bluuebunny/crossref_metadata_2025 huggingface dataset:
THE MAIN DONEGAL GRANITE
Authors: PITCHER WALLACE SPENCER , READ HERBERT HAROLD , CHEESMAN R. L. , PANDE I. C. , TOZER C. F.
Published: October 2009

The Main Donegal Granite is described in its regional setting and details are given of the envelope of Dalradian metasediments and the relation to the earlier members of the granite complex. A separation is made into the Main Granite Proper and the structureless Trawenagh Bay Granite, covering areas of 140 and 20 square miles respectively.

The Main Granite Proper is a biotite-granite showing a medium-grained, grey, apparently marginal type in the south-east of its outcrop, and a coarser, lighter-coloured variety in the north and west. Pegmatite forms a roof facies in the south-west. Flow structures are shown by mineral orientation and a perfect banding ; the latter is produced by granites of varying grain and biotite content, the finer-grained biotite-richer type being of earlier consolidation and possibly constituting a roof phase. Banding is everywhere steep and along the NE.–SW. length of the Main Granite Proper. Within the Granite, perfectly aligned trains of free-swimming rafts of country rocks, seen to be derived from roofs or walls, extend for some dozen or more miles in the Granite and agree perfectly with its flow pattern.

The contact-zones of the Main Granite Proper show marked sheeting by granite and, in these zones, high-grade contact schists are produced with staurolite and garnet—deformation, and heating have acted together. The marginal parts of the Granite and the adjacent contact-zones show an intense shoar structure, lineation and mullioning, the planar structures running vertically NE.–SW. and the linear elements plunging gently north-eastwards in the north-eastern part of the outcrop and south-westwards in the south-western. The production of these structures was contemporaneous with that of the contact schists and is related to the emplacement of the Main Granito Proper.

The phenomena shown by the Main Granite Proper and by its roof and walls are consistent with the almost horizontal flow, from north-east to south-west, of viscous magma in a long narrow body beneath a pronged roof and between steep walls. A broad divergence of raft-trains as they are followed into the granite shows that it cannot be of replacement origin, nor can the room problem be solved by major stoping. The authors propose that
lateral magmatic wedging
is the mechanism of emplacement this great granite body.
THE LUDLOVIAN AND DOWNTONIAN ROCKS OF THE KNIGHTON DISTRICT, RADNORSHIRE
Authors: HOLLAND CHARLES HEPWORTH
Published: October 2009

The Knighton district displays a thick “ basin facies ” succession of over 6000 feet of Ludlovian rocks, which has been divided into five groups. The Old Red Sandstone, above the basal
Platyschisma helicites
Beds, is divided lithologically into Yellow, Green, and Red Downtonian. Correlation is made with successions in other Welsh Borderland areas.

Conditions of deposition of the Ludlovian rocks are considered. The Ludlovian succession shows two distinct faunas separated by a group of very poorly fossiliferous strata, apparently representing conditions unfavourable to the development of benthonic forms.

Structurally the most notable feature is a disturbed belt some 3½ miles wide, which occupies the western part of the area. It comprises a set of NE.–SW. folds associated with strike-faulting and much fracturing. The belt can be traced north-eastwards and south-westwards considerably beyond the limits of the Knighton district.
ANTHRACONAIA PULCHELLA
SP. NOV. AND A STUDY OF PALAEOECOLOGY IN THE COAL MEASURES OF THE OLDHAM AREA OF LANCASHIRE
Authors: BROADHURST FREDERICK MUNRO
Published: October 2009

A new species of non-marine lamellibranch,
Anthraconaia pulchella,
is proposed in place of
A. pulchra
(Wright
non
Hind) from the Lower
similis-pulchra
Zone of the Coal Measures. A detailed study is made of the relationship between the shells of
A. pulchella
sp. nov. and the enclosing sediments at Oak Victoria Colliery, Oldham. Shell size is shown to be directly related to the organic carbon and detrital quartz contents of the sediment and inversely related to the macroscopic pyrite content. The conditions under which the sediments were laid down are deduced, partly from study of the sediments themselves and partly from study of the disarticulation/ articulation ratios of the shells and the orientation of the shells relative to the sediments. It is concluded that
A. pulchella
sp. nov. thrived under conditions of relatively turbulent water but was dwarfed under conditions of relatively stagnant water. The cause of dwarfing is ascribed either to failure in food supply (possibly allochthonous organic debris in the main), or to the establishment of foul bottom conditions, or to a combination of both factors.

In addition to
Anthraconaia,
the
pulchella-bearing
bed also carries occasional specimens of
Anthracosia,
which become more common towards the base, although they never dominate the faunal assemblage. Immediately beneath this bed, however, there is a band (10 inches thick) in which
Anthracosia
becomes dominant. Possible causes of the change from an
Anthracosia-rich
to an
Anthraconaia-rich
fauna are considered.
THE PRE-PERMIAN FLOOR BENEATH BILLINGHAM, COUNTY DURHAM ,AND STRUCTURES IN OVERLYING PERMIAN SEDIMENTS
Authors: RAYMOND LEO RICHARD
Published: October 2009

The paper discusses the pre-Permian floor beneath Billingham, County Durham, and its regional effect on the overlying Main Anhydrite. Several types of structure exposed by mine workings in the Main Anhydrite are described, and their formation and age considered. The Main Anhydrite and associated beds have been affected by movements on several occasions.
LOWER CARBONIFEROUS ROCKS IN COUNTY WEXFORD
Authors: GEORGE T. NEVILLE
Published: October 2009

The Lower Carboniferous rocks of the Wexford syncline rest unconformably on the Bray Series. Basal conglomerates are followed by highly fossfliferous limestones and shales, with some dolomites, of mid- and upper Tournaisian age, the Old Red Sandstone and the Lower Limestone Shales being overlapped. The earliest beds of the Viséan stage are algal limestones and calcite-mudstones. They are overlain by crinoidal dolomites probably no younger than Upper Caninian in age.

The Tournaisian rocks are closely similar in facies to those of Hook Head . The basal Viséan rocks compare in lithology with, and are of about the same age as, the Calcite-Mudstone Group in South Wales. They are probably the correlatives of the lower part of the Waulsortian reefs of the Ardmore - Cork outcrops, and they suggest that no part of the Hook sequence is younger than Tournaisian.

The local migratory shoreline of the Dinantian Leinster massif is defined by the Tournaisian base, the rate of overlap reflecting a coastal slope of at least 65–70 feet to the mile. The a brupt change in lithology from Tournaisian to Viséan rocks hints at the occurrence of a westerly continuation from South Wales of the mid-Dinantian break, though proof is lacking. A pre-Viséan down warp may be discerned along the line of the present-day St. George's Channel.
THE STRATIGRAPHY OF THE UPPER CARBONIFEROUS ROCKS OF THE BIDEFORD REGION, NORTH DEVON
Authors: PRENTICE JOHN EDWARD
Published: October 2009

The succession in an area lying mainly north and west of Bideford is described. The Northam and Abbotsham Beds, of “coal measures” facies, are followed by the slumped Greencliff Beds and then by the greywackes of the Cockington Beds. These are unconformably overlain by Permo-Triassie breccias.

The structure is interpreted as a series of E.–W. trending, faulted periclines super-imposed upon a southerly early regional dip. The folding and most of the faulting can be shown to be pre-Permo-Trias in age.
THE CRETACEOUS SYSTEM IN NORTHERN IRELAND
Authors: HANCOCK JOHN MICHAEL
Published: October 2009

This paper is a general study of Cretaceous stratigraphy in Ireland. The Cretaceous here is broadly divisible into two parts—an upper division of pure hard chalk known as the White Limestone and a lower division of more or less glaucontie sediments known as the Hibernian Greensands. The Hibernian Greensands are found in two districts: County Derry where they are mostly Senonian, and south-east Antrim where they are Cenomanian and Senonian. They are very variable from place to place and sometimes much condensed. Although limited to lowland areas, the original Lower Cenomanian transgression in Antrim probably extended farther west than the present limits of the Greensands. These more westerly sediments were upfaulted and eroded, mostly during the Middle Senonian, before the
mucronta
Zone transgression carried chalk sedimentation over most of Ireland.
MORPHOTECTONICS AND THE GEOMORPHOLOGICAL SCIENCES WITH SPECIAL REFERENCE TO AUSTRALIA
Authors: SHERBON HILLS E. , GEOLOGY PROFESSOR OF , MELBOURNE MINERALOGY AT THE UNIVERSITY OF
Published: October 2009

The apparent decline of Davisian geomorphology is less than might appear from the literature, as genetic geomorphology has found increasing application in photogeology and is widely used in all geological reconnaissance. Structural geomophology has grown slowly but is now an established technique whereby one of the Davisian trilogy—structure—may be inferred from geomorphological observations. Morpho-tectonics involves a study of external form of major topographic units as well as of their internal structure and permits tectonic inferences relative to areas as large as continents. Both structural geomorphology and morphotectonics add considerably to the techniques available for the study of cratons, and in Australia the results indicate long-continued activity along ancient lines of weakness and considerable evidence for greater mobility of the cratonic units than is normally attributed to them. Lineaments and blocks are prominent and many of the geological basins are framed by lineaments. There are similarities with the neotectonic characteristics of the Russian platform, especially in the reflection of ancient structures in younger and the evidence for recent movements which may be of a continuing nature. This is one point in which the Davisian trilogy is deficient; but genetic geomorphology has afforded a sound basis for understanding when its principles have been rigidly applied.
THE THREE FOLD-SYSTEMS IN THE METAMORPHIC ROCKS OF UPPER GLEN ORRIN, ROSS-SHIRE AND INVERNESS-SHIRE
Authors: FLEUTY MICHAEL JOHN
Published: October 2009

The major structures in the area immediately north-east of the Monar area (
Ramsay 1958
) are a synform and a neutral fold with axes plunging south-west and south respectively. They appear to have formed on the western limb of a larger and earlier major N.–S. antiform. They are, however, separated from the axial region of this fold by a slide, which cuts out a maximum of 7700 feet of the structural succession, and was apparently formed contemporaneously with the synform and neutral fold.

All these structures were affected by refolding and distortion during a third phase of folding; this gave rise to structures plunging south-west, which on occasion obscure the earlier structures. It is suggested that the divergent attitudes of the major synform and neutral fold were one effect of this distortion.

This three-fold structural history is supported by evidence of the relations of minor structures to the major folds and by observations of earlier small-scale structures refolded or overprinted by later ones.

Petrofabric diagrams demonstrate that recrystallization and reorientation accompanied all three phases of folding.
GEOLOGICALIN TERPRATION OF MAGNETIC ANOMALIES OVER THE ASKRIGG BLOCK
Authors: BOTT MARTIN HAROLD PHILLIPS
Published: October 2009

A vertical field magnetic survey of the Askrigg block discloses an E.–W.-striking belt of magnetic basement rocks between Wensleydale and the Craven faults, terminated to the west by the Dent line. These rocks are thought to underlie directly the Carboniferous Limestone in the region of maximum anomalies and to underlie the Ingletonian rocks farther south. The northern margin of this belt is apparently the steeper.

Gravity anomalies observed over the northern half of the block suggest that the northern margin of the magnetic belt may be pierced by a small granite mass elongated also in an easterly direction. The postulated granite appears to have a slight magnetic effect. Two-dimensional models that are approximately consistent with the gravity and magnetic profiles have been constructed with the help of rapid computing methods.

The belt of magnetic basement rocks, together with the postulated granite, appears to have stabilized the subsequent structural history of the southern half of the Askrigg block. The outcrop-pattern of the Dent and Craven lines correlates closely with the margin of this resistant block, and this fact suggests that it is the resistant block, rather than wrench-faulting, that has controlled the pattern. It is also notable that mineral veins are commoner to the north and south of the belt. There is no clear connexion between the distribution of mineral veins and the postulated granite.
THE PETROLOGY OF THE LOWER MAGNESIAN LIMESTONE OF NORTH-EAST YORKSHIRE AND SOUTH-EAST DURHAM
Authors: RAYMOND LEO RICHARD
Published: October 2009

The petrology of the Lower Magnesian Limestone in an area extending from near Darlington to beyond Whitby is described. The paragenesis of the various rock-types is discussed. The relationships between sulphate and carbonate and the origin of talc and sulphur are discussed in detail. The origin of the Lower Magnesian Limestone in the area is also considered.
THE EARLY PLEISTOCENE OF EASTON BAVENTS, SUFFOLK
Authors: FUNNELL BRIAN MICHAEL , WEST RICHARD GILBERT
Published: October 2009

Analyses have been made of pollen and Foraminifera of Early Pleistocene sands and clays in the cliff-section at Easton Bavents, Suffolk. The pollen diagram shows a cool-temperate forest period with
Tsuga,
followed by a period with oceanic heaths when the climate became very cold. Previous records of marine molluscs from the Easton Bavents section are related as far as possible to the sequence described. Environments of deposition indicated by the Foraminifera and the molluscs are discussed. The lower shelly sands of the section are considered to be inner sub-littoral in origin; the main clay horizon probably accumulated in a glacial sea. A heavy-mineral analysis from this clay is reported in the Appendix.

Correlations are made between the Easton Bavents section and the Early Pleistocene deposits at Bramerton Common and in the Ludham borehole. The lower sands are correlated with a level towards the top of the upper division of the Norwich Crag and partly with the temperate Antian stage (pollen zone L3) of the Ludham borehole, and the clay is correlated with the clay of the glacial Baventian Stage (pollen zone L4) at Ludham.
THE TECTONIC AND METAMORPHIC HISTORY OF THE PRE-CAMBRIAN ROCKS OF THE MBEYA REGION, SOUTH–WEST TANGANYIKA
Authors: BROWN P. E.
Published: October 2009

The Mbeya region is situated at the branching of the western and eastern rift valleys. The Mbeya section of the western, or Rukwa, rift is bounded on its north-east flank by the Mbeya range, which is formed predominantly of quartzo-feldspathic cataclastic rocks. These were developed from the older Ubendian rocks of the region by axial-plane shear in a north-westerly trending fold-system provisionally correlated with the Ukingan orogeny. A north-westerly trending zone of lateral shear separates the Mbeya range from the Ubendian rocks of the Lupa area to its north-east. On the south-west flank of the western rift valley there is a further zone of mylonitic rocks which also trend north-westwards. Cataclastic rocks are thus widely developed and are predominant among the Pre-Cambrian rocks of the area. The north-westerly trend of the Pre-Cambrian rocks is closely followed by the younger structures of the western rift valley, but the Usangu scarp cuts across the older structures of the eastern rift valley.
OUR SOCIETY AND THE GEOLOGICAL SCIENCES
Authors: HOLLINGWORTH SIDNEY EWART
Published: October 2009

Two major topics are considered. First, the activities of the Society : its publications, its services to Fellows (particularly those resident overseas), its finances, and the possibility of its contributing more effectively to the development of education and research activities in geology and in promoting their applications. Secondly, consideration is given to means of promoting the greater effectiveness of geological sciences in the life and economic health of the nation, especially in activities overseas.

Other countries have large government-financed organizations for exploring and developing mineral resources. In Great Britain there appears to be a contrast between the official attitudes towards mineral resources on the one hand and to other national assets, such as agriculture and manufacturing industry, on the other.

The massive growth of technical aid to the emerging nations, especially those of Africa and Asia, makes the development of mineral resources a matter of overriding importance. Relatively small numbers of British geological personnel appear to be engaged in major international aid programmes to which Great Britain makes substantial financial contributions.

Many other countries provide official teams of geologists and mining engineers for aid programmes abroad. In the U.K., unfortunately, an obvious nucleus for such operations has to a large extent been dispersed.

It is suggested that a major reorganization of British-based geology is required which would provide careers for a substantial number of geologists who would be available for secondment overseas. There is a considerable potential for the greater use of the staffs of geology departments of the universities of this country in co-operation with those of the new overseas universities in aid programmes. Other fields of growing importance, such as hydrogeology and marine geology, are mentioned.
Current-swept sea floors near the southern half of Great Britain
Authors: STRIDE ARTHUR HAROLD
Published: October 2009

Since 1952, geological mapping of the continental shelf around southern Britain has been carried out with echo-sounders, and more recently by the echo-ranging equipment on R.R.S.
Discovery II,
which produces acoustic maps of the sea floor. The character of the superficial sediments is here interpreted in terms of sedimentation processes and it is argued that these are controlled by the strong tidal currents. Regions of deposition and their supply paths are indicated and it is shown that only one sand stream is heading for the deep sea floor. The subsequent history of land deposits after a marine transgression and of younger material on present-day current-swept sea floors is stated and the facies that are being produced are mentioned.
Ring-structures in the Sara-Fier Younger Granite complex, Northern Nigeria
Authors: TURNER DAVID CHARLES
Published: October 2009

The Sara-Fier complex is composed mainly of granites, but also includes minor acid volcanic rocks and a few small intrusions of basic and intermediate composition. The acid intrusive rocks of the complex form five distinct ring-centres which overlap in a north-south line. An ideal order of events in these ring-centres, applicable to the Nigerian Younger Granite province as a whole is: (i) early volcanic rocks, mainly rhyolitic; (2) ring-fracture, cauldron-subsidence, and the intrusion of a ring-dyke, often of hornblende-granite-porphyry or horn-blende-pyroxene-fayalite-granite; (3) the emplacement of a succession of granites within this ring-fault, generally in a concentric fashion, and including hornblende-biotite-, biotite-, and riebeckite-granites. Intrusive activity seems normally to have been confined within the outer ring-dyke and to have been completed in each centre before the beginning of a new centre. The early ring-dykes are steep structures and since they may be up to a mile wide their emplacement cannot be explained by simple cauldron-subsidence. Later ring-dyke-like bodies and stocks do, however, show outward-dipping contacts, and their emplacement seems to have been controlled by underground cauldron-subsidence beneath dome-shaped fractures.
The stratigraphy and tectonics of the Manx Slate Series, Isle of Man
Authors: SIMPSON ALEXANDER
Published: October 2009

The geosynclinal sequence of the Manx Slate Series has been subdivided into eleven distinct formations with a thickness of about 25 000 ft. This thick sedimentary pile was deposited in the Caledonian geosyncline and is most probably all of Cambrian age. The stratigraphical positions of two thick sheets of slump-breccia have been established.

The tectonics of the Manx Slate Series are more complex than previously envisaged. The island forms part of the polyphase Caledonian orogenic belt. Three phases of tectonic movement (
F
1
,
F
2
,
F
3
) each formed large-scale folds and a suite of minor structures. Later structures deform those that originated earlier.

The fundamental structure that affects the whole island is the acute Caledonoid Isle of Man syncline of
F
1
age. During the second movement-phase (
F
2
) this pre-existing fold was flexed into a major synform and two complementary antiforms. These more open flexures have Caledonoid hinges and their axial planes dip gently north-westwards. During the last phase of folding (
F
3
), the complexity of the pile was further increased by several large, open cross-flexures round axial planes dipping steeply east-north-east.

The final event in the Caledonian deformation was a brittle fracturing of the complex block by a sinistral system of large and small transcurrent faults with a north-westerly strike. Most of the small normal faults that also intersect the Manx Slates are probably post-Carboniferous in age.
The structure of the Rogart igneous complex, Sutherland, Scotland
Authors: SOPER NORMAN JOHN
Published: October 2009

The Rogart igneous complex, Sutherland, is of Newer Granite age and consists of a zoned tonalite-granodiorite-granite body (the central granodiorite complex) emplaced in Moine metasediments which to the east and north are involved in a peripheral zone of migmatization (the migmatite complex).

Although the migmatite complex is genetically related to the central complex, it is not a static contact-effect. Evidence is presented which suggests the following sequence of events. An ascending body of granodiorite magma was preceded by a 'front' of migmatization. When it reached a higher crustal level, migmatization ceased and continued forceful intrusion of the magma deformed the migmatites into a plastic envelope around the expanding magma body, which consolidated as tonalite and granodiorite. Lateral distension exceeded upward movement and a partly funnel-shaped structure resulted. The granite cross-cuts structures in the tonalite and granodiorite and was emplaced later under more brittle conditions.

An analysis of the deformation of 'regional' linear structures around the complex confirms the forcefully intrusive nature of the igneous mass. The geometry of the deformation of the migmatites during the emplacement of the central complex is related to the stress field obtaining at this period as deduced from planar and linear structures in the tonalite.
On the geology of central Badakhshan (north-east Afghanistan)
Authors: DESIO ARDITO , MARTINA ERCOLE , PASQUARÈ GIORGIO
Published: October 2009

Territory explored by the Italian geological expedition to Badakhshan during the summer of 1961 is described.

The metamorphic rocks have been divided as follows: Faydzabad Gneiss, Qara Mughul Gneiss and Rabat Gneiss (pre-Devonian);

Halqa Jar Amphibolite (from Devonian to Jurassic); black slates (undivided and probably of different ages).

Besides these complexes there are several lithostratigraphic units, with semi-metamorphic facies.

The igneous rocks are granite, granodiorite, quartz-diorite, and tonalite of three ages: Upper Permian-Lower Triassic, Upper Jurassic-Lower Cretaceous, and Tertiary.

The sedimentary rocks, Cretaceous, Eocene, and Neogene, have been subdivided as follows: Shingan Formation, Qara Bulaq Formation, Mashad Limestone, Mohammad Aba Sandstone, Gazestan Formation, Baba Darwes Formation (marls and limestones with Cretaceous fossils), Kharakan Formation (with Eocene fossils), Kokcha Formation (Neogene), and Taluqan Gravel (Quaternary). Fluvio-glacial deposits, loess, alluvial and lacustrine deposits, landslides, and talus slopes, all Quaternary, are also present.

Several formations border an old anticlinal core formed by the Faydzabad Gneiss. The anticline trends north-south. Groups of formations separated by unconformities are deformed to varying degrees of intensity.
Layered intrusive rocks in the Lewisian of the North-West Highlands of Scotland
Authors: BOWES DONALD RALPH , WRIGHT ALAN EDWARD , PARK ROBERT GRAHAM
Published: October 2009

Layered ultrabasic and basic intrusive rocks occur in three structural environments in the Lewisian of the North-West Highlands of Scotland and 41 such layered masses, or groups of masses, in the area between Loch Laxford and Loch Torridon are recognized and described. Their igneous origin is indicated by the common mineralogical banding, the occurrence of sedimentation features, particularly current-and wedge-bedding, and by the association, in banded sequence, of ultrabasic, basic, and anorthositic rocks which are similar in chemical composition to corresponding rock-types in other layered igneous complexes.

One group of metaperidotites and metagabbroic rocks has undergone coeval, or near-coeval, granulite-facies metamorphism and folding, probably after an earlier period of disruption. Subsequently, about 2400 m.y. ago, further disruption and amphibolitization took place. No evidence of the later events is shown by most of these masses, but they have moved tectonically, as units, by slip around their margins during subsequent episodes of deformation. The masses are usually in the form of massive metaperidotite lenses generally concordant with the banding of the adjacent gneisses or granulites, although a few serpentinite masses now have the form of tectonic diapirs. Low-grade retrogressive metamorphism in zones of steep reverse faulting affected some of the masses.

Another group of metaperidotites has been deformed by isoclinal folding on axes trending nw-se with steeply dipping axial planes so that the mineralogical banding of the ultrabasic bodies is now vertical. Subsequent hydrous metamorphism, sometimes with the introduction of potassium, has caused marginal alteration of many of these masses to talc-trem-olite-carbonate-serpentine rocks, sometimes with biotite and muscovite. Complete minera-logical reconstitution to this low-temperature hydrous assemblage has taken place in some cases, but relict banding remains. After this episode, which was about 1500 m.y. ago, the rocks were deformed by a series of box-like folds, with steeply plunging axes, causing local deflexion of the banding from its
nw-se
trend.

A small group of banded picrites and gabbros has intrusive relations to these gneisses and shows subsequent retrogression with the uralitization of the pyroxenes.
The Songwe scarp carbonatite and associated feldspathization in the Mbeya Range, Tanganyika
Authors: BROWN PETER EVANS
Published: October 2009

The carbonatite and associated rocks described occur on the Mbeya mountain range, which is at the junction of the eastern and western rift valleys in south-west Tanganyika. The main occurrence of carbonatite is a dyke-like body, possibly in discontinuous lenses, with an approximately linear outcrop trending nw-se over a distance of some 12 miles at the base of the Songwe scarp. This scarp bounds the Mbeya Range and delimits the southern end of the Rukwa trough. The carbonatite was emplaced in a zone of structural weakness along which there was probably rift-valley faulting before the introduction of the carbonatite and along which there has since been considerable faultmovement. The rift-faulting here follows the north-westerly trend of the crystalline basement rocks. Typically the carbonatite is ankeritic, fine-grained, and not flow-banded. Commonly there is a fragmentary or brecciated texture, the fragmentary material consi sting largely of feldspathized and carbonated country-rock. Minor amounts of niobium, uranium, and thorium are present but the location of these elements is uncertain and rare accessory minerals have not been detected.

Feldspathization by the introduction of potassium is strongly developed in the immediate vicinity of the carbonatite and also sporadically elsewhere on the Mbeya Range; both quartzofeldspathic cataclastic schists and coarsegrained mica-garnet schists have been converted to aggregates of potassium feldspar. Such feldspathization is particularly well displayed in the vicinity of Itete on the north-east flank of the Mbeya Range, where elongated belts of feldspathized country-rock illustrate the strong control exercised over their formation by the regional schistosity. Injection and brecciation of these feldspathized schists by carbonatite veins is common.

It is suggested that the Songwe scarp carbonatite is a high-level representative of the crystallization of a parent carbonatite at depth; the unusual form is due to the strong structural grain of the basement schists of the area.
Pathological epipodials and tarsus in
Stretosaurus macromerus
from the Kimmeridge Clay, Stretham, Cambridgeshire
Authors: WELLS CALVIN
Published: October 2009

T
he
specimen discussed here (P1. 13a) is the left hind limb of a
Stretosaurus macromerus
(Phillips) which is now in the Sedgwick Museum, Cambridge, England (No. J.35, 990C–0). It has been described by Tarlo (1959, p. 51 and p1. ix, fig. 1; 1960, pp. 161–3, fig. 8). The specimen shows (Pl. 13b) extensive pathological changes that affect the tibia, tibiale, intermedium, first distal tarsal, and the (fused) second and third distal tarsal. The fibula and fibula are may also be slightly affected. The lesion appears chiefly to consist of an erosion of the distal surfaces of these bones together with a proliferative reaction on the margins of the eroded areas.

Since the ‘clinical’ course of disease has never been observable in
Stretosaurus
we cannot with any confidence affirm that the final lesion results from any well-recognized succession of pathological changes. We cannot even observe morbid processes in modern reptiles and assume that their precursors, living under Jurassic conditions 150 million years ago, responded to adverse stimuli in an identical fashion. A considerable body of evidence suggests that pathological changes then closely resembled those of today but it is probable that significant nuances of difference elude our detection.

This being so the study of an archaic lesion reduces us to a search for apparent resemblances, a groping for analogies, among recent forms of disease. We inevitably interpret this specimen in the light of what we know about osseous pathology. A glance at P1. 13b, however, shows that it is
Tertiary sediment cores and microfossils from the Pacific Ocean floor
Authors: RIEDEL WILLIAM REX , FUNNELL BRIAN MICHAEL
Published: October 2009

Tighty-five cores containing either Tertiary sediment or abundant reworked Tertiary micro-fossils have been selected for description from approximately 900 Pacific deep-sea cores collected by the Scripps Institution of Oceanography between 1950 and early 1961. The area covered by the 85 cores extends from about 45°
n
to 45°
s
, and from 151°
e
to 73°
w
, although most were collected within the tropics.

A brief lithological and micropalaeontological description is given for each core; wherever possible, a photograph of the core and a profile of the adjacent topography are provided. The Radiolaria, planktonic Foraminifera, and calcareous nannoplankton were investigated. Stratigraphical interpretations are based on all three groups and supported by lists of species of Radiolaria and Foraminifera. The ages range from Eocene to Pliocene, with reworked Cretaceous at one locality.

Tentative interpretations are put forward regarding the distribution of pelagic sediments and water masses in the Pacific during the Tertiary. Miocene and Pliocene sediments are similar at most localities to near-by Quaternary deposits, and it is concluded that near-surface currents and water masses were generally similar to those of the present day. The only apparent exceptions are a displacement of the northern boundary of the Equatorial Current System to a location about 5° north of its present position at 139°w, and possibly a 5° southward displacement of the southern boundary of the Subarctic Current at 173°w.

During the Oligocene, the northern boundary of the Equatorial Current System was apparently 7° north of its present position at 137°w. At 130–50°w, the southern boundary of that current system and the northern edge of the West Wind Drift appear to have been situated near their present positions.

Eocene occurrences show greater departures from the pattern of Quaternary sediment types. The northern boundary of the Equatorial Current System appears to have been situated about 9° north of its present position, at 135–65°w. The few occurrences of this age south of the Equator cannot readily be interpreted in terms of a pattern of water masses similar to that of the present day.

The evidence from the cores does not indicate any substantial lowering of the calcium carbonate compensation depth during the Tertiary, with the exception that in low latitudes in the north-east Pacific it may have been depressed to 5100m during the Oligocene.

No systematic relationship between topography and the localities of Tertiary sediments cropping out or shallowly buried has so far been worked out.
Three non-magnetic seamounts off the Iberian coast
Authors: BLACK MAURICE , HILL MAURICE NEVILLE , LAUGHTON ANTHONY SEYMOUR , MATTHEWS DRUMMOND HOYLE
Published: October 2009

The seamounts of the deep oceans are strongly magnetized and are made up of basic volcanic rocks with or without a capping of limestone. Some seamounts of the continental margins differ from these by being weakly magnetized. Three such seamounts are described. Magnetic surveys over them strongly suggest that they do not have cores of basaltic rocks. There is good evidence that pellet limestones are exposed in the flanks of one of them (Vigo Seamount). These rocks resemble pellet limestones of Jurassic age which occur in Portugal. The results of dredging and photography on the top of Vigo Seamount and on Galicia Bank suggest that detrital limestones, porcellanous limestones, and soft foraminiferal limestones, of Cretaceous to Eocene age, are exposed there. The facies of these calcareous rocks resembles that of the Mesozoic limestones of Portugal and southern France. The remainder of the dredged rocks are believed to be ice-rafted erratics from farther north in Europe or America. The results of seismic refraction work on Galicia Bank are consistent with a structure in which 0.4 km of uncemented limestones overlie 4.2 km of hard limestones that rest on a crystalline basement. The mode of origin tentatively suggested for the seamounts involves the formation of limestones during Mesozoic time on a gradually subsiding platform of continental rocks. As there is no substantial gravity anomaly, subsidence must have been accompanied by density changes or by removal of the lower part of the continental crust near the present position of the continental margin.
The Pre-Cambrian history of Sweden
Authors: MAGNUSSON NILS H.
Published: October 2009

Several difficult problems remain to be solved in the Pre-Cambrian of Sweden but in recent years progress has been made with the establishment of a time-scale. Two major phases of regional alteration, marked by extensive gneissification culminating in the formation of special granites and pegmatitic intrusion of regional extent, have been dated. In both cases temperatures were so high that argon-40 was entirely or almost entirely expelled. The ages obtained are therefore those of the rejuvenation of the rocks. The earlier of the two phases took place 1700 m.y. to 1800 m.y. ago, marking the close of Svecofennian-Karelian time. It corresponds to the Hudsonian in Canada and the Penokean in the U.S.A. A younger phase of regional alteration, the Sveconorwegian, is dated at 950 m.y. to 1000 m.y. and took place at the end of Gothian-Dalslandian time. This corresponds to the Grenville in both Canada and the U.S.A. The high-grade gneisses of south-western Sweden are bounded to the east by a zone of marked schistosity. Age-determinations from this zone have given an age of about 1200 to 1300 m.y.

These and other ages are discussed and an account is given of the complicated history of the Pre-Cambrian of Sweden.
The glacial and post-glacial history of the lower Teifi valley
Authors: JONES OWEN THOMAS
Published: October 2009

Gorges in the lower Teifi valley formed short cuts towards the end of the Glacial period; former meandering pre-glacial courses were abandoned and are now filled to considerable depths, mainly by boulder-clay. Each gorge must have been eroded by a river flow greatly exceeding that of the present river, even in the highest floods. During the retreat of the ice from south-west Wales and the Irish Sea, the margin of the ice lay near the mouth of the Teifi just below Cardigan and thence probably ran nearly eastward along the northern slopes of the valley. A glacial lake was then impounded in the valley and overflowed by various channels, beginning at a level of 650 ft, at first into Carmarthen Bay and later into the Bristol Channel through Milford Haven. When the ice retreated to the mouth of the Teifi most of the lake then remaining was drained and river flow was resumed. At this time erosion of most of the gorges began.

Because the coastline of Cardigan Bay was submerged under ice, an enormous volume of melt-water draining off the ice surface entered the Teifi valley and caused rapid erosion of the gorges. Glacial deposits removed from the wide parts of the valley between the gorges must have materially assisted in their erosion. When the ice retreated so far up Cardigan Bay as to reveal the coastline the flow of melt-water diminished until it ultimately ceased, and the flow of the river became comparable with its present value. Erosion in the gorges has since been insignificant.

The progress of erosion in one of the gorges at Henllan is shown by a series of river terraces at successively lower levels between Henllan and Newcastle Emlyn.

Because erosion of the gorges virtually ceased while the Irish Sea ice still occupied the northern part of Cardigan Bay, it is evident that this happened long before the end of the Glacial period in southern Britain.

The distribution of various deposits formed during the occupation of the valley by ice and the subsequent system of lakes are described.

The profile of the river for a distance of about 30 miles from its mouth has been ascertained by approximate levelling. Seismic investigations have revealed the present depth of the pre-glacial rock floor at three points. Near the mouth this is approximately 100 ft below the floor of the present channel.
Size distribution, composition, and growth kinetics of garnet crystals in some metamorphic rocks from the west of Ireland
Authors: JONES KENNETH ARTHUR , GALWEY ANDREW KNOX
Published: October 2009

A study of the composition and crystal size distribution of garnet from four metamorphic aureoles in the west of Ireland has been carried out in an attempt to derive information about the external factors controlling garnet formation. Garnet compositions varied between And
10
Gro
90
and And
30
Gro
70
.

The distribution curves all fit the same equation (Galwey & Jones 1963). Possible explanations of variations in the distribution functions for different aureoles are considered and it is concluded that these were controlled by rate of heating of the host-rock during metamorphism.
The geochronology of the Connemara granites and its bearing on the antiquity of the Dalradian Series
Authors: LEGGO PETER JAMES , COMPSTON WILLIAM , LEAKE BERNARD ELGEY
Published: October 2009

Thirty-eight whole-rock samples of Connemara granites give the following Rb–Sr whole-rock ages: Galway granite, 384 ± 1 m.y.; Omey granite, 3884 ± 17m.y.; Roundstone granite, 3954 ± 80m.y.; Inish granite, 404 ± 8m.y.; Oughterard granite, 510 ± 35 m.y.; potash-feldspar gneisses, 725 ± 175 m.y. As the field evidence shows that the Oughterard granite was intruded into the Dalradian metasediments post-
F
4
in the Connemara fold-sequence, and possibly post-
F
5
, this dates the fold phases
F
1
to
F
4
and the metamorphisms
M
5
to
M
1
as pre-510 ± 35m.y. The older isotopic age of the potash-feldspar gneisses agrees with their field-deduced age of post-
F
2
pre-
F
3
. Muscovite, potash feldspar, and whole-rock Rb–Sr analyses show that the Oughterard granite was metamorphosed about 444 ± 7 m.y. ago, which is close to the K–Ar age obtained from three hornblendes separated from potash-feldspar gneiss. These results indicate that the post-500 m.y. dates obtained from the Connemara Dalradian rocks, and therefore presumably the Scottish Dalradian also, are the dates of late metamorphisms. While the possibility of Pre-Cambrian metamorphism and folding in the Dalradian is apparent, the results are equally in agreement with a Cambrian age for the main metamorphisms
M
1
to
M
5
and foldings
F
1
to
F
4
, especially in view of the present uncertainty about the age of the Cambrian period. The base of the Arenig would seem to be younger than 510 ± 35m.y.
Melting-relations in the system NaA1Si
3
O
8
–NaA1SiO
4
–NaFeSi
2
O
6
–CaMgSi
2
O
6
–H
2
O, and their bearing on the genesis of alkaline undersaturated rocks
Authors: NOLAN JOHN
Published: October 2009

Experimental data are presented that constitute a basis for a more detailed treatment at present under investigation, involving the addition of the alkali pyroxene end-members acmite (NaFeSi
2
O
6
), diopside (CaMgSi
2
O
6
), and hedenbergite (CaFeSi
2
O
6
) to the silica- and potash-poor portion of ‘petrogeny’s residua system’.

Phase relations have been determined in the systems NaAlSi
3
O
8
–NaFeSi
2
O
6
, NaAlSiO
4
–NaFeSi
2
O
6
, NaAlSi
3
O
8
–NaAlSiO
4
–NaFeSi
2
O
6
at 1000 kg/cm
2
water vapour pressure; the partial pressure of oxygen was controlled in most of the experiments by a nickel–nickel oxide buffer assemblage. The composition of the ‘low melting-point’ in the system NaAlSi
3
O
8
–NaAlSiO
4
–NaFeSi
2
O
6
is located at Ab
15
Ne
30
Ac
55
. Little agreement was found between this point and the density distribution plot of normative Ab+Or, Ne+Ks, Ac+Di in a total of 256 volcanic and plutonic alkaline undersaturated rocks. However, with the addition of known amounts of diopside to the system NaAlSi
3
O
8
–NaAlSiO
4
–NaFeSi
2
O
6
, the determined phase relations show a close agreement with the normative plots for both alkaline and peralkaline undersaturated rocks. The possible genesis of alkaline rocks by processes involving crystal ⇋ liquid equilibrium is discussed in the light of this evidence.
The stratigraphy of the Bala district, Merionethshire
Authors: BASSETT DOUGLAS ANTHONY , WHITTINGTON HARRY BLACKMORE , WILLIAMS ALWYN
Published: October 2009

About 45 square miles of Ordovician and Silurian rocks exposed around the town of Bala have been mapped and their brachiopodtrilobite faunas studied in order to revise the stratigraphy of the Bala Group and effect a more exact correlation with other standard Ordovician sections. The succession established by Elles (1922
a
) has been emended to include a quartzite more or less contemporaneous with the Hirnant Limestone and an ash at the revised base of the Glyn Gower Siltstones, and to allow for hitherto unsuspected complications due to unconformities and faulting. The proposed changes in stratigraphical terminology have been framed in accordance with the American Code of Stratigraphical Nomenclature. The infra-Rhiwlas Limestone unconformity, first indicated by Bancroft (1928
c
) is now known to have involved great variation in the depth of erosion, especially northwards. Sudden localized changes in oversteps have been attributed to pre-Rhiwlas Limestone faulting. An outlier of high Ashgillian and Llandovery rocks west of their main outcrop has revealed the presence of another unconformity within the higher part of the Ordovician succession which may also be due to contemporaneous fault slip. These breaks suggest that the use of ‘Bala Series’ as a standard subsystemic division of the Ordovician should be discontinued although the term ‘Bala Group’, divided into ‘Lower’ and ‘Upper’ at the main unconformity, may be retained for Upper Ordovician successions of the region.

The discovery of new fossil localities, particularly in the Nant Hir Mudstones and Glyn Gower Siltstones, the recognition of assemblage zones in the Allt Ddu Mudstones, and a faunal succession in the Gelli-grin Calcareous Ashes permit correlation with the type-Caradocian although it has not been possible to locate the Caradocian stage boundaries precisely. The Lower Bala Group can be dated as Costonian to Longvillian in age, the base of the Lower Longvillian being more or less coincident with the base of the Gelli-grin Calcareous Ashes. The Rhiwlas Limestone, the basal member of the Upper Bala Group, contains a rich trilobite fauna that compares closely with assemblages from other British strata containing
Phillipsinella parabola
and is regarded as Middle Ashgillian in age. The Foel y Ddinas Mudstones, emended to include the Hirnant Limestone as a member, contain the youngest Ordovician shelly fauna known in Britain.
Deterministic models of living and fossil populations of animals
Authors: CRAIG GORDON YOUNGER , OERTEL GERHARD
Published: October 2009

The factors influencing the size-frequency distribution of living and dead populations of organisms are discussed. They include kind of recruitment (even recruitment, a broad wave of recruitment, a sharp wave of recruitment, and two waves of recruitment during the year); growth-rate (linear, high-to-low as in many invertebrates, and high-to-zero as in vertebrates) ; different coefficients of variation in the growth-rate; mortality rate (constant, increasing, and decreasing); and seasonal cessation of growth, with or without increased mortality.

Forty-two steady-state experiments using different combinations and permutations of these variables have been run in a computer and the results expressed as size-frequency graphs of the living and resulting dead populations. The graphs are intended to be used as an aid to the interpretation of size-frequency in living and fossil populations of animals. It is shown that the growth-rate and the mortality rate are the major factors influencing the primary shape of the size-frequency distribution in living and dead populations. Secondary peaks may be developed as a consequence of seasonal recruitment accompanied by seasonal cessation of growth, with or without increased mortality. The difficulties of interpreting mass mortality in fossil populations are discussed.