bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Geology of the District between Llanymawddwy and Llanuwchllyn, Merioneth
Authors: Pugh William John 
Published: October 2009

I. I
ntroduction
.

The country described in this paper is situated in South-Eastern Merioneth, but a narrow strip extends over the county boundary into Montgomeryshire. The northern margin is an east-and-west line through Llanuwchllyn, and this is also approximately the southern boundary of the district recently described by Dr. G. L. Elles. The western limit is the high ground made up of Ordovician volcanic rocks: namely, Aran Mawddwy, Aran Benllyn, etc., and the eastern margin is roughly parallel, at a distance of from 4 to 5 miles. The southern boundary is about a mile south of Llanymawddwy, and is adjacent to the Dinas Mawddwy country.
This district occupies an area of about 38 square miles, and is included in the 1-inch Ordnance Survey Map 136, in the Geological Survey Maps, Old Series, Sheets 60 N.W. & 74 S.W., and in the 6-inch maps, Merioneth, Sheets XXIX N.W., N.E., S.W., S.E., XXXIV N.E., S.E., and XXXV N.W., N.E., & S.W.
It is a thinly populated region; Llanymawddwy on the south and Llanuwchllyn on the north are the only villages. Parts of the area are somewhat inaccessible, but the old mountain-road from Dinas Mawddwy to Bala over Bwlch y Groes (1790 feet above sea-level) passes through the district. There is comparatively little ground that can be cultivated, and the area is given over almost entirely to sheep-farming.
The central part of the area is the watershed between three drainage-systems: namely, the Dyfi, the Dee, and the Vyrnwy (a tributary of the Severn). The
The Erratic Rocks and the Age of the Southern Limit of Glaciation in the Oxford District
Authors: Sandford Kenneth Stuart 
Published: October 2009

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ntroduction
.

In this paper I propose to study the material of which the Plateau Drift consists in the Oxford District, and to discuss the inferences arising therefrom. For the sake of brevity, and to avoid restating a host of facts already published, it will be assumed that the reader has access to the latest Memoir of the Geological Survey which deals with the district, wherein he will find a detailed account and a full bibliography.

In that Memoir certain problems of the erratic material which abounds in the local superficial deposits had to be left
sub judice
. Research was in progress, aided by the grant from the Daniel-Pidgeon Fund awarded to me in 1924, and I now present the results of the work, expressing gratitude to the Council of the Geological Society for the assistance thus afforded.

I have collected material from the Plateau Drift over a wide area for rather more than eight years, and Prof. W. J. Sollas put at my disposal his important collection, mainly derived from two localities close to Oxford:—Pickett's Heath (on Boars Hill) and Chawley Brickworks, on the flank of Cumnor Hill (Cumnor Hurst).
The considerable mass of material thus available has been reduced to about fifty rocks of essential importance from a petrological point of view, that is, to rocks of character so marked that they can be recognized without fear of grave error.
In the work of recognition, after initial research on my own account, I submitted the material to Mr.
Drifted Plant-Beds of the Upper Estuarine Series of Yorkshire
Authors: Black Maurice 
Published: October 2009

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The Estuarine Series of Yorkshire consists of non-marine sandstones and shales, which reach a maximum thickness of about 1000 feet. The series is interrupted by three marine bands, all of which may not be present at any given locality. The complete sequence of Middle Jurassic rocks in Yorkshire, as stated by the Geological Survey, is as follows:—
The term ‘Upper Estuarine Series’ appears to have been used for strata in Yorkshire for the first time by Fox-Strangways (1880, p. 3) to designate the strata above the Grey Limestone Series and below the Cornbrash.
Of the marine bands, the Cornbrash and the Grey Limestone Series are by far the most constant, with the result that the Upper Estuarine Series is much the best defined of the three estuarine groups.
The Upper Estuarine Series is exposed in the coast-section from the Wyke (2 miles west of Filey), as far as Ravenscar, where the outcrop turns inland. West of Ravenscar large areas of the moor are formed by outcrops of this series as far as Wheeldale Moor, where a pitch in the Cleveland Anticline brings up lower beds. North of the Esk valley, which cuts down into the Lias, a broad syncline preserves an outlier of the Upper Estuarine Series and the beds immediately above it.
The object of the present paper is to describe and discuss the significance of the variations in the lithology and in the flora of the Upper Estuarine Series, and to show how the nature of
Peterographical Notes On Rocks From The Basal Complex Of Jamaica
Authors: Higham. Frank 
Published: October 2009

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ntroduction
.

The notes contained in this appendix are based on the examination of about 120 specimens, which form a part of the collection made by Dr. Matley in the course of his work on the Basal Complex of Jamaica, the majority of the specimens coming from the Kingston district. They have been divided into the same sub-district groups as in the main paper. The other rocks which have been examined are: —first, from a group of andesites and associated instrusives, the position of which in the sequence is, at present, uncertain; and, secondly, a series of pebbles derived from the Complex.
The rocks of the Basal Complex of Jamaica are either igneous, or rocks which have undergone metamorphism. Although they fall into these two groups, the types, especially of the metamorphic rocks, are very varied.
(a) The Igneous Rocks.
Of the plutonic types of igneous rock, which are a part of the Complex, the most important is a granodiorite. Macroscopically, this rock is mesocratic, although some specimens are richer in ferromagnesian minerals than are others. The felspars, when fresh, are colourless; but, when they are slightly altered, the orthoclase assumes a faint pink coloration (K.P. 131). Quartz, a ferromagnesian mineral (usually biotite or hornblende), and sphene can generally be seen in the hand-specimen. A thin section of the granodiorite, examined under the microscope, shows hypidiomorphic crystals of plagioclase (oligoclase-andesine to andesine), which are sometimes poikilitically embedded in orthoclase, or surrounded by allotriomorphic quartz and orthoclase. The dark minerals are
The Geology of the District around Abbey-Cwmhir, Radnorshire
Authors: Roberts Richard Owen 
Published: October 2009

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The area described in this paper is situated in North-West Radnorshire. The village of Abbey-Cwmhir, which is about 5 miles north-east of Rhayader, is in the centre of the district. The southern boundary is about a mile and a half south of Nantmel, and runs approximately parallel to the main road from Rhayader to Pen-y-bont. The northern and eastern margins are defined by a conspicuous range of hills, which are made up of Wenlock shales and grits; namely, Yr Allt, Cefn Du, Ysgwd Ffordd, and Beddugre Hill, etc. The adjacent ground on the west was described by Dr. Herbert Lap worth in 1900. About 30 square miles have been investigated, and mapped on the scale of 6 inches to the mile. The area is included in the 1-inch Ordnance Survey Maps, Sheets 70 & 80 (coloured edition), and in the Geological Survey Maps, Old Series, Sheets 56 N.W. & N.E.
The district forms part of a dissected plateau, which attains an altitude of about 1500 feet, but Camlo Hill (1670 feet) stands up above the general level of the plateau, and is the highest point in the area. In this plateau, the streams are deeply trenched, and some of the valley-slopes are steep, particularly in the northern part of the region.
The rivers belong to the drainage-system of the Ithon, which joins the Wye about a mile and a quarter south of Newbridge. The principal stream in this district is the Clywedog Brook, with its tributaries (Pandy Brook,
Notes on the Petrography of the Borrowdale Volcanic Series of Kentmere, Westmorland
Authors: Mitchell George Hoole 
Published: October 2009

An account of the succession and structure of the Borrowdale Series in the neighbourhood of Kentmere has already been given. In the present communication some additional notes are given on the chemical composition of the rocks and the characters of the flow-brecciation, which is one of the most typical features of the lava-flows. The appearances of certain of the more important characteristics of the rocks when seen in thin section under the microscope are recorded in a number of photomicrographs. The chemical and microscopical work here described was carried out in connexion with the field-work, and the present details are recorded in order to give completeness to an aspect of the subject which was perhaps somewhat neglected in the original paper. It was then felt that the establishment of the structure of the area was the matter of paramount importance. These notes should, however, be read in conjunction with the previous paper, more particularly with reference to pp. 14–30.
It will be seen that the analyses set forth in the accompanying table confirm the descriptions of the lavas given in the previous paper. The Upper Rhyolites are apparently slightly less acid than the Kentmere Pike Rhyolites, while the most acid rocks exposed in the area are the quartz-porphyry intrusions. The differences already described between the andesite-lavas at different horizons are also well brought out in the percentages of silica in the analyses. The variation in the Upper Andesites east and west of the River Kent is especially well seen. Whereas
Fossil Insects of the South Wales Coalfield
Authors: Bolton Herbert 
Published: October 2009

I am indebted to the labours of many workers for the opportunity of preparing this paper upon the remains of fossil insects discovered in the Welsh Coal Measures during the last fifteen years.
Some of the specimens are in the National Museum of Wales, having been discovered in the collection of Coal-Measure fossils given to that Institution by Mr. David Davies, of Gilfach Goch.
Dr. A. E. Trueman and Miss E. Dix, M.Sc., have lent insect-remains from the Coal Measures of the Swansea area.
To Dr. F. J. North I am much indebted, not only for the opportunity of retaining specimens for examination over a long period of time, but for information respecting horizons at which the insect-remains occur.
To the Geological Survey and to Mr. John Pringle I am under obligations for the loan of a blattoid wing found by him in shales associated with the Mynyddislwyn Vein at Maes-y-Cwmmer (Glamorgan), and for an Archimylacrid pronotum from the Gwernau Level, three-quarters of a mile south-east of Maes-y-cwmmer, at the same horizon.
The series of wings represents nearly a score of individuals, and constitutes the largest group of Coal-Measure insects yet recorded at one time from any British coalfield. They are, with two exceptions, referable to the Blattoid families Archimylacridsæ, Handlirsch, and the transitional ‘Tribe’ named Heraimylacridia, Pruvost. Only two of the specimens are referable to the most archaic group of fossil insects, the Palæodictyoptera.
As we shall see later, the Hemimylacridian forms now known to occur in the South
Earth-Movements during the Closing Stages of the Neolithic Depression
Authors: Gilbert Charles Jesse 
Published: October 2009

Mr. Oldham's interesting paper has a much wider significance than appears upon the surface. I have recently been investigating the phenomena associated with the Neolithic depression in the coastal districts of England, Belgium, and Northern and Western France, and I find evidence of recent earth-movements of striking uniformity. Their sequence, moreover, bears a strong resemblance to those of the Rhôone Estuary; but this, of course, may be fortuitous.
Romney Marsh, in Kent, occupies a large portion of the site of an ancient bay, the shore-line of which ran along the present foothills and around the tributary bays of the river-valleys. Keeping pace with the Neolithic depression, shore-deposits of shingle and sand up to 70 feet in thickness were laid down over the bay. An uplift of at least 25 feet then occurred, and a new shore-line was created some 8 miles to seaward of the former base of the bay. During a considerable halt-stage the Forest of Anderida (which was occupied by Neolithic man) spread out over the enclosed area. The resulting Forest-Bed can be traced in deep drainage-sections in the Marsh and along the western shore-line to Fairlight.
During a subsequent depression a lagoon was formed, in which the alluvium of Romney Marsh and of the river-valleys of the Rother, the Brede, and the Tillingham was deposited; while the new shore-beach was gradually rolled back upon itself for some distance. As a result of this oscillation, about 100 square miles of the ancient bay were reclaimed.
A second uprise
The Glaciation of Clun Forest, Radnor Forest, and some Adjoining Districts
Authors: Dwerryhouse Arthur Richard , Miller Arthur Austin 
Published: October 2009

The district described, which comprises the county of Radnor and parts of Montgomeryshire, Shropshire, Brecknockshire, Herefordshire, and Worcestershire, is some 1000 square miles in area, and is included in Sheets 151, 164, 165, 166, 179, 180, 181, 196, 197, and 198 of the 1-inch map of the Ordnance Survey of England & Wales.
To be more precise, the area is bounded on the north by the River Severn from Newtown to below Welshpool; on the east by a line from Welshpool by Forden, Chirbury, and Church Stoke, to Craven Arms and Ludlow, thence by Woofferton and Tenbury to the neighbourhood of Bromyard, and so to Hereford; on the south by tho scarp of the Brecon Beacons and the Black Mountains; and on the west by the River Wye from Builth Wells to its junction with the Ithon, thence along that stream to its head, and so northwards to Newtown.
The country is somewhat complicated topographically, and the drainage-system has been rendered more intricate by the efforts of ice during the glaciation.
The two principal elevated areas within the district are Clun Forest (1666 feet above O.D.) and Radnor Forest (2166 feet O.D.), the former consisting of Ludlow rocks and Old lied Sandstone, and the latter of Wenlock and Ludlow Beds.
South-east of Radnor Forest lies a somewhat faulted belt of country consisting of Silurian rocks, in which the escarpments of the Aymestry and Wenlock limestones are prominent features.
South and east of the Silurian country lies an extensive area of
The Geology of the Country between Nant Peris and Nant Ffrancon, Snowdonia
Authors: Williams David 
Published: October 2009

The area here described lies immediately north of the Snowdon ‘massif’, and forms a part of the mountainous tract between the Passes of Llanberis and Nant Ffrancon. Its south-eastern boundary runs from the Ogwen Falls, through Llyn Idwal and Twll Du (Devil's Kitchen) to the upland tarn of Llyn y Cŵn and thence down the Afon Las to the Pass of Llanberis. For the greater part of its length this line approximately coincides with the axis of the Idwal syncline. The northern limit of the area is defined by the top of the Cambrian ‘slate-belt’, between the upper end of Llyn Peris and the northern shoulder of Bronllwyd, near Bethesda.
The area is about 8 square miles in extent, and is represented on the Ordnance Survey 6-inch map, Carnarvon 17 (four quarter-sheets), and on the Geological Survey 1-inch map, 78 S.E. (Old Series).
Owing to the general strike of the stratified rocks, the main ridges and valleys have a north-east to south-west trend. In succession from north to south are the long strike-ridges of Elidir Fach, Elidir Fawr and Carnedd y Filiast, Foel Goch, and Y Garn, all of which rise to over 2500 feet. A long ridge, running northwards from Twll Du to Carnedd y Filiast, crosses the general trend of the area almost at right angles, and forms the watershed between Nant Ffrancon and the Pass of Llanberis. On the east of this divide is a series of eight magnificent hanging cwms which formerly contained tributary glaciers flowing
The Carboniferous Inliers at Codrington and Wick, Gloucestershire
Authors: Smith Stanley 
Published: October 2009

On the eastern side of the Bristol coal-basin, south of Chipping Sodbuiy, the Lower Carboniferous rocks are concealed by Mesozoic strata. Near Codrington and in the vicinity of Wick, however, they are exposed as a number of small inliers. These inliers are the subject of the present paper.
The Codrington Inliers are situated 2 miles, the Wick Bocks Inlier 5 miles, and the Grandmother's Rock Inlier, 6½ miles south of the continuous outcrop (see fig. 1, p. 332). The last-mentioned inlier is 14 miles north of the Mendip outcrop. The village of Wick is 7 miles east of Bristol, and the Wick Rocks Inlier, which lies on the north side of the village, occurs on the same line of latitude as the Avon Gorge, some 9 miles away to the west.

The several inliers expose, although not quite completely, a succession of beds ranging from the Tournaisian (Upper
Zaphrentis
Zone) to Coal Measures yielding a Yorkian flora. The upper part of the
Syringothyris
and the base of the
Seminula
Zones are not exposed, and within the ‘Millstone Grit’ a non-sequence undoubtedly occurs.

The arenaceous beds with thin intercalated limestones (D
3
) which succeed the limestone sequence (see table, p. 333) are better exposed in the Wick Rocks Inlier than anywhere else in the Bristol District. Although these beds are well developed on the north-west side of Bristol—at Clifton and Redland, they are no longer accessible there.

Generally speaking, the strata exposed in these inliers have a westward dip, but the actual
The Geological Collection from the South Centeal Sahara
Authors: Rodd. Francis R. 
Published: October 2009

As the Central Sahara is geographically one of the least-known areas in Africa, knowledge of its geology is naturally scanty, and all additional information is welcome, especially from its bearing on the relations of the North African and Equatorial seas and on the problem whether the Cretaceous sea of the Sahara and Northern Sudan is a branch of the Tethys, or crossed Africa from the Gulf of Aden to the Niger.
The collection made by Mr. F. R. Rodd, during his journey in 1927, has been sent to us for examination. He has described the geography of the area in the Geographical Journal and also in his book ‘The People of the Veil’. The Massif of Aïr was reported by H. Barth to consist of gneiss, slate, marble, and granite, with flows of basalt and trachyte, and to be flanked by sandstones. Knowledge of the geology of the Aïr Massif and its neighbourhood is due mainly to the work of R. Chudeau, who collected fossils there, and described its geology in his ‘Sahara Soudanais’ and in a series of papers. He discovered Cretaceous limestones with ammonites (1909, 2) and lamellihranchs, which he identified as Turonian; and, on the basis of his work, an extensive area in the Central Sahara has been since regarded as marine Upper Cretaceous and as connected either with the Mediterranean or with the Indian Ocean.
E. Haug, J. W. Gregory, and E. Hennig have represented the Cretaceous of the plains south of Aïr as part of
The Tuedian Beds of Northern Cumberland and Roxburghshire East of the Liddel Water
Authors: Garwood Edmund Johnston 
Published: October 2009

The object of this communication is to describe an interesting lagoon phase which occurs in the Tuedian Beds of Northern Cumberland and the neighbouring Border country in Roxburghshire, a feature of special interest being the development of algal limestones in the Cementstone Series.

The area dealt with is included in the sketch-map (fig. 1) and comprises

1.
The Northern Cumberland district drained by the River Lyne and its tributaries between the River Irthing and the Liddel Water.

2.
The part of Roxburghshire lying between the Liddel Water and the English Border.

3.
The western part of Mid-Northumberland south of the Cheviot.

The Northern Cumberland district is included in the Geological Survey 1-inch map of England and Wales, Sheet No. 106 N.W. (old series), while the Roxburghshire district is contained in the Scottish 1-inch map, Sheets Nos. 11 and 17. No memoirs have been published for any of these sheets. Three of the sections, however, which accompany the memoir on the Canonbie Coalfield by B. N. Peach and J. Horne traverse some of those parts of Roxburghshire dealt with here, and the authors give a list of fossils collected from this district during the progress of their survey.
The fullest development of the Tuedian Beds is found in the Cumberland portion of the area, and the succession there will be described in detail. Interesting sections also occur in the Scottish tract east of the Liddel Water, and an account of this area
The Flora of the Upper Portion of the Coal Measures of North Staffordshire
Authors: Dix Emily 
Published: October 2009

The stratigraphy of the Coal Measures of North Staffordshire is, perhaps, better known than that of any other coalfield in this country. This is undoubtedly due to the detailed work carried out by pioneer workers such as Wheelton Hind, John Ward and Mr. J. T. Stobbs, and also to the fact that this coalfield offers remarkable facilities for the study of the various horizons in the Coal Measure sequence. The upper portion of the Middle Coal Measures and the lower part of the Upper Coal Measures, in particular, are (owing to the economic value of the pottery clays and the Black Band Ironstones) admirably exposed in quarries and excavations. These sections give an almost complete succession from the Ash Coal to the Keele Series.
The present paper deals with the distribution of plants in the Coal Measures above the horizon of the Ash Coal. Most of the species here recorded were collected in the course of investigations chiefly concerned with the non-marine lamellibranchs in those measures, and undertaken while I was acting as research assistant to Prof. A. E. Trueman. A grant in aid of this work was received from the Department of Scientific and Industrial Research.
I desire to acknowledge the assistance which has been given by all owners and officials of mines and marl pits in North Staffordshire. They not only allowed access to sections, but also gave facilities for collecting both above and below ground. As a result, the original records given in this paper refer to
A Classification of some Rhyolites, Trachytes, and Phonolites from part of Kenya Colony, with a Note on some Associated Basaltic Rocks
Authors: Smith Walter Campbell 
Published: October 2009

In spite of the importance of the volcanic region of the Great Rift Valley of East Africa, very little attention has been paid in the past to the detailed petrography of the rocks of Kenya Colony.
Previous work on the subject may be summarized in a few sentences. August Rosiwal described the rocks collected by L. von Hohnel on Count Teleki's expedition in 1886–88 (1891, pp. 490–511).
Descriptions of some of the lavas of Mount Kenya were given by J. W. Gregory (1900) in his account of the geology of that mountain, which he ascended in 1893, and G. T. Prior (1903) described the rocks collected by Gregory in other parts of the Colony on the same expedition, and specimens from a collection presented to the British Museum (Natural History) by Sir H. H. Johnston in 1901. This paper contained five analyses. H. B. Maufe (1908) gave an account of the field relations of the rocks which he collected in 1905 and 1906 along the line of the Uganda Railway and on several traverses from various points along it. He followed Prior's nomenclature fairly closely. A few specimens collected by G. Uhlig, also on the line of the Uganda Railway, were described by M. Goldschlag (1912), who gave four analyses. Miss A. T. Neilson (1921) gave a brief description of the rocks collected by J. W. Gregory in 1919. Finally, A. Lacroix (1923) gave a short summary of the work of these earlier authors and added four new analyses of