYKES.

About 3½ miles south-west by south of Ashbourne, near Snelston Common, is an inlier of Mountain-Limestone surrounded by Keuper Marl. According to the Geolo~cal-Survey Map, the outcrop of limestone is roughly elliptical in shape, the major axis extending for a distance of about half a mile in a north-north-easterly direction, and the minor axis in a west-north-westerly direction for about one eighth of a mile. Coekshead Lane, the road from Norbury to Cubley Common, passes over the inlier, which only forms a slight feature in the landscape, at a height of about 600 feet above Ordnance-datum. On a clear day, some of the churches and chimneys of Derby, distant about 11 miles, can be seen from the top of the quarry.

The limestone has been quarried on both the north and south sides of Cockshead Lane for about 40 feet below the ground-level, so that the lane passes over a high wall of limestone-beds, which have been left intact between the two quarry-floors. The northern quarry is now disused. It contains lead-and copper-ores, which were worked about 30 years ago. It is outside the area of the main mass of Mountain-Limestone to which the curious lead-mining laws apply, and I was informed that the present owner does not allow the lead-ore to be worked.

The quarry south of Cockshead Lane is being worked for roadmetal.The inlier is in the form of a dome or pericline,with its greatest extension
Twin-Earthquakes
Authors: Davison Charles
Published: October 2009

I. I
ntroduction
.

T
he
essential characteristic of a twin-earthquake is the existence in the shock of two maxima of intensity connected by weaker tremulous motion, or the division of the shock into two parts separated by a brief interval of rest and quiet. This feature, however, is not entirely peculiar to twin-earthquakes; for, occasionally, one earthquake is succeeded by another so rapidly as to simulate a twin-earthquake in this respect. A closer investigation of the phenomena shows, as will be seen, that the two parts or maxima of a twin-earthquake originate in two detached, or practically-detached, foci; whereas, in a double earthquake, the foci are either coincident or overlapping. A further distinction, partly dependent on the former, may be noted. In all parts of the disturbed area the member of a double earthquake which occurs first is felt first. In a twin-earthquake, on the other hand, the second impulse may, but does not necessarily, occur before the vibrations from the first focus have reached the other; so that, over most of the disturbed area, the vibrations first felt are those which come from the nearer focus, whether that focus was first in action or not. In a double earthquake the second shock is a consequence of the first; in a twin-earthquake each is independent of the other. In other words, a double earthquake is the result of successive impulses; a twin-earthquake is due to a single generative effort.

As examples of twin-earthquakes, may be mentioned the Colchester earthquake of April 22nd,
On the Occurrence of
Elephas Meridionalis
at Dewlish (Dorset). Second Communication: Human Agency suggested
Authors: Fisher Osmond
Published: October 2009

I
n
June 1888 I read a paper before the Society on the occurrence of
Elephas meridionalis
at Dewlish in Dorset. Subsequent excavations were made by the late Mr. J. C. Mansel-Pleydell, of which he gave accounts in two articles in the Proceedings of the Dorset Natural History & Antiquarian Field-Club, vol. x (1889) pp. 12
et seqq.
& vol. xiv (1893) pp. 139–41, the second of these being illustrated by photographs of the deposit. Mr. Clement Reid also, in the latter part of 1888, spent four days in investigating the locality, and described it in the Geological Survey Memoir on the geology of the country around Dorchester, 1899. This memoir contains a drawing (p. 35) copied from one of Mr. Pleydell's photographs. The photographs themselves are now reproduced (Pls. III & IV). It is not necessary to describe the locality afresh, as that has been done already by Mr. Pleydell and by myself, and subsequently very clearly by Mr. Reid. The distant fence shown in Pl. III is on the brow of the hill, and the early finds were made just beyond it. The deposit was then opened on the opposite side of it, where the pelvic bone lies, the fence being left intact. The trench was afterwards followed for about 103 feet, until it suddenly terminated in a smooth ‘apse-like’ end. The photograph showing the pelvic bone (Pl. III) was taken from the farther end, looking about due north-west towards the brow of the hill. Both the views seem
The Superficial Deposits and pre-Glacial Valleys of the Northumberland and Durham Coalfield
Authors: Woolacott David
Published: October 2009

I. I
ntroduction
.

N
early
the whole of the rock-surface of the Northumberland and Durham Coalfield is covered by superficial deposits of an extremely variable thickness. After I had made some study of the thickness of these deposits and the pre-Glacial contour of the north-east of County Durham, Prof. Lebour suggested to me that results of some importance might be obtained from a thorough investigation of all the borings and sinkings made in the Northern Coalfield, and the working out of this subject has occupied the greater portion of my leisure-time for the last three or four years.

Nicholas Wood & E. F. Boyd, in a paper on the ‘Wash’ published as long ago as 1864 (1) first clearly showed that the deposits covering the rock-surface of this coalfield were not arranged in an irregular manner, but were found along valley-like depressions. Since then, little has been done towards the thorough elucidation of the Glacial and superficial geology of this area. Indeed, little of a detailed character could have been attempted until the publication in 1897 of the final volume of the ‘Account of the Strata of Northumberland & Durham, as proved by Boring & Sinkings’ (4). The six volumes published by the North of England Institute of Mining & Mechanical Engineers give details of 2,353 borings made in the Northern Coalfield, or in its immediate neighbourhood. A large number of these are useless for our present purpose, because their exact position is not known, many of them are vague and indefinite
On the Sporangium-like Organs of
Glossopteris Browniana
, Brongn
Authors: Arber E. A. Newell
Published: October 2009

I. I
ntroduction
.

G
lossopteris

is now among the most familiar of all fossil plants. The tongue-shaped fronds of this genus, with their reticulate lateral nervation, are exceedingly charactcristic of the Permo-Carboniferous rocks of India, Australasia, and Southern Africa, and occur also in the Permian of Russia, and in beds of Rhætic age in Tongking and China. So great is the abundance of these fern-like leaves in the Lower Gondwana Series of India, and its homotaxial equivalents in the Southern Hemisphere, that this plant has given its name to the flora of that former continental region.

Although a very large number of
Glossopteris
-fronds have been described by different authors, it is only within the last few years that we have learnt, anything as to
the general habit of this plant. We are chiefly indebted to the researches of Prof. Zeiller, of Paris, for progress in this respect. It has now been ascertained that this plant was
heterophyllous,—a fact which was first suggested by M'Coy in 1847. In addition to the larger and often tongue-shaped fronds, much smaller leaves, generally spoken of as scale-fronds,
were borne on a rhizome-like stem, which has been long known under the name of
Vertebraria
. The nervation of the scale-fronds resembles that of the larger leaves,
except that there is no midrib. In shape they are, as a rule, ovately triangular, pointed at the apex, and strongly concave. An average specimen measures one and a half centimetres or more in length.

Up to the present time we are without any definite
On the Occurrence of Rhætic Rocks at Berrow Hill, near Tewkesbury
Authors: Richardson Linsdall
Published: October 2009

B
errow
H
ill
(184·8 feet above Ordnance-datum) is a small outlier of Lower Liassic and Rhætic deposits, distant about 2 miles in a south-easterly direction from Chase-End Hill, the southern end of the Malvern Range. It occurs in the centre of a basin-shaped area formed by the Keuper Sandstone, which in this district comes about 215 feet below the base of the Rhætic. By means of this sandstone-deposit, it is possible to trace with very great accuracy the amount of flexuring that these Keuper beds have undergone. The causes and effects of this flexuring have been dealt with elsewhere, but it may be of interest to mention that at Berrow the sandstone is arranged so as to form a basin; and at Eldersfield—immediately to the south—the numerous exposures show the dip to be quaquaversal. In the past there was a complete ellipsoidal dome, but now the sandstone is much denuded, capping a central boss, while the main mass is at distances varying from a quarter to three-quarters of a mile away. East of the Eldersfield district the rocks are necessarily disposed synclinally: on the northern extension of this axis lies Berrow Hill, and on the southern Berth Hill. This hill, according to Symonds, is capped with Rhætic Black Shales. On the east again the Keuper Sandstone reappears to form an anticline, and then disappears, dipping gently eastward or south-eastward. A reference to the map (fig. 1, p. 425) and sections (figs. 2 & 3. p. 426) will explain much more lucidly
Notes on the Palæontology
Authors: Hind Wheelton
Published: October 2009

Introduction.

I
t
has been known for some time that thin bands containing marine shells occur in several coalfields, and from time to time figures and descriptions have been published. Among the earliest of these publications were Sowerby's descriptions and figures of the marine mollusca from the Pennystone Ironstone of Coalbrookdale, in Prestwich's memoir. Perhaps the other most important publication is that by Mr. George Wild, in which a large number of marine mollusca were figured.

So well known was the occurrence of marine fossils, as distinct from the bands of
Carbonicola, Anthracomya
, and
Naiadites
, that Prof. Hull, in his paper on ‘The Upper Limit of the Essentially-Marine Beds of the Carboniferous Group of the British Isles’, included the Gannister Series or Lower Coal-Measures with the Millstone Grits and the series of shales and black limestones below them, which he erroneously correlated with the Yoredale Series of Wensleydale.

This classification is obviously unsound; (1) because the Gannister Series is not wholly marine in origin, for it contains beds in which the marine fauna is absent; and (2) a marine fauna is not limited to the Gannister Series, but recurs at several horizons in the middle portion of the Coal-Measures, which are therefore not ‘essentially freshwater or estuarine beds.’ Indeed, there is an unbroken succession from the base of the Pendleside Series to the top of the Coal-Measures, at times marine, at times estuarine, or of freshwater origin. This thick series contains two distinct molluscan faunas, which recur with irregular alternations. One
Observations on some of the Loxonematidæ, with Descriptions of Two New Species
Authors: Donald Jane
Published: October 2009

T
he
genus
Loxonema
was founded by Phillips in 1841, and was thus described by him:— ‘Spiral, turriculated; whorls convex, their upper edges adpressed against the next above; without spiral band; mouth oblong, attenuated above, effused below, with a sigmoidal edge to the right lip; no umbilicus (?); surface covered by longitudinal threads or ridges, generally arched.’

He further states that these observations are merely provisional, until the form of the aperture is more perfectly known. In noting the number of species, he writes that most of them are probably ‘varieties of three or four types having
L. sinuosa
for one extremity and
L. Hennahii
for the other; a second related to
L. tumida
and
L. lincta
; a third to
L. rugifera
.‘ [
Loc. cit.
] Later researches show that this description is correct for the group of shells having
Loxonema sinuosum
for the type, and the generic name must be restricted to them. The essential characteristics are the possession of whorls adpressed at the suture and the presence of strongly-sigmoidal lines of growth. Shells having more convex whorls, or less sigmoidal lines of growth, must be placed elsewhere. Prof. Koken and other palæontologists have created several new genera for some of these latter. The type,
Loxonema sinuosum
, is the first species described by Phillips: it is a Devonian form from South Petherwyn, which he identifies with
Terebra (?) sinuosa
, Sow. from the Aymestry Limestone. They are probably distinct species, although Mr. Whidborne thinks them correctly identified. The striæ on the Devonian form
On the Geology of Arenig Fawr and Moel Llyfnant
Authors: Fearnsides William George
Published: October 2009

I. I
ntroduction
.

T
he
mountains known as Arenig Fawr and Moel Llyfnant are situated somewhat to the north of the centre of the county of Merioneth, and lie immediately east of the main water-parting of Wales. The area studied lies wholly within the quarter-sheets 13 S.E., 13 S.W., 21 N.E., & 21 N.W. of the 6-inch Ordnance-Survey maps of Merionethshire. Rising from a plateau some 800 to 1200 feet high, they attain heights of 2800 and 2437 feet respectively, and, being entirely above the cultivation-zone, are practically uninhabited. The Great Western Bala-Ffestiniog Railway crosses the northern end of the district, to which Arenig Station, close under the northern slopes of Arenig Fawr, affords easy access.

Although to a certain extent glaciated, the mountains are swept clean rather than Drift-covered, and it is only in the lower ground that moraines become inconveniently abundant. The adaptation of surface-forms to rock-structures is exceedingly complete, and few are the places where the ribs of harder rocks do not protrude through the scanty soil or turf. Being open to the full blast of the westerly and south-westerly gales from the ocean, the district, receives its full share of weather; and, in consequence, although the eastern slopes are often grass- or heather-covered, the steeper parts of the western slopes are rugged and bare, and afford magnificent exposures of the component rocks. Further, the structure of the district is fairly simple, and the cleavage, though present, is not so strongly developed as to prevent one from breaking the
V. Petrological Notes
Authors: Howe J. Allen
Published: October 2009

Rocks from the Neighbourhood of Buta.

Specimen No. 48.—This is a fine-grained, chocolate-coloured,laminated mudstone containing minute flakes of mica. There is no trace of any fossil, unless one or two microscopic pellets may be taken to represent coprolites.

No. 42, Rubi River.—From large blocks apparently embedded in the clayey alluvium of the river.

It is a compact cream-coloured rock, with well-marked oolitic structure. In the thin slice, opaque, dull, spherical grains are seen in a fairly-large amount of granular crystalline calcite, which forms the matrix. The grains are fairly uniform in size, and all possess a well-defined concentric structure; there is no trace of any radial structure, and the material is too dusty in character to give a cross in polarized light. The centres of the grains are usually filled with more or less clear granular calcite, and no organic or clastic bodies have been noticed in them. There are several compound grains, one large grain enclosing one or two smaller ones. (See P1. XLIV, fig. 2.)

The rock is suggestive of an oolite formed from a calcareous spring, but there is nothing to show that organisms have taken any part in its formation. In places the rock includes small pellets of grey clay [52], and where this is present the limestone tends to assume a stylolitic structure.

No. 51.—This specimen, said to be from the same locality as the preceding, is a compact rock of slightly-redder colour; in the hand-specimen it shows the spherical oolitic grains weathering more readily
A Contribution to the Study of the Glacial (Dwyka) Conglomerate in the Transvaal
Authors: Mellor Edward T.
Published: October 2009

W
ith
the exception of the gold-bearing conglomerates of the Witwatersrand, the Glacial or Dwyka Conglomerate at the base of the Karroo System has probably attracted more attention from geologists than any other rock occurring in South Africa. While, however, the rocks of the Rand derive their importance mainly from their economic value, the interest manifested in the Glacial Conglomerate over a period of fifty years has depended entirely upon purely-geological considerations. The diversity of views which so long prevailed, as to the origin of the Dwyka Conglomerate, was no doubt largely due to the fact that these views were in many cases necessarily based upon the examination of hand-specimens. The study of the rock in the field, however, can hardly be said to have resulted in any marked unanimity of opinion among local geologists, the majority of whom favoured an igneous origin for the rock in question; and, although the glacial view was stated by P. C. Sutherland as far back as 1868, and later supported by G. W. Stow, Mr. E. J. Dunn, and Dr. A. Schenck, it is only quite recently that the accumulation of evidence in favour of the glacial origin of the rock can be said to have led to a general acceptance of this view.

To South African geologists the Glacial Conglomerate affords the only common geological horizon as yet available for the various colonies, while its similarity to corresponding formations in India, Australia, and South America gives a wider interest to the investigation of
On a New Specimen of the Chimæroid Fish,
Myriacanthus Paradoxus
, from the Lower Lias near Lyme Regis (Dorset)
Authors: Woodward Arthur Smith
Published: October 2009

In 1871 the late Sir Philip Egerton communicated to the Geological Society an account of part of a fossil Chimæroid from the Lower Lias of Lyme Regis, remarkable as exhibiting a peculiar prolongation of the snout like that of the existing
Callorhynchus
. He named the specimen
Ischyodus orthorhinus
, In the following year he described the somewhat anomalous dentition of a much larger Chimæroid fish from the same formation and locality, and regarded it as representing a previously-unknown genus and species,
Prognathodus Guentheri
. With the aid of additional specimens in 1889, I was able to prove that the dorsal fin-spine of the so-called ‘
Ischyodus orthorhinus
’ was identical with an ichthyodorulite which had been named
Myriacanthus granulatus
by Louis Agassiz in 1837; while the dentition of the same fish, when satisfactorily preserved, agreed generically with that known as
Prognathodus
. I therefore inferred that the larger ichthyodorulite named
Myriacanthus paradoxus
by Agassiz, belonged to the same fish as the larger dentition named
Prognathodus Guentheri
; and in this determination I was confirmed by the discovery of a very similar spine in association with a
Prognathodus
-like dentition in the Lithographic Stone of Bavaria. The name
Myriacanthus
thus acquired a definite zoological meaning, and no longer denoted a mere ichthyodorulite of doubtful relationships.

Until the present time, however, the spine named
Myriacanthus paradoxus
has not been found in direct association with the dentition described as
Prognathodus Guentheri
. The expected discovery has at last been made, and as the new specimen displays some additional features of interest
The Glacial Period in Aberdeenshire and the Southern Border of the Moray Firth
Authors: Jamieson Thomas F.
Published: October 2009

I. Introductory

That north-eastern angle of Scotland which lies between the Moray Firth and the Firth of Tay presents some special features of interest in connection with the history of the Glacial Period, inasmuch as it seems to have been less heavily covered with ice than the rest of Scotland. Nevertheless, no part of the area appears to have escaped invasion, for the ice which filled the basin of the Moray Firth extended over all the southern border of that basin, and even overflowed a considerable part of Aberdeenshire, spreading southward until it met those streams which, proceeding from the Grampian Mountains, moved eastward along the valleys of the Dee and the Don. No part of the surface, therefore, escaped abrasion by the ice; and no remnant of pre-Glacial Tertiary deposits has hitherto been found in any part of the area, even in those spots where one would have thought that they might have been most likely to be preserved. Neither has any trace been obtained of the mammalian fauna which inhabited England during the inter-Glacial Period. No remains of the Mammoth, not even a tooth or a tusk, have been met with in any of the railway-cuttings or other excavations (so far as I am aware), although such have been found in Ayrshire and in the Basin of the Forth.

One of the most interesting features in the Glacial Geology of Aberdeenshire is the Red Clay which occurs along the eastern coast of that county. Some account of it
The Geological Structure of the Sgùrr of Eigg
Authors: Harker Alfred
Published: October 2009

I. Introduction

The Tertiary igneous rocks of the Inner Hebrides have from time to time engaged the attention of many eminent geologists; and the results of their labours, interpreted by their skill and insight, have become part of the common stock of British geology. In certain cases the investigation has been conducted on an extended scale. This is true more especially of the work of Macculloch in the earlier days, and of Sir Archibald Geikie and Prof. Judd among those who are still with us. Nevertheless, it is only recently that any considerable part of that large and complex area has been mapped with the close attention to detail requisite in a complete geological survey. Even apart from the time demanded by such a minute examination of the ground, the large-scale Ordnance maps which make it possible have been issued only within the last few decades. Thus, in the ten years which the present writer has spent on this work, it has been his good fortune to enjoy facilities denied to his predecessors, besides benefiting by the fruits of their labours in the same field. Fortified by these advantages, he has been enabled to pass with less diffidence from observation to inference, even when the latter is at variance with the views of geologists of much wider experience. For, as might be anticipated, the results of the detailed survey, while generally confirming the conclusions of the recognized authorities, have sometimes extended, restricted, or modified them, or have even led to
On a Case of Unconformity and Thrust in the Coal-Measures of Northumberland
Authors: Lebour George Alexander , Smythe J. A.
Published: October 2009

I. Introduction.

The object of this paper is to describe a case of unconformity, accompanied by a certain amount of horizontal thrusting, which occurs in the Coal-Measures exposed—chiefly at low water—on the coast of Northumberland at the foot of the Whitley cliff's, and is traceable for upwards of a mile.

The section studied stretches from the bold headland formed by the Table Rocks, northwards almost as far as the Brier-Dene Burn. At the southernmost end—that is, at the Table Rocks—the plane of erosion in question dips and disappears beneath the sea. Near the mouth of Brier Dene it is permanently covered and concealed by Drift and beach-deposits.

The Table Rocks consist of a series of ledges of sandstone, bedded almost horizontally, and presenting vertical cliff-faces to the sea. A little north of this the cliff becomes overhanging, owing to the undercutting by the waves of the soft beds which come to light at its base.

Near the spot marked M on the sketch-map (fig. 1, p. 532), the sandstone-cliff, which so far varies from 30 to 40 feet, gradually lessens in height, and is overlain by a considerable thickness of Boulder-Clay. Up to this point also the foreshore is free from cover, though strewn with boulders, and in places obscured by talus-heaps burying the cliff-foot, and the strata comprised in it can be well seen at low tide. Farther north, however, the boulder-strewn outcrops give place to a broad sandy beach (Whitley Sands proper), which is broken, near low-water-mark only,
Notes on the Genera
Omospira Lophospira
, and
Turritoma
; with Descriptions of New Proterozoic Species
Authors: Donald Jane , Longstaff G. B.
Published: October 2009

In my paper on some of the Proterozoic Murchisoniidæ, Pleurotomariidæ, and Turritellidæ, I referred to the researches of Dr. Ulrich and Prof. Koken among the earlier gasteropoda, and mentioned the groups into which those authors had divided them. We still require much more knowledge with regard to their origin and relationship before really-satisfactory divisions can be made. Unfortunately, the new species that I am about to describe are not sufficiently well-preserved to add much to the material previously available. None of them have the apex entire, and therefore no further light is thrown on the structure of the protoconch. These new species belong to three genera, characterized by the possession of a band on all the whorls, formed by the gradual filling-up during growth of a sinus, and not a slit, in the outer lip. To two of these genera I have already referred, namely,
Lophospira
, Whitfield, and
Turritoma
, Ulrich. The other genus is
Omospira
, Ulrich. Though
Lophospira
and
Turritoma
are not really true Murchisoniidæ, I have allowed them to remain in that family for the present.

Dr.Ulrich places
Omospira
in the family Raphistomidæ, but it is not a characteristic member, for the whorls are more convex and the spire is higher than is the case with the other genera belonging to the family. He describes it thus (
loc cit.
):—

‘Shell somewhat elongate turbinate, subturriculate; volutions seven or eight, ventricose, obliquely flattened in the upper part by an obtuse shoulder-like angulation; the latter, which may or may not constitute the
Recumbent Folds Produced as a Result of Flow
Authors: Sollas William Johnson
Published: October 2009

Our views as to the various kinds of deformation which affect the earth's crust received a remarkable extension with the memorable discoveries of Lapworth, Peach, and Horne in the north of Sutherland. These have now culminated in the long series of revelations which we owe to Bertrand, Rothpletz, Schardt, Kilian, Haug, Lugeon, Termier, Suess, and other workers in various regions of the Alps, who seem to have accomplished a veritable revolution in this branch of enquiry.

The long recumbent folds, which are perhaps the most surprising of the new forms of disturbance lately brought to light, can be more readily demonstrated than explained.

If we turn to one of the most complete and consistent accounts. of these phenomena, Lugeon's description of the pre-Alps of Chablais, we perceive a series of recumbent folds, so gleatly exceeding in horizontal extension their thickness vertically, that they are commonly spoken of as sheets rather than folds: they lie with remarkable flatness one on the other; and as a rule those higher in the series extend farther to the front than those below, a feature referred to as ‘déferlement’ by the French, or ‘leap-frog’ as translated by my friend, M. Allorge.

The roots or origin of several of the lower of these folds are visible in the high Alps adjacent, but the roots of the higher folds, which form the pre-Alps, must be sought in the zone of Mont Blanc and the Brianconnais. Thus, some of the uppermost folds mav have surmounted the obstacle presented
The Influence of Pressure and Porosity on the Motion of Sub-Surface Water
Authors: Baldwin-Wiseman William Ralph
Published: October 2009

Since the early part of the last century the question of the behaviour of underground water has received the attention of numerous investigators, whose labours have resulted in the compilation of a most voluminous and scattered bibliography, comprising records of field-observations, experimental data, and mathematical deductions, many of which are difficult of access. I have therefore, although deeply conscious of the omission of the names of many worthy investigators, endeavoured to summarize briefly the more important investigations on this subject, with the view rather of outlining the work, than of giving a full record of workers.

In 1837, Robert Stephenson (1) first noted the formation of a cone of depletion in the water-logged sands of the Inferior Oolite, during the progress of the construction of the Kilsby Tunnel on the London & North-Western Railway; and in a later report to the London & Westminster Water Company, he remarked upon the high absorptivity of the Chalk and the intermittent nature of its surface-streams.

The first systematic well-measurements were made by Bland (2) in 1831, along two parallel lines from Sittingbourne to Maidstone; and ten years later Clutterbuck prepared a somewhat similar section on a line from Dunstable to Watford.

In 1851 Ansted (3) experimentally determined the rate of percolation of water through Chalk, under comparatively-low pressures; and seventeen years later, in 1868, Isaac Roberts (4) published a few figures showing the effect of pressure on the rate of flow of water through the Red Sandstone of the Liverpool district.

In 1856
A Silurian Inlier in the Eastern Mendips
Authors: Reynolds Sidney Hugh
Published: October 2009

I. I
ntroduction
. T
he
Mendip Hills consist of four periclinal upfolds of Carboniferous Limestone, arranged
en échelon
from north-west to south-east. Each perieline includes a core of Old Red Sandstone, and the south-eastern or Beacon-Hill pericline further shows a series of igneous rocks. It is with these that the present paper deals. The existence of igneous rocks in the Eastern Mendips was first noted by Charles Moore, who described them as ‘a basaltic dyke of considerable thickness emerging from beneath the Old Red Sandstone at East End near Stoke Lane.’

He considered that, from the general physical character of the Mendips, it was not improbable that the dyke might be co-extensive with their range. He not only attributed the upheaval of the whole Mendip range to the intrusion of this igneous mass, but also considered that it was responsible for the remarkable inverted character of the Carboniferous beds at Luckington, where the Coal-Measures are worked under the Carboniferous Limestone.

John Morris refers to the rock at Stoke Lane, as ‘a dyke of considerable thickness, emerging from beneath the Old Red Sandstone, occurring as bosses in the field, but, traced for some distance over the district, it is conglomeratic in places, and pronounced by Mr. D. Forbes to be dolerite.’

The igneous rocks are not shown in Sanders's map of the Bristol Coalfield (published in 1864), but appear in tile map of the Geological Survey (1884) as a series of isolated patches extending from Downhead on the east, to Beacon Plantation, southwest