bluuebunny/crossref_metadata_2025 huggingface dataset:
Tertiary igneous tectonics of Rhum (Inner Hebrides)
Authors: Bailey Edward Battersby
Published: October 2009

A great dislocation is associated with the Tertiary igneous complex of Rhum. In 1903 it was described by Harker, following closely upon Geikie, as an early Palaeozoic thrust. It is now claimed as a Tertiary ring-fault with central uplift. Harker was influenced by the curvature of its outcrop, a feature that at the beginning of the century was regarded as almost diagnostic of a low-angled thrust; today, of course, steep ring-faults * have become a commonplace. Harker was further misled by slump-bedding in the Torridonian, which he interpreted as tectonic; by a patch of Trias with basal cornstone, which he mistook for crushed Torridonian overlying transported Durness Limestone; and by superposition of Lower Torridonian shales on Torridonian sandstone, which latter he thought was post-shale Applecross Grit, instead of pre-shale Basal Grit. Harker misidentified these two grits, largely because he considered that certain associated gneisses were banded Tertiary intrusions, though Geikie had previously recognized their true nature as part of the Lewisian complex. Another correction may here be advanced. Harker took a set of Tertiary explosion-breccias which accompany the tilted Torridonian inside the ring-fault for crush-breccias developed by early Palaeozoic thrusting. Geikie had been hesitant; but Judd had been confident that these rocks were products of Tertiary explosions. The present account is in many respects an elaboration of some of Judd's ideas published in 1874. The outstanding tectonic feature of Rhum is a block uplift, with an elevation amounting locally to about 7000 feet. The uplift was accomplished at the start of Tertiary volcanicity, and was indirectly responsible for the famous inter-lava river gravels of the neighbouring island of Carina. The peridotites of Rhum were later than the block uplift, and they rose along ring-fissures about a centre well to the west of that surrounded by the great initial ring-fault.
The Valentian succession around Llanidloes, Montgomeryshire
Authors: Valory Jones William David
Published: October 2009

Llanidloes is situated in the Severn Valley, in the western part of Montgomeryshire, and is surrounded by areas which have been described by other authors. The area of Tarannon (Wood 1906) lies to the north, Ponterwyd (O. T. Jones 1909) to the west, Rhayader (H. Lapworth 1906) to the south, and Abbey Cwmhir (R. O. Roberts 1929) to the south-east. Most of the ground between these areas has now been mapped on the scale of 6 inches to the mile.

Very little detailed work has previously been done in this area. Sedgwick amde journeys across it and Murchison makes occasional references to it; Professor O. T. Jones (1922), however, has discussed in detail its ore occurences.

The greater part of the country is dissected by the Severn drainage system, and the main sequence is exposed in these streams. The Wye system is confined to the south-west and reveals a few good sections in rock-groups near the top of the Valentian. The average height of the higher land is between 1000 and 1500 feet, but the ground rises to nearly 2000 feet in the extreme east. All the higher ground is pasture, while the lower country of the valleys is usually cultivated.

The strata range from Upper Bala to Salopian in age, but only the Valentian rocks are described in detail. Mudstone is the dominant lithological type; intercalations of thin shales occasionally yield graptolites. These organisms are the sole fossils found in the area and are preserved either in full or in half relief; they afford an interesting comparison with the forms preserved in the flattened condition.

The fundamental structure of the district'is a dome which has been named the Clywedog Dome, from the river of that name which joins the Severn at Llanidloes. The Central Wales Syncline passes through the area near its western margin and exhibits a culmination of pitch near tne northern margin. The Towy anticlinal axis does not enter the area but runs some three miles to the south-east, near Abbey Cwmhir (R. O. Roberts 1929).

Faulting" is an important feature; several of the major faults have been identified as belonging to the group of faults and lodes occurring in the Ystwyth Valley, 4 miles to the west. Strike-faulting is not common, but locally the major faults may behave as strike-faults.
The Carboniferous Rocks of the Edale Anticline, Derbyshire
Authors: Hudson Robert George Spencer , Cotton Geoffrey
Published: October 2009

The Edale Shales, which both outcrop in Edale and were passed through in the upper 325 feet of a boring in that valley, consist of 150 feet of beds of
Reticuloceras reticulatum
(R
1
) age, 100 feet of
Homoceras
(H) age, 220 feet of
Eumorphoceras Bisulcatum
(E
2
) age, and 406 feet of
E. pseucdobilingue
(E
1
) age. The faunas of the zones and subzones are described and comparison is made with those of Alport Dale to the north and Mam Tor and the Hope boring to the south near Castleton. It is shown that the upper beds (upper E
2
, H, R
1
) in general retain their thickness southwards from Alport to Castleton, where they rest on the Carboniferous Limestone, thus overlapping the lower beds (E
1
and lower E
2
). It is suggested that the greater part of this overlap takes place immediately north of the limestone massif.

In a boring in the Edale Anticline the beds from 325 to 757 feet, the final depth of the boring, were of Upper Viséan age. Goniatites of the genera
Neoglyphioceras
and
Goniatites
occurred in the upper beds, and the zonal scheme based on goniatites was therefore used for the division of the upper part of the succession. Since most of the other fossils were brachiopods, corals being extremely rare, the allocation of the beds to the
Dibunophyllum
zones, D
1
, D
2
and D
3
, was made in part by comparison of the lithologicaI succession with those of other areas with more definite zonal faunas. The lithological succession and the zonal division adopted were aa follows :—
Notes on the Geology of the Southern Rumanian Oil District with Special Reference to the Occurence of a Sedimentary Laccolith
Authors: De Raaf Johan Ferdinand Maurits
Published: October 2009

The Tertiary stratigraphy and tectonics of the Carpathian foothills, north of Bucharest, are briefly described. Apart from slow movements during sedimentation there are two major folding phases, in pre-Burdigalian and post-Levantine times respectively. Normal salt plugs, similar to the “salt domes” of other countries, occur usually in the core of anticlines. Elsewhere along faults intrusions of salt-breccia have been observed. In the vicinity of Campina an intrusion of clayey salt-breccia, along bedding-planes in the Sarmatoid sequence is described in detail. This body of salt-breccia does not represent an ancient mud-flow contemporaneous with the Sarmatoid beds, but an intrusion at a later date of foreign sedimentary material. Rock-salt, although present near the surface in its immediate vicinity, has not been observed in the above-mentioned intrusion, for which tlie author uses the term “sedimentary laccolith”.
The Barrow Hill Intrusion, South Staffordshire
Authors: Marshall Charles Edward
Published: October 2009

Geological, magnetic and resistivity surveys indicate that the igneous rock is very largely confined to he higher parts of Barrow Hill, with near-vertical contacts on the northern, eastern and south-eastern flanks. Towards the west and north-west the base of the main intrusion rises transgressively at an angle of approximately 30°; in this direction the country rock (Middle Coal Measures-Etruria Marl) is greatly disturbed and subject to highly irregular, small-scale injection. Pre-intrusion, penecontemporaneous and post-intrusion faulting is in evidence.

The igneous rock is dominantly an extremely fine-grained analcite-bearing olivine-basalt, most frequently microtaxitic in character. Local country-rock zenoliths occur in large numbers, exhibiting a wide range in degree of alteration. The distribution and character of the changes produced, together with the nature and relations of the later-stage mineralization, indicate the importance of the volatile phases in the consolidation history of the igneous rock.

Field and laboratory studies suggest that the Barrow Hill intrusion most probably represents a late Carboniferous feeder.
The Genus
Phialaspis
and the “
Psammosteus
Limestones”
Authors: White Errol Ivor
Published: October 2009

1. At least two species of the genus
Phialaspis
are represented among the ostracoderm remains from the Downtonian commonly identsed as “
Psommostrus anglicus
”,
P. symondsi
and a small new form,
P. pococki
, of which a distinct variety and a sub-species are also known.

2. Seventeen records of the genus have been established, which, apart from one , in Scotland, are all in the Anglo-Welsh area. The localities are recorded and the associated faunas listed.

3. It is pointed out that the two species have never been found together, although the localities are interspersed : at all those yielding
P. symondsi
, ten in number, the beds are in Wickham King's stage 1.8 (“
Psammosteus Limestones
”) ; whereas five of the seven occurrences of
P. pococki
are in earlier strata, the age of the fifth being disputed and of the sixth unknonn. The possible use of these species for zoning is noted.

4. It is considered that for the most part the Downtonian and Dittonian vertebrate faunas were not autochthonous, but were of freshwater origin.

5. The new specimens of
Phialaspis
are described in detail. Almost the whole of the carapace is now known, chiefly from specimens from two new localities, Gardener's Bank, Salop, and Sharpness, Gloucestershire, and this shows a number of pteraspid and, to a lesser extent, cyathaspid features ; but it also shows specialized characters that are peculiar to the genus, which is accordingly made the type of an independent group of heterostracans.

6. What is believed to be the earliest instance of vertebrate palaeopathology is recorded.
The Geological Results of the Search for Oilfield in Great Britain
Authors: Lees George Martin , Taitt Alfred Harold
Published: October 2009

The search for oil in Great Britain has been carried out in five separate geological provinces—in the Mesozoic of southern England, the Carboniferous of the eastern Midlands, the Triassic and Carboniferous of Lancashire, the Permian of North Yorkshire and the Calcirferous Sandstones Series of the Midland Midland Valley of Scotland. Four oilfields have been discovered in Nottinghamshire and a small field in Lacashire. In addition, a large amount of new stratigraphical information has beeb provided by the exploration borings and extensive geophysical surveys have added cosiderably to existing knowledge of the structure of the Carboniferous in the eastern Midlands. The boring records have given much new information on the development of coal seams in the areas east and sout-east of the present Nottinghamshire Coalfield. A boring in North Yorkshire proved the presence of potash salts in the Permian indicating conditions comparable with those of North-West Germany.
Ophthalmidium:
A study of Nomenclature, Variation, and Evolution in the Foraminifera
Authors: Wood Alan , Barnard Tom
Published: October 2009

Some variable foraminifera from the base of the Upper Lias at Byfield, Northamptonshire, have been used as evidence supporting completely opposed "evolutionary series" based on the "law" of recapitulation and its converse, proterogenesis. The authors obtained closely spaced samples of this foraminiferal clay and studied them in order to establish the actual succession of forms.

The first major portion of the paper (section III), a complicated discussion of nomenclature, is necessary in order to give a name to the forms studied. Here a number of genera and species are established or redefined.

The following section (IV) attempts to establish the bounds of the species by means of a detailed variation study. It is found possible to define closely the species studied; though they are highly variable, no transition from one species to another is seen.

Finally, in section V it is shown that the actual succession of forms does not support the theory of proterogenesis, but rather that of recapitulation. A marked shift of the mode of variation is observed within a time interval represented by the deposition of 2 feet of clay. The contribution which the variation study can make to systematics is also discussed.
Metamorphism of the jasper bars of Western Australia
Authors: Miles Keith Rodney
Published: October 2009

Until comparatively recently the true jasper bars of Western Australia have been regarded by local geologists as silicified and replaced shear-zones in greenstone. The evidence in the paper suggests that these jasper bars, like the banded ironstones in the Pre-Cambrian of many other countries, were originally sedimentary formations which have experienced varying degrees of metamorphism leading to the development of certain characteristic mineral associations. No account has been taken of the many superficial so-called jaspers, silicified limonitized surface gossans either of fault gouge or of schists originally impregnated with iron sulphides, which have often in the past been mistakenly identified with the true banded iron formations or jasper bars.

Beds of banded iron formations and related rocks are found associated with rocks of several distinct series of the Pre-Cambrian in Western Australia, namely : the younger Pre-Cambrian (Proterozoic) rocks of the Nutlagine Formation, and the Mosquito Creek, Whitestone, and Older Greenstone Series which form portions of the older Pre-Cambrian rocks. The ironstones of Nullagine age have been subjected only to mild metamorphism and have remained relatively unchanged, except where, under special conditions, fibrous riebeckite (crocidolite) seams have been formed by growth in situ from beds of unique composition.

The banded ironstones and jasper bars of the older Pre-Cambrian series have been metamorphosed both regionally and locally in varying degrees. With increasing grades of metamorphism they have been recrystallized, and the original iron in the more ferruginous types has reacted with silica to form minerals such as grunerite, hedenbergite, iron-rich hypersthene, and fayalite. The grade and type of metamorphic conditions which these rocks have experienced are to some extent indicated by the quantity and the species of the ferrous silicate minerals developed.

It is believed that the failure of early observers to recognize the true nature of these ferrous silicate minerals in jasper bars from highly metamorphosed areas (particularly in the Yilgarn Goldfield) was primarily responsible for the growth of the "shear-zone" theory. Early geologists, mistaking these minerals for amphi-boles similar to the actinolites and hornblendes in the adjacent amphibolitic schists and greenstones, concluded that the jasper bars represented amphibolitic schist partially replaced along parallel shear-planes by later silica and iron ore. This would account for the statement that jasper bars may be seen grading along strike and dip into the adjoining greenstone.
The Compaction of Muddy Sediments
Authors: Jones O. T.
Published: October 2009

In his attempt to correlate pressure with the void-ratio of shales encountered in oil wells Professor Jones made two assumptions, one regarding the relation between pressure and void-ration and one regarding hydrostatic uplift.

Since the relation between pressure and void-ratio under high pressure is a matter of general interest, the writer induced Professor R. B. Peck of the University of Illinois to make consolidation tests on clay under pressures up to 2000 kilograms per square centimetre. These pressures correspond to a depth of overburden of at least 30,000 feet. It was found that the line representing the relation between the void-ratio and the logarithm of the pressure is, for a range of pressure between about 20 nd 2000 kilograms per square centimetre, almost perfectly straight, without any tendency to flatten out. However, it is doubtful whether the compaction of sediments under high overburden pressures follows exactly the same law, because the increase of the overburden pressure is associated with a considerable increase of temperature. Exposure to relatively high temperature over a long period of time is likely to involve mineralogical changes. Such changes may represent and additional source of compaction, not present in laboratory tests. The occurrence of mineralogical changes is indicated by the fact that a shale cannot be reconverted into a clay slurry, whereas the clay which was subjected in the laboratory to a pressure of almost 2000 kilograms per square centimetre still was a clay. It is also indicated by the observation that the transition of a
The Carboniferous Rocks of the Edale Anticline, Derbyshire
Authors: Hudson R. G. S. , Cotton G.
Published: October 2009

From
Mr. R. C. S. Walters :—

The authors are much to be congratulated on giving the full analyses of water from the Barber Booth Well. Such data should prove valuable in any research into the origin of the composition of underground water. Presumably the rest level remained stationary at 200 feet below the surface, but it would be interesting to have the probable levels of lowering in the water when the several quantities of water were abstracted. What is the equivalent of a barrel in gallons?

The volumes of the waters struck were tested by bailing. The maximum amount that could be bailed was about 37 barrels (of 40 imperial gallons) per hour; with any substantially smaller inflow than this the hole was bailed dry and the reported inflows were with the hole approximately in this condition.

At 563 feet the level could be reduced only about 50 feet when bailing 37 barrels per hour, the first 6 barrels removed lowering the level about 30 feet and the next 18 barrels only lowering it 10 to 20 feet farther. At 652 feet the water level could be lowered only 40 feet by removing about 55 barrels in 1| hours, and at 662 feet hours bailing failed to lower the level at all.

In the Alport boring, some 4 miles to the north, no water at all was encountered down to 2555 feet.
Geological factors in gravity interpretation illustrated by evidence from India and Burma
Authors: Evans Percy , Crompton Wilfred
Published: October 2009

The interpretation of gravity data has suffered from lack of collaboration between geodesists and geologists, and few general discussions of the subject have made adequate allowance for the effects of relatively light sedimentary rocks in diminishing the observed values of gravity. In an extensive gravity survey of Burma and north-eastern India gravity anomalies (that is, the difference between the observed and computed values) were determined at over 6000 stations, and an endeavour was made to resolve the anomalies into the portions due to known geological causes and the residual (regional) portions due to deep-seated variations in density.

Although the need for applying to gravity data a correction for known geology was emphasized by David White in 1924 and has been discussed by several subsequent writers, so far no attempt seems to have been made to carry out the necessary computations for an area in which sediments are thick. The calculations are laborious, but a graphical method supplied by Colonel (now Brigadier) E. A. Glennie, of the Geodetic Branch of the Survey of India, proved very useful. Difficulties were encountered in determining appropriate densities applicable to sediments buried at great depths, a branch of geology which has received little attention. Sections through representative gravity stations were drawn from geological maps, and by the graphical method it was possible to estimate the gravity effect attributable to known or inferred geological structures. This was subtracted from the anomaly to obtain a
geologically corrected
or
residual
anomaly

Some of the geological corrections are of the same order as many of the anomalies, but in general their application does not lessen the anomalies, and the results confirm the view of de Graaff Hunter and Glennie that it is incorrect " to quote India as a region supporting the hypothesis of Hay ford isostasy ". The residual anomalies show a close relation to the main tectonic lines. A pronounced gravity minimum follows the lines,of maximum uplift in the hills separating Assam and Bengal from Burma and a gravity maximum almost coincides with the nearly parallel volcanic line of Burma. Both these lines can be correlated with the even larger anomalies described by Vening Meinesz in the Netherlands East Indies. A gravity minimum follows the general trend of the eastern Himalayas. The Bengal and Irrawaddy deltas (like the neighbouring deltas of the Indus, Mekong, and Red River or Tongking) are areas of excess gravity. All these major regional anomalies are attributable to variations in the depths to the basic and ultra-basic crustal zones. The broad regularity of the gravity features is interrupted by several local anomalies, of which the most important coincides with a belt of thrusting and may be due to hitherto unsuspected igneous intrusions.
Erosion and tectonics in the East African Rift System
Authors: Dixey Frank
Published: October 2009

From consideration of the Karroo and Jurassic structures within the Rift Zone it is suggested that major folding that took place in later Jurassic time raised locally to great height the resistant pre-Karroo complex, out of which, in successive cycles, the high-level residual plateaux have been carved. In general, throughout the Rift Zone the surviving larger tracts of Karroo and Jurassic sediments still occupy low-lying areas representing the original major synclines, but in some cases trough-faulting that succeeded the folding carried down into the elevated areas strips of sediments which were subsequently eroded to form ancestral " rifts "; within these " rifts " much of the Pleistocene rifting took place and thus formed narrow lake basins within an ancient topography.

The pattern of the ancient residuals on the main watersheds of the Rift Zone indicates that these watersheds were original features on the Miocene peneplain, inherited from the great framework of the Jurassic folds.

Until the rifting of about the Middle Pleistocene carried down the floor of the Nyasa and Tanganyika troughs to form the existing lakes, the history and form of these troughs differed in no essential respect from that of the Karroo troughs of the Luangwa Valley and the middle and lower Zambezi. These troughs had been developed in their present form by a prolonged sequence of planation, continental uplift, and erosion that intervened between the fracturing of the post-Karroo period and that of the Pleistocene. The Pleistocene rifting accordingly took place along existing troughs of ancient origin of which the form was accentuated by the erosion of the Miocene and Pliocene cycles. Similarly, many of the Pleistocene rift fractures of Tanganyika Territory followed ancient fault-line scarps and troughs. The major rifts of the northern part of the Rift System, including the Abyssinia Rift, also show a pronounced pre-Pleistocene phase of ancient origin preceding the Pleistocene rifting, and in two localities there is evidence, too, of movements of Lower Miocene age
The supposed Cambrian foraminifera from the Malverns
Authors: Wood Alan
Published: October 2009

The only foraminifera of Cambrian age with wall-structure preserved were described by Chapman in 1900. Originally considered to be derived from a calcareous band in the White Leaved Oak Shales (Upper Cambrian), these specimens are here shown to be derived from a loose fragment of Rhaetic of Lower Liassic limestone. As " the earliest-known well preserved foraminifera ", these have had a great influence on the classification of the group, and the views of certain authors as to the evolutionary sequence of foraminiferal types will have to be completely revised. The genera
Lagena, Nodosaria, Dentalina, Cristellaria, Spirillina
and
Marginulina,
previously considered to range unchanged from Cambrian to Recent, probably range from Mesozoic only. The isolation of Palaeozoic foraminifera becomes now much more marked and the incoming of Mesozoic types must have relatively rapid.
The type specimen of the genus Ophthalmidium
Authors: Wood Allan
Published: October 2009

As stated in a previous paper,
1
the genotype of the foraminiferal genus
Ophthalmidium
, hitherto believed lost, has been made available for study. The type figure being incorrectly drawn, the genus has been consistently misinterpreted. The purpose of this note is to refigure and redescribe the original material, the existence of the specimens being discovered too late to permit of a figure or full discussion being included in the paper cited. A diagnosis of the genus, and a historical survey of previous work, was, however, given and need not be repeated.

The specimen is mounted in Canada balsam, together with much unsorted residue, on a small slide labelled “ Jurensis. n. Only one specimen of
Ophthalmidium
is present, which accords with Kuler's (1870) statement, “ Unicum“, but not with the original statement of 1866, " Haufig ". The latter may refer to the abundance of the genus in the Jurassic rocks. Detailed description of the specimen is rendered unnecessary by the figures here given. In the line drawing the imperforate layer between the chambers is dotted, the chambers themselves being left blank. The portion of the test around the aperture, obscured by a foreign body in the photograph, is restored in the line drawing by inspection under a low power (x 80) lens from the other side of the slide. The only feature calling for discussion in detail is the nature of the junction between the fourth and fifth chambers, and their relative proportions. The normal type of chamber junction is
The petrology of two granite-slate contacts at Cape Town, South Africa
Authors: Walker Frederick , Mathias Morna
Published: October 2009

The porphyritic biotite-granite of the Cape Peninsula is intrusive into the tightly folded pre-Devonian Malmesbury Series which consists of psammitic hornfelses with subordinate politic intercalations. At two localities within the Cape Town municipal boundary, namely Sea Point and Kloof Quarry, the contact aureole is well exposed and includes a zone of spectacular migmatites. With the aid of 14 new chemical analyses it is shown that the contact phenomena probably arose in four main stages:—

(i) Intrusion and differentiation of a contaminated biotite-granite magma,

(ii) Permeation and softening of the Malmesbury hornfelses by alkaline emanations from the granite,

(iii) Penetration of the hornfelses by granitic material with the formation of migmatites.

(iv) Felspathization of the granite and migmatite zone by late potassic solutions which gave rise to potash pegmatites and large crystals of perthitic micro-cline.

The evidence for the formation of an Mg-Fe front outside the migmatite zone is inconclusive.
The geology of the Silurian rocks west and south of the Carneddau Range, Radnorshire
Authors: Jones Owen Thomas
Published: October 2009

An account is given of the geological succession from the Upper Llandovery to the lower part of the Lower Ludlow. The former group is developed in two distinct facies—an eastern facies of calcareous sandstones with
Pentamerus oblongus
, and a western facies of green mudstones and dark shales containing
Monograptus crenulatus
and other graptolites. The Wenlock rocks are dark graptolitic shales which have been divided into two sub-groups. They include the six graptolite zones erected by Dr. G. L. Elles in 1900. The Lower Ludlow rocks consist of shales with
Monograptus nilssoni
.

In the Upper Wenlock and above the
M. nilssoni
shales there are important developments of slumped mudstones which have been mapped in detail.

The area is a shallow syncline traversed by a series of powerful faults ranging mainly in the direction of the strike. Some of them behave as block faults. One fault appears to be a tear which has shifted earlier faults. Cleavage is sporadically developed.
A geological museum of the early seventeenth century
Authors: Bromehead Cyril Edward Nowill
Published: October 2009

The paper describes the five volumes labelled “Fossils” which are among the Italian drawings purchased by George III in 1762, and which are now in the Library at Windsor Castle. The drawings have been identified as representing some of the specimens in the Museum of the Academy of the Lynxes in Rome in 1626. It is shown that these unique documents throw much light on contemporary thought, and indicate the emergence of a genuine science of Geology from the mists of magic, imagination and fable. Published accounts of similar collections, notably those of the Vatican as catalogued by Mercati, Aldrovandus, and Nehemiah Grew's catalogue of the Royal Society's museum, are quoted to show the opinions held at the time as to their origins and uses.
The structure of the Coal Measures in the Pontardawe-Ammanford Area
Authors: Trotter Frederick Murray
Published: October 2009

The tectonic structures described lie in Coal Measures on the northern limb of the major South Wales Syncline. The Coal Measures sequence is divided, for mapping purposes, into seven groups. The earth-movements which have affected the area can be divided into three episodes.

The first is referable to the Armorican orogeny, when forces directed from the south gave rise to differential northward movement of the strata, observable along north-north-westerly trending tear-faults. The northerly moving strata were forced against the pre-existing Towy Anticline and west-south-westerly structures were developed in the younger Palaeozoic rocks parallel to that Caledonoid massif, of which the Cwm Twrch and the Ammanford compressional belts are the most important. The compression-belts consist of folds, thrusts and lag-faults.

The second episode was a period of tension during which a second system of north-north-westerly faults was developed. These elevated or depressed pre-existing structures but did not displace them laterally. During this period the region was tilted southwards and this tilt gave rise to the west-south-westerly pitch of the folds formed during the compression period. The tear-faults also moved vertically during the period of tensional stress and there are three cases of tensional sags and associated trough-faults developing on the western side of pre-existing tear-faults. Four stages in the development of a fault-trough from a sag are illustrated by sections across the Cwm Clydach trough.

In the last tectonic episode, the structures of the two previous episodes were moved laterally by the north-easterly trending Tawe Valley tear-fault.
Some English Cretaceous and Eocene Hexacorals
Authors: Thomas Henry Dighton
Published: October 2009

A new species of
Oculina
is described from the Hythe Beds (Upper Aptian) of Surrey. This is a surprisingly early occurrence of the genus, which is not otherwise known before the Tertiary. Two other corals— one a new species of
Oculina
, and the other a specimen of
Paracyathus caryophyllus
(Lamarck)—are described from the Blackheath Beds: they are the oldest English Tertiary corals known. A re-description of
Heterocoenia reticulata
(Duncan) is also given.

I am indebted to Mr. A. G. Davis, Mr. F. J. Epps, the late C. W. Hobley, C.M.G., and Messrs. C. W. and E. V. Wright for the material of the new species; to Mr. C. W. Wright also for providing me with notes on the horizon of the two pits at Taylor's Hill, Godstone, Surrey; and to my colleague, Mr. W. H. T. Tams, for the excellent photographs of the corals.

Genolectotype
(see Edwards and Haime 1850, p. xix).—
Oculina virginea
Lamarck 1816, p. 285 (non
Madrepora virginea
Linnaeus 1758, p. 798, nec
Madrepora virginea
Ellis and Solander 1786, p. 154, pl. xxxvi), Recent, West Indies =
O. diffusa
Lamarck 1816, p. 285, Recent, West Indies.

Material
.—The holotype and seven paratypes, all silicified, preserved in ferruginous sandstone, from the Lower Greensand, Hythe Beds, Upper Aptian,
martini
zone, Taylor's Hill Pit (North), south of Godstone, Surrey (National Grid reference, 357507).

Holotype
.—R.35210 (C.W. and E. V. Wright collection).

Paratypes
.—R.33690–R.33695 (A. G. Davis collection) and R.33696 (C. W. Hobley collection).

Diagnosis
.—
Oculina
forming a reticulate corallum, with calices from 1·3 to 1·5
The occurrence of Moinian rocks in Ireland
Authors: Anderson John Graham Comrie
Published: October 2009

The paper deals with an extensive area of metamorphic rocks north of Lough Erne in North-West Ireland. Metamorphosed sedimentary rocks form a conformable succession consisting of the Lough Derg Psammitic Group (oldest), the Oughtadreen Pelitic Group and the Calcareous Group. Altered igneous rocks are represented by epidiorites and amphibolites.

Evidence is brought forward that the Lough Derg Psammitic Group, consisting mainly of granulites, is of Moinian age; the other two groups are placed in the Dalradian.

In the Pelitic Group, kyanite, garnet and biotite zones of metamorphism have been mapped. The high-grade metamorphism is related to a belt of intense pegmatitization and injection—the Lough Derg Injection Complex—which is similar to the injection complexes of the Scottish Highlands.

Structurally, the metamorphic rocks form the Lough Derg Anticline, a Caledonian fold with north-easterly pitch. On their west side they are also affected by gentle Armorican anticlines, the westerly pitch of which carries them beneath Carboniferous rocks, and on their south-east side they are brought against the same strata by a powerful north-easterly fault.
Marine Bands and other faunal marker-horizons in relation to the sedimentary cycles of the Middle Coal Measures of Nottinghamshire and Derbyshire
Authors: Edwards Wilfrid , Stubblefield Cyril James
Published: October 2009

Systematic examination of the cores of several deep boreholes drilled during the past seven years has increased to ten the number of known faunal marker-bands in the Middle Coal Measures of the Nottinghamshire and Derbyshire Coalfield. Details of the stratigraphy and of the geographical distribution of these bands have been supplemented by reference to outcrop and underground workings and to fossiliferous samples from colliery shafts.

Each band is considered as part of a cycle of sedimentation which has distinctive characters over substantial areas of the coalfield. Nine of the ten cycles contain marine phases and all but the earliest occur within the thousand feet of strata representing the Similis-Pulchra Zone.

The constitution of the cycles is discussed and the faunas listed. Notes and illustrations are given of some of the fossils, including foraminifera, which group occurs in five of the marine bands.

Correlation is indicated where possible with Yorkshire and other neighbouring coalfields. An appendix embodies results of a detailed petrographical examination of two of the cycles at one locality.
The Sequence and structure of the southern portion of the East Crop of the South Wales Coalfield
Authors: Moore Leslie Rowsell
Published: October 2009

The paper describes the sequence and structure of the Upper Carboniferous rocks along that part of the East Crop of the South Wales Coalfield between Pontypool in the north and Risca in the south. The Coal Measures of this region have hitherto been regarded as representing a thin but nevertheless complete succession. Nowhere, however, along this portion of the East Crop is there a complete sequence of Coal Measures, as that formation is developed in more westerly parts of the coalfield. Indeed, there is no outcrop of the Lower Coal Series over some considerable part of this tract; that series is represented in other parts only by its basal strata. In certain transverse valleys a fuller (but still incomplete) sequence of the Lower Coal Series is represented at outcrop by measures including the Similis-Pulchra Zone.

Likewise the Pennant Series, which in this paper is subdivided into Upper, Middle, and Lower groups, is incomplete; only the Upper and Middle groups are represented along most of the East Crop. The Upper Pennant Group is that portion of the Pennant Series which has hitherto been regarded as alone constituting the “Pennant Sandstone” of Monmouthshire. The Middle Pennant Group, which contains massive conglomerates and carries coloured measures previously known as the Deri Group, has in the past been erroneously included in the Lower Coal Series.

Thus the relationship of the Coal Measures along the East Crop is conditioned by major unconformity of Morganian age, which was accompanied by overstep and overlap, so that high horizons within the Pennant Series rest unconformably upon the Lower Coal Series and sharply overstep on to the Millstone Grit.

The region has suffered from movements of two definite ages :—

(a)

An earlier period, of Morganian age, resulting in the elevation of a land-mass east of the coalfield from which was derived sediment incorporated in the Middle Pennant Group.

(b)

A later, Hercynian (Variscan) period.

These combined movements have resulted in monoclinal folding along north-north-east to south-south-west lines, the older rocks being more steeply inclined than those of the Pennant Series. The dominant north-north-east to south-south-west folding of the eastern end of the South Wales Coalfield is described, and the considerable structural similarity between the east crops of the South Wales and Forest of Dean coalfields is indicated.

The effects of Morganian uplift are considered to have been widespread and may have affected an area including the Forest of Wyre, Forest of Dean, and Somerset and Gloucestershire coalfields.

The paper includes a comparison of the sequence in the area under description with that in other more westerly parts of the South Wales Coalfield and presents a suggested correlation of the Pennant Series of these areas. The Forest of Dean sequence is correlated with that of South Wales.
On lineation and petrofabric structure, and the shearing movement by which they have been produced
Authors: Anderson Ernest Masson
Published: October 2009

The currently accepted view of lineation regards it as being perpendicular to the direction of shearing or “transport”. This conclusion appears to have been arrived at by petrologists mainly on two grounds: (1) the evidence obtained by Schmidt in the Leoben district of Austria and in the Tauern Mountains, and (2) the “argument from symmetry”. Sehmid's evidence is re-examined in this paper, and it is concluded that more data than he has given would be needed to make the inference convincing. The inconclusive nature of the “agrument from symmetry” has, on the other hand, been shown very clearly by schmidt himself.

The contrary view that lineation is parallel to the shearing movement is certainly true with regard to one district in Norway, as has been demonstrated by Kvale. In several localities, in different countries, it has also been found that the direction of lineation is that of the longest dimensions of pebbles and larger fragments in distorted conglomerate. The possibility that the pebbles themselves are elongated at right angles to the shoaring, and the plane of distortion, is discussed in this paper, and reasons are given against it. it is therefore inferred that shearing and lineation are most probably parallel, according to present evidence.

This conclusion, if accepted, will lead to a revision of present ideas of petrofabric structure, in particular about the formation of single quartz and mica girdles. The direction of shearing, or “transport”, must, in fact, be normal, and not parallel, to the plane of the girdles. It is claimed, however, that this type of diagram may be as well, or perhaps better, explained according to the writer's hypothesis.
The structure of the wall of the test in the Foraminifera; its value in classification
Authors: Wood Alan
Published: October 2009

The terms so widely used in the classification of the Foraminifera, “perforate” and “hyaline”, “imperforate” and “porcellaneous”, are shown to be based on characters of entirely different significance. Perforation or non-perforation of the test-wall may occur in any group, while the hyaline or porcellaneous appearance, fundamentally depending on the microstructure of the wall, is much more reliable. The structure of the test-wall as observed in polarized light is described for all the main groups of Foraminifera, and the conclusion is reached that the microstructure is a character whose importance differs somewhat in different groups. In part this may be ascribed to the actual time of appearance of the particular structure, and the degree of differentiation that has since occurred. There is little doubt, however, that the microstructure of the test is a character of taxonomic importance.
Preliminary note on the structure of the foraminiferal genus
Archaias
and Related Forms
Authors: Henson Francis Roger Spencer
Published: October 2009

While studying foraminefera from the Tertiary of Iraq and Iran, which had been referred to in literature under the name of
Archaias aduncus
(Fichtel and Moll), the author concluded that the structure of these organisms does not conform to the description of
Archaias
[
Orbiculina
] given by W. B. Carpenter (
Phil. Trans. Roy. Soc.
, Vol. 146, 1856, part II, pp. 547–52, pl. xxviii, figs. 1-16; pl. xxix, figs. 1-3) and generally accepted in standard text-books on the Foraminefera (Galloway 1933; Cushman 1940; Glaessner 1945). According to these authors,
Archaias
may be described as a large, compressed
Peneroplis
sometimes becoming cyclical in the later stages, and with the primary chambers sub-divided into rectangular chamberlets by transverse secondary septa. In specimens from Iraq and Iran, however, sections parallel to the equatorial plane but very near the lateral surfaces of the test showed no subdivision of the primary chambers.

Following up this observation, sections were cut through the primary chambers in directions normal to given radii of the discoidal shell; and these preparations showed clearly that the internal structures traversing the primary chambers are not secondary septa, but pillars normal to the primary septa. The pillars are numerous and alternate in position with small perforations (apertures) through the primary septa

The question immediately arose whether these Middle Eastern forms should be assigned to a new genus or whether Carpenter's description is erroneous.

It was thought that a distinction might be found between Recent and Tertiary forms attributed from localities in the Caribbean region and
Note on the Aperture in
Nummulites
Lamarck
Authors: Grimsdale Thomas Francis , Smout Alan Hilder
Published: October 2009

The aperture of
Nummulites
is commonly described as a slit at the base of the septum, where the latter approaches the periphery of the previous whorl. Thus Cushman, in his text-book
Foraminifera, their Classification and Economic Use
, 1940 edition, states (p. 217): “Aperture simple, at the base of the apertural face, median.” Galloway, in
A Manual of Foraminifera
, 1933, describes (p. 418) the aperture as “a simple V-shaped opening at the base of the septal face.” Glaessner, in
Principles of Micropalaeontology
, 1946, is less convinced; he writes (p. 175): “Aperture at the base of the septum,
externally rarely clearly visible
in complete tests.“ [The italics are ours.]

All the aforementioned authors use the name
Camerina
, which should now be relinquished in favour of
Nummulites
.

while examining a collection of well-preserved small
Nummulities
[
N. planulatus
(Lamarck) forma A ═
N. elegans
Sowerby], we came across a few specimens in which the final chamber was intact, and noticed—as did Glaessner, evidently—that no aperture was visible. This seemed surprising to us, since the preservation of the specimens was, though not perfect, fairly good; and in broken examples in the same collection, in which one or more of the latest-formed chambers were missing, the supposed aperture—actually the principal channel connecting adjacent chambers of the same whorl—was clearly to be seen, much as described by Cushman and by Galloway.

We were thus convinced that the orthodox representation of the aperture in
Nummulites
was incorrect for this species at least; and we at once
Gravity data obtained in Great Britain by the Anglo-American Oil Company Limited
Authors: White Peter H. N. , Lovely H. R.
Published: October 2009

The paper describes the widespread and detailed gravity surveys carried out over much of England by the Anglo-American Oil Company. An account is given of the operating method, and the results in individual areas are analysed in detail. The surveys have been of material assistance in outlining the broad geological framework of the areas, and the gravimeter has been successful in depicting with considerable accuracy minor structural features, notably in southern England and the eastern Midlands. The discovery of several important subsurface tectonic features, hitherto unknown, can be directly attributed to the gravimeter. Gravity surveys of this nature, by indicating areas worthy of further examination, serve as a necessary prelude to detailed investigation by seismic methods.
The devolatilization of coal seams in South Wales
Authors: Trotter Frederick Murray
Published: October 2009

In South Wales there is a pronounced regional devolatilization of the coals towards a major thrust—the Main Thrust—which is observable immediately beyond the north-western margin of the coalfield. There is also a subsidiary regional devolatilization towards the Gower zone of compression, but this is apparent only on the southern rim of the coalfield.

In South Wales, as well as devolatilization in a horizontal plane, there is marked devolatilization of coal seams with depth. This devolatilization in a vertical plane is towards a plane of shear or of stress (inferred to be the underground extension of the Main Thrust) and is demonstrated by the trend and by the values of the coal-seam isovols. From the trend of the isovols it is deduced that at depth the plane dips gently, approximately towards the south-south-east.

The proposition is propounded that the volatile content of a South Wales seam (dry ash-free basis) expressed as a percentage of the original volatile content of a true coal seam, varies with the square of the distance of the seam from the plane of shear or stress, and the following formula is deduced :— where
V
1
represents the volatile content (expressed as a percentage as indicated above) of the upper seam;
V
2
the volatile content of the lower seam;
y
the vertical distance in feet between the seams; θ the angle of inclination of an underlying plane of shear or stress.

The formula is tested in 49 cases where the volatile contents of upper and lower seams in vertical sequence have been determined by chemical analyses. These cases cover the full range of coal types with vertical distances between the seams up to 2457 feet. The close degree of correspondence between the actual and calculated values constitutes a measure of the validity of the formula. A corollary to the formula is the recognition of a coal-type band for South Wales. With the aid of the formula, the South Wales anthracite field is delimited, and the net reserves are estimated at 4000 million tons.
On The ages of African land-surfaces
Authors: King Lester Charles
Published: October 2009

The conclusion is reached that the land-surfaces of central and southern Africa are older than has generally been supposed. The primitive surface of the southern lobe of Africa, hitherto termed “Miocene”, is regarded as a modified “Gondwanaland” surface; the erstwhile “end-Tertiary” surface as having been initiated following the break-up of Gondwanaland; and later surfaces only as having been carved by new cycles following uplift of continental dimensions in the mid-Tertiary and later.

The “uplift of Africa” is thus considered not to have been much more than 2000 feet (other than locally) since the margins of the continent were roughed out. Local deformation is assigned a more active role than it has been given in literature : African landscape development involves not a static mass occasionally uplifted but a mobile surface undergoing intermittent or rhythmic minor or local modification.