bluuebunny/crossref_metadata_2025 huggingface dataset:
A Revision of the Orbitoides of Christmas Island, (Indian Ocean)
Authors: Nuttall Winfred Laurence Falkiner
Published: October 2009

In Andrews's monograph on Christmas, Island, published in 1900 (11), Prof. T. Rupert Jones & Mr. F. Chapman contributed an article on the Tertiary foraminiferal limestones, and described several new species of Orbitoides. It was my original intention to examine the Orbitoides, in order to ascertain whether with their aid new light could be thrown on the age of the deposits, as at the time when they were described the genus
Lepidocyclina
was little known. In doing so I found that the above-mentioned authors, in describing the species, omitted details which of recent years have become of prime importance in the recognition of these forms. Since their descriptions are frequently inadequate, considerable confusion about the Christmas Island Orbitoides has appeared in the literature. I have, therefore, been led to attempt a revision of Jones's & Chapman's species. I have been fortunately able to prepare numerous new microscopic slides from rock-material preserved in the British Museum (Natural History). and also have examined the slides containing Jones's & Chapman's figured types. Dr. W. D. Lang and Mr. W. Campbell Smith have kindly helped by arranging to have numerous sections cut in the Geological and Mineralogical Departments of the Museum. In all, about a hundred slides have been examined.

In studying the Orbitoides the chief difficulty is that they are irregularly distributed in massive limestone, so that it necessitates much care to cut a section through a specimen in a particular desired direction. In no case are specimens weathered out so as to
The Volcanic Rocks of Christmas Island, (Indian Ocean)
Authors: Smith Walter Campbell
Published: October 2009

Christmas Island occupies a very isolated position in the eastern part of the Indian Ocean in lat. 10° 25′ S.. long. 105° 42′ E. The nearest land is Java, 190 miles away to the north; a little south of west, at a distance of about (650 miles, are the Islands of Cocoa and North Keeling; while the nearest point on the Australian mainland is 900 miles distant on tlie south-east.

The greatest length of the island is 12 miles, and its greatest width 9. It forms the flat top of a submarine mountain, the base of which is 14,400 feet below sea-level and its summit about 1000 feet above. The slopes of this mountain are steep, depths of 1100 feet being found less than 4 miles out, and the base, 14,400 feet, being within 20 miles of the coast of the island. The slopes of the upper part are nearly alike on all sides, and are about 2 in 5 [1, p. 295].

A scientific exploration of the island was made by the late Dr. C. W. Andrews in 1897–98, the late Sir John Murray defraying the cost of the expedition and presenting the collections. to the British Museum (Natulral History). These collections were the subject of an important monograph published in 1900, to which Dr. Andrews contributed chapters on the physical features and geology [1], and it is from these that the following brief outline of the geological history of the island is taken.

Dr. Andrews showed that the
The Depth of Origin of Earthquakes
Authors: Oldham Richard Dixon
Published: October 2009

It is a peculiarity of the present state of seismology that it is necessary to define the meaning which one attaches to the word. earthquake. Up to the end of the last century this was hardly necessary, the word was still used in its old-fashioned sense of a quaking, or shaking, of the earth which could be felt and, when violent enough, caused damage. When it was found that, with suitable instruments, disturbances could be detected, which could not be felt, and it was observed that some of these were evidently connected with great earthquakes, it was too readily assumed that this was true of all, and a new connotation of the word arose. This newer branch of seismology has been more and more extensively followed up, until it has almost ousted the older seismology, and some of its devotees are inclined to refuse the right, of the Disturbance which can be felt, to the name of earthquake, unless it is accompanied by long-distance records. In what follows the word is used in the old-fashioned sense, and the earthquakes dealt with are the disturbances which can be felt, which are essentially phenomena of the outer crust, and as such belong to the domain of geology.

In the study of these, one of the first objects is a determination of the depth of origin, and several distinct principles are involved in the methods which have been proposed. Robert Mallet believed that that angle of emergence could be determined from the measurement
The Pleistocene Deposits of the Lower Part of the Great Ouse Basin
Authors: Marr John Edward
Published: October 2009

A paper by the present Author in the Quarterly Journal of the Geological Society (vol. lxxv, 1919–20, p. 204) dealt with the Pleistocene deposits in the immediate vicinity of Cambridge. In the present paper it is proposed to consider further discoveries there, but more particularly to describe the deposits over a wider area, and to include some general observations concerning glaciation, earth-movements, and river-diversions which were barely mentioned in the previous paper.

It will be convenient to consider the sequence of events, so far as possible, in the order of their occurrence.

The evidence, part of which has been published, points to the following sequence of events in the area during the Pleistocene Period:—

(1)

Early glaciation: (Riss?).

(2)

Aggradation of valleys: climate becoming somewhat warm, but later in the period again cool. Acheulean, Micoque, and possibly also early Mousterian? (Riss-Würm Interglacial?).

(3)

Glaciation: Mousterian? (beginning of Würm?).

(4)

Erosion, with subsidiary aggradation: cold, with temporary period of less cold in the middle. Aurignacian, Solutrean, and Magdalenian epochs (Bühl or recrudescence of Würm glaciation at the end, but the ice did not reach the South-East of England).

(5)

Azilio-Tardenoisian period.

For many years the first appearance of Man in this country in post-Glacial times was generally regarded as established. This is no longer the case, and it is necessary to obtain fresh evidence as to the actual sequence of glacial and genial periods in Pleistocene times.
Notes on the Lamellibranchia
Authors: Cox Leslie Reginald
Published: October 2009

Lamellibranchia, belonging mostly to two or three common species, are fairly abundant throughout the
obtusus
shales, but their state of preservation is very bad. The species
Plagiostoma giganteum
and
Oxytoma inæquivalve
are to to be found at most horizons. Of these, the former occurs as a small variety about 15 mm. in diameter. It is impossible to define any specific distinction between this variety and the larger specimens of the species to be found at lower horizons; nor have I yet been able to detect any characters in which the
Oxytoma
of the Lower Lias, to which some authors apply A. d'Orbigny's name O.
sinemuriense
, differs from the typical
O. inæquivalve
of the Middle Lias.
Inoceramus faberi
is a third abundant species, it being worthy of note that the genus
Inoceramus
is very well represented in the Dorset Lower Lias at all horizons, from the Shales-with-‘Beef’ upwards. The following notes refer to the few little-known species that have been found in the
obtusus
shales. Two imperfect specimens from the Upper Cement Bed (82) are referable to this, or to a closely-related species. Unfortunately, the ears are broken away, but the surface-ornament is well preserved. The disc of the valve is almost circular, the diameter of the larger specimen. L40675 (apparently a left valve), being about 27 mm. The inflation of this valve does not seem to have been very great; the specimen has, however, been somewhat flattened out by pressure. The surface is ornamented with closely-spaced concentric rows of minute
Note on certain Echioceratidæ
Authors: Trueman Arthur Elijah , Williams Daisy Mary
Published: October 2009

No well-preserved Echioceratid ammonites had been examined from below the Watch Ammonite Stone until after the completion of the studies on which the present nomenclature is based. Dr. Lang has recently collected a series of specimens from the upper part of the Lower Clays with
Raricostatus
(98), and one of these has now been figured as
Homechioceras simile
Trueman & Williams. Another specimen (W. D. Lang coll. 6670) closely resembles
Ammonites spiratissimus
Quenstedt (1852, pl. xxvii, fig. 9), but this must be regarded as a strikingly homœomorphous species, since it is a member of another family, the Arietidæ.

The genus
Homechioceras
was proposed for regularly costate Echioceratids with simple sutures, which do not become raricostate. The members of this genus differ from
Echiocera
s in the earlier development of a carina, sometimes with feeble sub-sulci. The more primitive raricostate members of
Echioceras
are frequently uncarinate or feebly carinate, and these forms were probably preceded by closely-ribbed species which may presumably be distinguished from
Homechioceras
by the absence of a carina. Such costate species as
Ammonites robustus
and
A.. gracilis
should be referred to
Homechioceras
, since they are already carinate; probably in
Homechioceras
as in
Echioceras
, there are several more or less parallel lineages.

Dr. A. E. Trueman said that all interested in the stratigraphy of the Lias were indebted to the Authors for their detailed investigation; he believed that their researches would produce results which would also be of value to those working on the zonal succession of other rocks. During
Appendix: Description of a New Species of
Spirifer
and of one of
Reticularia
from the Lower Carboniferous near Clitheroe
Authors: Muir-Wood Helen Marguerite
Published: October 2009

The following specific descriptions are based, partly upon material in Dr. D. Parkinson's collection at Birmingham University Museum and lent to me by the courtesy of Dr. Parkinson & Dr. L. J. Wills, and partly upon material in the British Museum (Natural History) especially from the Gilbertson Collection.

Diagnosis.3-
Spirifer
resembling
S. striatus (Conchyliolithus Anomites
(
striatus
) W. Martin, 1809, ‘Petreficata Derbiensia’ pl. xxiii, figs. 1 & 2) and allied forms, but differing from these in having (1) narrower and more numerous costæ with more frequent bifurcations; (2) the median fold prominently raised; (3) the anterior margin of the fold so excavated as to produce a more highly-arched anterior commissure; (4) rounded cardinal extremities; and (5) the cardinal area with converging sides.

Description.—Shell transverse, nearly twice as wide as long, valves biconvex; hinge-line slightly less than the greatest width of the shell: cardinal extremities rounded.

Pedicle-valve with a broad, rounded, median sinus produced into a long rounded tongue, and dorsally deflected; lateral slopes convex, not sharply demarcated from the sinus except on the umbo; umbo acute, elevated, and incurved; cardinal area curved, outline triangular and tapering towards the cardinal extremities, transversely striated; delthyral angle 58°. Brachial valve with a rounded median fold, increasing in width and prominence anteriorly; lateral slopes convex, demarcated from the median fold by a narrow sinus; cardinal area narrow and flattened.

Surface of shell with twenty-one to twenty-five prominent rounded costæ on each lateral slope, and nineteen to twenty on the fold and in the sinus; costæ irregular
Cretaceous Glaciation in Central Australia
Authors: Woolnough Walter G. , David T. W. Edgeworth
Published: October 2009

In 1894, H. Y. L. Brown recorded in the part of his annual report (Geological Survey of South Australia; entitled ‘From Strangways to Mount Paisley’, p. 10, the following:— ‘Over all these stony downs and plains at intervals waterworn boulders, attaining often a considerable size, are thinly scattered on the surface. These are composed of quartzite, sandstone, quartz-felspar-porphyry, etc., all fragments of primary rocks which do not come to the surface anywhere in the neighbourhood. . . . The only theory which will account for their presence here, as well as in numerous other places where I have previously observed them, is that of their having been transported by drift-ice at the time when the central portion of Australia was under water.’

Various other references have been given in the bibliography quoted by the above-mentioned author, as well as by R. Lockhart Jack, Prof. Walter Howchin, L. K. Ward, and the present authors. One of us (W. G. W.) contributed a preliminary note on the occurrence of big erratics on the plains near the foot of the eastern escarpment of the Flinders Kange, at Muloowurtina, south-west of Lake Callabonna. Since then he has revisited the locality, which is situated in lat. 29° 58′ S., long. 139° 44′ E., about 370 miles north-north-east of Adelaide, and has been fortunate enough to obtain important palseontological evidence as to the age of the glaciation.

The object of the present note is particularly to record these latest observations, in the light of recent conclusions
The Geology of the District around Towyn and Abergynolwyn, (Merioneth)
Authors: Jehu Ralph Maurice
Published: October 2009

The area to be dealt with in this paper lies south-west of the Corris-Aberllefenni district, recently described by Prof. W. J. Pugh. It includes about 35 square miles, extending from the coast, in the vicinity of Towyn, to Taren y Gresail in the east. The northern boundary is the Dysynni Valley, and a line due east from the Birds' Rock (Craig yr Aderyn) to the head of Glyn Iago; while the southern limit runs through Ffridd Cefn-isaf, Cwm Dyffryn, and Mynydd y Llyn, and thence north-east towards Corris. The area includes the mountain-country lying south and south-west of Cader Idris. Its most striking feature is the long, straight, steep-sided valley which runs south-westwards from Tal-y-llyn to Towyn, namely, the Tal-y-llyn or Bala Fault-Valley. The Dysynni river, which drains the greater part of the area, occupies this valley from Tal-y-llyn to Abergynolwyn, but at this point it is diverted through a narrow gorge into the broad alluvial valley known as Dyffryn Dysynni.

Between the Tal-y-llyn and Dysynni valleys the ground rises steeply to an average height of 900 feet, but Foel Caer-berllan (1233 feet) and Foel Wyllt (1013 feet) stand up above this general level. South of the Tal-y-llyn valley the country is more mountainous, and constitutes the main watershed between the Dysynni-Tal-y-llvn and the Dyfi drainage-systems. This watershed slopes south-westwards from 2187 feet in Taren-y-Gesail to 1332 feet in Corlan Fraith. The mountain-country is dissected by deeply incised tributary valleys running north-west and south-east–that is, at right angles to the
A Contribution to the Geology of the Eastern Part of the Denbighshire Moors
Authors: Boswell Percy George Hamnall
Published: October 2009

The complex structure of the country around the Vale of Llangollen, the Clwydian Range, the Vale of Clwyd, and the Denbighshire Moors is to a large extent accountable for the attraction which this part of North Wales offers to the geologist. Between the Llanelidan fault system, (which forms the southern boundary of the Vale of Clwyd) and the Berwyn Hills is an area that has been studied in detail by Dr. L. J. Wills & Dr. Bernard Smith; but the full significance of the tectonics cannot be realized until the succession and structure of the country on the north and north-west, including the Clwydian Range and the Denbighshire Moors, have been unravelled. The geology of the central portion of the Clwydian Range has recently been investigated by Mrs. E. G. Woods & Miss M. C. Crosfield.

The present paper is a first contribution to the revision of the geology of the Denbighshire Moors. It presents the results of investigation of the eastern part of the area, between Llanefydd, Denbigh, Ruthin, and the centre of the Moors. It deals, therefore, with merely a part of a much larger area which must eventually be considered as a whole: for, not only is the succession of Salopian rocks incomplete here, but reference to the tectonics of the entire region is necessary, in order to interpret fully the structure of this part. It would seem undesirable, however, to postpone publication until the neighbouring areas have been investigated, for this would involve considerable delay, and
The Shineton Shales of the Wrekin District: with Notes on their Development in other parts of Shropshire and Herefordshire
Authors: Stubblefield Cyril James , Bulman Oliver Meredith Boone
Published: October 2009

The Shineton Shales crop out on the south and south-west of the Wrekin in a more or less rhomboidal area, extending for a distance of about 9 miles from just north of Maddock's Hill to Shadwell Coppice (Acton Burnell Park), and from the neighbourhood of Dryton, 2½ miles south to the Harley-Kenley Road section near Stone House.

The area comprises parts of the following 6-inch Ordnance Survey quarter-sheets:—Shropshire XLII N.E, S.E., S.W.; XLIII N.W.; XLIX N.E.; L N.E., N.W.

Probably the earliest reference to the geology of the area here described is contained in Murchison's ‘Silurian System’ 1839. All rocks of this district older than the May Hill (Llandovery) Sandstone were apparently regarded as being of Caradoc Sandstone age, and were thus described in Chapter xix; in particular, on p. 233, he stated:— ‘The stratified deposits through which the trap rocks of the Wrekin protrude are of the same age as the Caradoc Sandstone.’

Aveline & Salter (1854) described all the shales of the area— comprising those seen at Acton Burnell, Cressage Park, Harnage, and at Shineton—as of Lower Llandeilo and Bala age (the Caradoc Sandstone of the ‘Silurian System’), and they were recognized as being overlain by the Hoar Edge Grit at Harnage and Cound. The authors recorded from Shineton the three fossils
Olenus
sp.,
Agnostus
sp., and
Asaphus
sp., and the last-named was noted as occurring in some abundance.

In 1867, Salter referred the Shineton Shales to the ‘top of the Llandeilo Flags proper’ (p. 203; but in
Preliminary Notes on the Geology of the Eastern Parts of Central Spitsbergen; with special reference to the Problem of the Hecla Hook Formation
Authors: Odell Noel Ewart
Published: October 2009

It must be well known to most readers that Spitsbergen has not lacked some measure of geological exploration, although, mainly owing to its geographical position and to the shortness of the season when ice-conditions allow of free access and the winter covering of snow has vanished, geological investigation has been decidedly intermittent.

By far the greater amount of work has been done on the western coast, which is much the most accessible part of the country during a normal summer, and where, fortunately for the owners of them, the great fields of Tertiary coal exist. But it is in this region of the west that some of the most considerable earth-movements have taken place, and the oldest rocks in particular have suffered such deformation that their stratigraphy is in consequence extremely difficult to decipher.

Swedish, Norwegian, and British geologists have all contributed to the investigation, but their various labours cannot be entered into here, except in a few specific instances.

In Eastern Spitsbergen, or rather what, to adhere to current usage, must more properly be called Eastern Central Spitsbergen, much less has been accomplished, owing mainly to difficulty of access. The pioneer sledging journey of Prof. E. J. Garwood and Sir Martin Conway from the head of the Ice Fiord, in 1897, was the first real attempt to penetrate into the interior of this region; and, although the explorers were greatly hampered by adverse weather conditions, some interesting observations were made, one in particular being that the major portion of
The Geology of the Austral or Tubuai Islands (Southern Pacific)
Authors: Chubb Lawrence John
Published: October 2009

The following paper embodies the geological results of the St.
George
Expedition to the South Pacific Ocean, organized by the Scientific Expeditionary Eesearch Association, in so far as they relate to the Austral or Tubuai Group. This group (see map, fig. 1, p. 292), which constitutes part of the Etablissements Français de l'Océanie, extends for a distance of about 750 nautical miles between lat. 21° 44′ S. and 27° 55′ S., and between long. 143° 26′ W. and 154° 48′ W. It includes seven islands, as well as several isolated rocks and shoals, which are arranged along lines having a west-north-westerly and east-south-easterly trend. These lines are continued westwards in the Cook Group, and are parallel to the trend-lines in the Society Islands on the north, and the Tuamotu Archipelago on the north-east.

Soundings are few and scattered in these regions, but the general depth of the ocean appears to be between 1900 and 2500 fathoms, with a bottom of red clay.

The expedition spent several weeks in this group in April and May, 1925. The islands are mainly volcanic, with or without coral-reefs. Little work on the geology of the region appears to have been done in the past. Four of the islands (Rapa, Marotiri, Rurutu, and Rimatara) are described here, and references to previous work on them will be found in the following pages. The others have received only the scantiest attention in geological literature.

Rapa Island is situated in lat. 27° 35′ south, long. 144° 17′ west.
On the Geology of Maiao (Society Islands)
Authors: Chubb Lawrence John , Smith Walter Campbell
Published: October 2009

The island of Maiao, also called Tubuai Manu or Tapamanoa, lies in the central Pacific Ocean in lat. 17° 38′ south, long. 150° 37′ west. It is a member of the Society Group, and is situated about 50 miles west of Tahiti. It was discovered by Capt. Wallis in 1767. Charles Darwin describes it as a small island rising to a height not exceeding 500 feet, and surrounded by a reef at a considerable distance from the shore.

It was visited by the first-named Author and other members of the
St. George
Expedition in March 1925, and was found to consist of small volcanic island, about a mile long, surrounded by a barrier-reef, which has an extreme diameter from east to west of 6 miles (see figs. 1&2, p.343). At the spot where the landing was made, on the northern coast, there is a reef-flat, 200 or 300 yards wide, covered at high tide by about 6 feet of water in its central part, but by not more than a foot at its edge. At the back of the flat are traces of a limestone platform elevated to about 2 feet above sea-level and undercut.

Behind this platform, and in places concealing it, a beach of calcareous sand and coral-dé slopes up gradually to a height of 6 feet above sea-level. The crest of the beach forms the highest point of the barrier-reef island, which swlopes down very gently to the lagoon, and is here between 500 and 600 yards
The Geology of the Saltern Cove Area, Torbay
Authors: Anniss Leslie George , Smith Stanley
Published: October 2009

The small complex of Lower, Middle, and Upper Devonian rocks which occupies a mile by half a mile, immediately south of Paignton, lies between Goodrington and Broadsands. The sequence and structure are well seen in the cliffs and the railway-cutting, but farther inland there is a lack of good exposures. The topography of the area is influenced by the geology in a marked manner. The Massive Limestone forms the high ground on the south and south-east, ending in a steep escarpment. The igneous intrusion with the overthrust limestone forms a remarkably steep-sided, conical hill—the Sugar Loaf. The deep valley between the two hills has been cut in the soft shales and associated tuffs of Upper Devonian age.

The locality is of special interest, since it was here that the Upper Devonian was first recognized in South Devon by Mr. J. E. Lee in 1877 (7).

Since Lee's paper, nothing worthy of mention has been published concerning the beds, except that included in the map and memoir of the district by W. A. E. Ussher (16). Concerning the literature of the area prior to Lee's paper, there is little to mention. De La Beche in 1835 (2) mentions Saltern Cove, and records the occurrence there of altered limestone, shale, and trap. Etheridge in 1867 (4) suggested the probability of the presence of Upper Devonian near Newton Bushel. Holl in 1868 (5), if we may judge from his map, places the shales and the volcanic rocks in his Lower South Devon Group
Palæontological Notes on the Silurian Inlier of Woolhope
Authors: Reed Frederick Richard Cowper
Published: October 2009

Shell ovate, with sides subparallel and very slightly arched; anterior end broadly rounded, subtruncate. Pedicle-valve with umbonal edges diverging at about 110°. Interior of pedicle-valve with a large, elongated, subrhomboidal, thickened area extending for nearly half of the length of the valve and produced in front into a long, tapering point reaching to about three-fourths of the length of the valve; area defined by narrow raised ridges which arise near the beak, and run outwards and forwards on each side with increasing strength and slight curvature to the widest part of the area, thence curving inwards and converging, at first at about 60° and finally at a rapidly diminishing angle, to meet in a sharp point in the middle line. Concrete laterals narrow, triangular, extending for more than half of the length of the area, forming an elongated, subrhomboidal scar divided by a rather broad, rounded median groove continued forwards to the anterior point of the area; centrals transverse, oval, oblique, large, lying in front of and alongside of the concrete laterals, separated anteriorly by the median groove. Cardinal margin of valve somewhat thickened and flattened internally.

Dimensions.—Length of valve = 26 mm. Width of valve = 19 mm. Length of area to tip=17 mm. Width (maximum) of area = 9 mm.

Horizon and locality.—Woolhope Limestone, Littlehope.

Remarks.—The internal characters of this shell are closely similar to those of
L. lewisi
Sowerby, from the Aymestry Limestone; but the internal area is more developed as a platform, the median ridge is
The Stratigraphy and Geological Structure of the Cambrian Area of Comley, Shropshire
Authors: Cobbold Edgar Sterling
Published: October 2009

The object of this paper is to record the exact position of the excavations which I carried out at Comley between 1906 and 1915, and to describe the stratigraphy and tectonics of the Comley area as revealed in the natural and artificial exposures.

With a few exceptions, the fossils found have already been described (11) (12) (13) (14),1 the faunal assemblages have been tabulated, and the strata assigned to some twenty faunal horizons

The excavations were undertaken with financial assistance from the Committee of the British Association for the Advancement of Science appointed ' for the excavation of critical sections among the Palaeozoic rocks of Wales and the West of England,' and the results were reported to the Association as the work proceeded. A few additional excavations have been made during 1926, notes on which will be found below (p. 555).

The Comley Cambrian area, with the sub-area of the Cwms, is barely one-third of a square mile in extent. It is bounded (see map, PI. XLIII) on the west by the pre-Cambrian rocks of the Caradoc range; on the south by red grits and conglomerates that are referred in this paper to the Torridonian (?), and correlated with the Western or Wentnor Series of the Longmyndian, (17) pp. 327 & 334; on the east by the Uriconian of the Hope Bowdler and Cardington mass, and by the Caradocian of Hoar Edge and the Chatwall Ridge; northwards the boundary is ill-defined. The Shineton Shales {Dictyonema and higher beds) occur in
Description of
Camarotœchia
crebrilineata
sp. nov.
Authors: Reed Frederick Richard Cowper
Published: October 2009

Shell transversely subpentagonal, rounded, subglobose, unequally biconvex. Pediele-valve shallower than the brachial valve, with a broad, weak, undefined, median sinus, widening anteriorly; beak high, rounded, incurred, pointed; interior of valve with the walls and floor of the umbonal cavity thickened, with thin low dental plates fused to the sides and supporting small short teeth ; umbonal cavity sharply separated in front from the base of the deeply sunk subpyriform muscular area, extending about half the length of the valve, and composed of a pair of elongated flabelliform diductors enclosing very narrow shorter adductors.

Bmchial valve deeper and more convex than the opposite valve, with a low, median, undefined, rounded fold; the interior of the valve has a long, lanceolate, well-defined muscular area extending fully three-fourths of the length of the valve, and composed of a pair of narrow adductors separated by a low, thick, median septum; hinge-plate thick, large, with a concave semicircular face divided by a narrow median slit into a pair of triangular areas; erura stout, rod-like, cylindrical, closely placed in the middle line.

Posterior margins of both valves slightly thickened internally. Surface of valves covered with regular rounded fine thread-like riblets, 40 to 50 in number, 9 to 12 lying in the sinus.

Dimensions.—Length=10 to 12 mm Width=12 to 14 ram.

Remarks.—The material consists of several more or less perfect internal casts of complete shells, or single valves with impressions of the external surface of a few of the same specimens. The internal characters are well preserved,
The Serpentines and Associated Rocks and Minerals of the Shetland Islands
Authors: Phillips Frank Coles
Published: October 2009

The Shetland Islands consist largely of a foundation of metamorphic rocks—schists and paragneisses, with associated limestones and quartzites—upon which rest, with marked unconformity, patches of sediment of Old Red Sandstone age. In the north of Mainland is a magnificent development of igneous products of this same age. Earlier than the Old Red Sandstone however, there was injected into the older rocks a series of intrusions, rolled pebbles of which occur in the basal conglomerates of the Old Red. These older intrusions range from granites to the ultrabasic rocks which, more particularly form the subject of the present investigation.

Shetland has so far received scant attention from geologists; hence very little previous literature can be noted. So far as petrographical investigations are concerned, the field is practically untouched. The earlier writings of Jameson (1) and Hibbert (2) are of historical interest only. Heddle (3, 5, 7, 19), who carried out an exhaustive study of the mineralogy of the islands, seems to have given less attention to the geology He does devote some space, however, to the question of the origin of the serpentines, and concludes that they were produced by the metamorphism of the associated gabbro (3, p. 12). This view was accepted at a later date by Peach & Home (4, p. 782), but to these authors belongs the credit for most of the really sound work contributing to our knowledge of the geology of the area. Sir John Flett mentions the serpentines and pyroxenites in a discussion on a
The Salopian Rocks and Tectonics of the District South-West of Ruthin (Denbighshire)
Authors: Boswell Percy George Hamnall
Published: October 2009

A recent communication to the Society dealt with the stratigraphy and tectonics of the area of Lower Ludlow rocks west of Denbigh. The area was limited on the south by an east-and-west line through the town of Ruthin, in the Vale of Clwyd. The stratal sequence included the zones of
Monograptus nilssoni, M. scanicus
, and
M. tumescens
, and among the tectonic features discussed was the predominance of north-and-south faulting which determined the main structure and topography.

The present paper forms a continuation of the account of these Ludlow rocks in the district south and south-west of Ruthin that is, in the south-eastern part of the Denbighshire Moors. This area is in turn limited on the south by a notable tectonic feature, the east-and-west Llanelidan fault-system, which also forms the southern boundary of the Yale of Clwyd. On the east it is flanked by the rampart of Carboniferous Limestone (with, in places, the Basement Beds) which forms the western slopes of the Vale of Clwyd. On the west, the area extends as far as the head-waters of the River Clwyd (see map, Pl. LIV). In extent this area is about 20 square miles and is represented by the following quarter-sheets of the 6-inch map:–18 N.E., S.E.; 19 N.W., S.W., S.E.; 25 N.E.; and 26 N.W. and N.E. The succession is more complete than in the area previously described, for it includes in the lower part the Upper Wenlock mudstones (and possibly the zone of
Monograptus vulgaris
), and in the upper part
The Kateruk Series and Associated Rocks of the Northern Suk Hills (Kenya Colony)
Authors: Glenday Vincent G. , Parkinson John
Published: October 2009

The district where these completely metamorphosed sediments, temporarily termed the Kateruk Series, occur lies on the extreme north-eastern flank of the Chemerongoni or Northern Suk Hills, an important if but little-known range, reaching elevations of 5000 to 5500 feet, and having a total length of about 55 miles, in the north-western portion of Kenya Colony.

Geographically, it is terminated on the south by the Swam or Turkwal River, on the north by the Turkana Plains.

The route taken by one of us [V. G. G.], from Kacheliba in Tranz-Nzoia, was past the south-eastern face of Chau or Kapchok (6870 feet), a rugged hill of the typical granitoid gneiss of the district, thence eastwards to the Ngoron or Murwon River, before turning northwards along the eastern escarpment of the hills.

On the Murwon River the rocks seen consisted of the same gneiss and compact hornblende-schists.

The planes of foliation dip slightly to the south of west at high angles, and are frequently cut by bands of a pink felspar-pegmatite, containing white mica and having a fairly constant trend to north 60° east. These veins vary from half an inch to 6 inches across. On the Kasey Pass, dividing the southward from the northward flowing tributaries of the Swam, the dip of the planes of foliation changes to almost due east.

Crossing the summit of the Pass, we find a precipitous descent to the Chepurwa River, rising on the south-eastern slopes of Tarikot. Here the principal rock is a quartz-mica-schist, associated with
Geology of the Naparima Region of Trinidad, British West Indies
Authors: Illing Vincent Charles
Published: October 2009

In the middle of the Island of Trinidad, south of the Central Range, is a broad undulating lowland. It stretches across the Island at its narrowest part, practically in the latitude of San Fernando. Towards the west it is the heart of the sugar-cane industry; towards the east it merges into the low ground of the Nariva, a derelict lowland of forest and swamp. It is to the western portion of this lowland that the name Naparima is usually applied. The present paper is concerned with the area extending from the Gulf of Paria on the west to Princes Town on the east. Its northern boundary is formed by the foothills of the Central Range, while on the south it extends practically to the Oropuche lagoon, a total area of approximately 35 square miles.

The Naparima area includes a large portion of the famous black soils of Trinidad, which have been utilized extensively for sugar-cane plantations. From it almost every vestige of the primitive forest has long been removed, and the undulating lowland is now one broad expanse of cane-fields, while in places a less fertile patch is given over to grass or guava scrub. From the distance it looks like one broad plain, but actually it is covered almost entirely by a complicated valley-system, leaving the intermediate high ground as a ‘fingering’ system of hog-backed ridges. These practically all attain the same general height, and are the remnants of an uplifted and partly dissected peneplain, tilted gradually westwards to
The Stratigraphical Distribution of the Cornbrash: I. The South-Western Area
Authors: Douglas James Archibald , Arkell William Joscelyn
Published: October 2009

The detailed investigation of the stratigraphical distribution of the Cornbrash which has resulted in the present paper was commenced in 1921 by Mr. R. W. Segnit, who, however, left this country in the following year for Australia after completing little more than the study of the sequence in the immediate neighbourhood of Oxford. When, after the lapse of several years, there seemed to be no hope of his return, the present writers, one of whom (J. A. D.) had already shared much of the work, decided to continue the research into other areas, and together have completed the investigation of the formation from Oxford to the South Coast at Weymouth.

That part of the outcrop now described runs through the counties of Oxfordshire, Wiltshire, Gloucestershire, Somerset, and Dorset.

Since the publication in 1894 of H. B. Woodward's Geological Survey Memoir on the Jurassic Rocks of Britain, if we judge from the scanty references to the formation made by later writers, the Cornbrash has been regarded as of comparatively little stratigraphical interest, exhibiting only slight variation in character when traced along its outcrop, and admitting of no detailed subdivision.

Although J. F. Blake, in his unfinished Monograph of the Fauna of the Cornbrash, the first part of which was published in 1905, gives no account of the zonal distribution, it has long been known that two main zones can be recognized: a lower zone characterized by
Clydoniceras,
and an upper by Ammonites of the
Macrocephalites
group.

The critical faunas of these
The Gastropod and Lamellibranch Molluscs [from the Belemnite Marls of Charmouth]
Authors: Cox Leslie Reginald
Published: October 2009

The material on which the following notes are based has, for the greater part, been collected by Dr. W. D. Lang; a few specimens, however, have been obtained by myself during a number of visits to Charmouth, while one or two others, chiefly from the Belemnite Stone (an easily recognized matrix) have long been in the British Museum (Geological Department), where all the material is now deposited.

Owing to its moderately deep-water facies, gastropods are extremely rare in the Dorset Lias at all horizons below the uppermost beds of the Belemnite Marls. In the lists of fossils published by Dr. Lang in his previous three papers, dealing with the sequence below the Belemnite Marls, only two gastropods are recorded; these are a badly-preserved
Pleurotomaria
from Bed 23, and a small internal cast of a ‘
Trochus
’ from Bed 99. By an oversight, however, in the paper on the ‘The Black Marl of Black Ven & Stonebarrow’, no mention is made of three gastropods collected from the beds in question; the present opportunity may therefore be taken to record them. They are a cast of
Pleurotomaria similis
from Bed 99, a large patelliform cast (‘
Patella
’ cf.
sabrina
Tate) from Bed 91, and a smaller ‘
Patella
’ (possibly the same species) attached to an
Oxynoticeras
from Bed 92. This occurrence of ‘
Patella
’ is of interest, since the horizon is about the same as that of the holotype of Tate's species, which came from Gloucestershire.

In the Belemnite Marls a few indeterminable pyritized casts, probably
Brachiopods [from the Lower Carboniferous of the Menaian Region of Carnarvonshire]
Authors: Muir-Wood Helen Marguerite
Published: October 2009

The
Producti
belong, with a few exceptions, to the
giganteus
and the
latissimus
groups. The bulk of the material is poorly preserved and fragmentary. Some of the forms are new and undescribed, and one of these new forms,
Productus
aff.
giganteus
sp. nov. i, appears to be peculiar to the district.

Productus giganteus (Martin) is represented by two big forms with a rounded outline (Ar 315, Ar 459) from D
2
, and a smaller specimen (Ar 381) from the D
1
limestone.

Productus aff. giganteus sp. nov. i is a small form of the
giganteus
group, very globose and having a highly arched venter and large ears. The costæ are moderately coarse, and the shell has slight longitudinal folds developed below the spine-bases, which are numerous on the venter. This form is represented by a few well-preserved specimens from D
2
(Ar 314, Ar 254, Ar 257, Ar 374
e
, & Ar 256 (=Brit. Mus. B 46780)).

Productus aff. giganteus sp. nov. ii occurs in the D
1
limestone. Most of the specimens are in a poor condition (Ar 399, Ar 465, Ar 468, Ar 476, Ar. 478, & Ar 467 (=Brit. Mus. B 46781)). This form is coarsely costate, and approaches
Productus maximus
McCoy in size and ornamentation; but the ears are less strongly demarcated. There are examples of this form in the British Museum (Natural History) from the Upper Grey Limestone of Treflach, Oswestry, a higher horizon than that of Nantporth. The Treflach specimens are considerably more convex, but have similar ornamentation.

Productus
The Major Intrusions of South-Eastern Iceland
Authors: Cargill Hilda Kathleen , Hawkes Leonard , Ledeboer Julia Augusta
Published: October 2009

The intrusions of plutonic habit in Iceland have their greatest development in the south-east of the country, and our present knowledge of them is summarized by Thoroddsen, who gives the location of the main occurrences (VII, pp. 264–87). Beyond this little is known of the relationship of the intrusions to the country- rocks or their petrological character; there is one short paper by Helland dating from 1884 (V).

The present study is the result of four summer field excursions by the second-named author, and one excursion by his collaborators, who are responsible for the section on the Slaufrudal stock only. Some intrusions have been mapped on the ‘Generalstabens Topografiske Kort’ (1: 50,000) ; but this map is not yet completed, and more detailed work on certain areas is on that account held up.

The country-rocks are mainly plateau-basalts of Tertiary age, with some rhyolitic lavas, tuffs, and breccias, having a north-westward to west-north-westward dip of 5° to 20°, and cut by numerous dyke-intrusions of a regional north-easterly to north-north-easterly trend. Some of the gabbros are beneath the Vatna Jökull ice-cap, and are represented by pebbles in the southern outwash fans. The outcrops of the rocks here described are indicated on the sketch-map (fig. 1, p. 506).
On some Dolerite-Sills Containing Analcite-Syenite in Central Ayrshire
Authors: Tyrrell George Walter
Published: October 2009

The petrographical province of analcite-rich rocks in Ayrshire is thoroughly basic in character. The most abundant type is teschenite, which frequently passes into picrite and peridotite. Other thoroughly basic types, such as kylite, essexite, crinanite, and monchiquite, are known ; while the effusive phase of this igneous episode has, in the Mauchline basin, given rise to olivine-basalts, analcite-basanites, nepheline-basalts, monchiquite-lavas, and limburgites, which verge on the ultrabasic. It is all the more interesting, therefore, to find in a few localities subacid rocks rich in analcite, evidently belonging to the same suite. This rock constitutes a new type, analcite-syenite. The rock is so fresh, and the primary character of the analcite so undeniable, that this occurrence must take its place as the principal type of this rock-species.

Alkali-syenites and felspathoidal syenites of any description are rare in the British Isles. The best-known examples are found in the remarkable masses of Cnoc-na-Sroine and Loch Ailsh (Suther-land). Prof. S. J. Shand described one of the rocks from the first-named locality as ‘analcite-syenite ’; but in a later paper he withdrew this term, as the analcite was found to be secondary, and he then regarded the rock as merely a leucocratic unspotted variety of borolanite. An analcite-syenite was also described by Hibsch from Grosspriesen in the Bohemian Mittelgebirge, but later the rock was described as sodalite-syenite with a little secondary analcite. Many nepheline-syenites, as, for example, those of Madagascar, contain analcite, some of which Prof. A. Lacroix now believes to be of primary
A Note on the Pleistocene History of Western Buchivacoa (Venezuela)
Authors: Parkinson John
Published: October 2009

During 1925 and part of 1926 scattered observations on the occurrence of Pleistocene or late Pliocene beds were taken over a stretch of country in Western Buchivacoa, the area being defined as follows:—--From about 30 miles east of Altagracia, on the eastern shore of Lake Maracaibo and opposite the town of that name, in a straight line about 10 miles eastwards, thence southwards for 30 to 35 miles, the rectangle, when completed, embracing an area of between 300 and 350 square miles.

The observations, although necessarily incomplete, proved very considerable changes of sea-level and also peculiarities of deposition of sufficient interest, it is hoped, to deserve brief description.

The solid geology of the district passed through consists of an alternating series of false-bedded sandstones and sandy clays, the whole essentially arenaceous, and in many localities very sharply folded along east-north-easterly axes.

When sufficiently eroded, the centres of the folds show Burdigalian and Aquitanian fossils. It was in the upper beds, about 3 miles south of the El Mene Oilfield, that the bones of the new genus of Toxodont were found (see map, marked x ). The age of these upper beds is uncertain, owing to an unconformity between them and the underlying beds of Lower Miocene age, and the lack of fossils, as the deposits are estuarine or freshwater. They are in the locality concerned nearly horizontal or very gently undulating; whereas, as exposed a few miles away, the lower series is tightly folded. A Lower to Middle Pliocene age appears most probable.
The Geology of the District around Meifod, Montgomeryshire
Authors: Robinson King William Bernard
Published: October 2009

Previous work in the area.—The Meifod district was visited by Sedgwick on various occasions in 1832, and again in 1842 and 1843, in the last-mentioned year in company with J. W. Salter. It was from this district that several of the types described by McCoy were collected, and also many of the fossils recorded in Salter's catalogue were obtained during these visits.

It seems strange, since this district was in many ways a connecting link between Sedgwick's Bala succession and Murchison's Shropshire succession, that no further work has been published since Salter's catalogue in 1873.

The general succession was established by Sedgwick, but the exact horizons of some of the beds and the relationship between them needs revision in places: thus Sedgwick attributed the absence of the May Hill Sandstone to the unconformable overlap of the Wenlock Series, whereas, as will be shown in the sequel, the succession is complete at this horizon. It is also unfortunate that the beds in the Mathrafal section were placed by Salter in the Upper Bala (Llandovery rocks = Lower Llandovery of the Geological Survey), since it would now appear that they belong to the base of the Upper or top of the Middle Llandovery of the type area.

The Caradocian deposits on the whole occur in the northern part of the area under discussion, where they form the folded southern flank of the Berwyn dome and the cores of the series of anticlines which run off south-westwards from the main dome. The strata