bluuebunny/crossref_metadata_2025 huggingface dataset:
Quartz Fabric Reorientation in the Region of Benmore Assynt, North-West Highlands of Scotland
Authors: Crampton C. B.
Published: May 2009

In the Assynt area of the North-West Highlands of Scotland a regional preferred orientation of quartz [0001]-axes of sedimentary origin in Cambrian quartzites has withstood considerable deformation and destroyed only with the onset of granulation in the immediate vicinity of thrust planes. After partial granulation the remaining scattered quartz grains develop a preferred orientation of [0001]-axes quite distinct from the sedimentary fabric. Recrystallization is apparent well away from the thrust planes, but only supersedes granulation along certain sections of the major Moine Thrust plane. The preferred orientation of quartz [0001]-axes in these recrystallized fabrics is somewhat variable. The regional quartz fabric of metamorphic origin in Moine rocks immediately above the thrust planes can experience a similar deformation, recrystallization following granulation with the development of quartz fabrics similar to those in recrystallized quartzites below the Moine Thrust plane.
The Wenlock sediments of north-west Galway, Ireland.
Authors: Laird M. G. , McKerrow W. S.
Published: May 2009

This work describes the Wenlock sedimentary sequences south of Killary Harbour where the fullest successions in north-west Galway are exposed; much of the Upper Silurian in the east (Joyces Country) has been removed by erosion.

The Wenlock beds (the Upper Owenduff and Killary Harbour Groups) rest on shallow marine and continental sediments (the Lower Owenduff Group) of Upper Llandovery (C5–6) age. Conglomerates near the base of the Wenlock are followed by 1,500 m of sandstones, which are mostly turbidites and which contain Middle Wenlock graptolites. These basin deposits are succeeded by a transitional sequence of rise, slope and shelf clastics, also of Middle Wenlock age. The youngest Silurian beds exposed are 800 m of red lagoonal deposits withLingula.

During Wenlock times, the sediment supply to north-west Galway was mainly from the north and north-west. This observation fits well with the regional picture which places Galway near the north-west margin of a Silurian basin which extended eastwards across Ireland.
Appinite xenoliths and associated rocks from the Ben Nevis igneous complex
Authors: Haslam H. W.
Published: May 2009

An area is described in which the main rock type is a variable dioritic rock, thought to have been formed by the expulsion of the residual acidic liquid from a largely crystalline quartz-diorite magma. It contains xenoliths of pyroxenite and appinite. The latter consist largely of hornblende, with some diopside, quartz, orthoclase microperthite and oligoclase. They are considered to be the reaction products of the outer margin of a magma and the adjacent calcareous country rock.
Rubidium and Strontium age determination of some Pre-Cambrian granitic rocks, S.E. Uganda
Authors: Old R. A. , Rex D. C.
Published: May 2009

Whole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.
Diopside-Orthoclase-Hornblende Rocks from the Lewisian Paragneisses of South Harris, Outer Hebrides
Authors: Dearnley R.
Published: May 2009

An account is given of the petrography and chemistry of a diopside-orthoclase-hornblende rock within the quartzose garnetkyanite-biotite granulites of the Leverburgh Lewisian paragneiss belt of South Harris.
The Structure of the Scotia Arc
Authors: Hawkes Donald D.
Published: May 2009

It is suggested that the Scotia Arc was formed after the disruption of a continental strip between South America and Antarctica by an eastward advance of the Pacific crust; volcanic island arcs and associated trenches developed at the juction of the Pacific and Atlantic crustal types; the Scotia Arc migrated eastward with time; and that the crustal structure of the Scotia Sea is in the process of changing from an oceanic (Pacific) to a continental type.
Some Glacial Deposits and their Relation to the Hippopotamus-bearing Beds at Barrington, cambridgeshire
Authors: Norris G.
Published: May 2009

Till fabrics on the ridge above Barrington show a variety of preferred orientations and their origins are discussed. Not all the fabrics can be attributed to ice transport. Lowestoft and Gipping Tills are differentiated on their lithologies, fabrics, and erratics, and the contained heavy minerals and microfossils are also considered. Correlation of the associated solifluxion deposits with the sequence in Barrington Village has shown that the Hippopotamus-bearing Barrington Beds are not younger than the Hoxnian Interglacial (Elster/Saale) and may be considerable order.
Kentallenite-Lamprophyre-Granite Age Relations at Kentallen, Argyll
Authors: Bowes D. R.
Published: May 2009

An intrusive sequence of kentallenite-lamprophyre-granite is clearly indicated by cross-cutting relations at Kentallen. This sequence is the same as that recorded elsewhere in Argyll. It is suggested that the time gap between the intrusion of the kentallenite and of the lamprophyre is small compared with that between the intrusion of the lamprophyre and of the granite.
Element Distribution in Two Epidiorite Sills from the Central Grampian Highlands of Scotland
Authors: Ball T. K.
Published: May 2009

Magmatic differentiation is demonstrated in two epidiorite sills from the Grampian Highlands of Scotland, and the distribution of major and minor elements compared with data given for other intrusions, and for trace elements in the Whin Sill at High Cup Gill, Westmorland. The latter sill has Sr and Ba enriched towards the top. The element distribution for the epidiorite sills indicates that they are overturned. The data are conclusive for one sill but merely suggestive for the other, since such phenomena as multiple injection may also have affected the element distribution. The structural significance is briefly discussed.
The Phuket Group, Peninsular Thailand: a Palaeozoic ?geosynclinal deposit
Authors: Mitchell A. H. G. , Young B. , Jantaranipa W.
Published: May 2009

The Phuket Group is the oldest rock unit in the Phuket-Takua Pa-Krabi region of the Thai Peninsula. The Group comprises two Formations: a Lower Formation of Ordovician, or possibly Cambrian, to Lower Permian age, exceeding 3 km in thickness, and an Upper Formation of early Permian age between 100 and 200m thick.

Facies analysis shows that the Lower Formation consists of mass flow deposits and sandstones comparable to the deposits of modern continental rises and continental slopes. The Upper Formation was deposited in a shallow marine and probably deltaic environment. The Phuket Group and litho-logically similar sedimentary rocks to the north and south occupy an elongate belt extending from the Shan States of Burma to the Langkawi Islands in Malaysia. The sediments, which are rich in quartz, were derived from a continental area and deposited on its margin. In contrast to previous interpretations of the Palaeozoic history of Peninsular Thailand, it is considered that the continental source lay to the east. The continental margin resembled modern margins of either Atlantic or Japan Sea type.
Depositional Features of Dittonian Rocks: Pembrokeshire compared with the Welsh Borderland
Authors: Allen J. R. L.
Published: May 2009

The Dittonian Stage in Pembrokeshire comprises the Lower Marl Group (higher beds), the Sandstone-and-Marl Group, and the Upper Marl Group (at least lower half). These formations cannot be distinguished lithologically from Dittonian strata of the Welsh Borderland 100 miles away along the depositional strike.

Cyclothems of intraformational conglomerate (scoured surface below) → sandstone → siltstone with concretions recur vertically in each area. The conglomerates in both districts consist of intraformational siltstone and concretionary debris. Flat-bedding, primary current lineation, planar cross-bedding, trough cross-bedding, and ripple-drift bedding are common to the sandstones. Suncracked siltstones abound in both Pembrokeshire and the Welsh Borderland. Slumped bedding, sandstone pipes, and animal burrows are the structures penecontemporaneous with deposition in each area.

The Dittonian strata of the Welsh Borderland are shown to be probably floodplain deposits, by reason of their close similarity to the modern sediments of the Colorado Delta floodplain and Colorado River. The occurrence of an identical facies in Pembrokeshire suggests the even wider extent of this floodplain in early Lower Old Red Sandstone times, when the sea lay far to the south of both areas.
Analysis of the Strike Swing at Crockator Mountain, co. Donegal, Eire
Authors: Rickard M. J.
Published: May 2009

A detailed analysis is presented of a small complex bent-fold structure that occurs in the angle of the Donegal Granite outcrop. It is the most northerly expression of the major strike swing in South-West Donegal and may be of considerable importance to the interpretation of that phenomenon. Five different lineation types are related to events leading to the severe bending of a curved tight syncline in massive quartzite. The bending occurs with surprisingly little disruption of the quartzite and must have occured under plastic conditions possibly associated with granite intrusion.
Natrojarosite and ‘collophane’ in graphite-sillimanite-schist
Authors: Kempe D. R. C.
Published: May 2009

Some graphite-sillimanite-schists and -gneisses, containing natrojarosite and ‘collophane’, from north-east Tanzania, are described, with an analysis, and their sedimentary origin briefly discussed.
Gneisses in the north-western part of County Mayo, Ireland
Authors: Sutton J. S. , Max M. D.
Published: May 2009

A metamorphosed complex of basic and acid gneisses, which occurs in north-west County Mayo, Ireland, structurally underlies younger Moinian and Dalradian type metasediments. These gneisses are compared directly with the Lewisian ‘inliers’ of the western Highlands of Scotland.
Notes towards a theory of concentration of solids in natural sands
Authors: Allen J. R. L.
Published: May 2009

Theory based on the sphere as the ideal particle, fails to account satisfactorily for the concentration of solids observed in unconsolidated natural sands, which at the same time display a substantial degree of dimensional ordering of the particles. However, when the prolate spheroid of moderate axial ratio is substituted for the sphere, a theory which is satisfied by observation becomes possible, for the reason that equal spheroids can be regularly packed in both close and open ways. A spheroid assemblage of mixed open and close packings can retain a high degree of dimensional ordering of the constituent solids, yet have a relatively low particle concentration. Observations made on sandstones carefully selected for evidence of rapid cementation seem to bear out the theory as applied to natural sands. Clusters of grains resembling the open packings of equal spheroids are found in these sandstones to be uncommon but not rare, in accordance with the theory as thus far developed.
Early Tertiary Fold Movements in Mull
Authors: Cheeney R. F.
Published: May 2009

Evidence is presented which suggests that there is a strong angular unconformity between the Mesozoic sediments and the Tertiary lavas in certain parts of the Island of Mull. The conclusion is drawn that folding movements peripheral to the volcanic centre occurred both before and after the eruption of the main lava succession.
A Suspected Spilitic Rock from the Lower Cambrian Manganese Shale Group of the Harlech Dome, North Wales
Authors: Mohr P. A.
Published: May 2009

Mineral and chemical evidence suggest that an unusual rock from the Upper Manganese Shales of Diphwys is of spilitic origin, despite certain geochemical anomalies. Some similarities of the rock to the shales themselves are only superficial, and a metasomatic origin is precluded; the rock is also very distinct from the “greenstone” sills of the region.
Some Theoretical Factors in Geomorphological Analysis
Authors: Kennedy W. Q.
Published: May 2009

Consideration of the relative rates of uplift-erosion and erosion-denudation leads to the recognition of nine cases which define the conditions of geomorphological evolution. It is concluded that a peneplanated surface may develop during active tectonic uplift, and that the total volume of clastic sediments produced during any stage is inversely proportional to the rate of uplift.
The Buried Channel of the Bristol Avon
Authors: Hawkins A. B.
Published: May 2009

The paper discusses the buried channel of the Bristol River Avon. Borehole information indicates a buried channel to a depth of at least — 65 feet O.D. in the Avonmouth area. This has been correlated with other areas and suggests an erosional date of the First or Second Buried Channel Period of the Last Glaciation.
Clarification of the Polyphase Deformations of North Wales Palaeozoic Rocks
Authors: Lynas Bryan D. T.
Published: May 2009

Recent detailed mapping to the north-east of the Harlech Dome in North Wales has produced clear evidence of an early deformation. Thus four distinct deformations can be recognised in the Welsh Caledonides, and their resultant structures are described.
Morphology of Quaternary phonolite lavas from Tenerife, Canary Islands
Authors: Ridley W. I.
Published: May 2009

Phonolite lava from the Viejo and Teide volcanoes show a wide variation in flow morphology, from viscous, spoon-shaped lavas to thin flows more than 8km long that often show well developed lava channels. The apparent fluidity of these lavas is considered to be largely due to their strongly alkaline character.
Notes on some deformation structures of sedimentary origin in the Little Haven—Amroth coalfield, Pembrokeshire
Authors: Williams Peter F.
Published: May 2009

The morphology, origin, and orientation patterns of distinctive types of sedimentary deformation structure are considered. The structures described are laminar folds, load marks and pouches, and convolute and corrugated lamination. A set of criteria obtained from detailed field analysis of the structures is put forward to indicate minor lateral translations of mobilised sediment.

Laminar folds occur in a laminated mudstone/siltstone lithology and are the result of predominantly lateral movements in response to an unstable palaeoslope. Laminar folds are metadepositional or postdepositional in origin. Orientation patterns are characteristically unimodal. Load marks and pouches are preserved in a banded siltstone/sandstone-mudstone lithology, and result from sediment movements which are either vertical, or vertical with some lateral translation. They are syndepositional or metadepositional in origin. Orientation patterns are predominantly unimodal but bimodal and random patterns are also present. Convolute and corrugated laminations are found in thin siltstone/sandstone beds and have developed through sediment movements which were almost exclusively vertical. The convolutions and corrugations are metadepositional in origin. The majority of orientation patterns are unimodal but there is an increase in the number of random patterns.

The positioning of deformation units which show internal lateral translation in a broader stratigraphical and geographical context, suggests there may be a regional palaeoslope control on the lateral movement of mobilised sediment.
Age of the Jamaican Granodiorite
Authors: Chubb L. J. , Burke Kevin
Published: May 2009

Granodiorite intrusions in Jamaica were assigned by early workers to various ages from Pre-Cambrian to late Tertiary. Recent surveys have shown that the granodiorite intrudes Maestrichtian sediments and has provided material for pebbles in an Eocene conglomerate. Its age is therefore very late Cretaceous or very early Tertiary. Radio-metric determinations using Potassium/Argon; Rubidium/Strontium and isotopic lead methods suggest an age of 65 ± 5 million years.
Differing Powers of Crystal Nucleation as a Factor Producing Diversity in Layered Igneous Intrusions
Authors: Wager L. R.
Published: May 2009

To account for a type of rhythmic unit found in the Bushveld complex of South Africa and probably in other layered intrusions, a hypothesis is put forward dependent on the different powers of crystal nucleation from supersaturated magma. It is suggested, for example, that the three common primary precipitate minerals, chromite, bronzite, and bytownite nucleated in this order which is probably dependent on the differing complexity of their crystal structures and that the common rhythmic unit, beginning with chromitite, passing upwards into bronzitite and ending with a bytownite-rich rock is the result of these crystals accumulating successively at the bottom'of the liquid.
Greywacke Sedimentation in the Torridonian of Colonsay and Oronsay
Authors: Stewart A. D.
Published: May 2009

The lower Torridonian in its southernmost outcrops is built of felspathic greywacke turbidites, forming a succession probably 2–3 km. thick, overlain by 2 km. of pelitic and semi-pelitic sediments containing thick, current-bedded pebbly arkose horizons, especially near the base. Sedimentary structures in the greywackes include ubiquitous grading, together with flames, load-casts, convolute bedding, and sedimentary injection, brecciation and disruption phenomena. Palaeocurrents in both greywackes and arkoses indicate a southerly derivation. The detrital mineralogy also suggests a common provenance. It is suggested that the greywackes gradually filled their depositional basin and that later sedimentation occurred in a shallow water or fluvial environment.
A Drift-filled Valley at Thistleton on the Rutland–Lincolnshire Border
Authors: Rice R. J.
Published: May 2009

A borehole programme by Stewarts and Lloyds Minerals, Ltd., has shown that a narrow tongue of boulder clay conceals a deep steepsided valley cut into the Lincolnshire Limestone and filled with drift. Plotting of structure contours indicates that, even where thedrift is more than 100 feet thick, there is considerable “bulging” of the Upper Lias Clay.
The Geometry of Conjugate Fold Systems
Authors: Ramsay John G.
Published: May 2009

Conjugate shear fold systems are often developed when brittle laminated rocks are subjected to stress. These structures relationship of the principal axes of stress to the surface being folded. Within first order shear zones conjugate second order shear folds may be developed as a result of reorientation of the stress axes in these zones.

The axes of both first and second order conjugate shear folds may form at any angle to the principal stress axes and to the direction of movement within the shear zones. The principal axes of stress are most reliably determined from the orientation of the axial planes of the first order conjugate folds.
Structural Control of Uranium Mineralization in Australia
Authors: Rade J.
Published: May 2009

A deep seated flow of geoplasma (bathyrheal underflow) subjected crustal blocks to recurring horizontal movements causing north-east trending faults, shearing along anticlines and rotation of the separate crustal blocks. These movements produced extensive faulting and shattering in the South Alligator River area and north of Katherine, providing suitable loci for uranium mineralization. The mineralization occurs as a late phase open fissure filling and two types occur, (i) the nickel–cobalt–native silver type, and (ii) the quartz–pyrite–galena type. These characteristics provide a guide for future prospecting for uranium in Australia.
Boudinage Structure in West Cork, Ireland
Authors: Coe Kenneth
Published: May 2009

Boudinage occurs with great regularity in parts of West Cork. The principle break-up of competent beds is into boudins with the separation parallel to the dip of the bedding, but where the exposure permits examination in three dimensions it can be seen that incipient boudinage is developed with separation parallel to the strike of the bedding. The structure is shown to have originated after the main phase of folding by horizontal forces acting on steeply inclined beds. Some unusual features are described.
Fold Structures in the Dalradian Rocks of Knapdale, Argyllshire
Authors: Roberts John L.
Published: May 2009

In the Dalradian rocks of Knapdale in south-west Argyll two groups of minor folds have been developed which share the same axial plane; their fold axes lie at right angles to each other within the common axial plane. Field evidence indicates that the two fold groups are strictly contemporaneous. One group of minor folds plunges at 40° to 020° N., and the other group plunges at 45° to 235° N., the common axial plane dipping at 70° to 305° N. Major structures parallel to both sets of minor folds are developed in the area. The fabric diagram of the fold groups shows tetragonal symmetry and this is taken to indicate that the stress field responsible for the deformation had itself tetragonal symmetry. The maximum compressive stress acted almost horizontally in a N.W.–S.E. direction while extension took place equally in all directions in a plane normal to the axis of maximum compression. The relations of contemporaneous fold structures to three basic strain patterns are briefly discussed.
On Convolute Bedding in the Lower Ludlovian Rocks of North-East Radnorshire
Authors: Holland C. H.
Published: May 2009

Convolute bedding is described from the Lower Ludlovian in north-eastern Radnorshire in calcareous siltstones probably of the Monograptus tumescenszone. Examples of true slump-structures from the same area are given for comparison. The mode of formation of the convolute bedding is discussed and reference made to such directional information as is available from a study of the sediments.
Foraminiferal Faunas from the Lapithos Group of Cyprus
Authors: Cockbain A. E.
Published: May 2009

This paper reviews the stratigraphic micropalaeontology of the Lapithos Group of Cyprus, which is now known to be Upper Cretaceous to Lower Miocene in age. A three-fold subdivision, on the basis of planktonic foraminifera, into Lower (Upper Cretaceous) Middle (Danian to Eocene) and Upper (Oligocene to Lower Miocene) Lapithos Formations is suggested and a summary of the outcrops of each formation is given. The foraminiferal faunas of the Lapithos Group are discussed and it can be shown that a planktonic and a neritic faunal assemblage is present in each formation. The Terra Limestone, hitherto considered as part of the Dhali Group, shows faunal affinities with the Upper Lapithos neritic facies and is therefore placed in the Lapithos Group.
Pre-Cambrian Perthosites in Nyasaland
Authors: Morel S. W.
Published: May 2009

Attention is drawn to the widespread occurrence of perthosite bodies in the Basement Complex of southern Nyasaland, and a description of these rocks is given.

It is suggested that these rocks represent a late stage in the differentiation of basaltic or andesitic magma which produced basic intrusives and volcanics and ultrabasic complexes in the late Pre-Cambrian. These were subsequently metamorphosed at a high grade. The nepheline-syenite gneisses of Port Herald and Tambani are believed to be related to the same series.

The remarkable similarities between the late Pre-Cambrian igneous history and that of the Karroo to Chilwa Series period is commented upon, and the occurrence of similar “ring structuress” in both series is described.
The Relation Between the Quartz Fabric and Fold Movements in a Folded Calc-Silicate Rock from the Moines of Scotland
Authors: Dhonau T. J.
Published: May 2009

Petrofabric analyses of quartz c-axes have been made at four locations round a fold in a calc-silicate rock. The movement direction during the folding is deduced from the deformation of an older lineation. Two fabrics are present: the earlier, associated with the deformed lineation, is being replaced by a fabric associated with the formation of the fold. It is shown how the symmetry of the later fabric is related not to the axis of the fold but to the direction of the movement that produced the fold; and how the quartz c-axes lie on a conical surface, giving a small circle on a stereogram plot.
A Note on Cleavages in Crenulated Rocks
Authors: Rickard M. J.
Published: May 2009

Published descriptions and new field observations in Ireland and Canada confirm that strain-slip cleavage should not be classified with fracture cleavage. The termcrenulation cleavageis proposed to replace the generic one of strain-slip cleavage. Crenulation cleavage differs essentially from slaty and fracture cleavage in that it only develops in laminated rocks and is consequently nearly always a secondary structure. Intense metamorphism converts crenulation cleavage into a new schistosity or cleavage with characteristics similar to slaty cleavage. Two fundamentally different types are recognized and it is suggested that crenulation cleavage is a valuable indicator of metamorphic conditions during the various phases of deformation.
Co-existing Pyroxenes in Igneous Assemblages: a Re-evaluation of the Existing Data on Tie-line Orientations
Authors: Brown G. M.
Published: May 2009

Tie-line data are presented for twelve analysed igneous pyroxene pairs, from which it is demonstrated that a precise point of intersection, at or close to Wo75 En25 in the ternary diagram, does not exist. Eight tie-lines for pyroxene pairs from ultrabasic nodules in basalts are also considered. The tie-lines for metamorphic pyroxenes are compared with the igneous, and are shown to intersect over a similarly wide range, the average (Ca82 Mg18) being the same for both assemblages. It is shown that no conclusions can be drawn as to the genesis of the pyroxene assemblage, from the assumption of a characteristic tie-line intersection point. Optical determinations are considered, and shown to be of little practical value in this particular problem.
The stromatoporoid genus Milleporella Deninger
Authors: Hudson R. G. S.
Published: May 2009

The holotype of the stromatoporoid Milleporella sardoa Deninger, 1906, from the Senonian of Sardinia is redescribed and the genus Milleporella Deninger, 1906, and the family Milleporel-lidae Yabe and Sugiyama, 1935, are redefined. A new superfamily the MILLEPORELLICAE, is founded.
The Antipodal Location of Continents and Oceans
Authors: Evison F. F. , Whittle P.
Published: May 2009

Five-sixths of all the continental area on the Earth's surface has antipodes in oceanic regions. This proportion is not significantly different from what one would expect on the assumption that the continents are randomly situated.
Co-existing Pyroxenes: Some Causes of Variation and Anomalies in the optically Derived Compositional Tie-Lines, with Particular Reference to Charnockitic Rocks
Authors: Wilson Allan F.
Published: May 2009

Available data from charnockitic rocks (including twenty-eight new pyroxene pairs fromAustralia) suggest that a major cause of variation in optically derived compositional tie-line trends of co-existing pyroxenes is related to the geothermal history of the rocks concerned. It may yet be possible to subdivide the granulite facies, and also to detect mineral instability by critical study of tie-line trends. Recommendations are made whereby mineralogic and structural studies of charnockitic rocks can be integrated to yield more reliable chemical and optical data.
The Old Red Sandstone of Eastern Ekmanfjorden, Vestspitsbergen
Authors: Dineley D. L.
Published: May 2009

The Lower Old Red Sandstone deposits of Ekmanfjorden belong mainly to the Lykta Division, but pale sandstones with Giganthaspis representingthe Kapp Kjeldsen Division also occur in the core of what is probably a N.-S. striking anticline. The lower beds of the Lykta Division are soft, dull and silty and not very fossiliferous; above them are some 1,100 feet of sandstones and conglomeratic beds alternatingwith shales or marls. Locally abundant vertebrate remains include the guide fossil Doryaspis. Various sedimentary structures suggest rapid deposition on a broad shallow delta front.
Deformation Features in Cataclastic Quartz
Authors: Jenkins Glyndwr
Published: May 2009

Petrofabric analysis has been carried out on Carboniferous rocks involved in thrust masses of the Benton system in Pembrokeshire. Evidence is contributed, which indicates stages of fracturing and crystallographic control in the deformation of individual quarts grains.
Sedimentary Structures in the Epidotic Grits of Skye
Authors: Sutton John , Watson Janet
Published: May 2009

Sedimentary structures in the lowest sub-division of the Torridonian of Skye are described and figured. Trough cross-stratification of the type known as festoon bedding is widely developed in the coarser grits. Finer-grained sandstones show curly-bedding structures due to post-depositional disturbances. Siltstones and mudstones are characterized by a fine lamination and by such structures as ripple-marks, minute graded bedding and desiccation cracks. The orientation of cross-laminae in the festoon-bedded grits indicates that the currents depositing these rocks flowed towards the north-east or east.
New Hystrichospheres from the Upper Jurassic of Dorset
Authors: Sarjeant W. A. S.
Published: May 2009

From assemblages of Upper Jurassic organic-shelled microplankton from Dorset are described five new species of hystrichospheres. Of these, two are attributed to a new genus,Polystephanosphaera; one new species of the genusHystrichosphaeridium, and two of the genusBaltisphaeridiumare also described.
The Wenlock Strata of South Mayo
Authors: Anderson J. G. C.
Published: May 2009

South of Clew Bay, Co. Mayo, Wenlock strata, cut off to the north by a belt of serpentine marking the Highland Boundary, are divisible into three stratigraphical groups. The succession is repeated by a syncline overturned towards the south, which is modified by north-west cross-folds. The Wenlock strata have undergone low-grade “regional” metamorphism, in spite of which fossils have been preserved at a few localities.
A New Instrument for Determining Planar Orientation
Authors: Berry F. G.
Published: May 2009

A new instrument for the use of field geologists in orientation studies is described; the method of use is outlined and briefly appraised in comparison with common practice.
A Note on the Age of the Laig Gorge Beds, Eigg
Authors: Adams C. G.
Published: May 2009

The writer was asked to examine samples of the Laig Gorge Beds to try to determine from the micro-fauna whether or not the rock was of Jurassic age, as previously thought, or younger. Seven rock samples taken from various levels within the limestone and underlying sandstone were sectioned and examined, namely:—
The Feeding Mechanisms of Spire-Bearing Fossil Brachiopods
Authors: Rudwick M. J. S.
Published: May 2009

The lophophores of spire-bearing fossil brachiopods (Spiriferoidea and Atrypoidea) arereconstructed by homological comparison with living brachiopods. It is inferred that all spiral brachidia supported simple spiral lophophores. For each type of brachidium, only one arrangement of the spirolophe could have created an efficient filter-feeding system. The water would have entered the mantle cavity laterally and been ejected medially; but would have been filtered between the whorls of the conical spiralia either outwards (e.g. Atrypa) or inwards (e.g. Spirifer). These are the only possible alternatives: it is probable that both systems were evolved more than once.
Hornblende Orientation
Authors: Tocher F. E.
Published: May 2009

An ambiguity in previously published hornblende orientation data is pointed out and illustrated by measurements on an epidiorite. A method is proposed of differentiating in certain cases between (a) a fabric derived by crystallization of hornblende under stress and (b) that derived by alignment of pre-existing hornblende prisms.
Kilauea Magma 1959–60
Authors: Tilley C. E.
Published: May 2009

Variants of the 1959–60 eruptions of Kilauea are compared chemically with the preceding flank eruptions of 1955.
Microplankton from the Cornbrash of Yorkshire
Authors: Sarjeant W. A. S.
Published: May 2009

An assemblage of microplankton from the Cornbrash of Yorkshire is described. It consists dominantly of dinoflagellates, including three new species of Gonyaulax and one new species of Pareodinia. A relatively small number of hystrichospheres are present, including new species of Baltisphaeridium, Cymatiosphaera, and Pterospermopsis. The character and significance of the assemblage are discussed.
The Southern Upland Fault in Ireland
Authors: McKerrow W. S.
Published: May 2009

The possibility of the Southern Upland Fault of Scotland continuing to the west coast of Ireland is examined critically. No post-Carboniferous faulting has occurred along this line in Ireland. It cannot be connected with any major fault occurring in the Lower Palaeozoic rocks of County Mayo or County Galway; and there is no evidence that it continues as a structural line to the south-west of Carrick on Shannon.
On the Origin and Occurrence of Basic Bodies Associated with Discordant Bathyliths
Authors: Joplin Germaine A.
Published: May 2009

It is suggested that the rock-suite, characteristic of the discordant bathyliths and ranging in composition from ultrabasic to ultra-acid, is formed from two magmas, a basaltic and a granodioritic, that the basic rocks are emplaced among the geosynclinal sediments before the introduction of the acid magma, and that intermediate rocks are hybrids. Further, it is suggested that hybridization takes place in two stages: first, by reaction between basic rocks and water and carbon dioxide, released from sediments as a result of deep-seated metamorphism, and rising in advance of the acid magma; and secondly, by the magma itself. The first intrusions carry shattered country rocks and are stock-like bodies, and these are followed by successive emplacements of granodiorite, the earliest of which envelop most of the stocks and are, thereby hybridized to form tonalites. Only those stocks near the margins of the later intrusions are preserved, and hence occur as satellites about the larger more acid bodies.

The order of intrusion, the grainsize of the basic hybrids, and the occurrence of hornblende is discussed and it is concluded that dioritic rocks and dioritic magmas originate at a high level in the geosynclinal pile.
A Note on the Occurrence of Coal Measures in Eastern County Limerick, Ireland
Authors: Nevill W. E.
Published: May 2009

The purpose of this note is to put on record the discovery of Lower Coal Measure strata in the west of Ireland. The succession is approximately 500 feet thick and includes the Gastrioceras subcrenatum and the Gastrioceras listeri marine bands. Of particular interest is the occurrence of a coarse felspathic sandstone in the cycle of sedimentation which includes the G. listeri horizon: the sandstone is very similar in lithology to the distinctive Clay-Gall Sandstone of the Leinster Coalfield.
Palaeontological Evidence for the Age of the English Wealden
Authors: Hughes N. F.
Published: May 2009

Plant microspores and megaspores are used to correlate the separate occurrences of the English Wealden with the marine Lower Cretaceous of Lincolnshire and with a Netherlands succession. The paper is a preliminary statement on the representation of the Continental stages in the English Wealden.
Further Data on the Petrology of the Saxa Vord Schists of Unst, Shetland Isles
Authors: Snelling N. J.
Published: May 2009

The polymetamorphism and fades classification of the Saxa Vord Schists are discussed on the basis of further chemical and mineralogical data now available.
Devonian Limestone Pebbles in Central Devon
Authors: Hutchins Philip F.
Published: May 2009

The presence of locally abundant pebbles of Middle Devonian Limestone in the New Red Sandstone near North Tawton, Devonshire, is recorded. It is suggested that these were derived in Permian times from a nearby outcrop of Devonian limestones which projected through the Culm Measures of the mid-Devon syncline.
Age of Zircon from the Kunait Syenite Complex, South-West Greenland
Authors: Moorbath S. , Taylor S. R. , Upton B. G. J.
Published: May 2009

The age of zircon from the Kunait pluton in south-west Greenland has been measured by the lead-alpha method. The experimental data indicate a Cambrian age and the bearing of this result on the general geology of the area is briefly discussed.
On Post-Glacial Pelicans in Britain
Authors: Forbes C. L. , Joysey K. A. , West R. G.
Published: May 2009

A bone found in the peat near King's Lynn, Norfolk, has been identified as belonging to a pelican. This is the fifth fossil record from East Anglia but it is the first to be accurately dated, and it can be correlated with Godwin's pollen zone VII–VIII (Iron Age). Other fossil pelican bones from East Anglia and Somerset are identified as those of the Dalmatian Pelican rather than the White Pelican which now visits parts of north-west Europe.
Composite and Multiple Intrusions of Lamlash-Whiting Bay Region, Arran
Authors: Srirama Rao M.
Published: May 2009

In South-East Arran there are many Kainozoic composite and multiple intrusions, mostly in the form of sills, composed of basic, intermediate, and acid rocks, xenolithic enclosure of, basic members by less basic ones being common. The pyroxene of all the rock types is a normal augite and not a pigeonite. Contact hybridization has played an important role in the partial or complete digestion of xenoliths. The genesis of the different members of the intrusions is attributed to the complex process of deep-seated hybridization of two types of magmatic material of contrasting basic and acid composition. The order of injection of magma is, invariably, from basic to acid, though in the intrusions, the spatial sequence of the rock types varies much; their complicated structures are ascribed to a series of pulsations of contaminated magma with its composition tending progressively in the acid direction.
Granite: Some Tectonic, Petrological, and Physico-Chemical Aspects
Authors: Reynolds Doris L.
Published: May 2009

Granites of the main movement-phase of an orogenic zone form an integral part of the tectonic pattern being characteristically located at the intersection of cross- and main-folds. Here, an older granitic core pierces upwards through the anticlinal vault to form a diapir-fold in which migmatization, synchronous with movement, leads to the evolution of granodiorite. At higher structural levels where pressure is lower K-granites occur. Only at sub-volcanic levels has evidence of melting been found.

Recent hydrothermal investigations, by Bowen and Tuttle, show that synthetic haplo-pitchstones whichbeginto crystallize at minimum temperatures become richer in K as pressure decreases. These results are closely comparable with evidence provided by the sub-volcanic K-microgranites (migmatized Caledonian granodiorite) of Slieve Gullion, but have no application to the granodiorites.
Note on the Structure and Microstructure of Thecia swinderniana (Goldf.)
Authors: Lafuste Jean G.
Published: May 2009

A study of thin sections of Thecia swinderniana (Goldfuss) shows the trabecular nature of the skeleton. It also appears that there are neither horizontal pores not vertical tubules in the walls, which are compact. A review of genera regarded by various authors as allied to Thecia leads the writer to retain in the family Theciidae only Thecia Edwards and Haime and Angopora Jones, the genus Romingerella Amsden being considered a synonym of the latter.
The Metasomatic Rocks Associated with the Criffell-Dalbeattie Granodiorite
Authors: Phillips W. J.
Published: May 2009

The field relations and petrography of a number of small rock bodies occurring near Rockcliffe at the southern margin of the Criffell-Dalbeattie granodiorite are described. The evidence suggests that they were formed by the metasomatic replacement of greywacke and shale hornfelses by Na-bearing and later K-bearing solutions which preceded the ascending granodiorite magma. This metasomatic transformation brought about the development of two distinctive rock types. Equigranular quartz-dioritic rocks which generally grade into the hornfelses are regarded as the result of static metasomatic replacement of the hornfelses with no appreciable movement of the permeated rock. In contrast, rocks of similar mineralogy but occurring as sharply bounded bodies with a conspicuous porphyroblastic texture, are thought to have attained their characteristic features by a certain amount of metasomatic mobilization of the permeated material. Because of the intrusive appearance of these porphyroblastic rocks and their occurrence near the margin of the granodiorite pluton they are here referred to as “marginal porphyrites”.
The Mode of Cladial Generation in Cyrtograptus
Authors: Thorsteinsson R.
Published: May 2009

The morphology of Cyrtograptus rigidus Tullberg n. subsp. A is described from uncompressed material. Particular attention is directed to the sequence of development of the connecting structure of cladium and main branch, which is demonstrated with the aid of figured growth stages of cleared and uncleared specimens. Also discussed is the intimate relationship of relative rate of growth of characters of cladium to those on the main branch. Cursory study of numerous other uncompressed species of Cyrtograptus in the author's collection reveals that the principles of cladial development outlined here are of general application.
Structural Observations on the South-East Lizard
Authors: Sanders L. D.
Published: May 2009

Geometry of the boundary of the serpentine in the south-east Lizard indicates that it is a sheet. The serpentine sheet rests on hornblendic gneisses and their migmatized equivalents; the upper part of this basement represents a thrust-sole in which bodies torn from the base of the serpentine are enclosed. Coastal erosion of rocks beneath the serpentine tends to marginal collapse of the unsupported sheet, so that slipped masses may conceal its base.
Carboniferous Goniatites from Blacklion, Co. Leitrim, Ireland
Authors: Hodson Frank
Published: May 2009

The holotype of Brancoceras enniskillense Foord, 1903, is shown to be a specimen of Beyrichoceras excavatum (Phillips), 1836, the suture line of which has been misinterpreted. It is associated with Beyrichoceras castletonense (Bisat), indicating the presence of the Upper B2 subzone in the Carboniferous Limestone, of Blacklion.
The Mourne Mountains Granites—A Further Study
Authors: Brown P. E.
Published: May 2009

Chemical analyses and petrographic data are given of the eastern granites of the Mourne Mountains. It is shown that the main bulk of the granite is a uniform highly siliceous biotite-bearing type and that the intrusion of this was preceded by a smaller amount of less siliceous and more variable hornblende-bearing granite. The ferromagnesian minerals have a high iron to magnesium ratio.
Note on Factors Governing the Porosity of Wind Deposited Sands
Authors: Kolbuszewski J.
Published: May 2009

After establishing average velocity of wind/average porosity curve for wind deposited sands, where it was shown that low wind velocity produces higher porosity than high wind velocity, further investigation was made and sands of various characteristics were used. It was established that the velocity of wind/porosity of deposit relationship is a more complicated function than was previously expected and some of the reasons are explained. The first indication of the influence of shape of the grain and the specific gravity of grains on the obtained results is registered. Further steps in the research are indicated.
A New Species of Lepidostrobus containing unusual Spores
Authors: Chaloner W. G.
Published: May 2009

A new species of Lepidostrobus, L. zea, is described. Two cones, from Yorkshire and from Ayrshire, and some isolated megasporangia are known. The megaspores have long been known, occurring isolated in coal, and have been described as Triletes auritus Zerndt. The microspores, also known previously from coal macerations, are of the type described as Endosporites globiformis (Ibrahim) (E. zonalis (Loose) and the C1 type of Raistrick). Endosporites has hitherto been regarded as cordaitalean (gymnosperm) pollen, and this is the first record of Endosporites from a lycopod.
Gravity Measurements in Durham and Northumberland
Authors: Hospers J. , Willmore P. L.
Published: May 2009

Gravity measurements in Durham and Northumberland in the region of the Alston Block are described, and their reduction as well as the accuracy of the results discussed. It is shown that the results between and near Newcastle and Durham are fully consistent with the conception of a horst, uplifted between the Ninety Fathom Dyke and the Butterknowle Fault. The observations along the valley of the East Allen, however, require an entirely different explanation. It is concluded that a closed area of negative anomalies occurs, centred near Wear Head. This is interpreted as due to a granite intrusion not yet exposed by denudation. The mineralization of the area is discussed and it is shown that it supports the foregoing interpretation.
On the thecae of Monograptus scanicus Tullberg
Authors: Bulman O. M. B.
Published: May 2009

Monograptus scanicus is shown to possess thecae which terminate in a pair of laterally-placed, expanded lappets; these are elongateovoid in shape, set with their long axes at right-angles to the axis of the theca.
Gastropoda from the Karroo Beds of Southern Rhodesia
Authors: Cox L. R.
Published: May 2009

The occurrence, very rare in Karroo rocks, of a gastropod species in the Lower Beaufort stage (Upper Permian) of Southern Rhodesia is recorded. It is a small form apparently related to species found in the Tartarian stage of the Russian Permian. These species have been described under extinct marine genera, but on account of their morphology and non-marine habitat this is thought to be inappropriate. The new species much resembles some representatives of the modern genus Hydrobia, not previously recognized in pre-Mesozoic rocks, and it has been decided to describe it as a new species, Hydrobia gondwanica.
Age of the Wealden in North-Western Europe
Authors: Allen P.
Published: May 2009

The Wealden of the Weald is mainly post-Tithonian/pre-Aptian in age. The formation probably comprises the fullest non-marine record of the interval in north-western Europe, spanning most of Berriasian (Infra-Valanginian), Valanginian, Hauterivian and Barremian time. It is well suited to be the standard succession for purposes of direct correlation.

The term “ Wealden ” should, if used for beds outside the English basin, be applied only to those non-marine formations (1) clearly lying within the Berriasian–Barremian range and, if possible, (2) correlatable directly with the standard. Otherwise “ Wealden facies ” should be used.

Beds claimed as “ Wealden ” elsewhere in north-western Europe are examined in this light.
The Terms Teschenite and Crinanite
Authors: Wilkinson J. F. G.
Published: May 2009

Various aspects of the terms teschenite and crinanite are discussed, including their usage in relation to petrogenesis. It is suggested that the use of the term crinanite be discontinued.
The Mode of Occurrence of Sillimanite in the Glen District, Co. Donegal
Authors: Tozer C. F.
Published: May 2009

Sillimanite produced by the contact action of the Donegal Granite shows varied textural and time relationships with the other minerals of the schists in which it occurs. Early Sillimanite was formed in the main stage of metamorphism by destruction of biotite, K, Fe, and Mg being expelled in the process. A later influx of new K from the granite led to the growth of muscovite metacrysts. This was associated with destruction of part of the early Sillimanite, recrystallization of part, growth of a new crop of Sillimanite needles, and formation of muscovite-sillimanite intergrowths.