bluuebunny/crossref_metadata_2025 huggingface dataset:
Notes on the Structure of the Ben Lawers Synform
Authors: Treagus J. E.
Published: May 2009

A detailed examination of some new exposures in the Ben Lawers range reveals folds of three deformational episodes. These are described megascopically and microscopically. The foldgeometry is complex but the kinematic axes of each deformation are shown to be closely related. The folds of the first deformation have relationships which confirm the position of these rocks on the inverted limb of the Tay Nappe. Folds with relationships shown by those of the second deformation have not been described from adjacent areas. The folds of the third deformation are associated with the formation of the Ben Lawers Synform
A Primary Lineation at the Base of Certain Kenya Lava Flows
Authors: McCall Joseph
Published: May 2009

Fluting (magmatic rolls ?) resembling flow-cast structures in sediments is recorded from certain Kenya lava flows. It is attributed to flowage of underlying moist sediments under the weight of the overriding lava flow.
The Origin of the “Beach-Beds” in the Lower Carboniferous of Castleton, Derbyshire
Authors: Sadler Helen E.
Published: May 2009

The “Beach-Beds” at Castleton, Derbyshire, are shown to be detrital deposits containing numerous water-worn and broken brachiopod shell fragments set in a matrix of finely comminuted shell and crinoid debris. They occur at the junction of the fore-reef and basin facies of the Carboniferous Limestone. Previous interpretations of the “Beach-Beds” as cliff-foot screes or as beds lying above an unconformity are not supported, and it would appear that they are composed largely of debris transported down a submarine channel (the approximate position of which is now the dry valley of the Winnats) rather than in shallow water on a sea-beach, being deposited at the foot of the channel contemporaneously with the adjacent fore-reef beds.
The Pre–Cambrian–Palaeozoic Boundary of the Malverns
Authors: Phipps C. B. , Reeve F. A. E.
Published: May 2009

The nature of the contact between Pre–Cambrian and Palaeozoic rocks on the western flanks of the Malvern Hills is discussed. Evidence from the regional geological setting and from the contact exposed in Gullet Quarry is only consistent with a faulted junction. Interpretations by Butcher (1962), Reading and Poole (1961) cannot be supported in the field and it is proposed to revert to Groom's (1899) interpretation of the western margin of the Pre–Cambrian as the outcrop of a major fault.
Conditions in the Metamorphic Caledonides during the Period of Late-orogenic Cooling
Authors: Watson Janet
Published: May 2009

The paper deals with regional variations in the contact–effects of Caledonian granites and in the characters of certain associated minor intrusions in the metamorphic Caledonides. It is suggested that these variations are related to the thermal structure of the fold–belt at the time of emplacement.
The Continuity of Si and Se Surfaces in Garnets: An Observation
Authors: Saxena M. N.
Published: May 2009

Observations have shown that some garnets in the micaceous schists of the Chor area, Himachal Pradesh, India, still retain the continuity between the Se and Si planes. The Se and Si surfaces are continuous surfaces and not merely statistical as has been assumed by some.
New Occurrences of Tonsteins in England and Wales
Authors: Salter D. L
Published: May 2009

Seven occurrences of tonsteins are recorded, five from the South Staffordshire Coalfield (Westphalian C), one from Yorkshire (Westphalian A), and one from South Wales (? Westphalian D).
Basalt Textures from the Southeastern Lower Galilee, Israel
Authors: Oppenhein M. J.
Published: May 2009

Basalt groundmass textural nomenclature is reviewed and revised. The intergranular and ophitic extures are seen as end members of a series with steadily increasing grain-size, the international representative of which is here termed the “isogranular” texture. Undere intrusive conditions the series may be extended to include the poikilitic texture. Ophitic texture is regarded as an intergrowth;the term “sub-ophitic”s not suitable for basalts but may be retained for texturally isotropic rocks. When basalts cool hurriedly they will tend to develop an intergranular texture whereas extension of the crystallization period permits the formation of an ophitic texture. Cooling conditions will be determined by a combination of the effects of the volatile concentration and the flow characteristics, the latter partly depending on topography.
Sedimentology of the Partry Series in the Partry Mountains, Co. Mayo, Eire
Authors: McManus John
Published: May 2009

The Lettereeneen fault, a newly recognized structure, brings the Mweelrea and Maumtrasna Groups of the Partry Series (Caradocian-Llandeilian age) into contact. The stratigraphy of the Mweelrea Group, of red bed facies, is followed from the presence of welded tuff horizons; no such markers exist in the Maumtrasna Group which lies unconformably upon the former.

Sedimentary structures of shallow water origin occur in each group. Three types of conglomerate recognized in the area are examined. The immature feldspathic sandstones increase in arkosity upwards.

A proluvial or proluvio-marine environment of deposition is suggested, with debris derived from an eastward extension of the metamorphosed Dalradian rocks of the Connemara Cordillera and foothills of sedimentary and volcanic rocks.
New Magmatic Features in Makhtesh Ramon, Southern Israel
Authors: Garfunkel Z. , Katz A.
Published: May 2009

Six volcanic vents, trachybasaltic bosses, and new dykes replaced by kaolinite were discovered. The vents are built of trachybasaltictrachytic and basaltic plugs and of tuffisites and tuffs. In the trachybasalts, plagioclase and anorthoclase display complicated reaction phenomena, reflecting changes in crystallization conditions. The trachybasaltic and trachytic bodies were emplaced first and subsequently were altered to kaolinite (Upper Jurassic). Magmatic activity was resumed after an intense erosion period leading to the formation of the vents and of the Lower Cretaceous basaltic volcanic complex which was in part extruded through these vents.
Chemical and Mineralogical Changes Associated with the Laxfordian Metamorphism of Dolerite Dykes in the Scourie-Loch Laxford Area, Sutherland, Scotland
Authors: Burns D. J.
Published: May 2009

Chemical analyses of dolerites and metadolerites from the Scourie-Loch Laxford area have been made, together with analyses of amphiboles and a pyroxene from these rocks.

Chemical variation within the dykes as originally emplaced has been investigated. Introduction of material during metamorphism is limited, only potassium showing a marked increase in concentration. In the least-altered dykes a relationship between degree of clouding in felspar and amount of H2O+ present is indicated.

Chemical analyses and optical properties of amphiboles show no distinctive trends which could be associated with the progress of the metamorphism.
A Study of Density Variations in New Red Sandstones from the English Midlands
Authors: Brooks M.
Published: May 2009

Methods are outlined by which density changes due to burial and compaction can be studied, and results are briefly discussed of an application of these methods to New Red Sandstone rocks from the English Midlands. From density measurements on surface rocks and compaction tests on a disaggregated sandstone it is concluded that there is no significant increase in density with depth down to 10,000 feet if the original, depositional, porosity of the sediment is low. Compaction tests suggest that sands with a high original porosity will, over a similar depth range, undergo permanent (i.e. non-elastic) deformation producing a 10 per cent increase in density.
The Flora of the Brora Coal
Authors: Harris T. M. , Rest Jane A.
Published: May 2009

A flora of cuticle fragments obtained by maceration of the Bathonian coal of Brora is described together with some lycopod megaspores from the shale below the coal. All the species are known from the Bajocian or Bathonian of N. Yorkshire. Ptero-phyllum cycadites sp. nov. is described as new, the type being a Yorkshire specimen. The formation of the Brora coal is discussed.
A Geochronological and Strontium Isotope Study on the Garabal Hill-Glen Fyne Igneous Complex, Scotland
Authors: Summerhayes C. P.
Published: May 2009

The age of the Garabal Hill-Glen Fyne igneous complex has been determined as 392 ± 4 m.y., by the Rb-Sr method. The components of the complex had an average initial (87Sr/86Sr)0isotope ratio of 0·705 ± 0·003. Geological contamination of marginal components is reflected in the (87Sr/86Sr)0values of these rocks which were found to beca. 0·710, significantly higher than values from uncontaminated samples. The results are in accord with the view that the individual members of the complex had a common source, comparable with regard to the Rb/Sr ratio, to the source of basalts. It is inferred that complete melting of such source material followed by magmatic differentiation is an appropriate mechanism of origin for the complex.
Post-eruptive mechanical sorting of pyroclastic material — an example from Jamaica
Authors: Roobol M. J.
Published: May 2009

The unfossiliferous Maestrichtian Summerfield Formation of Central Jamaica is composed entirely of hornblende andesite. A measured section shows a 90 m-thick lower unit of greenish-grey, crystal-rich, pumice-poor sandstones and rare mudstones, which interdigitate with shallow-marine rudist limestone. The upper 370 m comprise pink-coloured, pumice-rich fluviatile sandstones and conglomerates with devitrified ignimbrites at two horizons. Although no lavas are exposed it is likely that the erupted magma is represented by the hornblende andesite boulders of the conglomerates. Whole rock chemical analyses show the lava boulders to have around 65% SiO2 the ignimbrites 62%, the shallow-marine crystal-rich sandstones 58% and the interstratified mudstones 69%. The marine sandstones are concentrations of phenocrysts and the mudstones represent the finest glassy ash — originally the liquid which coexisted with the phenocrysts before eruption. These variations illustrate that after leaving the vent the pyroclastic material lost much fine glassy ash during the pyroclastic flow stage to produce crystal-enriched ignimbrites. Where the pyroclastic material was deposited in a shallow- marine environment it underwent further mechanical separation with loss of pumice by flotation, lithics and separation into crystals (sandstones) and glassy ash (mudstones). Subtraction of glass (rnudstone) from the magma (conglomerate boulders) shows that the ignimbrite composition can be obtained by loss of around 40 wt. % of glassy ash. The crystal-rich marine sandstones – although no longer containing the phenocryst minerals in their original magmatic proportions – represent a loss of about 60 wt. % glassy ash.
Ignimbrite vents in the Sabaloka cauldron, Sudan
Authors: Almond D. C.
Published: May 2009

Large ignimbrite dykes continuous with an overlying sheet of rhyolitic ignimbrite have been found at two localities in the centrally-subsided block of the Sabaloka cauldron. There is good evidence that these dykes fed ash-flow eruptions. Other possible feeder vents occur along the marginal fracture zone of the cauldron but evidence for the origin of some of these structures is ambiguous. Ignimbrites within the dyke-shaped feeders contain a very strong eutaxitic foliation oriented parallel to the contacts and this feature is thought to result from inwardly-directed pressures exerted by the dyke walls during a collapse which followed eruption of the ash-flows. Vents of this type are believed to originate by permissive intrusion through the roof of a shallow-seated magma chamber, in contrast to forcefully injected diatreme vents. A broad genetic classification of these bodies is suggested, based on their mode of emplacement.
Thrust Devonian Sediments in the Kvamshesten area, Western Norway
Authors: Höisæter Trygve
Published: May 2009

It is demonstrated that the Kvamshesten area of continental Devonian rocks has been thrust over an older basement. The movements are correlated with the Svalbardian phase.
Inclusions in garnet: discussion and suggested mechanism of growth for syntectonic garnets
Authors: Cox F. C.
Published: May 2009

Inclusion textures within garnets are often used to demonstrate the relationship in time between garnet growth and deformation. The evidence for syntectonic growth is discussed, and it is shown that several thin sections are required before an accurate interpretation can be made. The patterns predicted by Powell & Treagus (1967) are matched with natural examples, and a mechanism for the aevelopment of these fabrics is suggested.
Folded overthrusts at Aljustrel (South Portugal)
Authors: Schermerhorn L. J. G. , Stanton W. I.
Published: May 2009

The Upper Palaeozoic rocks in the Aljustrel area of South Portugal suffered strong Hercynian deformation, including isoclinal overturned shearfolding of two important thrust planes bringing sub-Culm strata over Culm.
The breaking of magma
Authors: Walker G. P. L.
Published: May 2009

Breadcrust blocks (bombs) on Vulcano, Sicily, show features which indicate that when they were of viscous lava they broke when stress was applied rapidly, and later flowed when it was applied slowly. If the magma of granitic intrusions behaves similarly, the perplexing “relict dykes” can be explained as due to the breaking of the magma and the injection of dykes into the fractures.
Some Permian foraminifera from north-western England
Authors: Pattison J.
Published: May 2009

Eight species of foraminifera from the Manchester Marl are described and foraminifera recently discovered in the Magnesian Limestone of both the West Cumberland and the Eden Valley areas are also mentioned. All the described forms are similar to, and some are possibly conspecific with, foraminifera previously recorded from the Lower Magnesian Limestone of north-eastern England or Zechstein 1 of north-western Germany.
The mode of development of Isograptus manubriatus (T. S. Hall)
Authors: Bulman O. M. B.
Published: May 2009

The reverse aspect of a proximal end of I. manubriatus is described and its relation to the mode of development of some early biserial forms is briefly discussed. Two new names descriptive of types of development are proposed.
The magmatic affinities of some volcanic rocks from the Tweed Shield Volcano, S.E. Queensland — N.E. New South Wales
Authors: Wilkinson J. F. G.
Published: May 2009

Some basaltic and andesitic rocks from the Tweed Shield Volcano are tholeiitic in character as evidenced by their chemistry and the nature of their pyroxenes inferred from optical data. A common mineral assemblage in the more basic members is olivine-clinopyroxene-plagioclase-opaques-(glass). Petrographic criteria that characterize tholeiites are often lacking, and some of the more basic lavas appear to link the more typical tholeiites with transitional olivine basalts. Many of the Tweed volcanic rocks are more potassic than similar rocks in other tholeiitic sequences. The likelihood of differing lineages in the shield area is noted.
Stratigraphic classification in Pre-Cambrian rocks
Authors: Allen P. M. , Reedman A. J.
Published: May 2009

The system of stratigraphic classification used by field geologists working in Africa is briefly reviewed and a hierarchy of terms is suggested, taking into account the requirements of those interested in local field problems and those concerned with the tectonics and composition of the African continent as a whole. On the local scale, rock units are best named according to the lithostratigraphic classification. On a regional scale, the criteria for defining rock units are essentially tectonostratigraphic and two new terms for them, in ascending order of magnitude, Orogenic Assemblage and Orogenic Complex, are proposed. The two schemes are united through the Sequence, which can contain any number of lithostratigraphic units of any order of magnitude.
Gravitational sorting of phenocrysts in some Icelandic intrusive sheets
Authors: Blake D. H.
Published: May 2009

Some thin basaltic intrusive sheets in south-eastern Iceland consist in cross-section of a porphyritic central zone sharply bounded by non-porphyritic margins. Within the porphyritic zone phenocrysts of plagioclase, augite and olivine are arranged in two main layers, an upper layer containing mostly plagioclase phenocrysts, and a lower layer containing concentrations of augite and olivine phenocrysts. The phenocrysts are considered to have been gravitationally sorted during the passage through the sheets of a highly fluid and strongly flowing porphyritic basalt magma.
Banded Pumice in a Chilean Ignimbrite
Authors: Guest John Edward
Published: May 2009

Banded pumice from a late-Tertiary ignimbrite in northern Chile is descrived and its origin considered. Other phenomena within the ignimbrite, including a variation in mineralogy between the upper and lower units of the flow, are described.
The Petrology of the Guiana Dolerites
Authors: Hawkes D. D.
Published: May 2009

Two distinct suites of dolerite, the Roraima Intrusive Suite (Pre-cambrian) and the Minor Dyke Suite (?Mesozoic) intrude the Guiana shield. The dolerites of the Roraima Intrusive Suite, which occur as major dykes, inclined sheets and sills, are tholeiitic in character and have been strongly differentiated. The series orthopyroxene-dolerite → pigeonite-dolerite → ferrodolerite → leucogranophyre represents the main trend. Hornblende-granophyres represent heteromorphs of late pigeonite-dolerites and early ferrodolerites. Differentiation was accomplished mainly by crystal settling probably in the presence of convection currents; toward the close of crystallization a filter-press mechanism became operative. The Minor Dyke Suite comprises numerous small dykes of undifferentiated dolerite. The intrusion of these dykes may be related to orogenic movements in the adjacent Andean geosyncline.
Note onCampophyllum flexuosum(Goldfuss)
Authors: Hill D. , Jull R. K.
Published: May 2009

This note provides photographs of thin sections and cellulose peels prepared from the syntypes figured by Goldfuss (1826) ofCyathophyllum flexuosumGoldfuss, the type species by original designation ofCampophyllumEdwards and Haime, 1850.

It is concluded thatC. flexuosumis not a disphyllid, and thatCampophyllummay be maintained as a genus distinct fromCaninia, Caninophyllum, andPalaeosmilia. For the present it is placed alone in the family Campophyllidae Wedekind, 1932.
The Petrography and Provenance of the Coniston Grits East of the Lune Valley, Westmorland
Authors: Furness R. R.
Published: May 2009

The petrography of the Coniston Grits is described. Volcanic and sedimentary rock fragments suggest that the sediments were derived from the Ballantrae Series of the Southern Uplands, and not the Borrowdale Volcanic Series.

There is little palaeocurrent evidence for a border land mass, but it is suggested that coarse sedimentation during the Wenlockian was restricted to the Southern Uplands by a shallowing in the border area, which was finally overcome by Ludlovian times, to allow deposition of coarser material to the south.
A Llandovery Conglomeratic Limestone in Gullet Quarry, Malvern Hills, and its Conodont Fauna
Authors: Brooks M. , Druce E. C.
Published: May 2009

A conglomerate band exposed in Gullet Quarry, at the southern end of the Malvern Hills, contains a layer of shelly limestone in which are embedded large, often angular, boulders of Malyernian rock. The character of the limestone and the form and distribution of included boulders suggest that a near-shore environment of carbonate deposition was continually supplied with clastic material from adjacent sea-stacks. The limestone has yielded a conodont fauna indicative of a Llandovery age earlier than that assigned to the conglomerate by Reading and Poole (1961) on the basis of brachiopod evidence.
Accretionary Lapilli in a Geosynclinal Environment
Authors: Bateson J. H.
Published: May 2009

Accretionary lapilli have been described from rocks of all geological ages as well as from historical eruptions and in all cases they are associated with volcanic activity in which large amounts of steam accompany the eruption of dense clouds of ash material. Similar lapilli are described from deposits thought to have been deposited near to the flank of a well-established geosynclinal trough of the Precambrian Barama-Mazaruni Assemblage of British Guiana.
The Nature and Origin of the Groundmass Textures in Felsites and Granophyres from Rhum, Inverness-shire
Authors: Dunham A. C.
Published: May 2009

Chemical and mineralogical data are presented to demonstrate the overall similarity between granophyre and felsite from Rhum. However, although the compositions of the groundmasses of the two rock-types are very similar their characteristic textures are quite different. The felsitic texture is shown to be the result of devitrification of a glass, whilst the granophyric texture is attributed to the simultaneous crystallization of quartz and feldspar on the cotectic line in the system Ab–Or–SiO2–H2O. An explanation of the formation of the different textures is given in terms of the degree of super-cooling experienced by separate intrusions of the same magma in contrasted environments.
Quartz Microfracturing in the North Crop of the South Wales Coalfield
Authors: Roberts J. C.
Published: May 2009

A microscopic study of sandstones of Old Red Sandstone and Carboniferous ages along a part of the North Crop of the South Wales Coalfield reveals that the rocks are extensively fractured. The fractures occur in the quartz grains and are often filled with bubble-like inclusions. These planes of inclusion were studied in specimens over a wide area, and are related to the directions of faulting and jointing. The consistency in trend between the macro and micro-structures suggests a homogeneity of the deforming stresses.
Dictyonema from the Tremadocian of Estonia and Norway
Authors: Bulman O. M. B.
Published: May 2009

The Dictyonema species currently named flabelliforme (Eichwald) (as distinct from D. norvegicum Kjerulf) from the Tremadocian of Estonia is described and compared with the lectotype of Kjerulf's D. graptolithinum from Norway, and their synonymy is confirmed.
The Geology of the North Cork (Kanturk) Coalfield
Authors: Nevill W. E.
Published: May 2009

Basal and perhaps higher Coal Measures are overthrust by earlier rocks at the front of the Hercynian arc of southern Ireland. The marine bands, lacking cephalopod phases, are faunally poor and in respect are unlike the marine bands of the other Coal Measure outliers of the South. The coal seams are crushed and in part pulverized and appear to have developed a “pinch and swell” structure.
Origin of the White Allivalite, Western Cuillin, Isle of Skye
Authors: Hutchison Robert
Published: May 2009

Tholeiitic contact rocks and a wide zone (White Allivalite) rich in primary precipitate calcic plagioclase are marginal to a layered allivalite series in a funnel-shaped intrusion. The high structural level apparently precludes the possibility that the ultrabasic layered rocks are the basal part of an accumulate from a tholeiitic magma. It is suggested, therefore, that a suspension of calcic plagioclase in a liquid more basic than basalt gave rise to an approximately equal volume of layered ultrabasic rocks by fractional crystallization. Emplacement was probably initiated as a tholeiitic cone-sheet complex, followed by the injection of the ultrabasic suspension in a volume sufficiently large to form a funnel-shaped body within the cone-sheet complex.
Probable gasteropod tracks from the Kinderscout Grit of Soyland Moor, Yorkshire
Authors: Sheldon Raymond W.
Published: May 2009

Tracks believed to have been made by a crawling gasteropod are described from a loose block of Upper Carboniferous grit from Soyland Moor, near Todmorden, Yorkshire.
Cambrian trilobites in central Newfoundland volcanic belt
Authors: Kay Marshall , Eldredge Niles
Published: May 2009

The discovery of species of Kootenia and Bailiella known from the Middle Cambrian of western Newfoundland (“Pacific Province”) and southeastern Newfoundland (“Atlantic Province”) in limestone within volcanic rocks near New World Island, eastern Notre Dame Bay, is the first demonstration of the presence of Cambrian in the volcanic belts in North America, and also shows the mixing of forms from the two provinces.
The origin of heteradcumulate and adcumulate textures in the Jimberlana Norite
Authors: Campbell I. H.
Published: May 2009

In the Jimberlana Norite the heteradcumulate and adcumulate rocks are found in adjacent layers. The heteradcumulate occur immediately before the heterad minerals appear as cumulus grains in an adcumulate rock. It is considered that both heteradcumulate and adcumulate textures result from supercooling in the magma. Heteradcumulates develop when seeds of the heterad mineral are not available in the magma and adcumulates after they have formed.
A new Lower Llandovery graptolite from Coal Pit Bay, County Down
Authors: Toghill P.
Published: May 2009

Monograptus hipposideros sp. nov., a new Lower Llandovery monograptid, is described from Coal Pit Bay, Northern Ireland. With distinct “horseshoe” curvature and simple thecal shape it is similar to, and is compared with Monograptus cyphus s.l. Lapworth, M. gregarius Lapworth and M. leei Hsü.
The flow of basalt lava from air into water – its structural expression and stratigraphic significance
Authors: Jones J. G. , Nelson P. H. H.
Published: May 2009

When basalt lava flows from air into water it leaves a distinctive record of the waterlevel of the time in the form of lava sheets overlying and passing down into vitric breccia and/or pillow lava. Relative movements of waterlevel and a volcanic pile or terrain over a period of time may be readily deciphered from such records.
The significance of biotite selvedges in migmatites
Authors: Hughes C. J.
Published: May 2009

The biotite selvedges around potash-feldspar rich leucosome material in migmatites originate at phase boundaries between rocks containing hydrothermal and silicate pore-fluids and are thus indicative of incipient anatexis.
Dolomitization and dedolomitization in the Senonian chalk of Northern Ireland
Authors: Wolfe M. J.
Published: May 2009

A dolomite locality in the Senonian chalk at Mullaghcarton shows a sequence of fabric variations between the unconformity with the Trias and a discontinuity surface marking the top of the basal beds. The four main variations are (1) xenotopic dolomite at the base, (2) hypidiotopic dolomite with zoned crystals and a calcite sealed intercrystalline porosity, (3) zoned dolomite rhombs scattered in a microspar micrite matrix, and at the top (4) micrite with rhombohedral pores. The xenotopic fabric is interpreted as being due to distant source dolomitization and the hypidiotopic fabric with zoned crystals to local source dolomitization. The dedolomitization phenomena are related to the mechanisms of dolomitization; for distant source dolomitization the dedolomitization fabric mimics the dolomite fabric, whereas for local source dolomitization the dedolomite regenerates the pre-dolomitization fabric.
Retrograde contact meta-morphism in the granulite facies terrain of Mont Tremblant Park, Quebec, Canada
Authors: Katz Michael B.
Published: May 2009

The Pre-Cambrian rocks of the Grenville province of south-west Quebec in the Mont Tremblant Park area consists of granulites and associated gneisses formed under granulite facies conditions which are intruded by members of an anorthosite suite. At the contacts of these intrusives especially the late-stage members, the granulites and gneisses were found to be retrograded into rocks with mineral assemblages typical of the amphibolite facies. The transformation of the granulite facies rocks into rocks of lower amphibolite grade can be attributed to local introduction of water which was supplied during the emplacement and crystallization of this late-stage, volatile-enriched magma of the anorthosite suite.
Eyed Folds and Interference Patterns in the Sokumfjell Marble Group, Northern Norway
Authors: Nicholson R.
Published: May 2009

Complex fold patterns are described from a strongly deformed marble group in Northern Norway. The patterns are analysed in terms of fold superposition. One set of folds presents difficulties to such an explanation and an alternative possibility is discussed.
Evidence for the Geological Dating of the Granitic Gneiss of Western Ardgour
Authors: Dalziel I. W. D. , Johnson M. R. W.
Published: May 2009

Evidence is presented for the geological dating of the granitic gneiss of western Ardgour, the southernmost part of the discontinuous granitic gneiss outcrop which extends from Argyll to Inverness-shire along the Loch Quoich line between the “highly inclined” and “flat” belts of the Moines. The granitic gneiss is shown to have been formed before or early in the second of four main fold movements to which the surrounding metasediments have been subjected, and is thought to occupy the core of a complex anti-formal second major fold.
An Outline of the Geomorphology of Murrisk and North-West Galway
Authors: Dewey J. F. , McKerrow W. S.
Published: May 2009

The denudation chronology of the mountainous district of south-west Mayo and north-west Galway is closely linked with drainage superimposition from a deformed Carboniferous cover. Small outcrops of basal Viséan sandstones and conglomerates, lying on bevelled summits and wide bevelled tablelands demonstrate unequivocally that the west Connaught summit level corresponds to the base of the Carboniferous. Uplift, to produce a pre-glacial divide, is believed to have occurred in Mid-Tertiary times. Upon the uplifted, faulted, and warped Carboniferous cover a consequent drainage was developed. Superimposition on to the Caledonian basement followed and during the Pleistocene considerable glacial modifications of the pre-glacial drainage pattern took place.
The Age of Some Carbonatite Igneous Activity in South-West Tanganyika
Authors: Miller J. A. , Brown P. E.
Published: May 2009

Absolute age determinations by the potassium-argon method on biotite from the Musensi Hill intrusion and feldspar from a feldspathic breccia on the Mbeya Mountain Range indicate a Cretaceous age.
Evolution of Drag Folds
Authors: Ramberg Hans
Published: May 2009

Theory and experiments show that a component of compressive strain parallel to layering is necessary to develop drag folds. The component of shear strain needed for the monoclinic symmetry of such folds is not sufficient to form the wavy pattern. Based upon fluid dynamic theory and experiments with layered rubber slabs it is suggested that drag folds on flanks of major folds generally evolve as follows: Layer-parallel compression of more or less straight layered rocks causes some layers to shorten essentially by more or less uniform compressive strain and thickening (thick and not-so-competent layers), other layers to shorten essentially by buckling (thin and most component layers). In the course of time, however, the rate of buckling of the thick layers becomes significant relative to the rate of arc-shortening, and the thin layers with the early formed short buckles are forced to mimic the larger folds of the thick layers more or less passively. In this process the early formed short buckles become tilted and assume the typical drag-fold shape.
The Downtonian and Dittonian Facies of the Welsh Borderland
Authors: Allen J. R. L. , Tarlo L. B.
Published: May 2009

The succession of Lower Old Red Sandstone rocks found in the Welsh Borderland, is reinterpreted to reveal a shifting pattern of facies of far greater complexity than was hitherto realized. The sequence of vertebrate faunas is examined in conjunction with the sediments, and in this way a fuller account is given of the conditions of life of these early vertebrates, than was previously possible. The boundary between the Downtonian and Dittonian Stages is revised to coincide with the major palaeontological break in the region, and this is shown to approximate to a major lithological break, which is here accepted as the division between the local rock units known as the Downton and Ditton Series.
Agglutinate in North Jan Mayen
Authors: Hawkins T. R. W. , Roberts B.
Published: May 2009

In North Jan Mayen agglutinate is recognized as an important and widespread pyroclastic deposit of recent parasitic activity associated with the Beerenberg volcano. Lips of agglutinate along fissures, areas up to one square kilometre composed entirely of agglutinate, and other smaller morphological features are described. It is proposed to term the more widespread areas of agglutinate, “agglutinate fields,”, owing to their superficial resemblance to aa lava fields. Two varieties of agglutinate, one composed mainly of pancakes and bombs and the other of driblets of ankaramitic basaltic material are described, and conclusions given on their significance and formation.
A Reconsideration of Certain Aspects of the Rangwa and Ruri Carbonatite Complexes in Western Kenya
Authors: McCall G. J. H.
Published: May 2009

Dykes with melilite occur in the area peripheral to the Rangwa complex. A flow-lineated alvikite dyke situated in the area just outside the North Ruri complex contains calcitic pseudomorphs of phenocrysts, and it is suggested that the majority of these are after melilite. The significance of the observed restriction of melilitic dykes to the peripheral area of the complexes is considered in the light of the recognition of a gradational progression from kimberlite-alnöite dykes to beforsite and alvikite dykes at Alnö island and its environs in Sweden. The possibility that cauldron subsidence is involved in some of the Kenya complexes is considered.
Proterozoic Palaeocurrent directions in the Kimberley Region, Northwestern Australia
Authors: Gellatly D. C. , Derrick G. M. , Plumb K. A.
Published: May 2009

Palaeocurrent directions from cross-beds in the Proterozoic Kimberley Basin sediments, north-western Australia indicate sediment transport predominantly from the north-east in the lower part of the succession, and from the north-west in the middle and upper parts. Most of the sediment was probably derived from the north and only a little from the adjacent exposed areas of older Pre-Cambrian rocks to the south. The suggested northerly source of the sediment is consistent with a probable former position of Western Australia close to Peninsular India and to Burma.
Bathymetric distributions of Calcarea and Hexactinellida in the present and the past
Authors: Reid R. E. H.
Published: May 2009

Calcarea and Hexactinellida are now characteristic of different depth zones, and have shown comparable bathymetric zonation since the Carboniferous period. This paper reviews and discusses relevant evidence from modern and fossil sponge faunas, together with some problems involved in the use of the modern data for the assessment of past depths. The most important independent evidence is provided by calcareous algae and herma-typic Scleractinia.
The Raised Beaches of the North Coast of Sutherland, Scotland
Authors: King Cuchlaine A. M. , Wheeler P. T.
Published: May 2009

Measurements were made of features formed in relation to former sea-levels along the north coast of Sutherland between Melvich and Durness. The results suggest that four raised-levels can be identified. The uppermost, which is at a greater elevation on the east, is related to glacial and fluvio-glacial deposits, which indicate its formation in close proximity to glaciers. This level has been correlated with the “100 ft.” beach. The next level also shows slight tilting up to the east and seems to correspond with the “50 ft.” level elsewhere in Scotland. The two lowest levels are horizontal, and can be correlated with the “25 ft.” and “15 ft.” levels respectively.
Pumice Eruption in the Area of the South Sandwich Islands
Authors: Gass I. G. , Harris P. G. , Holdgate M. W.
Published: May 2009

An extensive pumice raft was encountered by H.M.S. Protector in the area of the South Sandwich Islands on the 14th March, 1962. Evidence is presented which suggests that this material was ejected on the 5th March, 1962, from a submarine eruptive centre 35 miles to the north-west of the existing islands but on the axis of the South Sandwich Arc.
A New Species of Pseudoclimacograptus from the Ordovician of Marathon, Texas
Authors: Clarkson Cynthia M.
Published: May 2009

Specimens of Pseudoclimacograptus marathonensis sp. nov., preserved in relief, from the Ordovician of Marathon, Texas, are described. An account of a series of sections of the proximal end is also given. The material is compared with the compressed syntypes and other specimens of Amplexograptus Confertus (Lapworth), with which the new species had been confused.
Lateral Cryptic Variation in the Great Dyke of Rhodesia
Authors: Hughes Charles James
Published: May 2009

A lateral cryptic variation is recognized in layered ultramafic rocks of the Hartley Complex, the largest of the four lopoliths that constitute the Great Dyke. Over a lateral distance of some 120 km, the En content of orthopyroxene from thick, continuous bronzitite layers is up to 6% less at the southern extremity of the Complex than in the central area. This is interpreted to be a result of more rapidly falling temperatures in a thinner body of basic magma that gave rise to a condensed sequence in marginal areas of the lopolith compared to the central area.

Following a well-marked period of addition of parental basic magma which appears to have had the incidental effect of linking up the four lopoliths, this compositional relationship in composition is reversed, i.e. the orthopyroxene from the base of an upper bronzitite layer of the southern marginal area of the Hartley Complex is more magnesian than that from the equivalent level in the central area. This is interpreted to arise from the proportion of fresh added magma to previously emplaced and partly crystallized magma being relatively greater in the marginal area than in the central area of the lopolith.
A new Campanile from the Palaeocene of Western Nigeria
Authors: Adegoke O. S. , Dessauvagie T. F. J.
Published: May 2009

Campanile nigeriense sp. nov. is described and figured from the Palaeocene Ewekoro Formation of Western Nigeria. Its juvenile whorls characteristically have four smooth and broad spiral ribs while adult whorls are completely smooth. Vertical ornamentations are lacking. This second record of Campanile from West African Palaeocene strata suggests that the genus may be a stratigraphically useful index fossil in West Africa.
Early joint formation in sediments
Authors: Cook A. C. , Johnson K. R.
Published: May 2009

Jointing in some ‘ironstone’ intraclasts in a sandstone from the Sydney Basin, New South Wales shows that the joints were developed prior to contemporaneous erosion. A number of other features observed in the Sydney Basin sequence support this conclusion and suggest that an anisotropic horizontal stress field developed in the sediments very soon after their deposition.
Some species of Bryograptus and Pseudobryograptus from Northwest Europe
Authors: Bulman O. M. B.
Published: May 2009

The genotype of Bryograptus, B. kjerulfi Lapworth, is figured and redescribed together with B. ramosus Brøgger, B. bröggeri Monsen and Pseudobryograptus cumbrensis (Elles).
The Petrography and Origin of Deposits filling Solution Pipes in the Chalk near South Mimms, Hertfordshire
Authors: Thorez J. , Bullock P. , Catt J. A. , Weir A. H.
Published: May 2009

Pipes and other solution cavities in the Upper Chalk near South Mimms contain deposits unlike those found in similar situations elsewhere in Great Britain. The cavities were formed near the sub-Palaeogene surface, and most of the deposits in them were derived from the basal Palaeogene beds (Thanetian and Sparnacian). A dark brown and very porous clay, which lines many of the pipes, is composed partly of the insoluble residue from the Chalk and partly of clay eluviated from the Palaeogene deposits. The clay was deposited from percolating water in spaces formed by dissolution of chalk at the margins of the pipes.
Size-graded layering in the Imilik gabbro, East Greenland
Authors: Brown P. E. , Farmer D. G.
Published: May 2009

Rhythmic layering in which the layers grade from coarse base to finer top is described in a plagioclase—pyroxene—olivine gabbro. The medium sizes of the various cumulus minerals at each level have significantly different settling velocities. Variation in the proportions of the cumulus minerals accompanies the size grading. It is shown that these characteristics can reasonably be accounted for if hydrodynamic factors exerted the main control, over-riding any chemical effects.
The intrusive form of some basalt dykes showing flow lineation
Authors: Roberts John L. , Sanderson David J.
Published: May 2009

The dilational intrusion is described of some basalt dykes of Tertiary age into the Easdale Slates at Easdale, Argyllshire. The intrusive form of the dykes results from the walls of irregular fractures, guided by pre-existing planes of weakness, moving apart under magma pressure. The propagation of the fractures is discussed in relation to the external stress field controlling the intrusion of the dykes and the direction of opening of the fractures considered in relation to the magma pressure and the external stress field. The flow lineations developed at the margins of the dykes are discussed in terms of their mode of origin. Although the attitude of these lineations varies with the intrusive form of the dykes, the overall direction of flow of the magma was upwards to the north of northwest.
Ocellar Hybrids from the Tyrone Igneous Series, Ireland
Authors: Angus N. S.
Published: May 2009

Ocellar hybrid rocks, formed by metasomatic transformation of basalt xenoliths engulfed in granitic magma, are characterized by numerous small, oval quartz porphyroblasts, each sheathed with narrow rims of amphibole. The progressive development of these quartz ocelli, together with the general texture of the ocellar hybrid, is traced through a number of intermediate hybrid types. In some instances, the ocellar hybrid displays an intrusive relationship toward basalt and is thought to have undergone a certain amount of metasomatic mobilization.
Vermiform Burrows and Rate of Sedimentation in the Lower Greensand
Authors: Middlemiss F. A.
Published: May 2009

Vermiform burrows, which are common in the Lower Greensand, can be used to estimate the relative rate of sedimentation, repeated penetration by burrowing organisms being taken as indicating slow deposition, a single undisturbed penetration as indicating rapid deposition. Application of this criterion is illustrated by reference to the Ferruginous Sands of the Isle of Wight.
Potassium–Argon Age Studies in Scotland
Authors: Miller J. A. , Brown P. E.
Published: May 2009

New potassium-argon age determinations are presented for rocks ranging in age from Lewisian to Tertiary. A late-Caledonian metamorphic event at about 422 million years is very important in the Highlands and the relationship of this to previous metamorphisms is discussed. Newer Granite emplacement took place about 400 million years ago and the Moine thrust movement also took place at about this date. Lower Carboniferous basalts yield, by whole rock methods, ages compatible with the time scales of Kulp (1960) and Holmes (1959). Volcanic activity in Mull is confirmed as Palaeocene or Eocene in age.
A Revision of Retepora nodulosa Phillips, 1836
Authors: Tavener-Smith R.
Published: May 2009

A fenestrate bryozoan species recently collected from the Visean of County Fermanagh, Ireland, appears to correspond in all respects with Retepora nodulosa Phillips, from a similar horizon in Yorkshire. The last-named form was never satisfactorily defined or illustrated, the original type material is lost, and after being neglected for many years the name was declared a nomen dumium by Miller (1961). It is now recognized that, because of the presence of biserial carinal nodes, the species properly belongs in the genus Minilya, Crockford, 1944. It is here redescribed on the basis of a neotype from Fermanagh.
Axial-trace-fractures and Deformed Concretionary Rods in South Pembrokeshire
Authors: Hancock P. L.
Published: May 2009

Axial-trace-fractures are defined as joint or fracture cleavage surfaces which intersect bedding surfaces parallel to adjacent fold axes, and which meet stratigraphically higher bedding surfaces at acute angles closing towards adjacent anticlinal hinges. In the Upper Palaeozoic rocks of South Pembrokeshire these fractures are developed equally on fold limbs, in regions of low dip, and around fold hinges. Characteristically they are interrupted at bedding surfaces and vary in frequency with lithology. The value of the angle they subtend with bedding surfaces varies with lithology and dip.

Calcareous concretionary rods, thought to have been originally normal to depositional surfaces, are now orientated parallel to axial-trace-fractures and at right angles to fold axes.

The axial-trace-fractures of South Pembrokeshire are considered to have been formed immediately before or at the start of the Armorican folding, and then to have been rotated and sheared during the folding.

Other joints associated with axial-trace-fractures are described and briefly discussed.
Structural Study of the Contorted Drift and Disturbed Chalk at Weybourne, North Norfolk.
Authors: Banham P. H. , Ranson C. E.
Published: May 2009

A structural analysis of the cliffs and one pit section in Pleistocene deposits at Weybourne has shown one major phase of ice movement only. Ice moving from approximately 210 degrees caused the disturbance of the upper part of the Chalk (together with the overlying Weybourne Crag) and the deformation and deposition of a chalky-boulder-clay, thought to be equivalent to the Lowestoft till.
The West Limb of the Loch Awe Syncline and the Associated Cleavage Fan
Authors: Borradaile Graham John
Published: May 2009

The Loch Awe Syncline (Bailey, 1913), affecting the Middle and Upper Iltay Dalradian Successions of Argyllshire, is recognised as an F1 structure. The present work shows that the west limb is arched over a pre-O.R.S., late Caledonian monoform responsible for the fan of first cleavage over the area investigated. Reflecting the style of the earlier Ben Lui-Tarbert Monoform (Roberts & Treagus, 1964), the newly described Kilmelford–Turnalt Monoform adds to the symmetry of the Iltay Nappe Complex. “Mushroom” Structure (Rast, 1963).
The Location of the Southern Uplands Fault in Central Ireland
Authors: Leake Bernard E.
Published: May 2009

It has been suggested that the Southern Uplands fault of Scotland does not continue across central and western Ireland. Published geophysical evidence, however, strongly suggests that the fault does continue, under the Carboniferous cover, at least as far as the neighbourhood of Galway.
The Influence of Geological Factors on the Strength of Coal Measure Rocks
Authors: Price Neville J.
Published: May 2009

A study has been made in the laboratory of the strength of a “suite” of coal measure rocks in uniaxial and triaxial compression. From the data obtained it is demonstrated that the compressive strengths are profoundly influenced by the composition, porosity and degree of compaction of the rocks. It is indicated that these factors also influence the tensile and cohesive strengths.
The elevation of the Lower Greensand ridge, south-east England
Authors: Chorley R. J.
Published: May 2009

The influence of three classes of factors—geological structure, lithologic composition and spatial control over erosion—are examined by trend-surface analysis, followed by stepwise regression, in order to determine their relative importance in explaining the variation observed in the elevation of the Lower Greensand ridge of south-east England. It is concluded that structural controls are dominant, lithological controls very subordinate and the spatial control of very marginal significance.