bluuebunny/crossref_metadata_2025 huggingface dataset:
Bala Lake and the River-System of North Wales
Authors: Lake Philip
Published: October 2009

In this paper the Author begins by showing that topographically Bala Lake belongs to the same valley as the River Wnion—the valley of the Bala Fault; and he believes that the whole drainage of the valley originally flowed south-westward, and entered the sea near Barmouth.

He then examines the possible outlets, and shows that the lake is probably rock-bound in all directions except towards the south-west, where there is no conclusive evidence.

He describes the faults which occur near the watershed that separates the Wnion from the streams flowing into Bala Lake, pointing out that they are closely related to the form of the valley, and that the watershed coincides with a transverse line of fault. Prom this he infers that the formation of the lake is possibly due to earth-movements.

The watersheds of several other similar valleys are examined, and are shown to lie in one straight line; whence it is concluded that they must have been produced by some general cause, probably a slight differential movement.

The general drainage-system of North Wales is next discussed. Attention is drawn to the existence of a series of long and nearly parallel valleys running from north-east to south-west, which divide the region more or less completely into a number of strips. The drainage of each strip is now independent, and flows in most cases into the long valley lying south of it. But from the fact that the chief streams in each strip have their representatives (flowing in the same line) in the adjacent strips, it is concluded that before the
formation of the long valleys the streams were continuous.

The centre from which these streams radiate lies in the high ground near the sources of the Conway; and the Author believes that this was the centre of an original radial system of drainage, and that this radial system was subsequently broken up into sections, by the formation of the long valleys which now run from north-east to south-west–each of these long valleys carrying away the drainage of one of the sections. He attributes the formation of the long valleys to faulting.
Fossils in the Oxford University Museum.—II.On Two New Genera and Species of Crinoidea (
Brahmacrinus ponderosus
and
Cicerocrinus elegans
)
Authors: Sollas W. J.
Published: October 2009

I.
Brahmacrinus Ponderosus
gen. et sp. nov.

(P1. XVI, figs. 1 & 2.)

This somewhat barbarically ornate crinoid is represented in the University Collection by two calyces, which are both devoid of arms and stem. One of the specimens is exceedingly well preserved, and affords a fairly complete knowledge of the structure of the calyx. In the British Museum (Natural History) five specimens of the same crinoid are displayed; these also are calyces without arms or stem. Some of the specimens in the British Museum were obtained from Preston (Lancashire), and some from Yorkshire; those in the Oxford University Museum are from the latter county, where they occur in the Carboniferous Limestone.

The size of the calyx is fairly constant in all specimens, measuring, in that selected for description, 45 mm. in height by 40 mm. in maximum breadth. The dorsal cup is obconic in form, with the apex (corresponding to the base of the crinoid) truncate; the ventral disc is gently convex, and supports an excentric anal tube.

The basals are large, and three in number; two are equal in size and larger than the third, which is the left anterior. The sutures, which are persistent, are not quite symmetric with regard to the radial plates, which they meet on one side of the median line. The basals, like the other plates of the calyx, are much swollen, except immediately over the sutures, which consequently lie at the bottom of a deep groove.

The five radials are also large,
The Zonal Classification of the Wenlock Shales of the Welsh Borderland
Authors: Elles Gertrude L.
Published: October 2009

I. Introduction.

In Southern Sweden occurs a series of shales of Wenlock age, which Tullberg divided into zones by means of their predominant graptolites.
1
During a visit to that country in the early part of 1896, I was enabled, through Dr. Törnquist's kindness, to spend some time in studying the fauna of these zones, and I determined that when I returned to England I would ascertain whether some such zonal classification did not also hold good for the beds of Wenlock age in our own country.

During the past four years I have studied in detail the strata and the graptolites of the Wenlock Beds of the Welsh Borderland, and I find that such a classification can certainly be made. Further, as the existence of Tullberg's zones
2
has recently been called in question, and doubt has been thrown upon the validity of several of his species, it seems only fair to the memory of that geologist to bring forward the results that I have obtained, which appear to me to confirm his work completely.

A glance at the Geological Survey maps of the Welsh Borderland would seem to indicate that the Wenloek Shales cover a considerable extent of country. This, however, is not really the case: far from being of wide extent, the Wenlock Shales are generally present as a mere fringe below the Ludlow rocks. It is the Ludlows, and particularly the Lower Ludlows, which occupy the greater part of the area. Frequently the so-called ‘Ludlow’ of the Geological
The Lower Ludlow Formation and its Graftolite-Fauna
Authors: Wood Ethel M. R.
Published: October 2009

I. Introduction.

The Lower Ludlow Shales, which form the lowest section of the Ludlow division of the Silurian System, are most typically developed in the neighbourhood of the picturesque old town of Ludlow. It was in this district that they were first defined and described by Murchison. Lithologically, they are here essentially an argillaceous group of strata, the lower and upper limits of which are well marked by two distinct calcareous beds—the Wenlock Limestone below and the Aymestry Limestone above. Palæontologically, the Lower Ludlow Shales are rich in fossils: brachiopods, cephalopods, crustaeea, and graptolites.

When the Lower Ludlow Beds are followed from the Ludlow district north-eastward along their line of strike as far as the valley of the Severn, south-westward as far as Aymestry, and eastward as far as the Malverns and Mayhfil, they are seen to retain their lithologieal characters unaltered, and the Wenlock and Aymestry Limestones are both well developed. But when these beds are traced from the typical area to the west and north-west, the limiting calcareous strata dwindle away and eventually disappear, until, finally, the Lower Ludlow Shales merge lithologically on the one hand into the Wenlock Shales below, and on the other into the Upper Ludlow Flags above. It is clearly impossible, therefore, in these westerly districts to separates on purely lithological grounds, the Lower Ludlow Beds as a distinct group from the formations which overlie and underlie them.

The proofs that the Lower Ludlow Beds of Britain contain a Characteristic graptolite-fauna have been gradually
On Kentallenite and its Relations to other Igneous Rocks in Argyllshire
Authors: Hill J. B. , Kynaston H.
Published: October 2009

I. Introductory.

In Mr. Teall's well-known work on ‘British Petrography’ a remarkable rock from the Kentallen quarries, near Ballachulish in Argyllshire, was figured and briefly described,
1
but it was not until the rock had been mapped by Mr. J. Grant-Wilson in 1896 that its peculiar characters were recognized and more fully described by Mr. Teall in the Annual Report of the Geological Survey under the term olivine-monzonite.
2
This term was assigned to the rock on account of the resemblance which it showed to the monzonitegroup of Prof. Brögger.
3
Mr. Teall pointed out, however, that there was at the same time a considerable difference, consisting mainly in the relative proportion of magnesia, between the Highland rock and the olivine-monzonite rock of Brögger. Since that time similar and closely-allied rocks from other localities have been investigated by us; and it is our object in the present paper to endeavour to point out the relationships of this unique petrological type to the granites and other intrusive rocks of Argyllshire, and so to remove it from a hitherto somewhat isolated position. Moreover, an examination of several varieties of the normal type has led us to reconsider the advisability of retaining Prof. Brögger's term for a group of rocks which evidently show in certain respects a marked divergence from the original type.

The term monzonite originates from Prof. A. de Lapparent (1864), who applied it to the well-known augite-syenite of Monzoni, in the Tyrol. Since then the term has been employed by different authors slightly
Mechanically-formed Limestones from Junagarh (Kathiawar), and other Localities
Authors: Evans John William
Published: October 2009

I. The Original Structures of Mechanically-formed Calcareous Rocks—Subaqueous, Littoral, and Æolian

We are apt to think of the calcareous rocks as being laid down differently from other sedimentary strata. It is recognized at once that the deposition of the latter involves the mechanical forces of rivers, currents, waves, or winds ; but the former―when they are not the result of chemical precipitation―are often spoken of as if they represented merely the undisturbed accumulation of calcareous material, which either remains where the organism, of which it formed part, ceased to live, or sinks by its own weight at once to the sea-bottom.

This distinction is, however, as every one would admit, only very partially valid. All the structures characteristic of the sedimentation of arcnaceous beds are exhibited, on occasion, by calcareous rocks ; though when these are formed in the sea, the phenomena are restricted and modified by the fact that carbonate of lime is soluble to a very large extent in water containing carbonic anhydride.¹

As a general rule, the water of rivers, lakes, and seas is not completely saturated with carbonate of lime, and therefore acts as a solvent of that substance. A small calcareous particle—whether it is derived from the erosion of a limestone; or is the result of the comminution of shells, corals, and other organic remains; or represents the test of a minute organism—will not remain long suspended in water which is still capable of taking up carbonate of lime, before it disappears into solution. Fine-grained
Notes on the Consolidated Æolian Sands of Kathiawar
Authors: Chapman Frederick
Published: October 2009

In Kathiawar and Kach, on the littoral between the peninsula of India and the mouth of the Indus, are some interesting calcareous deposits which, both in structure and composition, present many points of interest. They are usually known under the name of the Miliolite-formation, given by H. J. Carter, who was the first to investigate them.

Dr. J. W. Evans, who was formerly State Geologist to the Government of Junagarh in Kathiawar, has supplied me with four specimens from different localities in the Junagarh State, as well as a microscope-section made in India. I am indebted to Prof. T. Rupert Jones for another specimen from the hills north-east of Porbandar. I have carefully examined these specimens for organisms, both in thin sections and in the disintegrated rock.

The material investigated by Carter was from the locality ,mar Porbandar, where it is quarried and exported for building purposes under the name of Porbandar Stone. He refers to it as follows
1
:—

—The Poorbandar limestone derives its specific denomination from the place near which it is quarried in Khattyawar, and is imported at Bombay in the shape of blocks and flags for building purposes. It is of a brownish-white colour, uniform in structure, granular, and composed of oolitic particles of calcareous sand united together into a firm compact rock.—

On examination by Dr. Carter it yielded numerous foraminifera, among which those of the genus
Miliolina
were conspicuous. The rock, however, resembles the Miliolitic Limestone of the Paris Basin neither in age nor in
On Radiolaria from the Upper Chalk at Coulsdon, Surrey
Authors: Holmes W. Murton
Published: October 2009

The occurrence of radiolaria in the Chalk of this country is sufficiently rare to call for some notice, and the present paper has been written at the suggestion of Mr. William Hill, F.G.S., who saw some of my specimens. As was suggested by Messrs. Hill & Jukes-Browne in their paper on Chalk radiolaria,
1
one would have expected the physical conditions of the Upper Cretaceous period to have been more favourable to the existence of such organisms than those of the Lower Cretaceous or of Jurassic times, in the rocks of which periods radiolaria are not uncommon on the Continent.

One reason may be that, as in recent deep-sea dredgings, we find the ooze in some instances to contain radiolaria in considerable numbers, while in others they are either entirely absent or very scarce; so it is possible that in certain tracts of the Chalk there were no radiolaria present when that was deposited. Again, the ready solubility of radiolarian tests, more especially when in contact with carbonate of lime, will account for the disappearance of large numbers.

Dr. Cayeux
2
has given a summary of the papers which been have published on Cretaceous radiolaria.

Prof. W. J. Sollas found some in the Cambridge Greensand in 1873. These, however, were not described. Geheimrath K. yon ZiLtel found in 1876, in the Upper Senonian of Northern Germany, six species of radiolaria belonging to four known genera. Signor Pantanelli in 1880 noted the presence of one species in the Cretaceous of Tuscany. The late
Appendix. Report on the Inorganic Constituents of the Crag
Authors: Lomas Joseph
Published: October 2009

For the purposes of this enquiry the proposed zones of the Red Crag—Waltonian, Newbournian, and Butleyan—may be taken together, as no essential differences in the contained minerals can be detected.

Very marked distinctions in colour are noticeable in different localities, but these largely depend on varying degrees of impregnation with iron. The iron-staining undoubtedly took place after the beds were deposited, and differences in amount can be traced to the flow of water containing iron in solution. Thus, it is found that where the Crag rests upon a clayey foundation, as at Beaumont, the line of parting has formed a channel along which water has flowed.

In some cases, as is well seen in the pit near Beaumont Hall, the lines of infiltration run across the bedding in wavy lines. It is evident that water percolating through porous rock must trend towards an outflow. When a line of flow has once been established, most of the water will move through certain channels and, carrying iron in solution, there will be a tendency to form pipes by the deposition of iron-oxide in the interstices of the sand.

Where pits have been for a long time unworked and a cliff of Crag has been left exposed, the porous rock has served as a passage for surface-water, which oozes out from the face of the section. Here the staining can be directly associated with lines of flow. In some instances the iron-oxide has cemented the sand and shells together, and, where a part
Additional Notes on the Drifts of the Baltic Coast of Germany
Authors: Bonney T. G. , Hill Edwin
Published: October 2009

I. Introduction

We quitted Rügen in 1898 with no expectation of ever seeing it again. But after completing the paper which has appeared in the Society's Quarterly Journal, we felt the usual desire of once more going over the work. When there seemed a possibility of gratifying this, we should have withheld our paper, if a special reason had not existed for an early publication of our views. We determined, however, in 1899 to cover a wider field and to examine not only Arkona (which want of time had prevented us from visiting), but also some sections at Warnemünde which we expected to prove very different from those in the Jasmund district. This was the case, though they were not exactly what we had been led to anticipate.

In looking for papers on Rügen we unfortunately missed a small monograph by Dr. Rudolf Credner (‘Rügen: Eine Insel-Studie,’ 1893), which would have been very useful as a clear statement of one view and as containing a list of the literature after 1886. He considers that in the Arkona and Jasmund areas (but not universally) the ‘Diluvium’ is naturally separable into a lower member consisting of two greyish-blue boulder-clays with an intervening bedded sand; and an upper one, of boulder-clays, gravels, and sands, which is unconformable with the other. He regards the boulder-clays as true ground-moraines; the sands and gravels as produced from these by denudation. The dislocations to which he attributes the peculiar association of the Chalk and the Lower Drift
Bajocian and Contiguous Deposits in the North Cotteswolds: The Main Hill-Mass.
Authors: Buckman S. S.
Published: October 2009

I. Introduction

This paper is a continuation of two former communications published by the Society, namely, ‘The Bajocian of the Mid-Cotteswolds,’ Quart. Journ. Geol. Soc. vol. li (1895) p. 388, and ‘Deposits of the Bajocian Age in the Northern Cotteswolds: The Cleeve Hill Plateau,’ vol. liii (1897) p. 607. So far as the sequence of the strata themselves was concerned, the results arrived at in these two papers may be best expressed in Table I (p. 127).

What the Table indicates is this:—In a north-easterly traverse from Birdlip to Cleeve there are found, at Leckhampton Hill five distinct beds separating two strata which at Birdlip were in juxtaposition; and at Cleeve Hill, three more distinct beds separating two beds which at Leckhampton Hill were in juxtaposition, namely, the Upper
Trigonia
-grit and the Notgrove Freestone, and another distinct bed separating two other beds similarly placed at Leckhampton—the Snowshill Clay and the Upper Freestone. Consequently where nothing is intervening at Birdlip there are five beds inserted at Leckhampton Hill, and nine beds inserted at Cleeve Hill: that is, with regard to the five at Leckhampton, three additional at the top, and one more at the bottom.

The interest which attaches to the exploration of the North Cotteswolds is to ascertain how and in what manner this intervention of strata continues in a farther north-easterly traverse. The results are these:—That the three upper intervening beds at Cleeve Hill—the
Phillipsiana-Witchellia
-beda—have been planed away, so that Upper
Trigonia
-grit rests upon Notgrove Freestone; but in the
Notes on the Geology of South-Central Ceylon
Authors: Parkinson John
Published: October 2009

I. Introduction

The following notes are the result of a tour of a few weeks' duration in the south-central parts of Ceylon. The time spent in the island was brief, and the work was done entirely upon inland sections; but in many places the exposures of rock are good, especially along the lines of railway. Petrological descripions of Ceylon rocks are not wanting, but details of their field-relations are few, and it is hoped that the following paper may direct attention to the interesting problems which are likely to arise from such an investigation.

II. The Gneissoid Granulites

(
a
) On the Ceylon Government Railway: from Rambukkana eastward in the direction of Alagala.—Leaving the station at Rambukkana, and proceeding along the metals, we walk over country which is flat, or nearly so, for about 1/2 mile, when we come to a small cutting. Here is exposed a rather coarse granitic rock with pinkish-brown felspars up to ·3 inch across. In about 6 yards this gives place to one more finely grained, rather saccharoidal in appearance, and speckled with patches of mica.

On the opposite Bide of the railway-line the rock is banded, but not in the clear even way which, for instance, characterizes the gneiss on the south side of the St. Gotthard Pass. The darker parts are rich in hornblende and brown mica, and contain little or no quartz. These bands often have a wavy habit, as though torn, and sometimes small black patches, like fragments
On a Remarkable Volcanic Vent of Tertiary Age in the Island of Arran, enclosing Mesozoic Fossiliferous Rocks.
Authors: Gunn William , Peach Benjamin Neeve , Newton Edwin Tolley
Published: October 2009

Part I. The Geological Structure

During the progress of the geological survey of the Island of Arran Mr. Gunn mapped the network of igneous rocks that occurs about halfway between Brodick Bay on the east and Machrie Bay on the west, and lying to the south of the String Road which crosses the island from Brodick to Shiskine and Blackwaterfoot (Sheet 21 of the 1-inch Geological Survey Map). These rocks form the mass of high ground culminating in Ard Bheinn (1676 feet), A'Chruach (1679 feet), and Beinn Bhreac (1649 feet), whence the headwaters of the Glen Cloy Burn and Benlister Burn drain to the east and the Black Water and Machrie Water to the west. The area in which these igneous rocks are exposed has obviously been a focus of great volcanic activity. It may be compared with some of the larger and more complex vents of Palæozoic and Tertiary age in Scotland, but it is exceptionally gigantic in its proportions. It is oval in shape, and covers an area of about 7 to 8 square miles. Its greater axis, which trends east-north-east and west-south-west, is 3½ miles long, and its shorter axis is about 3 miles in length. It is surrounded by various formations, ranging in age from the Lower Old Red Sandstone to the Trias. On the north side, conglomerates, sandstones, and mud-stones of Lower Old Red Sandstone age, dipping steeply southeastward, strike obliquely against its northern margin. On the east side, the Lower
The Igneous Rocks and Associated Sedimentary Beds of the Tortworth Inlier
Authors: Morgan Conwy Lloyd , Reynolds Sidney Hugh
Published: October 2009

I. Introduction

The Silurian rocks of the Tortworth district in Southern Gloucestershire present several features of geological interest. Lying to the north of the horseshoe ridge of Carboniferous Limestone, which forms the rim of the Bristol Coalfield, they share in the synclinal disposition of the Palæozoic strata. They underlie the attenuated Old Red Sandstone, which in this district is not more than some 200 or 300 feet thick; but the exact relation of Silurian to Old Red is nowhere clearly seen. The strata include beds of Ludlow, of Wenlock, and of Upper Llandovery age, the last-named being originally regarded as Caradoc. The chief points of interest are: (1) the remarkable attenuation of the upper strata, the Ludlow Beds not exceeding 100 feet in thickness, and the Wenlock attaining a thickness of at most 700 feet, probably less; (2) the limited number of fossils recorded; and (3) the occurrence of igneous rocks interbedded with the Upper Llandovery strata, and passing up to, or perhaps just into, the Lower Wenlock Beds. It is with these igneous rocks and their relation to the sedimentary beds that this paper deals.

The trap-rocks were carefully studied and described by Thomas Weaver in 1819. He regarded it as ‘evident that the trap constitutes discontinuous beds included in and parallel to the continuous series of the stratified transition-beds’; but, as a faithful disciple of Werner, he hastened to add that, since these stratified beds were ‘undeniably aqueous products, I do not perceive how we can avoid extending
On the Skull of a Chiru-like Antelope from the Ossiferous Deposits of Hundes (Tibet)
Authors: Lydekker Richard
Published: October 2009

Exactly twenty years ago I proposed the provisional name of
Pantholops hundesiensis
for an extinct species of antelope, typified by an imperfect skull figured in J. F. Royle's ‘Illustrations of the Botany, &c. of the Himalayan Mountains’ 1839, pi. iii, fig. 1. I had only the figure to go by, as the paper was written in India, and the specimen was said to be in the Collection of the Geological Society of London. And till the other day, when my attention was called to it by Mr. C. D. Sherborn, I had never seen the specimen. Having, by the kind permission of the Council, obtained the loan of this skull, I am happy to say that my original determination is in the main confirmed by actual examination of the specimen. And since the fossil is of more than ordinary interest, and the original figure is highly unsatisfactory, I have thought it desirable to offer the present note to the Society.

The specimen was obtained by Messrs. Webb & Trail from Tibetan traders, by whom it was brought from the Hundes plain, on the far side of the Niti Pass ; and it was presented to the Society by Capt. Webb.

The skull in its present condition comprises the brain-case in a fairly perfect state, although lacking the edge of the frontal portion of the orbits. The right horn-core is broken off obliquely a short distance above the pedicle, while the second has been broken through the pedicle itself, showing the
On the Occurrence of Silurian [?] Rocks in Forfarshire and Kincardineshire along the Eastern Border of the Highlands
Authors: Barrow George
Published: October 2009

I. The Mode of Occurrence of the Rocks

Along the south-eastern border of the Highlands, between Blair-gowrie and Stonehaven, a remarkable group of rocks has been mapped in the course of the geological survey of that region. They occur as isolated lenticular strips, which intervene between the schistose rocks of the Highlands on the north-west and the boundary-fault that truncates the Old Red Sandstone on the south-east. The first and largest of these lenticular strips is about 20 miles long, extending almost from Cortachy in Forfarshire to about a mile beyond the Clattering Bridge in Kincardineshire. In the valley of the North Esk it is
about ¾ mile broad, but elsewhere much narrower. The second lenticular mass begins at a point about a mile north of Drumtochty Castle, and stretches for 6 miles in a north-easterly direction to the Braes of Bervie. Part of a third strip is shown on the eastern margin of Sheet 66 of the 1-inch Geological Survey Map of Scotland, on the north side of the Highland Fault. The lenticular mode of occurrence of these rocks is due to the alternate approximation and recession of their northern margin from the great fault which everywhere forms their southern boundary.

Notwithstanding the mechanical deformation which these rocks have more or less undergone, we are still able to ascertain their original characters and mutual relations. They may be arranged in two divisions, namely :—(1) the Jasper and Green-Bock Series; and (2) the younger Margie Series.

An almost complete section
On the Geological and Physical Development of Antigua
Authors: Spencer Joseph William Winthrop
Published: October 2009

I. Introduction and Early Observations

The island of Antigua may be taken as a starting-point for the study of the Windward Islands, as within its area of 100 square miles almost all of the geological and geographical features of the region, except the later volcanic phenomena, are developed in such a way as to be easily understood. The only other island comparable for a base of study is Guadeloupe, which furthermore includes all the recent volcanic features on a grand scale, but some other features less easily distinguishable than in Antigua.

On November 5th, 1819, Dr. Nicholas Nugent, a physician of Antigua, communicated to the Geological Society of London ‘A Sketch of the Geology of the Island of Antigua’; but a ‘Memorandum’ of this had been sent to Benjamin Silliman on April 10th, 1818, and was published two years earlier in America than the fuller London paper. Nugent also sent to the Geological Society large collections of the rocks and fossils, carefully labelled as to their horizons. These remained almost unstudied for over forty years, when P. Martin Duncan made an elaborate study of the corals contained in them, which appeared in 1863–64.

Nugent had a companion in his studies of the island in the person of Dr. Thomas Nicholson, who wrote a short account of the geology of the island in the ‘Antigua Almanac & Register,’ a work forgotten or lost. Prof. S. Hovey visited the island, with Nugent as his guide, and published a sketch of the ‘Geology
On the Geological and Physical Development of Anguilla, St. Martin, St. Bartholomew, and Sombrero
Authors: Spencer Joseph William Winthrop
Published: October 2009

I. Introduction

The drowned plateau, standing boldly above the great submerged Antillean ridge, now forming the slightly sunken banks, out of which rise Anguilla, St. Martin, and St. Bartholomew, with some small outlying islands, is a repetition of the Antigua-Barbuda mass; in size a little larger, drowned a little deeper, more broken, and with its marginal declivities strikingly indented. Sombrero is an isolated feature.

Apart from the excellent contribution of Mr. P. T. Cleve, there appears to be no geological account of the islands; but the discovery of mammalian remains by Edward Cope, among the bones obtained in Anguilla by Mr. Wager Ray, of that island and the study of fossil echinoderms of the same island by Mr. K. J. Lechmere Guppy, are important additions to our knowledge of the region.

The south-eastern extension of the St. Martin plateau, with its surface covered by only about 200 feet of water, is separated from the Antigua-Barbuda platform by a depression 18 miles across, but its depth beyond 858 feet has not been determined. The valley between the sunken tableland and Saba, to the south, is 20 miles wide and reaches a depth of 2934 feet; while that separating it, on the west, from Sombrero is scarcely wider, with the depth to the ridge crossing it reduced to 1800 feet. Beyond Sombrero is a channel of phenomenal depth, the only one of its kind, dissecting the Antillean chain, entirely cutting off the sunken plateau of the Virgin Islands to the westward.

The
Note on a Submerged and Glaciated Rock-Valley recently exposed to view in Carmarthenshire
Authors: Codrington Thomas
Published: October 2009

In a paper published in the Quarterly Journal for 1898 I gave particulars of submerged rock-valleys in South Wales. Further instances of the same sort have since come to light, one of which is sufficiently remarkable to deserve description. It was discovered in building a bridge across the River Towy, at Drysllwyn, 9 miles above Carmarthen (to which place the tide now flows), and about 18 miles from the mouth of the river. The sources of the Towy are some 40 miles from Drysllwyn, on the borders of Cardiganshire and Radnorshire, at about 1700 feet above the sea; but tributary streams descend from the Black Mountain, 2000 to 2600 feet above sea-level, on the south of the Towy Valley, 12 to 16 miles above Drysllwyn.

At the bridge, the valley is narrowed by a detached hill of Lower Silurian rock rising about 180 feet above the river, which stands out into the valley and contracts the width to half a mile. The river now flows at the foot of the hill, which rises at an angle of 40° with the horizon, and is crowned by the ruins of Drysllwyn Castle.

Near the water’s edge on the north of the river, the rock was laid bare, for the foundation of the abutment of the bridge, over an area of 30 by 20 feet. It sloped down gradually to 23 feet below summer water-level at the western or down-stream side, and it was glaciated in large fullows, a foot and more across,
On the Meteorological Conditions of the Pleistocene Epoch
Authors: Ekholm Nils
Published: October 2009

In his interesting paper entitled ‘The Influence of the Winds upon Climate during the Pleistocene Epoch,’ Mr. F. W. Harmer has endeavoured to describe the meteorological conditions of that epoch by means of the theories and facts of modern meteorological science. The subject is no doubt one of great interest, but also of great difficulty. We still know too little concerning the nature, origin, and development of the great atmospheric eddies, the cyclones and anticyclones, to be able to reconstruct their average positions and tracks on the globe during a past geological epoch. Furthermore, it is very difficult to estimate the influence of those eddies on climate. As my opinion on this matter differs in some important respects from that expressed in Mr. Harmer's paper, I crave permission to discuss the question briefly. It may be conveniently divided under the following heads:—

(1)

What are the meteorological conditions necessary and sufficient to produce a permanent ice-sheet, or glaciation such as that of the Great Ice-Age?

(2)

What will be the influence of such a glaciation on the meteorological conditions, especially on the cyclones and anticyclones, over the ice-covered land and its neighbourhood?

In order to answer these questions we must consider the present climatic conditions of the earth, and draw our inferences there-from.
On the Relation of Certain Breccias to the Physical Geography of their Age
Authors: Bonney Thomas George
Published: October 2009

Breccias and conglomerates have always attracted me, and the former especially since I had opportunities, about ten years ago, of examining one of the most interesting examples in Europe. They afforded problems, to which I failed to find answers in all respects satisfactory; so in the hope of obtaining further information I spent, during the summer of 1900, some days in the Western Thüringerwald, with my friend the Rev. Edwin Hill, in order to study the noted breccias of the Rothliegende, and last July again examined, and more fully than before, the beds of breccia, sections of which are well displayed along the high road in the Val des Ormonts above Le Sepey. In former years I had visited the Permian Breccias of the English Midlands and those now assigned to that period in Devon. All these exhibit certain features in common, some of which are also found in the so-called Dolomitic Conglomerate in the South-west of England. So I purpose to give a brief summary of the principal characters of each of these deposits, concluding with some comparatively modern breccias, in order that, if I cannot completely unravel their history, I may at least bring the more significant facts into a clearer focus.
On the Origin of the River-System of South Wales, and its Connection with that of the Severn and the Thames
Authors: Strahan Aubrey
Published: October 2009

I. Introduction.

The Welsh rivers, of which I shall endeavour to trace the history in the following pages, flow through a hilly region composed almost wholly of Palæozoic rocks. The greatest height is attained in the Old Red Sandstone of the Brecknock Beacons, which fall but little short of 3000 feet; but the Coal-Measures also rise into escarpments exceeding 2000 feet, and form large areas of mountain-land with an elevation of 1000 feet or more. This high ground is trenched by a series of valleys, of no great length, but important from their depth and from the fact that they penetrate a busy region, otherwise difficult of access.

A watershed map of Wales presents at first sight the appearance of a meaningless mosaic, and it will be convenient to commence by dis-entangling its leading features. A main water-parting, separating the westward- from the eastward-flowing rivers, runs from the northern coast of Pembrokeshire near Fishguard, through the counties of Cardigan and Montgomery. It will be noticed that it commences with an east-and-west trend, but curves gradually northward in Central Wales, keeping near and almost parallel to the west coast. Westward from this water-parting there runs a series of short streams into the Irish Sea; eastward from it flow the Severn and the Wye, both of which traverse Wales in a south-easterly direction, but then turn south-westward to the Bristol Channel. South of the Wye we come to a group of rivers rising on subsidiary water-partings in the counties of Brecknock, Monmouth,
On a Remarkable Inlier among the Jurassic Rocks of Sutherland, and its Bearing on the Origin of the Breccia-Beds
Authors: Blake John Frederick
Published: October 2009

I. Introduction

The remarkable deposits, consisting of large angular and rounded stones, that skirt the western shores of the Moray Firth, on either side of Helmsdale, have already attracted the attention of two eminent geologists.

Sir Roderick Murchison, who was the first to describe them in 1826, I considered them to be the result of the upheaval of the neighbouring granite. This upheaval of the granite, in his view, broke up the Jurassic rocks along its south-eastern border, and scattered their fragments haphazard in the neighbourhood of the fault. In the phraseology of some modern writers he considered them to be crush-conglomerates, but his own name for them was ‘brecciated beds.’ This name and his explanation assumed the exclusively Jurassic age of the fragments, and both were therefore rendered untenable by the discovery in some of these fragments of Old-Red-Sandstone fish-remains.

Prof. Judd, who, in 1873, first determined the general age of the rocks as Upper Jurassic, and described them in far greater detail, would not bind himself to any definite theory of their origin, but hoped that at some future time the question would be elucidated by the discovery of analogous phenomena elsewhere—a hope which the present communication aspires to fulfil. Meanwhile he suggested as the most probable hypothesis at that time, that the blocks composing the breccia had been carried by floods in a large river that did not reach the sea-shore in the form of a glacier.

At the present time, the only possible
The Inverness Earthquake of September 18th, 1901, and its Accessory Shocks
Authors: Davison Charles
Published: October 2009

I. Introduction. The earthquakes of Inverness and Comrie, though never so strong as those of Essex and Hereford, bear, in their long trains of aftershocks, a far closer resemblance to the great earthquakes of other countries. Since the Comrie earthquake of October 23rd, 1839, which was followed by 330 tremors and earth-sounds within little more than two years,
1
no British earthquake has been attended by so many accessory shocks as that which occurred in the neighbourhood of Inverness on September 18th, 1901. The unusual intensity of the earthquake, its apparent connection with the great northern boundary-fault of the Highlands, and the possibility of tracing vscillations in successive centres of disturbance along the faultsurface, combined in rendering a detailed investigation desirable.
2
The names of all those who have assisted me are too numerous to :mention here; but, in offering my best thanks to them collectively, I should like to acknowledge my special indebtedness to Mr. W. J. Watson, l~ector of the Royal Academy, Inverness, Mr. A. S. Reid, F.G.S., of Trinity College, Glenalmond, Mr. S. Archibald of Dalarossie, and Miss Isabel Forbes of Teanassie, near Beauly, for the most useful series of accounts which they have kindly collected. Valuable records of after-shocks have also been communicated to ~e by the following gentlemen :—Mr. D. Forsyth (Inverness), Mr. James Fraser (Aldourie), Mr. John E. Fraser (Dores), Mr. P. Fraser (Holm, near Lentran), Mr. A. Grant (Drumälan, near Drumnadrochit), Mr. W. Grant (Invermoriston), Mr. R. Keillar ,(Lochend, Aldourie), Mr. W. Mackenzie
On Pliocene Glacio-Fluviatile Conglomerates in Subalpine France and Switzerland
Authors: Preller Charles S. Du Riche
Published: October 2009

I.Introductory.

In a paper read before this Society in the year 1896,I described a series of Glacio-Fluviatile deposits which, occurring at varying altitudes in the Limmat Valley above, near, and below Zurich, and being the indirect product of the first general advance of Alpine glaciers in Upper Pliocene times, appeared to show that, at the time of their formation, not only the great Alpine but also the principal Subalpine river-valleys of Switzerland had already been eroded approximately to their present depth, while the lake-basins came into existence at a later period.

The study of a large number of other deposits in the lower parts of the Limmat and Aare Valleys, and along the Rhine above and below its junction with the Aare, and, further, of various deposits of so-called ‘alluvion ancienne’ in the Rhône Valley between Lausanne and Lyons, have, however, led me to modify my conclusions with respect to the configuration of Subalpine Switzerland and France towards the end of Tertiary times ; and the object of the present paper is to lay briefly before the Society the further evidence that I have thus collected, together with some conclusions which it tends to warrant.

II. Deposits in the Limmat,Aare,and Rhine Valleys. (Figs.1–5)

(1)

In the paper already quoted, I showed that, as regards the district immediately above and below Zurich, the deposits of the conglomerate now generally known as ‘Deckenschotter’ form a chain along the summit-line of the range of hills on the left of the present
Overthrusts and other Disturbances in the Braysdown Colliery; and the Bearing of these Phenomena upon the Effects of Overthrust-Faults in the Somerset Coalfield in general
Authors: Steart Frederick Anthony
Published: October 2009

The Somerset Coalfield is a remarkable one in many respects. Unlike most of the larger coalfields of this country, by far the greater part is concealed by Secondary rocks, consisting of Oolites, Lias, and Trias, which lie almost horizontally upon the disturbed Coal-Measures beneath. Faults in these newer rocks are comparatively few and small. The Coal-Measures, however, present a marked contrast in this respect—for this coalfield is in part the most disturbed and contorted of those known and worked in the United Kingdom. Its area covers about 240 square miles, and it is presumably an isolated basin, bounded on all sides by anticlines of older rocks. On the north, in the Coal-Measures at Kingswood, near Bristol, there is an anticline and overlap-fault, which separates the Somerset Coalfield on the south from the Bristol or Gloucestershire Coalfield on the north, on the borders of which the margin of older rocks is clearly defined. On the south and south-west the great Mendip anticline separates it possibly from a similar coalfield, concealed beneath the thicker Secondary rocks on the farther side of the Mendip Hills; and on the east, the anticline which passes from the far north near Cromhall, in Gloucestershire, through or near Yate, probably continues slightly to the west of Bath and thence to Frome on the south.

The object of this paper is an attempt to describe the overfaults and related phenomena in a single colliery, namely that of Braysdown, near Radstock, and to show how the conclusions that may
The Red Sandstone-Rocks of Peel (Isle of Man)
Authors: Dawkins William Boyd
Published: October 2009

I. Introductory.

The Red Sandstone Series, ranging along the coast eastward from Peel to Will's Strand, is faulted into the Ordovician massif of the Isle of Man, and so covered with Drift that the only clear sections are to be found along the line of cliff, and in the quarries at Ballaquane. There is, therefore, little reason for surprise that it; should have been assigned to various geological horizons. It has been referred to the Old Red Sandstone by Cumming, to the Calciferous Sandstones by Mr. Horne, and to the Permian by myself (in a paper read before the Manchester Geological Society in 1894), and by Mr. Lamplugh in 1896 to the Basement Carboniferous. It is so described by him in his Appendix to the British Association Handbook for 1896 (Liverpool), and is so represented in the Geological-Survey map of the island, and in the ¼-inch Geological Map of England and Wales, both published in that year. Since 1894, in continuation of my work in mapping the island on the 6-inch scale, I have collected further evidence as to its geological age, and have refreshed my memory by a visit to the most important localities in the Lake District where the Permians can be studied. The results of this enquiry are embodied in the following paper.

II. The Lower Red Sandstones and Brockrams of Ballaquane and Creg Malin.

The Red Sandstones exposed in the cliffs at Creg Malin, and in the quarry at Ballaquane, dip at
The Point-de-Galle Group (Ceylon): Wollastonite-Scapolite Gneisses
Authors: Coomáraswámy Ananda K.
Published: October 2009

I.Introduction.

Prof. A. Lacroix has recorded the existence of wollastonite- and scapolite-bearing rocks in Ceylon. The specimens examined by him can hardly, however, have come from Galle, as they contain garnet, a mineral never found in the rocks of the Galle Group described below. It seems therefore probable that rocks allied to those of Galle, but differing from them in petrological details, will be found elsewhere in Ceylon.

I have on a former occasion given a short description of the Galle rocks, and am now able to supply a more detailed account of the rocks and to describe their field-relations. There are excellent exposures at Galle, within the Fort on the western side, between the Signal flagstaff and the north-western bastion ; outside the Fort below the north-western bastion ; and south-west of the Victoria Park near the remains of an old powder-magazine. All these exposures can be easily visited in the course of one whole day spent at Galle.

II. General Description.

The Galle rocks differ from normal types belonging to the Charnockite Series in the following ways :—

(1)

The presence of wollastonite, scapolite, and sphene.

(2)

The existence of definite dykes and segregation-veins crossing the foliation.

(3)

The absence of garnet, hypersthene, mica, and original hornblende, and bands of ‘granular quartz-rock’.

(4)

Somewhat coarser grain.

But resemble them closely in

(5)

The variability of chemical and mineralogical composition.
Tin and Tourmaline
Authors: MacAlister Donald A.
Published: October 2009

Cassiterite hardly ever occurs without tourmaline, although the latter is found without the former; hence it appears that tourmaline-producing constituents and influences are of wider range than are those of cassiterite. Boron-trioxide is an extremely common accompaniment of volcanic action, and there can be no doubt that it has acted powerfully in changing such original minerals as the micaceous and felspathic ingredients of crystalline rocks. From a comparison of formulæ representing tourmaline and felspar, it is evident that the act of tourmalinization has been accompanied by a loss of soda (which alone is capable of action on tin). The excess of boric acid (which is over and above that required for tourmalinization) will combine with this soda, forming metaborate and pyroborate of soda. The former, acting on disseminated tin-ore, might result in the production of sodium-metastannate and borax. The soluble metastannate is capable of being leached out of the magma, and, by a new reaction, tin-oxide may be precipitated and concentrated, sodium-metaborate being liberated. According to the principle underlying the cooling-curves of solutions, in all probability deposition of cassiterite would take place more rapidly at a certain stage in the process of cooling than at others.