bluuebunny/crossref_metadata_2025_split huggingface dataset:
Additional Notes on the Dimetian and Pebidian Rocks of Pembrokeshire
Authors: Hicks Henry 
Published: October 2009

Conclusions
We are now, I think, in a position to attempt an inquiry into the probable physical conditions, locally at least, of these Pre-Cambrian epochs.
In the oldest formation, the Dimetian, we have not, unfortunately, at St. David's, a base to start from, since in no case probably have we reached the lowest beds. There are no true conglomerates in the whole series; and of the lowest beds, or those which seem to form the centre of an anticlinal, we are not sure whether they may not even be intrusive. The next beds in this group are a great series of altered quartz rocks and very fine-grained quartzites; but with these are associated a few of the ashy-looking bands mentioned as either intrusive along the bedding or contemporaneous basaltic flows. These beds alternate with one another, and hence appear as if contemporaneous. The prevalence of volcanic action at this time is therefore rendered more than probable. Still the enormous preponderance of quartz rocks throughout the whole formation, and the absence of ashy beds and of felstone lavas and volcanic breccias of any great importance, indicate to my mind that it was probably chiefly detrital in its origin, the result of the wearing-down of previously existing rocks. Whether this formation is chiefly made up of detrital or volcanic materials, however, is a question chiefly for the chemist and mineralogist.
The question which to us is now of importance is that of its position geologicaily ; and upon this point I venture
Appendix on the Microscopic Structure of some Dimetian and Pebidian Rocks of Pembrokeshire
Authors: Davies Thomas 
Published: October 2009

D
imetian.

1. The rock from near the Church School is seen macroscopically to consist largely of quartz in individual crystalline grains, or in groups, thickly distributed through a porphyritic-felsite ground-mass. In fissures and nests in the mass of the rock much chlorite and also some epidote are present. Its affinity to the quartz porphyries is only apparent when examined in thin section under the microscope. Here the quartz is seen to be distinctly crystallized, with characteristically rounded edges, and also with inclusions of the ground-mass. The felspar crystals are numerous, and much altered though the indications of banding of a plagioclase felspar are not wanting.
The ground-mass is microcrystalline throughout, consisting of quite individualized grains of quartz and felspar, and in many parts presents a peculiar structure. Around the quartz and felspar crystals an incipient spherulitic arrangement has taken place, resembling to some extent that seen in some rhyolites ; but here the radial texture is modified by a tendency to a dendritic or a branched structure, a peripheral outline being in all cases absent. This structure is also developed from numerous individual centres in the ground-mass, having no apparent nucleus ; it bears no resemblance to the rhyolite of the breccia before described, though it is probably but a modified form of spherulitic structure. Much grer chlorite and a black indefinable substance is dispersed through the ground-mass.
2. This fine-grained, chlorite-spotted rock presents in thin section a completely crystalline ground-mass of felspar and quartz grains, the latter being but
The Precarboniferous Rocks of Charnwood Forest.—Part II
Authors: Hill E. , Bonney T. G. 
Published: October 2009

The Microscopic Structure of the Charnwood Rocks.

In many cases the task of determining the nature and structure of these rocks is comparatively easy; but in others it presents great difficulties. These arise from the amount of metamorphism which the rocks have undergone since they were first deposited. This metamorphism may be said to be of a double nature :—the one, readily apprehended by the eye, that which has converted sandstone into quartzite, and fine felspathic detritus into something resembling a felspathic igneous rock, being in all probability the combined effect of pressure, heat, and water; the other, almost wholly revealed by the microscope, in which the last of the above-named agents of change has probably been the most active, and which may still be in progress—namely, the gradual decomposition of the minerals which once composed the rocks, and the formation of new ones by fresh combinations of the chemical elements thus set free. This process often obscures, far more than the former, the original structure of the rock; and it is this accordingly which causes our main difficulty in the study of these Charnwood rocks.
To investigate microscopically all the varieties of stratified rocks found in the Forest would be a most laborious task; and in all probability the result would not compensate for the labour. We have therefore selected a series of specimens which appeared either typical of the more important varieties, or likely to be useful in illustrating some point of structure or stratigraphy. Forty-four slides in
On the so-called “Greenstones” of Central and Eastern Cornwall
Authors: Phillips J. Arthur 
Published: October 2009

Conclusion
In addition to the rocks which occur in Western Cornwall, some of the areas forming the subject of the present paper afford numerous examples of ancient lava-flows so interbedded with the slates and schists of the district as to lead irresistibly to the conclusion that they are contemporaneous igneous products.
These lavas, notwithstanding the alteration to which they have been subjected, closely resemble those of more modern date, and contain cavities which are now filled either with a mixture of viridite and calcite or with quartz through which vermicular chlorite is distributed. They sometimes assume a distinctly schistose structure, and contain crystals of a sanidine-like felspar, many of which are broken, while others have become sphærulitic, through a rearrangement of their constituents.
The crystalline greenstones of Central and Eastern Cornwall afford a more varied and instructive series than is furnished by those of the western portion of the county. Among them are typical dolerites on the one hand, as at South Petherwin, while on the other there are rocks which, as at Carkeel, are so altered as to consist only of a granular indefinite material traversed by indistinct microlitic bodies, and, in patches, stained brown by oxide of iron.

The pyroxenic constituent of these rocks, wherever its crystals admit of identification, is augite ; and they are consequently dolerites. By many petrographers they will doubtless be classed either as
diabases or melaphyres
; but when it is remembered that they differ from modern dolerites only in age, and by reason
The Secondary Rocks of Scotland. Third Paper. The Strata of the Western Coast and Islands
Authors: Judd John W. 
Published: October 2009

C
onclusion
.

Although, as I have before stated, it has been thought advisable to postpone the discussion of the numerous problems of interest which suggest themselves to the student of the remarkable relics of the Secondary rocks in the Scottish Highlands, until the fourth and concluding portion of this memoir is published—yet there are several questions which at the present time engage the minds of geologists upon which, as it appears to me, the facts and arguments of the present part of this memoir have an important bearing; and these it may not be undesirable to notice briefly at the present stage of the inquiry. Other and more general discussions will be allowed to stand over till such time as I have made the proposed comparison between the characters and modes of preservation of the beds under consideration and those of their equivalents in Ireland, England, Scandinavia, and other portions of the Continent.
I may briefly point out in the first place the great interest which attaches to the fact that there exists in the north-western part of the British archipelago a series of strata of Cretaceous age exhibiting evidence of the prevalence of estuarine alternating with marine conditions. The great and deserved amount of attention which is now directed to the similar beds, developed on such a grand scale in Western America, renders the discovery of the minute Scottish representatives of the period particularly important at the present time. It is tantalizing, however, to the British geologist to have to
On an Unconformable Break at the Base of the Cambrian Rocks near Llanberris
Authors: Maw George 
Published: October 2009

T
he
short paper which I have to lay before the Society has been suggested by several previous communications on the subject of rocks older than, and unconformable to, the Cambrian Slates of North Wales.

In the year 1867 I brought before the British Association at the Dundee meeting the accompanying section on the Llanberris and Carnarvon Railway, then for the first time exposed in a new cutting near Llanberris. The section was subsequently published in the ‘Geological Magazine’ for March 1868, to which I must refer the reader.
Up to this time no suspicion existed of the occurrence of an unconformable series of ancient rocks in North Wales older than the Cambrians.
Previous to this the researches of Dr. Hicks in Pembrokeshire established in that district the fact of the occurrence of great series of beds unconformable to the overlying Cambrians; but during the succeeding seven or eight years no fresh observations were made in the Llanberris district.
At the reading of Dr. Hicks's paper on December 2, 1874, I pointed out an apparent analogy between the Pembrokeshire series and that at Llanberris; and this, I believe, induced Professor Hughes and Dr. Hicks to visit Llanberris, and their observations on that district were recently communicated to the Society (Q. J. G. S. vol. xxxiv. pp. 137 & 147).
Rather singularly, they disagree with me in the conclusion 1 arrived at, that there was a visible break in the series of rocks exposed in the Llanberris railway-cutting, but admit that such
Notes on the Palæontology and some of the Physical Conditions of the Meux-Well Deposits
Authors: Moore Charles 
Published: October 2009

T
he
various deep borings which have been put down at Crossness, Harwich, Kentish Town, and more recently at Meux's Brewery, in the Tottenham Court Road, have amply established the correctness of Mr. Godwin-Austen's deductions that a ridge of Palæozoic rocks passes under the Jurassic and Cretaceous beds of the south-east of England, the probability, if not the certainty, being that the rocks of which that ridge is formed are a continuation of those which skirt the South-Wales coal-basin, and which, in passing through Somersetshire, are continued in the Mendip range until lost under Secondary deposits near Frome.

In the above districts I have previously pointed out that the representatives of some of the Secondary beds are found associated with the older rocks, under very peculiar conditions, through a line of country from east to west of about sixty miles. At one spot thin deposits or pockets of Inferior Oolite may be seen lying unconformably upon the highly inclined but planed down edges of the Carboniferous Limestone; at another, conglomerates of Liassic or Rhætic age of a few feet in thickness, some of them exhibiting shore-conditions, may be found filling depressions in the limestone or passing down its vein-fissures; and however thin these deposits may be, they can be recognized as distinct, and as representing on the sides or otherwise of the southern portion of the Palæozoic anticlinal the presence in the district of Rhætic, Liassic, and Oolitic formations.
Perhaps the most interesting evidence of these peculiar physical conditions is seen
A Contribution to the Physical History of the Cretaceous Flints
Authors: Wallich  
Published: October 2009

Some years ago, whilst endeavouring to clear up the obscure points in the history of the Cretaceous flints, I naturally turned for guiding data to such analyses as were forthcoming of the Chalk and Globigerine ooze of the Atlantic. But the further my inquiries were pursued in this direction, the stronger grew my conviction that no more fallacious test of the percentage of silica originally present in the White Chalk could be resorted to than that of assuming as a standard the percentage it now contains, and hence that any comparison of the calcareous mud with the ancient Chalk, instituted with the view to determine this percentage, must necessarily prove equally fallacious.
This result, however, was only to a certain extent unlooked for, inasmuch as I had long previously suspected, on entirely distinct grounds, that the almost complete absence of silica in the flint-bearing Chalk did not arise from any deficiency in it of that substance whilst it was yet in a plastic state at the bed of the ancient sea, but was due to certain special conditions, which led not only to the continuous elimination of the siliceous material for a time mechanically associated with the calcareous mud, but to its consolidation in the stratified layers alternating with the Chalk, which constitutes by far the most striking and, at first sight, unaccountable feature in this formation.
In directing attention, at the outset of my observations, to the writings of those who have preceded me in this line of inquiry,
Petrological Notes on the Vicinity of the Upper Part of Loch Maree
Authors: Bonney T. G. 
Published: October 2009

The relations of the rocks on the western border of Ross and Sutherland have long been a subject of controversy. Into the details of this it is needless to enter on the present occasion, as they have been recently recapitulated to the Geologists′ Association and published in their Proceedings*. The materials for this sketch are mainly contained in our own Journal; and the last contribution to the subject was a paper read by Dr. Hicks on May 22, 1878†. After listening to the ingenious theory put forward by that author, it occurred to me that the question was one on which the testimony of the microscope ought to be especially valuable. According I spent some days last summer at Kinlochewe, in order to examine the rocks in the field and to obtain specimens for microscopic work. I have now the honour of laying before the Society the results of these investigations.

(1)
Syenite of Glen Laggan.

Previous writers on the above section have agreed in stating that a mass of igneous rock makes its appearance on the floor of Glen Laggan, about two miles from Kinlochewe, and extends for some distance up the bed of the stream, apparently cutting off the quartzite from the newer group. This rock is called diorite by Nicol, syenite by Murchison, Geikie, and Hicks; it is shown by the last author upon a section‡ as intrusive among the calcareous series which overlies the quartzites.
Almost immediately on reaching the spot where the “syenite” first appears
On the Geological Relations of the Rocks of the South of Ireland to those of North Devon and other British and Continental Districts
Authors: Hull Edward 
Published: October 2009

Having in a former communication to this Society* endeavoured to prove that the great series of purple and green grits and slates which form the southern highlands of Ireland belong to the Uppermost Silurian period, and that between them and the succeeding beds of the Old Red Sandstone there occurs everywhere a wide hiatus (a gap of unrepresented geological time), indicated not only by visible unconformities but also by absence of intervening beds at various points, it now becomes desirable to inquire, and, if possible, to determine what formations in other districts may be supposed to fill up the hiatus above referred to, and then, having determined this point, to see what inferences may be drawn concerning the physical geology of the regions referred to at the various stages indicated both by the presence and the absence of consecutive strata.
This inquiry naturally leads one to cast a glance at the neighbouring coasts of England and Wales as the districts where light may be looked for on these questions; and I propose in the following pages to make a comparison of the series of beds in both countries, namely the South of Ireland and North Devon, and adjoining districts north of the Severn†. It will also be desirable, with a view to a fuller investigation, to refer, when necessary, to the Devonian and Carboniferous series as it occurs in Belgium and Scotland, and to see how far it is comparable with, and sustains our observations of, the Devonshire section.
Views
The Gold-leads of Nova Scotia
Authors: Poole Henry S. 
Published: October 2009

The character of the auriferous rocks of Nova Scotia was a subject of some discussion a few years ago*, when it was suggested that the gold obtained was from “quartz beds of contemporaneous age with the quartzite and the slate with which they are interstratified.”
Dr. T. Sterry Hunt, reporting on this province the year before the subject was brought to the attention of this Society, wrote:—“So far as my present observation goes, I think that to describe the gold-lodes otherwise than as interstratified beds would be to give a false notion of their geognostic relations. The laminated structure of many of the lodes, and the intercalation between their layers of thin continuous films or layers of argillite, can hardly be explained in any other way than by supposing these lodes to have been formed by successive deposition at what was, at the time, the surface of the earth.”
This description well expresses, the appearance of our gold-districts; but the theory that the “leads,” as the lodes are locally called, are contemporary beds with the slates and quartzite has not since been generally accepted; nor has it gained ground with the further knowledge derived from working, nor been adopted by any of the miners, among whom are men experienced in other gold-producing countries.
My position having enabled me to visit frequently the several districts and see the leads in their varying stages of exploitation, I have kept in mind the theory in question, and especially examined the relation of the
Iguanodon Prestwichii
, a new Species from the Kimmeridge Clay, distinguished from
I. Mantelli
of the Wealden Formation in the S.E. of England and Isle of Wight by Differences in the Shape of the Vertebral Centra, by fewer than five Sacral Vertebrœ, by the simpler Character of its Tooth-serrature, &·c., founded on numerous fossil remains lately discovered at Cumnor, near Oxford
Authors: Hulke J. W. 
Published: October 2009

These fossils, which Mr. Prestwich has kindly given me an opportunity of studying, are, for the extent of information they convey of nearly every part of the skeleton, the most important Iguanodont remains yet discovered at any one time in this country. The only others that may vie with them are those in the well-known Mantellian Maidstone block, in the British Museum, and some, said to represent the greater part of a skeleton, reported to have been found several years since at Hastings, preserved in a private collection, inaccessible, which in their entirety have not, so far as I can learn, ever been examined by an anatomist.
The Cumnor fossils appear to have formed part of one skeleton. They represent an animal between 10 and 12 feet long, which had not reached maturity. Its head was lizard-like, with large eyes and capacious nostrils. Its neck was very flexible and moderately long. Its trunk, particularly the thoracic region, was long, and borne on stout clawed limbs, of which the hinder were much stouter than the fore. The tail, of considerable length, tapered very gradually; and for more than half its length it was flattened laterally.
Unfortunately, as too frequently happens, the removal of the fossils by the unskilful hands of day-labourers has occasioned much damage and many losses. The bones had been already much crushed by the pressure of the beds ; but many of the fractures are plainly quite recent. These injuries are not, however, without some compensating circumstances ;
The Newer Pliocene Period in England
Authors: Wood Searles V. 
Published: October 2009

T
he
movements by which the conditions of sea and land have changed in England from the time when the Red Crag began to form appear to me to have been so continuous that the formations from this point onwards can be studied with advantage only as one geological group; and as these have all accumulated during one great movemeat of depression and reelevation, the Newer Pliocene period seems to me the most suitable term for the lapse of time which they mark.

The commencement of this Crag ia England is marked by the accumulation of those beds of which a small remnant is preserved in the cliff at Walton Naze. During its progress the continuous destruction of the antecedent accumulations of the same formation, as well as of the beds of the Coralline Crag, furnished that peculiar mass of comminuted shell of which the successive portions of the formation are made up. The character of the beds, and the highly and often continuously oblique character of the bedding, with other evidence on which I do not stop here to dwell, indicate that nearly all that part of the formation to which the term Red Crag (as distinguished from the part represented by the Chillesford beds) has been applied was accumulated between high- and low-water marks, when the rise and fall of the tide was considerable.
The Walton bed, as my fat;her has shown, is destitute of many species of Mollusca which occur in the Red Crag of the northern(or .
Interglacial Deposits of West Cumberland and North Lancashire
Authors: Kendall J. D. 
Published: October 2009

Seldom do we find the whole three members present in one section. Sometimes the Lower Boulder-clay alone is found ; at others this is overlain by sand or gravel or clay, or by some or all of these rocks. In other cases we find the series complete. They occur almost continuously, in more or less completeness, from the sea-shore to an altitude of 500 feet ; and from that level they appear in patches up to 1000 feet above the sea.
The two Boulder-clays have the ordinary character, and are very much alike, except that the lower is tougher than the upper and contains larger boulders. The character of the included stones is the same in both clays, as well as in the middle sands and gravel.Some most remarkable facts are presented by the distribution of these boulders.
Associated with these glacial beds, and occurring at various places, sometimes inland, sometimes along the sea-coast, between high- and low-water marks, there are a number of deposits of vegetable matter, which hitherto have been almost entirely neglected by geologists.
When occurring on the sea-shore, these deposits usually pass by the name of “submerged forests.” I am, however, inclined to doubt the accuracy of this appellation. After a long and careful investigation into the nature of these deposits, I have come to the conclusion that they are not forests at all, nor the sites of forests,as will appear further on.

2.
Observed Facts

Lindal deposit
. —The first of these deposits to which I shall