bluuebunny/crossref_metadata_2025 huggingface dataset:
Tertiary Foraminifera from the Naparima Region of Trinidad (British West Indies)
Authors: Nuttall Winfred Laurence Falkiner
Published: October 2009

This paper presents the results of an examination of a large collection of Miocene and Upper Eocene Foraminifera from the Naparima region of Trinidad (British West Indies). The material was assembled by Prof. V. C. Illing, who is describing the stratigraphical and structural geology in a separate paper (1927, GN). One hundred and forty-four species of Foraminifera have been identified, and certain forms have been found to be of value in determining stratigraphical horizons.

I am indebted to Mr. C. Forster Cooper for giving me access to the Brady Collection of Foraminifera at Cambridge. Mr. R. Kirkpatrick kindly gave me facilities to examine that portion of the Brady Collection which is preserved in the Zoological Department of the British Museum (Natural History). Dr. W. D. Lang lent a small collection of specimens from the Trinidad Tertiary strata named by R. J. L. Guppy, who had placed them in the Geological Department of the British Museum (Natural History). Mr. E. Heron-Allen has kindly given advice regarding the identification of a few rare forms. I have studied a sample of Orbitoidal rock from Mount Moriah (Trinidad) collected by Mr. I. A.Stigand, and deposited in the Sedgwick Museum, Cambridge. The type-specimens and other material have been placed in the Sedgwick Museum, Cambridge.

Since the date of completion of the manuscript of this paper, Dr. J. A. Cushman has introduced a re visionary classification of the Foraminifera; also, several important papers on American Tertiary Foraminifera have appeared. It is regretted that no reference is
The Ammonites
Authors: Spath Leonard Frank
Published: October 2009

With the exception of certain pyritized ammonites from a few horizons, notably the Tropidoceratids discussed below, the specimens from the Belemnite Marls are not in a good state of preservation. Some, like the
Polymorphites
of the
lineatus
type, from Bed 112, or
Phricodoceras taylori
from the base of the Marls, are not difficult to recognize, even in crushed impressions, while from the occurrence, in Beds 115–118
a
, of numerous small pyritized ‘
Uptonia bronni
’ (Rœmer) it may be inferred that the associated traces of larger whorl-fragments belonged to the adult
Uptonia jamesoni
. The poor state of preservation of the ammonites is all the more regrettable, since certain examples from the comparatively unfossiliferous lower three-quarters of the Marls cannot be definitely identified, even generically. Correlation with other areas where the
jamesoni
zone is well developed, for instance Pabay or Wurtemberg, cannot thus be more accurately established than in my previous paper (Spath, 1923, p. 6).

Of the family Deroceratidæ of the lower beds,
Apoderoceras
Buckman and
Phricodoceras
Hyatt are alone definitely recognizable, while
Metaderoceras
Spath and
Hyperderoceras
Spath are represented only by imperfect specimens of uncertain affinities. Still more doubtful are the fragments provisionally referred to
Tetraspidoceras
Spath, and it is possible that at least some of these may belong to the Liparoceratid genus
Parinodiceras
Trueman. Of the presumed derivatives of Deroceratidæ,
Cæloceras
Hyatt, on the one hand, is represented by pyritized examples; but the forms of
Liparoceras
Hyatt, on the other, are badly preserved, as are the specimens of its probable ‘degenerate’
The Lower Carboniferous Rocks of the Menaian Region of Carnarvonshire: their Petrology, Succession, and Physiography
Authors: Greenly Edward
Published: October 2009

The ancient name ‘Arvon’ compounded of ‘Ar’ = ‘opposite to’ and ‘Von’ = ‘Mon’ = ‘Anglesey’, may be adopted as a concise designation for the country which, extending from the vicinity of Aber to the western coast a few miles beyond Carnarvon, lies between the Menai Strait and the mountain-land. For some eight years past I have been surveying this country, and hope to present the results from time to time.

As its Upper Palæozoic rocks have now been completely surveyed, and as fossils amply sufficient to establish the zonal divisions have been obtained, their lower division can with convenience form the first instalment of ‘the Geology of Arvon.’

Without the contribution of Dr. Stanley Smith, this paper could not have been written at all, for he has undertaken the palæontology in general, besides the determination of the corals, which is entirely by him, and he spent several days with me on the ground. He is also responsible for part of the Limestone petrology, and procured the analysis of the ooliths made by Mr. T. W. Harrison. The numerous
Producti
were all named by Miss Helen Muir-Wood, while Mr. John Walton determined the plants. Certain fishes were named by Sir Arthur Smith Wood-ward, the ostracoda by Mr. T. H. Withers, while Mr. J. Wilfrid Jackson examined other forms and lent some fossils for comparison. Prof. P. G. H. Boswell has examined the heavy minerals of several of the formations, and Mr. H. C. Sargent has seen the cherts both in
The Pre-Cambrian Complex and Associated Rocks of South-Western Lleyn (Carnarvonshire). With a chapter on the Petrology of the Complex by Edward Greenly
Authors: Matley Charles Alfred , Greenly Edward
Published: October 2009

The district with which this paper is concerned is the oblong coastal strip of the Lleyn peninsula of Carnarvonshire, about 14 miles long and 1 to 3 wide, that extends from Nevin in a south-westerly direction to Bardsey Sound and Aberdaron Bay. The coast-line forms a natural boundary on the north, west, and south, and the eastern boundary runs inland from the northern coast near Nevin to the southern coast on the east side of Aberdaron Bay, along an important line of dislocation (called in this paper the Boundary-Thrust) which separates the Pre-Cambrian country on the west from the Palæozoic region farther east. This latter region will form the subject of a separate communication, but lying within the Pre-Cambrian tract is an area of Palæozoic rocks around the village of Aberdaron which it will be more convenient to include in the present paper.

The study of the solid geology is rendered difficult by the thick mantle of Glacial drift, consisting of boulder-clays, sands, silts, and gravels, which have filled up the old drainage-basins to a great height and the ancient bays to a depth below present sea-level, as, for instance, at Forth Nevin and Porth Dinllaen on the north and Aberdaron Bay on the south. The present drainage is carried by little streams which for the greater part wander through the drift, but occasionally cut into the Pre-Glacial rock-floor. The sea-cliffs of drift often reach from sea-level to a height of 100 feet or more; but, fortunately for geological investigation,
The Volcanic Complex of Calton Hill (Derbyshire)
Authors: Ivanovich Tomkeieff Sergei
Published: October 2009

The Carboniferous volcanic rocks of Derbyshire have been already described by A. Geikie, H. H. Arnold-Bemrose, and Mr. H. G. Sargent, and in particular Dr. Bemrose has published a paper dealing specially with the inclusions in the Calton Hill basalt. The subject, however, is by no means exhausted. Since the opening of a road-metal quarry at Calton Hill, a new and most interesting section has come into view, the study of which led me to undertake a detailed investigation of the volcanic complex of Calton Hill and the related lavas of Miller's Dale.

Calton Hill is situated 3½ miles east of Buxton, and a mile and a half south-west of Miller's Dale station. Seen from the north, it appears as a clearly outlined rounded hill, standing as a buttress against the escarpment of Chelmorton Low. Its height is 1319 feet above O. D., and it rises about 200 feet above the general level of the limestone plateau. It is situated in the horizon of the upper lava (‘loadstone’) which, according to Dr. T. F. Sibly, occurs in the Carboniferous Limestone between Zones D
1
and D
2
.

On the north-eastern slope of Calton Hill, approximately a third of the way up, is situated the newly developed road-metal quarry. It is entered by a narrow level-cutting and is roughly divided into three separate bays. Fig.1.—
Geological sketch-map of the road-metal quarry at Calton Hill (Derbyshire)
. Fig. 2.—
Profile of the quarry-cutting at Calton Hill
. Fig.3.—
West-to-East section of the quarry at the Calton Hill
.

The Rather
The Geology of Part of North-Western Rhodesia
Authors: Murray-Hughes Robert
Published: October 2009

I. I
ntroduction
.

The literature with special reference to Northern Rhodesia is not abundant. A. J. C. Molyneux made several visits to the country, but, although he must have collected a good deal of general information, he published only the results of his work on the distribution of the Karroo System in Northern Rhodesia (15). His work was confined to the stretch of country bounded on the north by the Kafue and Zambezi Rivers, on the west by the railway-line, and on the south and east by the boundary of Southern Rhodesia.

The outstanding piece of work was that of F. E. Studt (22). I suppose that only one who knew the country at about the same time as that during which Studt's mapping was done, can really appreciate the immensity of the task which he set himself. He certainly had Cornet's and others' investigations to aid him in his preliminary work in the Congo, but none for Northern Rhodesia.

Unfortunately for me, Studt's paper did not fall into my hands for several years after my interest in the geology of Northern Rhodesia had been quickened; neither did I have access to the publications relative to the Belgian Congo. So, for a long time, I traversed a road already surveyed. The greater part of the work was done in my own time during snatched shooting expeditions. In 1925 a year's field work was begun for the Rhodesia Minerals Concession Limited, and a good deal of the topography shown east of the
The Pliocene and Pleistocene Deposits of Wadi Qena and of the Nile Valley between Luxor and Assiut (QAU)
Authors: Sandford Kenneth Stuart
Published: October 2009

I. I
ntroduction
.

In §§ V, VI, & VII the following plan is adopted:—Wadi Qena, being well adapted to the purpose, is taken as a type-area in which to explain general principles; the region between Luxor and Qena is used for a like purpose.

A rapid survey is then carried northwards along both sides of the Nile, the principles being taken for granted, and only new features emphasized and their bearing upon the general condition explained. Economy of space is thus effected.

For bibliography such references are given as will deal with the question in hand, and will lead to the full literature; no attempt is made to give a complete bibliography within the paper itself.

In the summer of 1925 Sir Flinders Petrie, F.R.S., on behalf of the British School of Archæology in Egypt, invited me to investigate certain problems which required purely geological training. These had already been set forth in print.

I went to Egypt in November of that year, and spent the winter months with a small camel-caravan on a march of some 600 miles (excluding offsets); the route is shown in Pl. XXVI.

The results, so far as the particular task was concerned, have been published in part, together with certain geographical, archæological, and other data. In the course of the work, however, allied problems of more general importance presented themselves, and provided the solution of the original object of research. I propose now to present and discuss the geological results of the survey. Between Assiut
The Glaciation of Eastern Edenside, the Alston Block, and the Carlisle Plain
Authors: Trotter Frederick Murray
Published: October 2009

I. I
ntroduction
.

The glaciation of the area herein described first interested me while re-surveying the Longtown Sheet of the Geological Survey Map (N.S. Sheet 11) and the northern part of the Carlisle Sheet (N.S. Sheet 17). In this area there was evidence of two glaciations, and the later of these appeared to have emanated from the Southern Uplands of Scotland. The retreat of this ice-sheet was followed westwards along the northern shores of the Solway Firth in my vacation during the years 1921–22.

During the year 1923, the first year of the re-survey of the Brampton Sheet (1-inch N.S. 18) by the Geological Survey, a wealth of glacial retreat-phenomena of the earlier glaciation was discovered near Brampton, and briefly described in the Summary of Progress for that year. The evidence for a westward retreating ice-sheet was incontestable, but the direction of the drainage of the impounded glacier-lakes suggested the operation of Lake District rather than Galloway or Southern Upland Ice. The composition of the drift also threw grave doubts upon the accepted Scottish origin of this ice-sheet. Nevertheless, there were some puzzling features connected with the distribution of the erratics and the drift. To cite but one example: although Lake District erratics, principally lavas and ashes of the Borrowdale Volcanic Series, predominated in the drift, suggesting Lake District ice moving down Edenside, yet the drift did not contain a single boulder of Shap granite, a boulder to be expected from such an ice-movement. Therefore, before I committed myself to a
Foliation and its Relations to Folding in the Mona Complex at Rhoscolyn (Anglesey)
Authors: Greenly Edward
Published: October 2009

In ‘The Geology of Anglesey’ it was pointed out that little had really been ascertained concerning the laws and chronology of the foliation of the Mona Complex. A chronology was given, but the foliation of Holy Isle was therein treated as a unit, whereas it has proved to be much more than a unit.

I found in 1922 that the most favourable sections for further investigation were those of the South Stack Series on the sea-cliffs of Rhoscolyn, especially under Rhoscolyn Hill, opposite the Maen-y-fran islets (G. of A., folding-plate ii). For, in the core of that major anticline, the beds are, as wholes, nearly horizontal for a quarter of a mile, which eliminates complication due to dip on major folding. The present paper is the outcome of some four weeks' study of the section in 1922 and 1923, followed by reexamination of the thermal aureoles of the basic intrusions of Holy Isle.

The original character of the rocks, their anamorphic condition, and their tectonics, have already been described. Here, therefore, it need merely be recalled that they were originally grits and shales; and that, as Rhoscolyn lies within one of the four anamorphic maxima of the Mona Complex, there are no catamorphic textures, but that all are now holocrystalline schists. Considered with regard to capacity for foliation, there are seven principal types :—(1) The massive green grits of the Stack Moor division of the South Stack Series (which are sometimes 30 feet thick); (2) the somewhat similar green grits
The Avonian Succession in the South of the Isle of Man
Authors: Lewis Herbert Price
Published: October 2009

The Carboniferous rocks described in this paper occur within an area some 8 to 9 square miles in extent surrounding the ancient town of Castletown. The district is coastal and low-lying, a considerable portion being less than 100 feet above sea-level. The highest ground lies north-west of Ballasalla, where a few small tracts rise slightly above 200 feet.

The solid rocks are for the greater part obscured by a thick covering of drift, alluvium, or blown sand, and the chief outcrops are on the coast, usually between tide-marks. Most of the inland outcrops are confined to quarries lying west of the village of Ballasalla, to the Silver Burn, and to its tributary the Awin Ruy.

The heavy growth of seaweed and the honeycombing of the boring molluscs near low-water-mark render difficult the collecting of fossils, which, in many places, are also partly or totally destroyed by dolomitization, especially near the more important faults. Stretches of sand, shingle, and displaced joint-blocks break the continuity of the beds in the cliffs and on the foreshore, so that direct measurement of thickness is often impossible.

The Carboniferous rocks are bounded on the north-west by the Port St. Mary—Arbory Fault, which extends from Perwick Bay to near Ballashimmin (a distance of 5 miles), and with variable throw brings up the Manx Slate Series. Elsewhere on land the boundary is an unconformable or faulted junction with the Lower Palæozoic rocks. A similar junction probably exists a short distance below low-water-mark between the mouth of the
Petrographical Notes on the Geological Collection from the south Central Sahara made by Mr. Francis R. Rodd
Authors: Tyrell George Walter
Published: October 2009

There are four volcanic rocks in the collection, two basalts and two trachytes. They all come from the volcanic region north and north-east of Auderas (Central Air), 1 which, from Mr. Rodd's mention of ‘isolated volcanic domes’ and ‘conical peaks’, appears to be of Recent, or, at the earliest, of Kainozoic age.

The two basalts are labelled ‘Tighummar’, a locality about 14 miles north of Auderas on Rodd's map. One specimen is of the porous character and pale-grey tint so frequent in Kainozoic and Recent basalts, and shows small phenocrysts of olivine and augite, the former weathering into yellow limonitic spots. The other rock is darker and more slag'gy in appearance, and is devoid of determinable phenocrysts.

In thin section the pale-grey rock proves to be an olivinebasalt, with sparse and small phenocrysts of almost colourless augite, sometimes showing a faint purplish tinge, and olivines with thick investments of red iron-ore. The olivine forms some phenocrysts as big as the pyroxenes, but all transitions in size can be traced down to numerous, small, hæmatized crystals which form part of the ground-mass. The ground-mass consists of plagioclaselaths and microlites (labradorite, Ab
2
An
3
), granular augite, and magnetite-cubes, together with the above-mentioned olivines. There is a small amount of turbid isotropic base. The felspars show well-marked flow orientation, and range in size from microlites to microphenocrysts.

The second rock approaches the ultrabasic basalts in composition. It shows numerous small phenocrysts of fresh olivine and augite. The latter is dictinctly publish, but many sections have
The Origin of the Etruria Marl
Authors: Robertson Thomas
Published: October 2009

It has long been known that there lies immediately above the main productive Coal Measures of the Midlands a peculiar group of variegated clays. These beds are known by differ- ent names in the different coalfields, but the best-known term is that of Etruria Marl, first used by Dr. W. Gibson in his elucidation of the sequence in the Upper Coal Measures of North Staffordshire.

The position of this group in the Coal Measure sequence is as follows:—

A consideration of the nature and distribution of the deposits of Etruria Marl type in the Midlands shows

1.

That they are similar in macroscopic and microscopic character and in chemical composition to deposits undoubtedly formed by the decomposition of the basaltic rocks of the Midlands and of many other districts.

2.

That they contain, in the vicinity of the Midland basalts, actual fragments of decomposed basalt.

3.

That they were deposited at times during which we have proof of extensive denudation of basic volcanic rocks in the Midlands, and in the areas in which we have proof that the products of this denudation were deposited.

4.

That no known occurrence of earlier rocks is competent to produce a deposit corresponding in age, character, quantity and distribution to the Etruria Marl of the Midlands.

These facts appear to admit of no escape from the conclusion that the Etruria Marl was produced by the decomposition and denudation of the Midland Basalts in
The Geology of North-Eastern British Somaliland
Authors: Brown Charles Barrington
Published: October 2009

This paper deals with a strip of country lying along the 49th meridian east of Greenwich from the coast to about 80 miles inland, and with a belt 50 miles long running westwards of that meridian between latitudes 11° 00′ and 11° 08′. The political boundary between British and Italian Somaliland coincides with this meridian.

I was fortunate in being provided with the topographical map, contoured at 250-foot intervals, which had recently been made by the officers of the Anglo-Italian Boundary Commission. Part of this was enlarged to the scale of 1 inch to a mile, and with it I mapped geologically a considerable area.

North-eastern Somaliland has been visited previously by geologists on two occasions. R. A. Farquharson (1924), the Government Geologist of the Protectorate, made a reconnaissance from Las Khorai along the foot of the Al Hills for some 25 miles, and thence to Bunda Ziada, from whence he returned by a more northerly route. Prof. G. Stefanini (1925) journeyed southwards in 1924 from Bosaso on the coast, in Italian territory, and crossed into British Somaliland at Hegligab: thence he passed through Buran to the Nogal Valley. The greater part of the district I mapped had, therefore, been unvisited hitherto.

II. Topography.

The political boundary crosses four types of surface:―

(1) The Nogal Valley and Sorl Haud: drainage east-ward.

(2) The Hormo Plain: drainage eastward.

(3) The A1 hills: drainage south to south-eastward on one flank, and northward on the other.

(4) The coastal region: drainage northward.

(1)
Additional Fossils from the Cambrian Rocks of Comley, Shropshire
Authors: Cobbold Edgar Sterling
Published: October 2009

During the last 20 years a good many additions have been made to my collection from the Cambrian rocks of Comley. Some of these specimens indicate species new to the locality; others throw additional light on those previously described.

An attempt is also made in this paper to clear up a number of doubtful generic references that have appeared in my previous communications. Particularly is this the case with those species that were formerly referred by me to
Micmacca
Matthew and
Anomocare
Angelin. Matthew's genus is certainly present, but some of the specimens must be put under
Strenuella
. Angelin's genus is not represented, and the forms so designated seem to come under
Protolenus
and
Strenuella
.

Prof. P. E. Raymond (1913, p. 102) defines the family as follows:—

‘Hypoparia of small size, cephalon and pygidium subequal, free cheeks absent from the dorsal side, thorax of three segments; pygidium annulated or smooth. Lower and Middle Cambrian. Northern Europe and Eastern North America.’

He includes the following genera in the family:—
Eodiscus
Matthew, type species
E. schucherti
Matthew;
Goniodiscus
Raymond, type species
Microdiscus lobatus
Hall;
Weymouthia
Raymond, type species
Agnostics nobilis
Ford.

Unfortunately,
Goniodiscus
is pre-occupied, having been used by Müller and Troschel in 1842 for an asteroid. I do not propose any new generic name to replace
Goniodiscus
, for, on analysis of the published figures of the species of the Eodiscidae, I find that in respect of Raymond's first distinction, namely, the relative lengths of the glabellae, the two groups seriously overlap, and
The Stratigraphical Distribution of the Cornbrash : II. The North-Eastern Area
Authors: Douglas James Archibald , Arkell William Joscelyn
Published: October 2009

I. I
ntroduction

I
n
a previous communication to the Society (
Douglas & Arkell, Part I, 1928
) we gave a detailed account of the stratigraphical distribution of the Cornbrash in the South-West of England between Oxford and the Dorset coast, describing the more important features of the faunal sequence and giving our reasons for amending the list of brachiopod zones propounded by the late
S. S. Buckman (1927, p. 10)
.

The present paper deals mainly with that part of the Cornbrash outcrop which lies between Oxford and the Humber, running through the counties of Oxfordshire, Buckinghamshire, Bedfordshire, Northamptonshire, and Lincolnshire. Preliminary observations on the outcrop in Yorkshire are also included, but the detailed investigation of that county has not yet been completed.

Many of the conclusions arrived at during our study of the South-Western area have been strengthened or confirmed by discoveries made when following the outcrop farther north, and many new facts have come to light which show that our criticism of Buckman's clinal diagram (1927, p. 12), in which he sought to prove extensive penecontemporaneous erosion in the Cornbrash, was fully justified. As before, we have confined our attention chiefly to the brachiopod sequence, but it is hoped that the numerous ammonites collected will be dealt with at some future date.

It may be recalled that the exact stratigraphical position of two of the suggested brachiopod zones—those of Tegulithyris bentleyi and Obovothyris stiltonensis, yet remained to be proved. The first-named (Zone 11) was placed by Buckman at the summit of
The Geology of the Country around Mynydd Rhiw and Sarn, South-Western Lleyn, Carnarvonshire
Authors: Matley Charles Alfred
Published: October 2009

I. I
ntroduction

I
n
a recent communication to this Society (
Matley, 1928
) I showed that the Pre-Cambrian Complex of south-western Lleyn is separated from the Palæozoic region to the east of it by the Boundary Thrust, which runs from the south coast of the Lleyn Peninsula at Wîg, on the east side of Aberdaron Bay, in a northerly to north-easterly direction as far as Porth Nevin, where it passes below the sea. The present paper is concerned with about 9 square miles of the Palæozoic country that lies immediately east of the Boundary Thrust. The strip of coast between Aberdaron Bay and Porth Neigwl forms the southern base of the area, which extends northward as far as the most northern exposures of the Sarn granite. Its eastern boundary runs northward from the western side of Porth Neigwl till it meets the Thrust.

The lower ground of this tract is, for the most part, deeplycovered by glacial drift, but a broad stretch of high ground that extends from Mynydd Penarfynydd on the south coast northward through Mynydd y Graig to Mynydd Cefnamwlch, affords many exposures, chiefly of igneous rocks. Mynydd Rhiw, in the centre of this group of hills, rises to 994 feet O.D.; south of it lie Mynydd y Graig, between 700 and 750 feet, and Mynydd Penarfynydd, over 500 feet. The height of the granite hill of Mynydd Cefnamwlch is 598 feet. The streams are small and unimportant rivulets, except the Afon Soch, of which, however,
An Ordovician Grit from Anglesey, with its bearing on Palæogeography and on the Tectonics of the Mona Complex
Authors: Edward Greenly , Boswell Percy George Hamnall
Published: October 2009

I. I
ntroductory

S
ome
15 or 20 years ago, the rocks and slides collected by-Blake and Callaway were purchased by the Geological Survey. The Anglesey slides were put into the hands of one of us (E. G.), and many of them were used for the Memoir upon Anglesey. Later on, both collections were gone through systematically, partly for further description, but partly because, by means of the 6-inch geological maps, it had become possible often to state the localities with much greater precision.

One of the Blake slides (J.F.B. 315 = E. 10914) is an Ordovician grit. It is labelled ‘ South of Holland Arms ’, and while possibly from the floor of the steep lane about 100 yards south of the Inn, is more likely to be from Glanmorfa lane—a quarry in the Ordovician strip which, running for a mile from Berw-uchaf to Tai-hirion, may conveniently be termed the Berw strip.

It was found to be surprisingly rich in heavy minerals, and was therefore sent to the other author (P. G. H. B.). The Geological Survey also very kindly had a piece cut off Blake's specimen in order that the heavy minerals might be separated. In March, 1931, we re-examined, together, all the exposures of the Berw grits, and collected specimens for slicing and separation.

These Ordovician rocks are briefly described by Ramsay.In the Anglesey Memoir they are considered, under the subtitle of ‘ The Strips along the Berw Faults ’, on pp.
Petrology of the Volcanic Fields East and South-East of Ruwenzori, Uganda
Authors: Holmes Arthur , Harwood Henry Francis
Published: October 2009

I. G
eneral
D
escription of the
V
olcanic
A
reas

U
ntil
1891 the possibility was entertained that Ruwenzori, like the other high mountains of Central Africa, might be of volcanic origin. As a result of his explorations during that year,
Dr. F. Stuhlmann (1894)
showed that this preliminary suggestion was without foundation, adding that no signs of volcanic activity had been detected in the regions traversed. In 1894, however, G. F. Scott Elliot recognized three well-marked volcanic belts in the adjoining country east and southeast of Ruwenzori (
Elliot & Gregory, 1895, p. 674
;
Elliot, 1896, p. 168
). He described the bedded tuffs, craters, and crater-lakes of Toro (fig. 1) as occurring in the Vijonga area (Lake Kijongo), north-west of Fort Portal; the Butanuka or Kyatwa area, south of Fort Portal, locally forming the boundary of the low Toro plains to the east; and the Katwe and Kaihura Straits area (north-west of the Kazinga Channel between Lakes George and Edward).

It is remarkable that Stanley failed to recognize the volcanic origin of the famous salt-lake of the Katwe crater. He visited the locality in 1889 and commented on the deep depression and the salinity of the lake, and even recorded the occurrence of a spring of sulphurous water.

Scott Elliot also indicated that Karimi Hill, south-west of Ruwenzori (now in Belgian territory), might be of volcanic origin, and suggested that the different belts of cones and craters were alined on fissures radiating outwards from the uplifted massif of Ruwenzori. The nature of Karimi Hill
The Stratigraphy of the Valentian Rocks of Shropshire. The Longmynd-Shelve and Breidden Outcrops
Authors: Whittard Walter Frederick
Published: October 2009

I. I
ntroduction

I
n
Lower Valentian times South Shropshire was as yet uninvaded by the sea; but, by reason of the further subsidence of the south-eastern margin of the Silurian trough of deposition, the sea gained access to the region during Upper Valentian times. Doubtless as a result of the diversity of rock-types, the pre-Upper Valentian landmass exhibited a varied topography, which on partial submergence formed an irregular coast, similar probably to a rias coast. As first tentatively suggested by Callaway, South Shropshire may then have had the general appearance of an archipelago (
La Touche, 1884, p. 14
). The most important area of land in this complicated coastal region was that which is now known as the Longmynd and Shelve districts. On the northwest, the sea separated this area from the Breidden Hills, and on the south-east a narrow gulf intervened between the Caradoc Ridge and the Longmynd. On the south-east of the Caradoc Ridge was a more open and elongated expanse of water, which lapped against the main coastline situated still farther to the south-east. Thus the land was divided into three islands or peninsulas by gulf-like areas of sea, and the division is now reflected in the distribution of the three distinct outcrops of Valentian sediments fig. 1. Of these the most south-easterly has been selected as the type area and is known as the Main outcrop (
Whittard, 1927
). The next important development is the Longmynd- Shelve outcrop and the faulted outliers of Marshbrook
The Geology of some Salt-Plugs in Laristan, Southern Persia
Authors: Harrison John Vernon
Published: October 2009

Salt-Plugs occurring in a bare land such as Laristan are intriguing, on account of their fantastic shapes, their queer colouring, and their rock-assemblages. Their profusion here and in only a few other regions in the world awakes interest regarding causal forces, as also the desire to make comparisons.

During a reconnaissance in the season 1928–29 I had the opportunity, with A. H. Taitt, to visit or view thirty-three different salt-plugs. Although the needs of survey prevented us from making a detailed study of any of the occurrences, notes and specimens were collected in sufficient quantities to yield a considerable amount of new information, which is set forth below.

The extrusive salt has come to the surface at different periods from Oligocene to Pliocene, has formed hills and salt-gypsum ‘glaciers’, and has left after erosion great corries in the limestone ‘whaleback’ mountains of the region. It has penetrated the folds irregularly, so that the salt-masses show no recognizable order of distribution within the zone where they occur, an area determined by the front of the South Persian nappes. It is suggested that they have originated through tangential pressure acting on a series of beds which extends at least as low as the Ordovician in places, is up to 25,000 feet thick, and is underlaid by salt and gypsum of Cambrian or possibly pre-Cambrian Age.

A. T. Wilson (now Sir Arnold) (3), G. E. Pilgrim (2, 9, 11), R. K. Richardson (15, 25), K. Krejci (20), G. M. Lees (21, 24, 27),
The Iron-Ore Oolites and Pisolites of North Wales
Authors: Pulfrey William
Published: October 2009

I. Introduction and History of Previous Research

The oolitic iron ores of Anglesey, Carnarvonshire, and Merionethshire in North Wales (see fig. 1) have received attention from numerous authors since the middle of the nineteenth century. These ores, of variable nature and age, consist largely of chlorite with or without clastic constituents, and locally peculiar varieties contain haematite, pyrite, etc., usually associated with chlorite. They generally contain abundant nodules bearing sponge spicules.

The literature of the Welsh oolites is extensive and has been clearly summarized by Sherlock and Cantrill (1920) in a special report of the Geological Survey on iron ores. Two years previous to the publication of this report, Sherlock (1918) had described the pyritic ores of Trefriw, and had concluded that they are probably a highly metamorphosed pisolitic iron ore of Nemagraptus gracilis age. The Geological Survey Memoir on Anglesey (Greenly, 1919) gave an account of the oolitic iron ores of the island. Greenly distinguished three types of ore—feebly oolitic siderite rocks, ferrified grits, and ‘heavy oolites’, and proved most of the ores to be of
Nemagraptus gracilis
age.

A further special report of the Geological Survey, by A. F. Hallimond (1925), dealt with the nature and origin of the oolitic ironstones of Great Britain, including an account of some Welsh ironstones. Hallimond proved the almost universal presence in the English ores of chlorites allied to chamosite, but he believed that other chlorites would be found in the Welsh ores, owing to some degree of metamorphism. He concluded that
The Upper Devonian Rocks of The Chudleigh Area, South Devon
Authors: Anniss Leslie George
Published: October 2009

I. Introduction

The Upper Devonian rocks under consideration occupy a small portion of the area of the 1-inch geological map (Sheet 339). They occur as small faulted inliers on the north-eastern side of the Bovey basin in a region otherwise occupied by Culm overlain by Permian and Cretaceous strata. The main (Chudleigh) outcrop, which is a mile across at its widest part, extends from the neighbourhood of Harcombe to Chudleigh Rocks—a distance of
about 3½ miles. East of this outcrop, and on the same latitude as Chudleigh, is the small triangular patch of Lower Dunscombe, and farther south lies the much larger but partially concealed Ugbrooke-Well inlier, which appears on the map as three detached outcrops. The nearest edge of the Dartmoor granite
lies about 2½ miles to the west. The Devonian inliers include the upper part of the Massive Limestone of South Devon thrust over thinly bedded limestones and shales. The Massive Limestone is here shown to be Lower Frasnian and the thinly bedded limestones and shales Upper Frasnian and Famennian respectively. The Kate Brook, the main stream in the area, has cut its valley along the main outcrop of the Famennian shales. The lowest part of the valley lies below the 100-foot contour. The Massive Limestone flanks the depression on the east, rising to 300 or 400 feet; the surrounding Culm forms undulating ground 400 to 500 feet high. The Permian with its Cretaceous capping rises to 700 feet in the north-east.

My thanks are due to Lord
The Carnmenellis Granite: Its Petrology, Metamorphism and Tectonics
Authors: Ghosh P. K.
Published: October 2009

I. Introduction

The Carnmenellis granite and its metamorphic aureole were mapped, in 1839, by de la Beche. The area has since been re-surveyed by the Geological Survey and the results recorded in the one-inch maps, nos. 352 and 359 (New Series) and in the Survey Memoir on the Falmouth and Camborne district (Hill & MacAlister, 1906). The granite is an important unit in the chain of post-Carboniferous granite intrusions forming the backbone of the peninsula of Cornwall and Devon.

The consanguinity of these intrusions has long been known, but the recognition of the composite character of individual intrusions is comparatively recent. Intrusive relationship between major composite masses was observed on Dartmoor by the members of the Geological Survey (Reid & others, 1912), Brammall (1923), and Osman (1928), and on Bodmin Moor by myself (1927). Intrusion sequences are discussed by Brammall (1923 & 1932) and Osman (1928).

Important petrological contrasts between the Devonian and the Cornish granites were pointed out by Flett and Dewey (Reid & others, 1912), and problems of variation within individual complexes have since been made the basis of detailed study by Osman with special reference to the Dartmoor and Scilly Isles masses, by Richardson (1923) dealing with the St. Austell granite, and by myself in a paper on the Bodmin Moor granite (1927), and the Carnmenellis granite, the subject of the present contribution. I would add that, subsequent to the presentation of the paper to the Society, I have had the advantage of re-examining my analytical data
The Borrowdale Volcanic Series and Associated Rocks in the Country Between Long Sleddale and Shap
Authors: Mitchell George Hoole
Published: October 2009

I. Introduction

A remote and little frequented group of fells lying some ten miles to the north of Kendal in the eastern part of the Lake District forms the easterly portion of the mountainous country centred on High Street (Mitchell, 1931). The area is traversed by the main watershed of the Lake District extending from Harter Fell by way of Gatesgarth Pass, Tarn Crag, and Grey Crag to Shap summit on the L.M.S. Railway. The highest ground is in the west, where High Street and Harter Fell are more than 2500 feet in altitude. Eastwards the level falls steadily until the escarpment of the Carboniferous Limestone is reached between Shap summit and Bampton. Much of the fell is smooth in outline; but long stretches of craggy ground break the monotonous grass-covered slopes. This is specially noticeable in the valleys, for most of them exhibit signs of severe glaciation, which has resulted in those steep cliffs and bare rock faces which contribute in no small degree to the boldness of the scenery. In the Lowther valley near Shap, the ground is thickly smothered by glacial drift, which forms long mounds and hummocks, effectively masking the solid rocks over large areas.

To the south of the watershed, a number of streams flow in a south-south-easterly direction. Of these, the River Sprint in its upper reaches is formed by the junction of several small gills—Wren Gill is the largest—that have their sources on the southern side of Gatesgarth Pass. Almost at once the
The Age and Origin of the Lower Rhône
Authors: Oldham Richard Dixon
Published: October 2009

I. Introductory

In a previous communication to this Society it was shown that the region of the lower Rhône, bordering the main stream from Beaucaire and Tarascon to the sea, which has been currently accepted as a typical delta, was, genetically, of very different origin, the deltaic character having been impressed on it at a late period in the development of the river.

The stratigraphy of the alluvium is such that it can only be accounted for by a barrier having formerly existed beyond the sea-coast of the present day, and the Rhône having been compelled to flow westwards to the neighbourhood of Cette, or possibly still farther, before it found an outlet to the sea. Across this barrier a passage was opened, and became the main channel by which the river found access to the Mediterranean, but this occurred at a period which, geologically speaking, is extremely recent, though anterior to the first appearance of Roman power in this region.

A similar conclusion may be drawn from a study of the two branches of the Rhône. The eastern branch is not only the larger but is also materially shorter in length, measured from the bifurcation to the sea, and this condition is necessarily unstable; the greater volume and the steeper gradient would give greater power to the eastern channel, which must ultimately lead to a capture of the whole of the discharge of the river and to the disappearance of the western branch. Though the bifurcation must be regarded
The Downtonian and Dittonian Strata of Great Britain and North-Western Europe
Authors: King William Wickham
Published: October 2009

I. Introduction

The determination of a Siluro-Devonian boundary in Great Britain and north-western Europe has been dealt with by Barrels, Pruvost, and Dubois (1920), Stamp (1923), and Robertson (1928). My own investigation has been based in part on an application of the principles relating to deposition of sediments set out by Watts (1911), and more recently by Marr (1929). It has been shown (King, 1925) that the Down-Ionian and Dittonian strata of the West Midlands of England are mainly marls, belonging to one ldmud belt”, and laid down in epi-continental marine waters of moderate depth; and that they are a conformable sequence of beds transitional from the Upper Ludlow.

The discovery, described later, of a shell fauna, abundant in individuals but sparse in genera and species, reaching nearly to the top of the Downtonian, is of some utility if considered in connexion with the Merostomata and fishes, and with the physiographical conditions under which these sediments with a “red fades” were laid down in north-western Europe. I have, therefore, investigated this region, in part personally and in part by making use of the work of others, so as to trace the “variable”, and “mud,” and “organic” belts (not oozes) laid down in the Siluro-Devonian period on this continental shelf, the continuation of a north-western land which at first encroached on the sea to the south-east, but in Devonian times receded again. The following divisions and stages are now adopted for the West Midlands, including the Black Mountains, where the Downtonian
Appendix III.—Note On A New Cyathaspidian Fish From The Upper Downtonian Of Corvedale
Authors: Smith Woodward Arthur
Published: October 2009

The fragments of a Cyathaspidian fish from the Upper Downtonian of Corvedale are remarkable for their peculiar external ornamentation, which necessitates their reference to a new genus,
Corvaspis
. Closely arranged, smooth, and nearly uniform ridges of dentine (cosmine), as usual, cover the greater portion of shield; but a irregular network of fine grooves divides this ridge-ornament into small areas which have the false appearance of separate plates. Round the periphery, at least of the ventral shield, the smooth dentine forms a dense cluster of tubercles, which are very irregular in size and shape.

The most important specimen shows the anterior two-thirds of a ventral shield, which must originally have measured about 3.5 cm. in maximum width and between 5 and 6 cm. in total length. It is broken sharply across behind, and its anterolateral margins are a little imperfect; but its anterior end is clearly hollowed by a rounded excavation. Its lateral borders are flattened, but the greater part of the shield is slightly convex from side to side. Its external ornament is especially well seen in a cellulose impression of the surface prepared by Professor L. J. Wills (PI. XIX, fig. 1). The longitudinal ridges of dentine, though subdivided into short lengths by the network of grooves, are otherwise little disturbed. In general they remain parallel and uniform in width, without any tendency to become concentric with the borders of the several areas. These areas are very irregular, without bilateral symmetry in their arrangement; and the largest are at
The Eastern end of the Newry Igneous Complex
Authors: Livesey Reynolds Doris
Published: October 2009

I. Introduction

The Newry Igneous Complex, generally known as the Newry granite, extends from Slieve Croob in County Down, where it attains its greatest height, south-westward past Newry into County Armagh. A general account of the “granite” was given by J. E. Richey and H. H. Thomas in their recent description of the Tertiary Ring Complex of Slieve Gullion. As pointed out by Richey, it has an elongate outcrop with dimensions of roughly 26 by 6 miles, extending in a direction E. 35° N. to W. 35° S. parallel to the prevalent strike of the Silurian rocks, and can be assigned to the Old Red Sandstone period of activity.

The eastern end of the mass is now definitely dated by the fact that on Seeconnell it is cut by hornblende-lamprophyres (spessartites), similar to the uncrushed hornblendic types in the Ards Peninsula and there found to belong to the Caledonian period of activity, but to be post-Caledonian folding in age. This evidence, in conjunction with the absence of signs of crushing in the eastern end of the mass, fixes the age within narrow limits.

The present paper forms part of a detailed investigation of the area, and deals with the eastern end of the complex as far westward as Slievenaboley and southward to Lough Island Reavy, the region described being about 21 square miles. This small area is so crowded with interest in regard both to variety of rock-types and evidence of hybridization and ultrametamorphism, that it is considered to merit
The Loch na Cille Boulder Bed and its place in the Highland Succession
Authors: Elles Gertrude Lilian
Published: October 2009

I. Introduction and Literature

The authors of the Geological Survey Memoir on Knapdale, Jura, and North Kintyre stated in 1911 that the real interest of the Tayvallich peninsula was far from being exhausted in their account, and that the geologist who visited its western shores would be well rewarded.

This is undoubtedly true, for this region of the South-West Highlands, which includes all the promontories west of Loch Sween and south of Carsaig Bay and Loch a' Bhealaich, together with the adjacent islands, seems to afford some definite clues, hitherto apparently overlooked, which may prove to be important in the solution of the two great problems of Highland geology—the succession and the structure. To deal first with the succession: there may be said to be a general agreement amongst the workers in different parts of the area that the rocks seen belong to what has been termed the Loch Awe Group, which comprises the following members:—

Quartzitic Series

Limestone-Slaty-Schist Series (Tayvallich Limestones)

Boulder Bed

Tayvallich Volcanic Series

There is, however, considerable difference of opinion upon the relationship of these beds to each other, and to the rock-groups of other regions outside this district. Some geologists, reading the whole in the light of what is seen in the Loch Awe country and some supposed evidence in the lavas, would place the Volcanic Series at the top and the Quartzitic Series at the bottom; this is the interpretation finally put forward in the Survey Memoir, where the supposed evidence of