bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Micrometric Study of the St. Austell Granite (Cornwall)
Authors: Richardson William Alfred 
Published: October 2009

The St. Austell granite-mass has attracted considerable attention in the past, because of the economic importance of its mineral deposits and the petrological problems that arise out of the wonderful display of pneumatolytic activity manifested in the district. The principal references to the literature are given in the footnote, and since these contain full bibliographies, it is unnecessary to compile another for the purpose of this paper.
Two reasons induced me to undertake this work. In the first place, it appeared desirable to develop and apply to a coarse-grained igneous rock-mass quantitative microscopic methods. Secondly, it seemed probable that much light could be thrown upon the problems of the St. Austell granite by quantitative and qualitative data obtained from a larger number of representative slides than has been available hitherto. A preliminary investigation in the field soon revealed that the district presented some disadvantages in the application of the method, owing to the occasional occurrence of very coarse porphyritic structure in the granite; but, at the same time, it was evident that the results would outweigh a little uncertainty arising from this difficulty.
The present paper deals solely with the granite, and all post-consolidation and metamorphic changes are excluded from its scope. The aim has been to ascertain what evidence exists of differentiation and variation in the original rock. Certain pneumatolytic effects have been generally recognized as inextricably bound up with stages in the intrusion and crystallization of the original magma, and such, of course, come within the purview of
On Reptilian Remains from the Karroo Beds of East Africa
Authors: Haughton Sidney Henry 
Published: October 2009

The fossil remains described and discussed in this paper were taken from about the middle of the Karroo Beds near Tanga, on the coast of the Tanganyika Territory, by Mr. F. P. Mennell, F.G.S., who was good enough to forward the specimens to me for examination. They consist of portions of three animals, of which one is too weathered and too fragmentary for investigation. The other two are preserved on slabs of hard, blackish, somewhat micaceous shale; the more complete animal is smaller than the other, but, as will be seen in the sequel, in other respects they are sufficiently similar to be considered representatives of the same species.
It is not necessary to dwell on the importance of Mr. Mennell's discovery. From extra-South African areas very few of its animals have been found within the ancient boundaries of Gondwanaland: that some of them were spread outside its confines is well-known; but hitherto there has been a big geographical gap between the South African localities yielding a (Gondwana fauna and those of Europe. This discovery marks the first step in the bridging of that gap; and I am extremely grateful to Mr. Mennell for giving me the opportunity of placing it on record.
Of the described specimens, the smaller and better is placed in the Rhodesian Museum, Bulawayo; the other is in the collection of the South African Museum at Cape Town.
As preserved, the specimen has a length of about 380 mm. There are missing, however, the whole of
Contact-Metamorphism in the Comrie Area of the Perthshire Highlands
Authors: Tilley Cecil Edgar 
Published: October 2009

British petrographic literature is now so enriched by the detailed descriptions of contact-metamorphic aureoles, associated with plutonic intrusions—investigations largely conducted by the officers of the Geological Survey, and partly by independent workers—that it might appear that an investigation of an additional contact-zone would bring to light little but the usual well-known mineral-assemblage of aureoles already investigated: In the case of the aureole surrounding the Carn Chois diorite-complex of Perthshire, moreover, an inspection of the 1-inch Geological Survey map would tend to confirm this view—not only as to the nature of the mineral-assemblages, but also as to their apparently restricted variety. The diorite-complex is shown as intruded almost completely within the Ben Ledi Grit stratigraphical zone, touching only at its southernmost point rocks essentially of argillaceous composition— the Aberfoyle Slate-band.
Here, then, are presumably sediments of a restricted range of composition; the hornfelses derived from them may be expected to show the same limit of variation.
The examination that I have been able to make of this aureole shows quite clearly, however, that such a restriction in chemical composition is far from being the case. The thermal products show a wide range of composition, and the mineral-assemblages in the inner zone of hornfelses include types which (I believe) have not been previously recorded from British contact-zones, and some that I have not been able to match with any of the thermal products of extra-British contact-aureoles. Moreover, these unusual mineral-assemblages are by no means rare in the aureole itself, but have been
The Lower Carboniferous Succession in the Settle District and along the Line of the Craven Faults
Authors: Garwood Edmund Johnston , Goodyear Edith 
Published: October 2009

The district which is the subject of the present communication has attracted the attention of geologists since the days of Playfair (46) who, in his ‘Illustrations of the Huttonian Theory’ published in 1802, alludes to a visit that he paid, with Lord Webb Seymour, to Chapel-le-Dale and Thornton Force, and describes the unconformity between the Carboniferous Limestone and the underlying slates. Sedgwick (50), in a paper read before the Geological Society in 1831, described and illustrated the succession of the Carboniferous rocks which occupy the country between Penyghent and Kirkby Stephen. That paper, which shows a keen insight into the general structure of the district, was not printed in the Transactions until 1835.
The same year saw the publication of John Phillips's (44) classic work—‘The Illustrations of the Geology of Yorkshire’ the second part of which, ‘The Mountain Limestone District’, was issued in the following year. Phillips confined his attention to the lithological succession, and made no attempt to describe the distribution of the fossils, or to make use of them for the subdivision of the series, the palæontological portion of the work forming really an independent communication. It was impossible, however, that so careful an observer should fail to notice that certain fossils were more abundant at some horizons than at others, and, although he does not allude to this fact in the work mentioned above, it is evident that it did not entirely escape his notice: for, in his Presidential Address (45, pp. xxxviii-xxxix) to the Geological Society
The Development of the Severn Valley in the Neighbourhood of Iron-Bridge and Bridgnorth
Authors: Wills Leonard Johnston 
Published: October 2009

The late Prof. Charles Lapworth inspired me with a desire to test the validity of his hypothesis, put forward as long ago as 1898, that the Upper Severn was added to the Lower Severn as a result of the impounding of a glacial lake in Shropshire and Cheshire. The lake, according to the hypothesis, rose until it flowed out over the former watershed between the Shropshire plain (which originally had drained to the Dee or the Mersey) and the headwaters of a tributary of the Worcestershire Stour.
The same view was put forward independently by F. W. Harmer in 1907, in a paper accompanied by an excellent contoured map, which may be conveniently consulted in connexion with the present work.
Neither Lapworth nor Harmer attempted, so far as I know, to bring forward detailed evidence in support of the hypothesis. Lapworth called attention to the rejuvenation of the Severn and its tributaries, which he regarded as resulting from the diversion, into a diminutive tributary of the Stour, of the copious waters of the Upper Severn which had originally flowed into the Dee; while Harmer pointed out the existence of Glacial lake-deposits on the Shropshire Plain.

Harmer threw out the suggestion (
op. cit.
p. 479) that the Severn Valley from Bridgnorth to Bewdley was initiated as a marginal drainage-channel on the west side of the ice-lobe that left so many Scottish and Lake-District boulders around Wolverhampton and Bridgnorth.

As may be seen from any contoured map, the Cheshire-North Shropshire Plain is
On a Recently Discovered Breccia-Bed underlying Nechells (Birmingham), and its Relations to the Red Rocks of the District
Authors: Boulton William S. 
Published: October 2009

For many years it has been known that certain breccias occur immediately below the Bunter in the Birmingham district, irrespective of the well-known development in the Clent Hills and near Northfield, about 7 miles south-west of Birmingham. In 1890 C. J. Gilbert described such breccias at the base of the Bunter Pebble-Beds in Sutton Park, 7 miles north of the city, and showed that they lie with pronounced unconformity upon red clays and sandstones, and are covered unconformably by the Bunter Pebble-Beds. During the last ten years, my attention has been directed from time to time to similar occurrences at the base of the Bunter met with in borings for water in and around Birmingham. In the recent re-mapping of the district by the Officers of the Geological Survey, a considerable development of these breccias has been noted, more especially at Hopwas, 2 miles west of Tamworth, and in the district round Little Aston and Streetly, a little to the north of Sutton Coldfield. Mr. G. Barrow has proposed the name Hopwas Breccia for these beds, and a description of them and their relationship to the Trias above and the Carboniferous below will be found in the recently published Lichfield Memoir.
It is evident, however, that the Geological Survey is still in doubt as to the geological age of these rocks. In the Lichfield Memoir they are classed as Permian (?), and in the accompanying 1-inch map they are bracketed with the Trias; while the relation of the Hopwas to
The Geology of Southern Guernsey
Authors: Farquharson Donald John 
Published: October 2009

Guernsey, the second largest of the Channel Islands, has been described geologically in varying amount of detail by a number of previous investigators, who for the most part confined their attention to the northern portion of the island, and there are only scanty references to the metamorphic complex forming the southern portion. In 1884 the Rev. Edwin Hill & Prof. T. G. Bonney (6) announced the result of their first visit to the island, and gave a few general notes relating to the southern gneisses which they believed to be, as a whole, comparable with the Laurentian Gneisses of Canada. No attempt was made to distinguish between the various types of gneiss which are now known to occur in that area.
In a paper on Alderney Canon Hill (7) discussed the age of the Channel Island rocks and, incidentally, announced his conclusion that the ‘Guernsey Gneiss’ is mostly—perhaps all—of igneous origin, but subsequently crushed. The conclusions of the two writers above mentioned may be summarily stated as follows:—In all the islands there are plutonic rocks—diorites and hornblende-granites—which are posterior to the gneisses and other dynamically altered rocks, but are believed to be pre-Cambrian, since in Jersey these rocks are overlain by the Rozel Conglomerate (basal Cambrian) and in Alderney are succeeded unconformably by grits correlated with the Conglomerat pourpré (Ordovician).
The main object of the present paper is to give a description of the distribution, field relations, and petrographic characters of the different types which together make up the metamorphic
Descriptions of Gasteropoda, chiefly in Mrs. Robert Gray's Collection, from the Ordovician and Lower Silurian of Girvan
Authors: Longstaff Jane 
Published: October 2009

Since this contribution to the knowledge of the more ancient Palæozoic gasteropoda is primarily concerned with those from the Girvan district, contained in Mrs. Gray's magnificent collection, reference is made to others only where they afford further information concerning structure or distribution. Forty-one forms are dealt with, seven of which have been described and one named in MS. by previous authors.
Twenty-four species and one variety from the same district were described and figured by me in papers read before this Society in the years 1899, 1902, 1905, and 1906. Of these twenty-one species and a variety belong to genera referred to the Pleurotomariidæ; and now twenty-five species and a variety are added to this number.

I am following Dr. E. O. Ulrich in his classification of the family, only making exception in the case of
Omospira
. He considers this genus more akin to
Raphistoma
Hall. It is, however, distinguished by having a sinus in the outer lip at the periphery, also a band on most of the whorls; this latter is never present in
Raphistoma
according to Hall, and also according to Dr. Ulrich himself. So far, I have not met with any specimens bearing the characteristics of
Raphistoma
sensu stricto in the Scottish Ordovician. The internal moulds of certain forms have been mistaken for that genus; but, where the structure is preserved, as will be pointed out, there can be no doubt that they belong to
Liospira
Ulrich.

In what degree these ancient forms are really related one
The Old Red Sandstone of the Cardiff District
Authors: Heard Albert , Davies Richard 
Published: October 2009

The district which forms the subject of this communication is situate immediately north of Cardiff. It is bounded on the east and west by the Rhymney and Taff Valleys, and on the north by the Carboniferous rocks of the South Wales Coalfield. The area thus denned is about 16 square miles in extent.
We began a systematic petrological investigation of the Old Red Sandstone of this district in the hope that a more detailed knowledge of the sediments would establish a clearer conception of the conditions of deposition, of the probable source of the rocks, and of their relation to the underlying and overlying stratigraphical divisions. During the course of the work certain fossil localities were discovered. These represent the first records of Old Red Sandstone fossils within the area defined above.
The Old Red Sandstone of South Wales, which crops out round the greater part of the South Wales Coalfield, is a continuation of the Herefordshire outcrop; but, in the neighbourhood of Cardiff, it differs considerably in thickness from many other parts of the Old Red Sandstone around the Coalfield Syncline, and more especially from that of the North Crop.
There is a general lithological resemblance between the Old Red Sandstone rocks of the Cardiff district and those of the North Crop, although there are certain differences at particular horizons (see p. 496).
Prof. W. J. Sollas estimated the total thickness of the Old Red Sandstone of the Cardiff area to be 4273 feet, making his measurements along a
On an Olivine-Dacite in the Tertiary Volcanic Series of Eastern Iceland: the Rauthaskritha, Hamarfjord
Authors: Hawkes Leonard 
Published: October 2009

The flow of dacite to be described crops out in the face of the cliff bordering the north of Hamarfjord—one of the deep incisions into the Tertiary basalt-plateau of South-Eastern Iceland. A mass of acid rock occurring in a district entirely built up of dark basaltic lavas—it attracts attention by reason of the light colours of its different lithological members, and its unusually abundant screeformation. It is known as the ‘Rauthaskritha’, or ‘red scree’, and has been described by all geologists who have visited the district.
C. W. Paijkull examined this occurrence of ’trachyt‘, and regarded it as a dyke, giving a diagrammatic section in illustration (2). The dyke is shown more than half a mile thick cutting through the basaltic series, and terminated above by one of the basalts. A glassy facies is observed at the two vertical margins and also on the top. The mass exhibits contorted banding, and is cut by dolerite-dykes which fail to penetrate the overlying basalts. The country-rocks are quite undisturbed, and no suggestion is put forward as to how room was made for this remarkable intrusion. Other writers, Th. Thoroddsen (12) and A. Helland (6), have admitted the intrusive nature of the rock.
After making a detailed examination of this occurrence in the course of three summer visits, I have come to the conclusion that it represents a lava-flow.
These are regularly bedded plateau-basalts with interbasaltic partings of red lateritic deposits, dipping 5° to 7° westwards. Magnificent sections from 2000 to 3000 feet
A Preliminary Survey of Metamorphic Zones in the Southern Highlands of Scotland
Authors: Tilley Cecil Edgar 
Published: October 2009

I. Introduction.
Thirty-one years ago, Mr. George Barrow (1) presented to this Society his classic account of the intrusion phenomena of a group of ‘Older Granites’, in the Forfarshire area of the South-Eastern Highlands. That paper is distinguished by reason of the clear enunciation of the two outstanding conclusions to which the author was led. In the one was illustrated for the first time the effect of crustal stresses on the differentiation-course of igneous magma, a process which plays so important a part in present-day theories of petrogenesis; in the other, also for the first time, was indicated the subdivision of a group of highly-metamorphosed sediments into metamorphic zones characterized by the presence of critical index-minerals. So far as I am aware, his paper represents the first attempt in petrological literature to bring precision to the study of regional metamorphism, by laying upon a map zonal lines indicative of varying grades of metamorphism.
It is chiefly upon this aspect of Barrow's work that I shall dwell in the matter now set forth.
Nineteen years later (2) he extended the area of his zonal metamorphic map, at the same time increasing the number of zones. The map presented to the Geologists' Association thus covers the ground included in the quarter-inch sheet (No. 12) of the Geological Survey map of Scotland, extending to the Highland Border from Stonehaven to Dunkeld. In the meantime, other Scottish investigators by extended surveys of Perthshire and Argyllshire were bringing to light new data on the metamorphism
Petrographical Notes on the Stockdale Shales
Authors: Rastall Robert Heron 
Published: October 2009

A.

Atrypa-flexuosa
Zone, Skelgill.

This consists in part of finely-divided micaceous material, with chlorite of the usual type, and some quartz, but there is also a considerable amount of carbonate, and the rock effervesces freely with cold dilute acid. It differs therefore notably from the others, and may be described as an impure limestone [20,008].

B.

Green Streak,
Argenteus
Zone, Skelgill (with parts of adjoining graptolitic mud-bands).

This specimen shows very pronounced colour-banding. The pale greenish-grey ‘streak’ is strongly differentiated from the other part, which is dark-grey. On ignition for 30 minutes, the ‘green streak’ becomes somewhat paler, nearly white; and the dark bands are reddened.
Under the microscope the ‘green streak’ is seen to be closely similar to the Browgill Shale (G, p. 132), though of somewhat finer texture, and with much more pronounced orientation of the flakes of mica and chlorite. Grains of quartz determinable under a half-inch objective are quite rare.
The dark rock enclosing the streak, which belongs to the graptolitic bands, appears to be essentially of the same composition, although the structure is partly obscured by the presence of a large amount of dark brownish-black material. Since this reddens on ignition, it is probably in part ferrous sulphide and in part carbon [20,006].

C.
Green Streak, Pont Erwyd
This is quite similar in composition and general character to the ‘green streak’ from Skelgill, but slightly coarser in texture: very angular fragments of quartz are easily visible incertain bands.
The Rock
The Development of
Leptoplastus Salteri
(Callaway), and of other Trilobites (Olenidæ, Ptychoparidæ, Conocoryphidæ, Paradoxidæ, Phacopidæ, and Mesonacidæ)
Authors: Raw Frank 
Published: October 2009

I. Introduction.
The above-named species of Olenid was first recorded in 1874 by Callaway from the Shineton Shales of Shropshire, which he then claimed as of Tremadoc age.

It was described from imperfect material as a
Conocoryphe
, which name in 1877 he corrected to
Olenus
, giving at the same time a description of the entire trilobite.

A specimen for the first time exhibiting dorsal spines was in 1900 described by Dr. H. H. Thomas under a new name,
Olenus mitchinsoni
. An additional occurrence of the species was in 1905 recorded by Prof. W. G. Fearnsides under the name of ‘
Parabolinella salteri
’. It occurred in the upper part of his Nant-ddu or
Bellerophon
Beds, which follow next above the
Dictyonema
Band north-west of Arenig Fawr, and it is there accompanied by
Asaphellus homphrayi
Salter and
Parabolinella triarthrus
(Callaway), which species are also associated with it at Shineton. In 1907 I briefly described its development, and assigned it to a new sub-genus ‘
Leptoplastides
’. Finally, Mr. P. Lake redescribed it in 1919, under the name
Leptoplastus salteri
.

It is now many years since, at Prof. Charles Lapworth's suggestion, I undertook the study of the trilobite fauna of the Shineton Shale. The first collection studied was that collected by Mr. Rhodes for H.M. geological Survey, and lent to Prof. Lapworth by the then Director-General. Among these were several slabs covered with minute examples of the fossil in question, in different stages of development; and the early stages seemed so strange and unexpected that a special study
The Geology of the Llandovery District: Part 1.—The Southern Area
Authors: Jones Owen Thomas 
Published: October 2009

I. Introduction.
Near the small market-town of Llandovery, in the Towy Valley, the main river flowing southwards from the direction of Rhandirmwyn is joined by two important tributaries. East of the town the River Gwydderig enters from the east, and joins the Brân, which flows south-westwards along a strike-valley from the direction of the Sugar Loaf, between Llandovery and Llanwrtyd Wells. The town lies on an alluvial flat between the Towy and the Brân, which enters the main river about a mile below. It is served jointly by the Great Western and the London, Midland, & Scottish Railways. From the Sugar Loaf to Llandovery the railway skirts the valley of the Brân, and below the town it continues in the same direction along the broad floor of the Towy towards Llandeilo, Carmarthen, and Swansea. Between Llandovery and Llangadock, 6 miles below, there is a main road on each side of the valley, that on the north side being the more frequented. The district is included in the 1-inch Geological Survey map, Sheets 41 & 42 N.W. (Old Series); in the 1-inch Ordnance Survey map, Sheets 212, 213, & 196, and in the 6-inch sheets, Carmarthenshire 10 S.E., 11 S.W., 18, 19 N.W., 26 S.E., 27 N.W. & S.W.

The rocks near the town belong to the upper part of the Bala formation, but at the Sugar Loaf, 7 miles away to the north-east, a lower part of that formation, including the
Dicranograptus
-Shales, is rolled up in the core of a