bluuebunny/crossref_metadata_2025 huggingface dataset:
Historic Changes of Level in the Delta of the Rhône
Authors: Oldham Richard Dixon
Published: October 2009

About four years ago, a paper by M. Georges Denizot, of the University of Aix-Marseille, came to my knowledge. Not only did it contain interesting and important additions to the published descriptions of the geology, but it seemed to give also a clue to certain geographical and historical paradoxes, which have perplexed writers concerned with the delta of the Rhône. Since then I have made extensive research among the historical records, and have paid some visits to the region. So far as the observations recorded by M. Denizot are concerned, I can fully confirm the accuracy of all that have come under personal notice, but have not concerned myself greatly with this aspect of the question, as he is engaged in a detailed examination of the whole area, from which important results may be confidently expected. My own studies have been principally concentrated on historical records, from which certain facts come out that seem worthy of consideration, as bearing on principles of great interest and importance from a purely geological point of view; and for this reason I submit the paper which follows, although the actual amount of fresh field-work is very small.

As the deposits and the changes of level, which will be dealt with, all belong to the latter part of the geologically Recent period, it will be unnecessary to mention any formations earlier than the commencement of the Pleistocene, and even these will come in merely as the base and framework on which the Delta was built
The Geology of the Country around Bodfean, South-Western Carnarvonshire
Authors: Matley Charles Alfred , Heard Albert
Published: October 2009

The following account deals with a tract of country in Western Lleyn (Carnarvonshire) between Nevin and Pwllheli, chiefly in the parish of Bodfean. It is about 3½ miles long (from west-south-west to east-north-east) and 2 miles wide, and consists chiefly of Ordovician extrusive and pyroclastic volcanic rocks of varied composition associated with marine sediments. The hill of Gam Bodfean that rises steeply to a height of 918 feet is the most prominent feature of the area, although it is overtopped on the north by the larger hills north-east of Nevin and on the south by Carn Fadryn. Moel y Penmaen is a smaller and less conspicuous ridge, about 500 feet high. Most of the remaining country is thickly mantled with glacial drift, which has prevented us from working out the geological sequence and structure as fully as we wished.

As this area lies near the margin of the regions which we are separately investigating, we decided to deal with it jointly.

Although both authors have taken part in the field work, the first-named is more particularly, concerned with the stratigraphy and palæontology, and the second author with the petrology.

With the exception of Garn Bodfean and the recording of fossils from Bodfean Hall, the area has hitherto received little attention from geologists. In 1843 Sedgwick described the Palæzoic region of Lleyn, of which the tract here dealt with forms part, in general terms as ‘composed of greywacke (sometimes passing into a coarse arenaceous rock), and greywacke slate,... and these rocks
Some Valentian Corals from Shropshire and Montgomeryshire, with a Note on a New Stromatoporoid
Authors: Smith Stanley
Published: October 2009

The British coral fauna of the formations older than the Salopian has received but scant attention, and is surprisingly little known. A few species of corals have been described from beds of Caradocian and Valentian age, notably by Lonsdale, M'Coy, and Phillips, but in several cases these were founded on calice-moulds, with which it is extremely difficult to identify actual corals. The only work that deals with pre-Salopian corals which at all approaches monographic proportion is Nicholson & Etheridge's ‘Silurian Fossils of Girvan’.

Corals, it is true, have frequently been recorded in faunal lists, but usually in ambiguous terms such as ‘
Petraia
sp.’ or ‘
Lindstræmia
sp.’, or quite unwarrantedly in many cases under one or other of the trivial names introduced by the older writers whom I have mentioned. Many of the specimens thus recorded, it is only fair to add, have also been casts and moulds.

The Valentian corals described in this paper are, with few exceptions, from South Shropshire and from the narrow outcrop of the Llandovery which, emerging from beneath the Carboniferous near Buildwas, north of the Severn, runs west of Much Wenlock to the neighbourhood of the Onny River, where it is overstepped by the Salopian. The specimens were, for the greater part, collected by Mr. W Dewar, Mr. R. W. Pocock, Mr. J. Pringle, and Dr. T. Robertson during the recent revision of the area by H.M. Geological Survey. This material has been considerably supplemented by the loan from Dr. Whittard of the corals which
The Geology of the Shiant Tsles, Hebrides
Authors: Walker Frederick
Published: October 2009

The Shiant Isles form a small archipelago in the North Minch, some 5 miles south-east of the Park district of the Island of Lewis. Although grouped with Ross and Cromarty, they are 20 miles distant from Rudh Re—the nearest point of! the mainland. Geologically, the islands are connected with the Trotternish district in the north of Skye, showing as their principal feature thick dolerite-sills intruded into relatively thin Mesozoic sediments. The Shiants are, in fact, the northernmost representatives of the ‘trap isles’ of the Hebrides. The group contains three comparatively large islands—Garbh Eilean (the rough island), Eilean an Tighe (the island of the house), and Eilean Mhuire (Mary Isle). Of these the first two are the largest, both being about a mile in length, with a maximum breadth of about half that distance. They are connected by a shingle-beach (except during unusually high tides), one side or other of which provides a safe landing-place even in rough weather. Garbh Eilean, the northern island, rises to a height of 528 feet, and is bounded on the north and east by high cliffs. Those of the northern face are particularly impressive, showing at one point a sheer wall 500 feet high rising out of the sea. On the north-east and east the bottom of the clift's is buried under great scree-slopes which, being partly overgrown, form the nesting place of countless puffins. Eilean an Tighe is 410 feet in height, and is bounded on the east by similar high cliffs, together with
Pre-Ordovician Rocks of the McDonnell Ranges, Central Australia
Authors: Mawson Douglas , Madigan Cecil Thomas
Published: October 2009

During the last fifty years a number of explorers and a few trained geologists have contributed to our knowledge of the structure and lithology of the McDonnell Ranges, the inaccessibility of which has, until recently, been the obstacle limiting investigations. There has never yet been a thoroughgoing investigation of the area, and each observation has been in the nature of a brief reconnaissance in connexion with mineral resources or water-supply.

All work prior to the year 1925 is mentioned in an excellent summary and discussion contributed by Dr. L. K. Ward. For further information relating to such earlier work the reader is directed to that paper.

In his contribution Dr. Ward has combined and clarified the information gathered from these various sources, and he presents in excellent language a clear picture of the geology and physiography of the regions. The account also incorporates his own observations made on several occasions, when visiting the area in connexion with water-supply and mineral occurrences.

There is, however, one finding that appears in this very notable contribution which, while being a reasonable inference, could not be regarded as actually proven. This is a very important question: no less than the age of some 14,000 feet of sediments (Ward's measurement) and in a portion of which, at Acacia Well east of Alice Springs, Dr. C. Chewings had long ago reported the occurrence of cryptozoan fossils. The beds unconformably overlie the crystalline complex of accepted pre-Cambrian age.

Geologists had expressed diverse views on the matter. The
Upper Cretaceous Fossils
Authors: Weir John
Published: October 2009

The fossils here described were collected by Mr. Francis Rodd in the South Central Sahara in 1927. They were obtained from ‘a stratum of fossil shells under limestone’ at In Nuguren (19° 5' lat. N., 8° 20' long. E. approximately). The locality is marked on the accompanying map (Pl. XLI).

The fossils include some indeterminable casts of Dimyarian Lamellibranchs, in addition to the forms described below—
Exoygra olisiponensis
Sharpe,
E. tamalleni
Pervinquière, and
Plicatula ferryi
Coquand.

E. tamalleni
is recorded from the Senonian of Tunis.
P.ferryi
is a Turonian and Senonian species in North Africa, especially abundant in the Lower Senonian. The characteristic but highly variable
E. olisiponensis
has a wide distribution. It is found in Portugal, Spain, Southern italy and Sicily, Algeria, Tunis, Egypt, Palestine, the Sahara, Nigeria, and Angola. In Portugal, according to P. Choffat, the typical form of Sharpe attains its acme in the uppermost Turonian of Lisbon. In North Africa, Palestine, and Egypt it is a characteristic species of the Cenomanian. It occurs in the Turonian of Northern Nigeria and of the Sahara (northern border of the Central Massif), and is recorded from Angola in a position which, according to Choffat (
loc. cit.
), suggests a Senonian age. In the Cenomanian of Peru it is represented by a variety to which Steinmann gave the name
E. olisiponensis
var.
duplex
.

E. tamadleni
has been recorded only from the Senonian, but it may range down into Turonian; the association of
E. olisiponensis
and
P. ferryi
suggests Turonian (possiby uppermost)
Report on the Fossil Wood from the South Central Sahara
Authors: Williams Samuel
Published: October 2009

The material consists of a single block of silicified Gymnosperm wood collected by Francis Rodd on his last journey in the Central Sahara. The block measures 10 × 8.5 cm. (radial) × 8 cm. (tangential). It consists entirely of secondary wood, there being no trace of pith, primary xylem, or of any tissues outside the xylem. The preservation of the tissues is, for the greater part, poor, but certain areas are relatively well preserved, and permit of the following description.

Transverse sections (P1. XL, fig. 1) do not give any clear indication of the presence of ammal rings. There are, however, certain regions where, for a depth of two tracheids, the size of the latter is small compared with those on either side. The xylem appears to consist entirely of tracheids, there being no xylem parenchyma present. The tracheids themselves are of the Araucarian type, showing a single row of large contiguous pits which are flattened above and below (P1. XL, fig. 2). Very rarely the pits are in two rows, and, in these examples, the pits are placed alternately. The pits are confined to the radial walls. In transverse section many of the tmcheids show dark-brown contents, while in longitudinal section (P1. XL, figs. 3 & 4) the tracheids appear to be septate. These appearances are probably due to the presence of resin-plates.

The medullary rays (P1. XL, figs. 3 & 4) are invariably uniselriate, and are from 2 to 18 cells deep, the majority being from 5 to
The Age of the Midland Basalts
Authors: Pocock Roy Woodhouse
Published: October 2009

In the course of work on the Midland Coalfields one of the many problems that have occupied attention has been the question of the age of the basalts associated with the Coal Measures.

Extrusive basic igneous rocks that are known to be of Lower Carboniferous age occur at Little Wenlock in Shropshire, in the Bristol district, in North Staffordshire, in Derbyshire, and in Cumberland. Rocks of similar type are present in the Upper Carboniferous of the Midlands, but hitherto no definite evidence of their age has been produced. The distribution of these rocks is shown on the accompanying map (Pl. I).

The Butterton and Swynnerton dyke in North Staffordshire and the Grinshill and Acton Reynald dyke in North Shropshire both traverse the Keuper Marl and are therefore definitely post-Triassic.

Kinlet.—The Kinlet basalt lies approximately between the Sweet Coal (Yorkian) and Sulphur Coal (Staffordian) Groups of the Wyre Forest Coalfield; that is, in the position of the unconformity or ‘Symon Fault’ in the Coalbrookdale Coalfield.

In an old quarry about 300 yards S. 20° W. of Mass House Farm, near Kinlet, the following section is exposed:—

Feet.
Inches

Sandstone, yellowish-buff, flaggy. The lower layers are dark btrn in colour and consist of sand grains in a matrix of decomposed basaltic material with pebbles of basalt and portions of amygdales.
2
0

Coarse grit of small quartz pebbles up
The Unroofing of the Dartmoor Granite and the Distribution of its Detritus in the Sediments of Southern England
Authors: Groves Arthur W.
Published: October 2009

The Hercynian age of the Dartmoor granite is generally admitted, but little information has hitherto been available concerning the period at which this granite became contributory to sediments. The work described in this paper is an attempt to supplement this information by direct appeal to the sedimentary formations in the South of England. These have been systematically searched for detrital mineral species which, in respect of associations and both specific and varietal features, are in consistent agreement with the assemblage of accessory minerals characteristic of the Dartmoor granite as described by Dr. A. Brammall (1928).

Both the coarse and fine constituents of the Permo-Triassic strata in the West of England have been investigated within recent years. In the South of England pebble-beds of post-Triassic age are rare. For the special purposes of this paper, strata investigated by other workers have been re-examined, and gaps have been bridged by the study of intervening horizons.

The strata sampled and examined in the laboratory range from the base of the Watcombe Clay (Permian) to the Pliocene of the North Downs (Diestian), of St. Erth, and of St. Keverne in Cornwall. It was reasonable to assume that, in the chain of evidence sought, the first and strongest link would be found in the strata nearest the granite outcrop. West of the granite, however, the only strata known to be of post-granite age comprise a few small outliers of Permian and Pliocene.

The samples collected (about 250 in all) are fairly representative of the stratigraphical
Some Non-Marine Lamellibranchs from the Upper Part of the Coal Measures
Authors: Dix Emily , Trueman Arthur Elijah
Published: October 2009

The present paper deals with those non-marine shells which occur in the upper part of the Coal Measures: namely, in the Phillipsi and Tenuis Zones and in the higher portion of the Pulchra Zone. Those studies of the non-marine Lamellibranchs of the Coal Measures which have recently been published, have been directed chiefly to shells from the lower portion of the Coal Measures (Davies & Trueman, 1927; Wright, 1929; Clift & Trueman, 1929; and Hopkins, 1928, 1929). The shells which occur in the upper portion of the Coal Measures are mostly species of the genus
Anthracomya,
which have hitherto afforded evidence for no more than a broad classification of those measures; in the following pages we have attempted to define with greater precision the characters and ranges of these species.

These investigations have been carried out with the assistance of grants from the Department of Scientific and Industrial Research, and we are particularly grateful for the generous way in which the Council of that Department has supported the work. One of us (A. E. T.) also wishes to acknowledge a grant from the Royal Society, which has defrayed certain expenses incurred during the early stages of the investigation.

Most of the material described in the paper we have ourselves collected, and we wish to express our indebtedness to mine-owners and others for the cordiality with which we have been assisted in the various coalfields where collecting has been done. We have also had the advantage, through the kindness of Dr.
The Geology of the Dolwyddelan Syncline (North Wales)
Authors: Williams Howel , Bulman Oliver Meredith Boone
Published: October 2009

The importance of the Dolwyddelan syncline from a stratigraphical standpoint has long been recognized. It was considered by Ramsay to be a vital link or ‘key-area’ in the supposed correlation of the Snowdonian country with that of Bala. More recently, it was learned that the syncline contained graptolite-shales intimately connected with the Snowdonian volcanic rocks and offering definite evidence of their age. Considering, further, the unfortunate circumstance that on Snowdon itself the highest lavas are also the topmost beds, and that the lowest lavas are separated by a thick group of sediments from the highest graptolite horizon yet recognized there, the need for a re-study of the Dolwyddelan syncline, especially for more precise evidence as to the age of the Snowdon lavas, becomes apparent.

The limits of any syncline are, of course, arbitrary, and as our chief aim has been to examine the volcanic rocks and the sediments immediately associated with them, we have restricted ourselves to the re-mapping of a narrow zone extending for about a third of a mile on either side of the synclinal axis over a distance of some 6 miles. We have, in addition, made a reconnaissance traverse along the southern slopes of Moel Siabod in order to evaluate the relations of the Snowdonian lavas of the syncline to the Capel Curig lavas which underlie them.

The area illustrated on the map (Pl. XXXV) is also depicted on the 1-inch Geological Survey map (Old Series), Quarter-sheet 75 N.E., and comprises the 6-inch Quarter-sheet Caernarvon-shire 23
The South-West Highland Sequence
Authors: Green John Frederick Norman
Published: October 2009

This paper deals with the succession in the ancient (Dalradian) rocks of a part of the Western Highlands of Scotland, in the immediate neighbourhood of the Great Glen Fault. Along the line of the fault the length of the area is a little over 100 miles, and it extends to 30 miles south-east of it. The greater part of this region, however, is occupied by later igneous rocks or by the sea, which exposes a vast series of coast sections. It presents special advantages to a student of the ancient formations owing to the fact that the rocks are nearly all in a low stage of metamorphism, often resembling ordinary Lower Palæzoic rocks; while the members of the small portions which reach the Biotite Zone or, near Loch Leven and Dalmally, the Garnet Zone can easily be followed into the less altered stages.

Further, most of the area is readily accessible and the student has the boon of a complete set of excellent 1-inch maps and memoirs (see index-map, fig. 1) published by the Geological Survey.

Without this detailed Survey work, recording the various rock-types in all places, no general synthesis would be possible, as the complexity of structure is too great for any isolated worker. Some such synthesis is very necessary, as no section of the Highlands offers better chances of a clue to the intricate problems of the Scottish Archæan.

Up to the present there has been little agreement as to the connexions between adjacent sheets. Islay was
A New Plant (
Thallomia
) showing Structure, from the Downtonian Rocks of Llandovery, Carmarthenshire
Authors: Heard Albert , Jones John Frederick
Published: October 2009

The curious fossil which is here described and figured was discovered in a quarry about 50 yards north-west of Capel Horeb on the main road between Llandovery and Brecon (fig. 1).

Most of the rocks of the quarry consist of thickly bedded, bluish-grey, highly micaceous sandstones (Tilestones) of Lower Downtonian age, which locally approach quartzites in composition. Many calcareous bands of fossils are intercalated with these Tilestones. The fossil fauna of this quarry and of others in the immediate neighbourhood has been noted and recorded by several workers, including Dr. L. D. Stamp and, more recently, Mr. S. H. Straw, who records the following fauna from this horizon:—

Cornulites serpularius
Sclotheim.

Small Rhynchonellid.

Cucullella antiqua
(J. de C. Sowerby).

Grammysia extrasulcata
Salter.

Modiohpsis complanata
(J. de C. Sowerby).

Bellerophon trilobatus
(J. de C. Sowerby).

Holopella obsolete
(J. de C. Sowerby).

Platyschisma helicites
(J. de C. Sowerby).

Orthoceras sp.

Kloedenia (Beyrichia) wilckensiana
(Jones).

Fragment of a fish spine.

The plant recorded in this communication has been obtained, not from the sandstones which occupy the major part of the quarry, but from a lenticular patch of gritty micaceous shales which is interbedded with them (PL XLIII, fig. 1). The lenticle is bounded by a lighter-coloured zone, 4 inches wide, of fine-grained
The Upper Great Oolite, Bradford Beds and Forest Marble of South Oxfordshire, and the Succession of Gastropod Faunas in the Great Oolite
Authors: Arkell William Joscelyn
Published: October 2009

The line of division between the Forest Marble and Great Oolite in the Oxford district has been drawn at two levels by various writers. As the stratigraphical position of a rich and distinctive lamellibranch and brachiopod fauna is involved, together with that of a few gastropods and corals and the deinosaur
Ceteosaurus oxoniensis
, the question of the substage to which the beds containing them belong is of more than local importance.

The earliest writers on the subject, E. Hull and J. Phillips, who published descriptions of the sections at Kirtlington (Bletchington) Station and Enslow Bridge, about 8 miles north of the centre of Oxford, in 1859 (pp. 20, 21), and 1860 (pp. 117–18) respectively, already held differing views about the position of the junction.

Hull, who favoured a higher position than that adopted by Phillips, brought a wide experience of these formations, gained in the Cotteswolds, to bear on the Oxford district. It is significant that Hull's conclusions with regard to the relations of Forest Marble and Great Oolite at Kirtlington and Enslow Bridge were accepted and applied to the neighbouring sections at Hailey, Bladon, Shipton-on-Cherwell railway-cutting, and Islip by H. B. Woodward, who had already travelled over the whole outcrop in the South-West of England in the course of preparing his great work on ‘The Jurassic Rocks of Britain’, and who brought an even greater experience to bear on the subject than Hull (Woodward, 1894, pp. 372–7).

There followed in 1908 the Geological Survey Memoir in explanition of the
The Palæolithic Deposits of the Lower Thames Valley
Authors: Dewey Henry
Published: October 2009

I. I
ntroduction

T
he
part of the Lower Thames Valley with which this paper deals is that bounded on the west by the River Cray between Crayford and Erith, and on the east by the small stream Ebbsfleet, near Northfleet. The Pleistocene deposits of this area have long been known alike to geologists and archaeologists on account of the Palæolithic flint implements and the abundant remains of fossils found in them, and numerous descriptions of different temporary exposures of the beds have been published (see especially Hinton & Kennard, 1906). Collectors, however, desiring principally good specimens for their cabinets, did not ascertain the exact provenance of the pieces they purchased from the workmen, and no certain time sequence among the specimens could, therefore, be established. The investigations on the Palæolithic implements found in the Pleistocene beds of Northern France and Belgium had led to classifications that were generally accepted on the Continent and that were beginning to be applied to implements of similar form found in the Thames Valley, but the lack of accurate details of the discoveries in England rendered such correlation uncertain.

The Associated Portland Cement Company in 1912 informed the British Museum of their intention to remove at Barnfield pit, Milton Street, the overburden above the Chalk so that the latter could be quarried for cement-making. It was feared that the classic section in the pit would be finally destroyed, and a decision was made to examine each bed in such places as were not disturbed nor mixed
The ‘One Hundred Foot’ Raised Beach between Arundel and Chichester, Sussex
Authors: Fowler Joseph
Published: October 2009

P
restwich
, as long ago as 1859, described the raised beach between Arundel and Chichester under the title of ‘The Westward extension of the old Raised Beach of Brighton’. Clement Reid, referring to the same deposits, writes, ‘The work of the survey having thoroughly corroborated Prof. Prestwich?s view that these deposits
all belong to one period
, [the italics are my own] there will be no occasion here to discuss the question’ (
Reid, 1892, p. 346
). As a result of the general acceptance of this view of the continuity between the Brighton and Chichester deposits, it has been inferred that the underlying solid formations were not elevated horizontally, but with a considerable eastward lag; for the beach at the Brighton end is only some 15 feet above sea-level, while that at the Chichester end is 115 feet higher, though the distance between the two places is less than 30 miles. I do not know, however, of any indication of such differential movement, and it is far more likely that there are two distinct raised beaches here in Sussex, the one at about 15 feet, and the other at about 100 feet above existing sea-level. Clement Reid appears to give some support to this view, for he states (
1892, pp. 355-6
; and
1903, p. 40
) that his Bed 5 at Selsey contains deposits probably of the same age as the Brighton 15-foot stage, and he also thought the beach deposits in the Waterbeach pit to be of
A Fossiliferous Limestone associated with Ingletonian Beds at Horton-in-Ribblesdale, Yorkshire
Authors: Robinson King William Bernard
Published: October 2009

T
he
oldest rocks of the Ribble valley have long been known in the area around Horton, and they have always been considered a continuation of the larger outcrop near Ingleton.

The earlier writers included these beds as part of the ‘green slates and porphyry’ series, while in later times the name ‘Ingletonian’ has been given to this group of hard, green, felspathic grits and roughly-cleaved green mudstones.

Opinions regarding the age of the Ingletonian fall into two groups.
A. Sedgwick (1852, p. 35)
, the officers of the Geological Survey (
Dakyns & others, 1890, p. 10
),
T. McKenny Hughes (1867, p. 253 & 1902, pp. 323, 328)
, and, in more recent years,
Mr. J. F. N. Green (1917, pp. 95-7)
claimed that the Ingletonian belongs to some part of the Ordovician sequence— either to the Borrowdale Volcanic Series or to the beds which should come between the volcanics and the Coniston Limestone Series; while the other view, held by W. T. Aveline (in
Goodchild, 1892, p. 299
),
Prof. J. E. Marr (1892, p. 104)
, and
Dr. R. H. Rastall (1906, p. 99)
correlates the Ingletonian with some part of the Pre-Cambrian, such as the Longmyndian. The evidence for holding one view or the other rested mainly on the lithological characters of the rocks.

In the main exposure near Ingleton there are continuous sections in the valley for several miles, but near Horton only isolated exposures occur in the river bed and in and near the great quarry at Horton station. The
The Dartmoor Granites: their Genetic Relationships
Authors: Brammall Alfred , Harwood Henry Francis
Published: October 2009

I. I
ntroduction

S
ince
Sedgwiek and Murchison initiated the structural study of the West of England nearly a century ago a large amount of data has been applied to the interpretation of the granites of Cornwall and Devon—their age and origin, their space-form and attitude relative to the country-rocks, and their probable continuity at shallow depth.

Concerning the space-form of the Dartmoor granite, the ideas of
De la Beche (1839)
agree essentially with the modern conception of a batholith.
R. N. Worth (1888-9)
considered the exposed granite to be the lower portion of a volcanic focus denuded of its superstructure. On the other hand, A. R. Hunt (1894) considered the granites to be wholly plutonic. A laccolithic emplacement was suggested by
W. A. E. Ussher (1888)
, but he withdrew this theory four years later.

The laccolith theory was advanced as a probability by the authors of the Geological
Survey Memoir (1912, No. 338)
; laccomorphic internal features were described, and the composite character of the intrusion was recognized. Similar features, correlated according to type and emplacement-sequence, were described by the present authors (1923, 1926) and by
Mr. C. W. Osman (1928)
. Mr. R. H. Worth considers the West of England granites to be protrusions from a granite wedge forming the axis of the peninsula (1930, p. 94), and Dr. R. H. Rastall describes the Cornish granites as cupolas on a batholith with underground connexions at small depth (1931). None will question the reality of the cupola-feature, but the unqualified interpretation of the
Xenoliths of Igneous Origin in the Trégastel-Ploumanac'h Granite, Côtes du Nord, France
Authors: Thomas Herbert Henry , Smith Walter Campbell
Published: October 2009

I. I
ntroduction

I
n
the northern coastal region of Brittany, in the neighbourhood of Trégastel and Ploumanac'h (PL XVIII), to the north of Lannion, a red, mainly porphyritic, granite is admirably exposed in shore and inland sections, and is remarkable for the number of xenoliths which it contains, of a kind usually referred to as basic segregations or basic patches. Especially clear evidence is available to prove that these inclusions have had their origin in hybrid rocks formed from an earlier intrusion of olivine-norite. In view of the similarity of the xenoliths to basic patches that occur in other granites where evidence of their manner of formation is not so clear, it has been thought desirable to place our observations upon record.

The red granite of Trégastel and Ploumanac'h forms the outer and oldest member of a complex that consists of several distinct intrusions of granite and occupies the country between Ploumanac'h and Trébeurden, an area of some 40 square miles. It was regarded by
Prof. C. Barrois (1903)
as being of Devonian age since it has escaped the movements and foliation which have affected the older rocks with which it is in contact, but the more recent explanation of the Geological Survey map places its intrusion at the beginning of the Carboniferous.

The Geological Survey map shows this granite-complex asconsisting of three granitic masses. A centrally situated ‘granulite ’ in the He Grande and neighbouring mainland; an outer ‘granite porphyroïde rose ’ at Ploumanac'h; and, between these two,
Carboniferous Plants from Sinai
Authors: Seward Albert Charles
Published: October 2009

I. I
ntroduction

S
everal
years ago Dr. John Ball of the Egyptian Geological Survey handed to me for description some specimens of fossil plants which he had collected in the Sinai Peninsula : it is fitting that the long-delayed fulfilment of my undertaking should be accompanied by an apology.

The fossils were found in a district between the Wadi el Hommur and the Wadi Khaboba in the hills about the little Wadi Um Shebba. Dr. Ball described the locality as situated approximately on lat. 29° 7' N. and long. 33° 15' E., about 15 miles east of the Gulf of Suez and 7 miles south of the Tih escarpment.1 The diagrammatic section (fig. 1) is an enlargement of a drawing supplied by Dr. Ball : the position of the plant-bearing bed is indicated by crosses.

In
1868 Salter
gave a brief description of a species of Lepidodendron, which he named Lepidodendron mosaicum, believed to be from the district where Dr. Ball's fossils were obtained. Salter did not publish a figure of the new species, and his notes on it are inadequate as a diagnosis. A specimen in the British Museum (V. 19487 : PI. XXI, fig. 1) labelled Lepidodendron mosaicum from the Desert of Sinai, which is from the Sir Roderick Murchison Collection (old number 8950), may be the actual fossil on which Salter founded his species.

Dr.
Ball (1916, p. 152, fig. 25)
in his memoir on West-Central Sinai figured two decorticated specimens as Lepidodendron from Wadi Um Shebba which
Fossil Plants from the Bokkeveld and Witteberg Beds of South Africa
Authors: Seward Albert Charles
Published: October 2009

I. I
ntroduction

N
ine
years ago Dr. S. H. Haughton of the Geological Survey of the Union of South Africa sent to me for description a collection of fossil plants from the Bokkeveld and Witteberg Series of the Cape Province. At my suggestion Mr. S. L. Ghose, who was then a Research Student of Selwyn College, examined the material and incorporated a preliminary account of it in an unpublished thesis. Subsequently, Dr. T. M. Harris made a careful examination of the fossils and it was our intention to publish a joint paper : unfortunately, pressure of other duties rendered this impossible. I am greatly indebted to both these gentlemen, but I must accept responsibility both for the delay and for the conclusions reached in the present communication.

The specimens described in the following paper were obtained by Dr. Haughton from the upper part of the Bokkeveld Series at Schiet Kraal, Steytherville, in the south-central part of the Cape Province, about 80 miles north-west of Port Elizabeth, and from the Witteberg shales at Nourse Poort, Steytherville. One of the specimens (PI. XXIII, fig. 7) was found at a farm east of the Bezuidenhouts River, Uitenhage, in beds described by Dr. Haughton as the second shales of the Bokkeveld beds.

In a letter written by Dr. Haughton (December 14th, 1922) he stated that the plant-bearing shales described as Upper Bokkeveld should be assigned, from a palaeontological view, to the Witteberg Series. He added that ‘ in the field there is no clear line
Contact Metamorphism in South-Eastern Dartmoor
Authors: Fitch Albert Alfred
Published: October 2009

I. H
istorical
I
ntroduction

T
he
area mapped and described comprises Sheets CXIV S.W., CXIX N.E. and S.W., CXX N.W., and CXXV N.W. and N.E. of the six-inch Ordnance Survey series, Devon.

The history of research in the area may be considered to show three phases : (i) the pioneer observations, extending up to 1811; (ii) the investigation of the sequence and structure of the rocks outside the metamorphic aureole; and (iii) the investigation of the petrogenesis and structure of the rocks comprising the granite intrusion and its metamorphic aureole. The previous work (see list of references, pp. 604-7) deals with the second phase in some detail, but the third has received less attention. This paper will treat of the petrogenesis and structure of the thermo- and dynamo-metamorphosed rocks.

The earliest observations on the area which are of geological interest are found in the two early ‘surveys ’of the county of Devon by Risdon (1610) and Westcote (1630) respectively; they refer to the Brent lodestones. An account of a large Devon magnet, probably from Brent, is given in volume 2 of he Philosophical Transactions. Chapple (1785) gives further details of the Brent magnets. Following these come some notices of the occurrence of various rocks in the ‘agricultural surveys ’ of Fraser (1794) and Vancouver (1808), the general county histories of Polwhele (1797) andand Lysons (1822), and the ‘Natural History’ of Bellamy (1839).

The earliest petrographical observations are due to Maton, a keen observer, who thus described the Dartmoor granite in 1797: ‘The
The Geology of the Ruhuhu Coalfields, Tanganyika Territory
Authors: Stockley Gordon Murray
Published: October 2009

I. I
ntroduction

F
rom
June to October of 1930 it was my good fortune to survey the coalfields of the Njombe and Songea districts of Tanganyika Territory, east of Lake Nyasa; an area of some 1500 square miles, of which 1330 square miles are occupied by Karroo rocks. The coalfields stretch eastwards from the shore of the lake, their eastern boundary being formed by the disused motor-road from Songea township to Njombe; the northern and southern limits are defined by the faulted boundaries of the Karroo formation. The extension of the Karroo rocks beyond the eastern boundary is unknown; it is probable that they continue in a north-easterly direction as far as to the Rufiji River. An account of the coalfields, with especial reference to their economic possibilities, is in course of publication in a Government Bulletin. The description of the geology given in the present paper will serve as an introduction to the papers dealing with the palæontology of the Karroo rocks.

Very little work had been done in this area previously, although German geologists had determined roughly the extent of the Karroo formation.
Bornhardt (1900)
, the first geologist to visit the district, had examined a coalfield south of Manda in 1895-7 and condemned it. His observations are summarized by
Koert (1913, pp. 195-6, translation)
as follows:—

‘Bornhardt speaks of the Ruhuhu as a tableland intersected by faults, and divides up its beds as follows:—

River depression. The following were identified in the collection:—

(i) Petrified Fossil Wood from the
Lamellibranchia from the Karroo Beds of the Ruhuhu Coalfields, Tanganyika Territory
Authors: Cox Leslie Reginald
Published: October 2009

I. I
ntroduction

T
his
paper describes an interesting series of Karroo lamelli-branchs collected by Mr. G. M. Stockley during his recent survey of the Ruhuhu coalfields, east of Lake Nyasa. These fossils come from two distinct horizons, the lower belonging to the upper part of the Ruhuhu Beds, which overlie the local Upper Coal-Measures, and the upper to the Manda Beds, near the top of the Karroo System, as developed in this district.

The Ruhuhu Beds, which consist largely of fine-grained calcareous sandstones and shales, are overlain by the Lower Bone Bed (of Stockley), which contains reptilian remains determined by Dr. S. H. Haughton as belonging to a middle Lower Beaufort horizon. The lamellibranch fossils now described, which are very abundant in certain beds, are small freshwater shells referable to five species of the genus
Palœomutela
, two of which occur in South Africa, and one, P. oblonga (Jones), in Nyasaland. Wherever
Palœomutela
and the allied genus
Palœanodonta
have been found in Karroo beds, they always seem to occur at a Lower Beaufort horizon, and it is rather remarkable that they have not yet been found in the underlying coal-bearing beds of the Ecca stage. In view of this restricted range, it is most probable that the molluscan horizons of the Ruhuhu Beds, like the overlying Lower Bone Bed, are of Lower Beaufort (that is, uppermost Permian) age.

The most important work on these Karroo lamellibranchs is a paper by
Amalitsky (1895)
,1 who shows that most of the
On a Collection of Karroo Vertebrates from Tanganyika Territory
Authors: Haughton Sidney Henry
Published: October 2009

I. I
ntroduction

T
he
vertebrate bones described and discussed in this paper are part of a consignment sent for examination by Dr. E. O. Teale, Director of the Tanganyika Geological Survey, and collected by Mr. G. M. Stockley of that Survey in the Ruhuhu area of Tanganyika Territory. Gathered as they were during the course of a survey undertaken primarily for the study of the economic possibilities of the area, the bones consist almost entirely of weathered pieces picked up on the surface. They were sent to Cape Town in seven boxes, each piece of bone being marked with a special number which corresponded to a locality on Mr. Stockley's field-sheets.Examination showed that some of the fragments could be accurately fitted to make more or less complete bones or recognizable parts of a skeleton; in some cases fragments said to come from different localities were found to fit together, owing to errors in marking. Many others remained isolated, for one of two reasons: either the bone had been broken and rolled before being buried in the sediments, or the remainder of the pieces that were originally attached to it had not been collected.

Enough, however, has already been found to show that Mr. Stockley has discovered an area of great interest to students of the Karroo vertebrate material; and my thanks are due to him and to Dr. Teale for the opportunity of studying this interesting but tantalizing collection.

The following pages contain a description of the bearing
The Lavas of Mauritius
Authors: Shand S. James
Published: October 2009

The geology and physical geography of Mauritius formed the subject of a communication to the Geological Society by Major H. de Haga Haig in 1895,
1
which has been the basis of subsequent descriptions of the island in the
Encyclopædia Britannica
and elsewhere. Major Haig showed that Mauritius is formed of basaltic lavas and tuffs, and that several of the hills in the interior of the island are volcanic cones, some of them having well-preserved craters. His description of the lavas is inadequate from a petrographic standpoint, being based on megascopic characters only. The basalts are described as dolerites and diorites; by the latter term, horn-blende-basalt seems to be intended. The most arresting feature in Major Haig's account is the record of ‘ crystalline chloritic schist ’ on Mt. La Selle, near the middle of the island. Students of Wegener's hypothesis will recall that Wegener believed the volcanic islands of the great oceans to be fragments of the lithosphere, left behind by the westward-drifting continents. The apparent absence of continental types of rock such as granite and schist from these islands was explained by Wegener as a consequence of the thick veneer of lava acquired by the islands since they broke away from the mainland. Major Haig's record of chloritic schist on Mauritius seemed to offer striking confirmation of Wegener's view, and called for confirmation and amplification.

I visited Mauritius in January, 1931, with the intention of making such observations as time would permit among the lavas, and with the special
The Rocks between the Carboniferous and Trias in the Birmingham District
Authors: Boulton William S.
Published: October 2009

I. Introduction

In 1924, I described a group of breccias (Nechells Breccia) which was revealed by borings through the Trias in the eastern part of Birmingham (Boulton, 1924), and I attempted a correlation of the Nechells Breccia with other well-known pre-Trias breccias in the Midlands, including those of Clent and Northfield, some six miles south of Birmingham, and the Hopwas Breccia to the north, in the neighbourhood of Hopwas and Sutton Coldfield.

Evidence was adduced to show that all these breccias, with their associated sandstones, lie unconformably on the Calcareous Conglomerate group (Lower Enville Beds of the Geological Survey) or the Keele Beds, and that they are separated by a break from the overlying normal Bunter beds. Further, I suggested that in the absence of palaeontological evidence they should be retained in the Permian, in which system the Clent and Northfield breccias had been placed since the time of the original survey.

At that time (1924) the Survey were completing their 6–inch maps and memoirs of the district, and they adopted an interpretation somewhat different from mine. The Nechells Breccia was by them correlated tentatively with the Hopwas Breccia and linked up with the Trias, while the Clent and Northfield breccias were included in the Carboniferous (Geological Survey, 1925). No appreciable unconformity at the base of the Clent Breccia was admitted by the Survey, but only such small local discordance as one might expect at the base of such materials as scree beccias. Incidentally, the effect of the Survey classification
The Dalradian Succession in Islay and Jura
Authors: Allison Archibald
Published: October 2009

I. Intoduction

This paper is concerned only with rocks of accepted Dalradian age. I have, therefore, not taken into account formations lying south-west of the Loch Skerrols thrust, which include the problematical Bowmore Sandstone.

The succession, which I think may be considered as proved, is identical with that put forward by Prof. E. B. Bailey in 1917; but it has been established in the present instance mainly by consideration of current-bedding and graded bedding in several members of the sequence. The significance of certain conglomerates on Beannan Dubh, however, has again been investigated. In the following pages it is intended to retain the stratigraphical nomenclature used by Prof. Bailey, and also to discuss formations put forward by other authors in terms of this nomenclature.

The Dalradian succession in Islay and Jura, according to my determination, is as follows, the oldest rocks being at the bottom of the table :—

11.

Ardmore and Laphroaig Quartzites.

10.

Port Ellen Phyllites.

9.

Scarba Conglomeratic Group.

8.

Jura Slates.

7.

Main Quartzite.

6.

Dolomitic Group of North Islay.

5.

Power Fine-Grained Quartzite of North Islay.

4.

Portaskaig Conglomerate.

3.

Islay Limestone.

2.

Mull of Oa Phyllites.

1.

Maol an Fhithich Quartzite.

Since opinions on the geological structure of this area are many and varied, it does not seem out of place here to review and analyse very briefly
The Conglomerates and Grits of the Bala And Valentian Rocks of the District Between Rhayader (Radnorshire) and Llan-Sawel (Carmarthenshire)
Authors: Davies Kenneth Arthur , Platt John Isaac
Published: October 2009

I. Introduction and Historical Survey

During the survey of the country between Elan Valley (Radnorshire) and Pumpsaint (Carmarthenshire) (Davies, 1926 & 1928), a collection was made of the grits and of the pebbles from the conglomerates which occur at many horizons in the district. To these have been added further specimens from the country to the north-east, so that the arenaceous deposits between Camlo Hill (Radnorshire) and Llansawel (Carmarthenshire) are described in the following paper. The whole of the sediments dealt with occur in rocks of the graptolitic facies and lie on the north-western side of the Towy anticlinorium, and they range from the upper part of the Bala stage to the lowest part of the Gala stage. Although the largest accumulations of coarse rocks are confined principally to the Upper Bala and the Lower Birkhill stages, arenaceous material occurs locally throughout the whole succession, and it is only the Monograptus convolutus zone that lacks a noteworthy amount of coarse material; even at this horizon, however, grits up to 6 inches in thickness are found in the country near Ystradffin. As the rocks of the area consist predominantly of fine-grained shales and mud-stones, the widespread occurrence in them of arenaceous and conglomeratic deposits gives to these sediments an additional importance.

Some of the arenaceous deposits appear at first sight to occur at constant horizons, and therefore to afford data for correlation purposes throughout Central Wales. Closer investigation, however, proves that they cannot be so applied, since they are only local