bluuebunny/crossref_metadata_2025 huggingface dataset:
A primary igneous texture from the Lizard Peridotite, Cornwall
Authors: Rothstein A. T. V.
Published: May 2009

Detailed studies by Flett and Green have shown the Lizard complex to be a deformed body of considerable complexity. One of the principal results of the deformation has been the recrystallization of the primary peridotite. New evidence is presented concerning the original features of this high temperature peridotite. It is concluded that in some of the primary rocks there is preserved the structure and texture of the crystallization of an interstitial pore liquid trapped within a primary framework of olivine crystals.
Myrmekite from the Charnockitic Rocks of the Eastern Ghats, India
Authors: Bhattacharyya C.
Published: May 2009

The myrmekite occurring in acid to basic charnockites of the area around Garbham and Shikaruganji, Srikakulam district, Andhra Pradesh is described. Myrmekite, whenever present, occurs only at the contact of plagioclase and potash feldspar. The textures and paragenesis of minerals suggest that potash feldspar reacted with plagioclase giving rise to myrmekite under favourable stress condition, higher stress favouring the formation of myrmekite. The difference in the stress factor or the microstrain pattern in the rock can explain the presence of myrmekite at some contacts of plagioclase–potash feldspar and absence in others.
Mineralogy and Textures of some cordierite–sillimanite rocks from Labrador, Canada
Authors: Singh S. K. , Kamineni D. C.
Published: May 2009

The cordierite–sillimanite rocks first reported from Joan Lake Area, Labrador, show some unusual mineral associations and textures. Two myremkitic intergrowths, one among cordierite, potash feldspar and quartz, and the other between potash feldspar and plagioclase feldspar, are observed. The presence of microcline–microperthite and the textures described in the sequel indicate that these rocks were recrystallized at high temperature.
Authigenic Minerals in Carboniferous Sediments from Central Vestspitsbergen
Authors: Hutchins Philip F.
Published: May 2009

Postdepositional low-temperature mineralogical changes in Carboniferous sedimentary rocks from Vestspitsbergen are described. These include the crystallization of apatite, quartz, and feldspar, and the replacement of feldspar and quartz by calcite and dolomite. Minerals of the chalcedonite–lutecime–quartzine group also occur.
Skipsey's Marine Band and Red Coal Measures in Fife
Authors: Francis E. H. , Ewing C. J. C.
Published: May 2009

Mine sections beneath the Firth of Forth at Wellesley Colliery fill gaps in the Knowledge of the strata adjacent to the junction between Middle and Upper Coal Measures. A hitherto unrecorded marine band which may formerly have been confused with Skipsey's Marine Band is now placed about 70 feet lower in the succession. A coal seam near the base of the Upper Coal Measures contains a rib of kaolin mudstone comparable with tonstein. Local reddening and alteration of coal to limestone in the Upper Coal Measures and more particularly in the upper part of the Middle Coal Measures is typical of a zone of partial oxidation beneath some major unconformity which may lie within the Upper Coal Measures or at some unlocated sub-Permian horizon above. Structureless highly-coloured clayrocks in the Upper Coal Measures, however, are regarded as primary red beds comparable with, and perhaps the equivalents of, the Etruria Marl of the English Midlands.
The Pleistocene Drift Succession at Porth-Clais, Pembrokeshire
Authors: John Brian S.
Published: May 2009

The paper represents a reassessment of the drift stratigraphy at Porth-clais. The characteristics of the various Pleistocene deposits at the site are analysed in detail, and the sequence of drifts is then examined in its regional context. While the age of the raised beach at Porth-clais is still open to doubt, it seems that the non-calcareous till was deposited during a Late Weichselian glaciation by the Irish Sea glacier. This glacier probably extended much further south in St. George's Channel than suggested by other workers, although the ice stream which crossed St. David's Peninsula may not have been very thick.
Xenodiscacean Ammonoids and their bearing on the discrimination of the Permo-Triassic boundary
Authors: Tozer E. T.
Published: May 2009

Xenodiscacean ammonoids from Dzhulfa in Soviet Transcaucasia, assigned to Tompophiceras, Bernhardites and Paratirolites, have been interpreted as indicating that the enclosing beds, which also contain tetracorals, productacean brachiopods and goniatites, are Lower Triassic. Critical examination of the identifications shows that these beds should be regarded as Permian, not Triassic. Tompophiceras and Bernhardites are based on Triassic type species but the specimens from Dzhulfa are not demonstrably congeneric. Interpretation of Tompophiceras as a genus with a fastigate venter is rejected. Paratirolites, previously regarded as Triassic, is evidently Permian, and is now recorded from Madagascar, this being the first record outside Transcaucasus. New evidence is presented concerning the exact age of Glyptophiceras. The Dzhulfa section has been interpreted as providing a continuous transition, in the marine facies, between beds of Permian and Triassic age. This interpretation is rejected. It remains probable that there are no sections, in any part of the world, that do so.
The repeated development of identical joint patterns, north-east Tasmania
Authors: Williams Emyr
Published: May 2009

Examination of a contact between Late Devonian intrusive acid igneous rocks and Siluro-Devonian Mathinna hornfels. and the unconformity between these rocks and the overlying Permian beds, has revealed the relative ages of the joints developed. The steep joints of the acid igneous rocks are demonstrably of pre-Permian age although they form a pattern identical to those of the Permian beds, and each joint set is correlated with approximately parallel trending sinuous normal faults. The repeated development of the steep joints is attributed to reactivation of a fundamental mechanism. Some of the joints in the igneous rocks occur between compositional layers which have inherited their shape from the form of the joint-governed contact with the hornfels.
Some Holothurian Spicules from the Ampthill Clay of Melton, near Hull (Yorkshire)
Authors: Fletcher Brian N.
Published: May 2009

Several species of the Holothurian genus Achistrum, including three new form species, are described from the Ampthill clay of Melton, Yorkshire.
A Note on the Morphology ofHolectypus
Authors: Philip G. M.
Published: May 2009

Pedicellariae, sphaeridia, and radioles associated with a specimen ofHolectypus depressus(Leske) from the Bathonian of Wiltshire, are described and figured.
A Graphical Method for Analysing Fossil Distortion caused by Tectonic Deformation
Authors: Wellman H. W.
Published: May 2009

A simple graphical method is presented for determining the tectonic strain ellipse of a bedding plane from the distorted shapes of randomly orientated brachiopod shells.
Evidence from Recent Plankton Regarding the Biological Affinities of Tasmanites Newton 1875 and Leiosphaeridia Eisenack 1958
Authors: Wall D.
Published: May 2009

Following a bricf survey of previous literature concerning microfossils of the genera Tasmanites Newton 1875 and Leiosphaeridia Eisenack 1958 (generally known as leiospheres), two present day green algae are described (Pachysphaera pelagica Ostenfeld 1899 and Halosphaera minor Ostenfeld 1899). These organisms are compared with members of the fossil genera reviewed above and on the basis of this comparison it is concluded that the biological affinities of Tasmanites and some species of Leiosphaeridia lie with the Chlorophyceae. A possible mode of life is suggested for the fossils and the systematic position of the genera Tasmanites and Leiosphaeridia is reviewed but not altered.
Geochemical comparison of the Stillwater complex and alpine-type ultrabasic complexes, Beartooth Mountains, Montana and Wyoming
Authors: Bowes D. R. , Skinner W. R.
Published: May 2009

The field of composition and the geochemical trend of the lower portion of the stratiform Stillwater igneous complex correlate well with the field and trend for alpine-type ultrabasic masses in the nearby gneissic basement of the Beartooth Mountains. This is consistent with a derivation of some alpine-type masses by the tectonic disruption and metamorphism of stratiform complexes.
Faunal Realms in Jurassic and Cretaceous Belemnites
Authors: Stevens G. R.
Published: May 2009

Boreal, Tethyan, and Indo-Pacific faunal realms may be recognized in belemnite faunas of Callovian and most of later Mesozoic time. The presence of such clearly-defined realms indicates restriction of belemnite migration and perhaps the belemnites were confined to the shelves, extensive areas of deep water forming barriers. Migration of belemnites in the Tethyan and Indo-Pacific realms may be explained in terms of deep water barriers, but delimitation of the Boreal realm is thought to be a result of climatic zoning.
Some Unusual Ripple Marks in Carboniferous Limestone near Spittal, North Northumberland
Authors: Shiells K. A. G.
Published: May 2009

Ripple marks of unusual dimensions are recorded from the Sandbanks Limestone (Middle Limestone Group) at a foreshore locality 3 miles south of Spittal in North Northumberland. The structures are thought to have been formed in a partially cohesive calcareous mudas wave-oscillation ripples which have undergone penecontemporaneous modification.
Pseudomigmatites in the Abitau Lake Area, District of Mackenzie, Northwest Territories, Canada
Authors: Harry W. T.
Published: May 2009

The Abitau Lake area, N.W.T., chiefly consists of medium-to-coarse-grained quartzo-feldspathic gneisses. Many of these are granoblastic, presenting little or no microscopic evidence of deformation. Others are highly tectonized and foliated varieties that sometimes form pseudomigmatites easily mistaken in the field for true migmatites formed by lit-par-lit injection of pink granite into more basic grey gneiss. The last, however, are found after detailed examination to be granitic rocks that owe their misleading appearance and distinctive fabric to deformation during isochemical amphibolite fades metamorphism. Surprisingly they are not mylonites. Their fabric, like that of the other foliated gneisses is dominated by the parallelism of dark minerals and elongated quartz crystals. It resembles that of typical European granulites and often seems largely due to compression acting in a direction normal to the foliation plane with little or no transport in that plane. Tectoniza-tion did not promote the formation of myrmekite or microperthite but may have assisted to some extent the production of epidote from hornblende in certain specimens.
Layered ultrabasic lavas from Cyprus
Authors: Searle D. L. , Vokes F. M.
Published: May 2009

Ultrabasic lavas of variable picritic-peridotitic composition are found widely distributed in the Upper Pillow Lava member of the Troodos Volcanic Series in Cyprus. Recent work reveals layering of olivine crystals in both lava flows and pillows. An account is given of the field relations of the layered units, their petrography, mineralogy and chemistry.
Disturbed Keuper Marl beneath the river gravels of the Soar basin
Authors: Bridger J. F. D. , Rice R. J.
Published: May 2009

A recent excavation at Newtown Unthank, 9 km west of Leicester, has permitted study of the sub-alluvial gravels of the Rothley Brook valley. The junction of the gravels with the underlying Keuper Marl is sharply contorted, with an upward progression from undisturbed bedrock, through displaced marl and siltstone layers into masses of marl which have apparently been thrust up into the overlying gravel and incorporate many foreign stones. Possible causes of the structures are outlined, and reasons adduced for believing them to be of periglacial origin and of Weichselian age. Comparable occurrences have been recorded from elsewhere in the Soar basin, and also from other parts of the Midlands, and these are briefly discussed.
Six New Genera of Mesozoic Brachiopoda
Authors: Elliott Graham F.
Published: May 2009

Six new genera of terebratellacean brachiopods are proposed; one Triassic, one Jurassic, and four Cretaceous.
Minor Acid Intrusions and Dykes of Lamlash—Whiting Bay Region, Arran
Authors: Srirama Rao M.
Published: May 2009

Thin sills and dykes of pitchstone and felsite and dykes of crinanite, olivine-dolerite, tholeiites of different types, quartz-dolerite, andesite, craignurite-pitchstone, felsite and porphyry are described and the importance of contact and deep-seated hybridization of two magmas of contrasting basic and acid composition in their formation established. Among the dykes, the sequence of intrusion is surmised to be as follows: basic, sub-basic, intermediate, acidic, and, again, basic.
Early Slope Development in an Expanding Stream System
Authors: Carter Carol S. , Chorley Richard J.
Published: May 2009

A study of the morphometry of an ephemeral stream system which is incising itself into a terrace of the Farmington River, Connecticut, supports the regional relationship between stream-channel gradient and valley-side slope angle suggested by Strahler (1950). The continuing areal extension of the system allows stream order to be employed here as a relative measure of the passage of time. Thus it is possible to recognize that steepening and parallel development of a given valley-side slope may have their place in a sequence of early stage erosional development characterized by headward channel extension and ramification.
Some Namurian Conodonts from North Staffordshire
Authors: Higgins A. C.
Published: May 2009

The paper describes a conodont fauna from the Namurian of North Staffordshire. Seventeen genera and thirty-four species are identified in the fauna, of which Hibbardella fragilis, Hibbardella pennata, Lambdagnathus macrodentata, Mestognathus bipluti, Neoprioniodus spathatus, and Subbryantodus subaequalis are new species. The composition of the fauna and its correlation with similar faunas in the United States of America and Germany are discussed.
Lepidostrobophyllum fimbriatum (Kidston 1883) from the Drybrook Sandstone (Lower Carboniferous)
Authors: Allen K. C.
Published: May 2009

Lepidostrobus fimbriatus Kidston is redescribed as Lepidostrobophyllum fimbriatum (Kidston) from a new locality, in the Drybrook Sandstone of the Forest of Dean. The sporophyll consists of two parts bent at right angles, forming a heel of hard tissue. The sporangium is attached to a small area by the midrib, and is only partly occupied by the four spiney megaspores. A ligule is present.
On the Basis of Pleistocene Correlation in East Africa
Authors: Flint Richard Foster
Published: May 2009

The scheme currently used in East Africa for Pleistocene stratigraphic correlation is bases on climate. This basis is thought to be undesirable because it consists of second-order concepts rather than of primary, objective units and because its unconventional character inhibits correlation between East Africa and other regions. Furthermore the conceptual sequence of pluvial and interpluvial Pleistocene climates is not fully supported by the field evidence described thus far. Local support exists for the Gamblian and post-Gamblian and post-Gamblian wet climates, and at one locality a wet phase of pre-Gamblian age is admissible. The other units of the current scheme require factual support before they can be accepted. It is suggested that a more conventional basis of Pleistocene correlation in East Africa is desirable.
On Garnet Coronites from Koraput, Orissa
Authors: Bose Mihir K.
Published: May 2009

Development of garnet coronas in a small meta-mafite body, forming a tilted dome within the parametamorphics, is reported and the petrography of the coronites is described. Garent coronation marks a stage in the metamorphic and textural evolution of the rocks. The origin of coronas and related features is discussed.
An Occurrence of Mugearite in Antrim
Authors: Walker G. P. L.
Published: May 2009

Mugearite is described for the first time from the Tertiary lava series of Antrim, Ireland.
On the Nature of the Coralline Crag
Authors: Baden-Powell D. F. W.
Published: May 2009

A new fossiliferous section in the Coralline Crag of Suffolk is described, and its fauna is analysed as a clue to the conditions under which these beds were formed; in particular, the theory that the temperature of the Crag sea was affected by the alternate breaching and closing of land-bridges to the north and south of the North Sea area is considered unnecessary to account for the facts as seen in the field. Further, the Coralline Crag is correlated with the Astian formation of the Mediterranean, and reasons are brought forward to show that the supposed “Boytonian” Zone of the Coralline Crag does in fact not exist.
Petrography of the Mesozoic Succession of South Wales
Authors: Crampton C. B.
Published: May 2009

The heavy mineral suites of the Trias, Rhaetic and lowermost zones of the Lower Lias in the Vale of Glamorgan of South Wales are described. The northerly coastline of the Mesozoic sea, roughly coincident with the present-day periphery of the Coalfield, consisted mainly of Carboniferous Limestone and in places, the Old Red Sandstone and Millstone Grit. The mineral assemblage at any particular point in the littoral zone was determined largely by the nature of the outcropping rocks of the coastal mainland, the derivation of detritus being very localized. Within this zone some degree of gravity sorting of the detritals occurred, this implying a relatively steeply inclined coastal sea-bed. An off-shore current carried detritus from the Armorican land-mass of Britanny and granite of South-West England to this area where the detritals were dispersed thinly throughout the locally derived sediment.
Ignimbrite in the Kilchrist Vent, Skye
Authors: Ray P. S.
Published: May 2009

Ignimbrite steeply intrusive into the basaltic agglomerate of the Kilchrist vent is described. Like the intrusive ignimbrite near Kilchoan, Ardnarnurchan, it shows flow structure parallel to the walls, flow being similarly expressed by the elongation and alignment of the constituent shreds of devitrified glass and pumice lapilli. Fragments of basalt, derived from the vent agglomerate, are sometimes also drawn out in the direction of flow.
The Form of the Beinn An Dubhaich Granite, Skye
Authors: King Basil C.
Published: May 2009

The form of the Beinn an Dubhaich granite was considered by Harker to be boss-like. Here evidence is put forward to suggest that it may have the form of a sheet emplaced along the Torridonian-Cambrian thrust plane. The alternative hypothesis has the merit of avoiding the serious difficulties appreciated by Harker regarding the mode of emplacement of the granite.
Azimuths of Primary Linear Structures in Folded Strata
Authors: Norman Teoman N.
Published: May 2009

Primary linear structures on plunging folds, when rotated to the horizontal about the strike of the bedding plane, are clearly not in their original “primary” directions. The amount and sign of error has been studied and a method of “plunge correction” is suggested.
The Strength and Stress-Strain Characteristics of Oakdale Coal under Triaxial Compression
Authors: Hobbs D. W.
Published: May 2009

Laboratory measurements of the effect of a confining pressure on the strength and stress-strain characteristics of a metallurgical coking coal are described. Several-fold increases in the strength, the Young's modulus and the elastic strain at failure were found as the confining pressure was increased to 5,000 lb./n.2. The results are discussed in relation to various criteria of failure. It was found that failure was represented by Coulomb's equation relating shear stress and normal stress, provided the observed angles of fracture were not influenced by local edge stress concentrations.
Archaean Palaeogeography of Eastern and Northern Singhbhum, Eastern India
Authors: Naha Kshitindramohan , Ghosh Subir Kumar
Published: May 2009

Geological studies in eastern Singhbhum and critical analysis of Dunn's published work in surrounding regions suggest that during the Archaean times a volcanic geanticlinal arc, now represented by the Dalma lavas, tuffs and agglomerates extended roughly east–west for more than 150 miles. The geosynclinal trough in the southern, concave side of the arc was filled with argillaceous sediments, thin subgraywackes and orthoquartzites derived from a land mass to the south. The trough in the northern, convex side of the arc was filled with a huge thickness of argillaceous sediments associated with graywackes, siliceous limestones, sandstones and pre-orogenic ultra-basic and basic intrusives. Both the troughs near their border with the volcanic arc were filled with pyroclastic materials.

During orogenic movements two anticlinoria were formed in the supracrustal sediments above the two troughs separated by a syncline above the geanticline, with a granulite-migmatite core in the heart of the outer geosyncline.
Reversed Graded Beds from the Dalradian of Inishowen, Co. Donegal
Authors: Knill J. L. , Knill D. C.
Published: May 2009

A sequence of reversed graded beds occurs in a group of flaggy rocks intercalated within the Upper Dalradian grits of Inishowen. Usually these beds have a thickness between ½ inch and 2 inches, and are characterized by a laminated, argillaceous base which grades up into a fine-grained, arenaceous upper member.
Modal Variation and the Form of the Beinn an Dubhaich Granite, Skye
Authors: Whitten E. H. Timothy
Published: May 2009

Regional variations in modal analyses of the Chandos Lake pluton (Ontario) and the Beinn an Dubhaich granite are compared. Trend surface analysis maps for the latter area show a southwest “grain” parallel to the axis about which King (1960) suggested the sheet of granite is folded. The modal data thus appear to confirm King's hypothesis, and to indicate a more mafic base and increase in quartz content upwards through the sheet. The value to petrogenesis of quantitative variation studies of rock masses is briefly discussed.
Intrusions of Gabbro and Granophyre in the Snaefellsnaes, Western Iceland
Authors: Upton B. G. J. , Wright J. B.
Published: May 2009

Two adjacent areas of intrusive plutonic rocks, occurring in western Iceland are briefly discussed. These intrusions are of gabbros and granophyres, believed to be of Tertiary age, of types closely comparable to those of S.E. Iceland.
Replacement Veins in the Dahomeyan of Ghana
Authors: Burke Kevin
Published: May 2009

A basic gneiss in Ghana is traversed by light veins which are considered to have originated by replacement because gneissic mineral banding persists through them. Veins make up to 10 per cent of the rock over hundreds of square miles. It appears that a very large amount of material has been transported through the basic rocks without destroying their gneissic structure.
An Olivine-bearing Hornfels from South-Eastern Queensland
Authors: Phillips E. R.
Published: May 2009

Contact metamorphism by a gabbro of an unusual slightly metamorphosed argillite with comparatively high magnesia and total iron has produced an olivine-bearing hornfels. The sediment is of such a chemical composition that an almost isochemical transformation is considered to have taken place. Only Mg shows any significant change from the sediment to the hornfels.
The Amphibolite of Doir'a'Chatha (Durcha), Sutherland
Authors: Francis G. H.
Published: May 2009

The amphibolite at Durcha passes from a dark, hornblende-rich rock, through every gradation of delicate striping and banding by quartzo-feldspathic material out into psammitic Moine schist, within a few metres. Irregular cross-cutting bands of quartz and feldspar which seem to “ feed ” the delicate stripes can be seen and there are intergrown mixtures of the dark and light components which recall appinites. Chemical and other evidence suggests that the dark rock is a concordant thpleiitic dolerite sill, whilst the macroscopic and microscopic evidence from the pale bands suggests that they are metasomatic in origin and connected with the widespread permeative alkali-injection of the Moine Schists. They seem to have been introduced into the sill along closely-spaced foliation planes parallel with those in the adjacent sediments and with the original contacts of the sill.
The Lower Middle Hecla Hoek Rocks of Ny Friesland, Spitsbergen
Authors: Wilson C. B.
Published: May 2009

This paper gives details of part of the Hecla Hoek Succession already outlined (Harland and Wilson, 1956). Field work in 1956 and 1957 in general confirmed the succession, and this account includes the results of the later work. A large-scale repetition of a sedimentary cycle is demonstrated, and the relationship with equivalent rocks in Nordaustlandet is discussed.
The Ages of the Hippopotamus and Elephas maximus Fossils in the Gem Sand of Ceylon
Authors: Deraniyagala P. E. P.
Published: May 2009

The extinct Ratnapura fauna of Ceylon is a radiation from the Indian Shivalik. In it occur a hexaprotodont hippopotamus and a race of Elephas maximus which is the most recent member of the Proboscidea. Since such an association is unknown elsewhere, it has given rise to many explanatory theories. A uranium test of associated fossils of both animals now establishes that this has resulted from redeposition and that the animals were not contemporaneous. This makes less vague the hitherto conjectural views regarding the earth movements, and the ages of the gem deposits and of the early human lithic artefacts in them.
Lineations in Three Artificial Tectonites
Authors: Williamson W. O.
Published: May 2009

Deformation of plastic kaolinite-illite clay caused alignment of authigenic prisms of rutile and tourmaline on surfaces produced by parallelism of the basal pinacoids of the clay-minerals. An a–lineation appeared in the outer layers of an extruded cylinder but a b–lineation in those of a cylinder formed by rolling. A Wineation occurred at the periphery of a circular disc made by spreading. Localized tensional failures, cognate with ac joints, accompanied the b–lineations which were in directions of elongation. The orienting movements were thought to occur in the water-films separating the clay-flakes, but the mechanisms which produce a– and b–lineations are presumably identical. Thus it can be argued that the a–lineation also follows a direction of elongation.
Additions to the British Eocene Brachiopod Fauna
Authors: Elliott G. F.
Published: May 2009

Two species of Argyrotheca new to this country are recorded from the type Bracklesham Beds, and a full description given of the associated Terebratulina edwardsi, previously known from immature specimens only. The British Eocene brachiopods are listed, and the ecological significance of their rarity and distribution briefly discussed.
The Old Red Sandstone Lavas of the Western Sidlaw Hills, Perthshire
Authors: Harry W. T.
Published: May 2009

The Old Red Sandstone lavas of the Perthshire Sidlaws are basalts with some andesite-basalts, andesites, and rare trachyandesite. The basalts comprise chiefly olivine-bearing flows that include feldspar-phyric and aphyric varieties; olivine-free basalts with two pyroxenes are of restricted distribution.

The significance of augite textures and their relationship to augite content in the basalts is discussed.

The lava pile is apparently composed of interdigitating lenticular flows that vary from a few feet up to about 80 feet in thickness.

Unlike most other Scottish Old Red Sandstone lava suites the Sidlaw suite is fairly fresh and, like the Eastern Forfarshire lavas, it is relatively basic.
The Development of a Diplograptid from the Platteville Limestone
Authors: Walker Margaret
Published: May 2009

This paper describes the development from the initial prosicula of the rhabdosome of Diplograptus cf. (Amplexograptus) maxwelli Decker. Points of comparison with other diplograptid astogenies are noted. Evidence about the structure of the interthecal septum is brought forward and so stages in the formation of one thecal segment can be defined. Mention is made of some abnormal specimens.
The Diorites and Associated Rocks of the Glen Tilt Complex
Authors: Deer W. A.
Published: May 2009

The diorites and Sron a' Chro' granite of the Glen Tilt complex enclose hornblende-schist xenoliths derived from the Dalradian epidiorites of the country rock. Small hornblendite xeoliths are found in the complex but are restricted to the diorite outcrop. Porphyroblastic hornblende is developed within the schist xenoliths and reaction zones rich in hornblende are formed around the xenoliths. The mineralogical and textural characteristics of these reaction products suggest that the typical two-hornblende generation appinites of the complex represent modified hornblende schist. A similar origin for the quartz-orthoclase-appinite of the complex is rejected and their development from hornblendite is indicated.
Seven New Genera of Jurassic Ammonites
Authors: Arkell W. J.
Published: May 2009

Well-defined genera of ammonites from the Toarcian, Bathonian, Oxfordian, Kimeridgian, and Tithonian are diagnosed and named.
Magnetometric Mapping for Haematite in South Wales
Authors: Blundell C. R. K.
Published: May 2009

In the search for large deposits of haematite and other feebly magnetic minerals, it is suggested that mapping the magnetic residuals may be of greater value than mere linear traverses. Not only is the method more suitable for exploring virgin areas, but it also affords a means of differentiating between the effects of large deeply buried masses and small objects at shallow depths. At the same time, the graphical expression of the results on the map becomes more easily intelligible.

The application of the method to known haematite ore-bodies in South Wales has yielded striking results and the extension of the survey into an unexplored area indicates the possibility of proving at least one further large haematite deposit.
Facies Changes versus Sliding—A Reply
Authors: Hardie W. G.
Published: May 2009

In my recent paper on the Lochaber Series (Hardie, 1952), I gave detailed facts about the lithology of several of the stratigraphical units, and I concluded that the remarkable thickness variations were due to original sedimentary processes rather than to mechanical rearrangement. Sir Edward Bailey, in his paper in this current number of the Geological Magazine, strongly disagrees with my views, and argues in favour of sliding. In reply I would like to make the following three points.
The Nephelinite of Etinde, Cameroons, West Africa
Authors: Tilley C. E.
Published: May 2009

Re-examination of the nephelinites of Etinde, Cameroons, carrying a composite structured “nepheline” mineral shows that the feldspathoid is a genuine nepheline, in part exhibiting twinned intergrowths, and not a potassic orthorhombic feldspathoid phase. Analysis indicates a composition with a mol. ratio of 3·6. Comparison is made with other nephelines in contrasted host environments.
The Extent of Glaciation in the Island of St. Kilda
Authors: Wager L. R.
Published: May 2009

Moraines which in one case at least contain striated boulders, show that, at the maximum of Quaternary glaciation, small, thin glaciers developed in the island of St. Kilda at certain favourable places. There is no evidence that the Hebridean ice sheet reached the island and no signs of raised beaches which would indicate recent emergence.
A Local Potassic Modification of the Ballachulish Granodiorite
Authors: Muir I. D.
Published: May 2009

The development of potash-rich pyroxene-bearing rocks around inclusions derived from the Appin limestone is associated with the transfer of magmatic silicon, aluminium, iron, and sodium. Calcium lost to the magma, by combining with further silicon, aluminium, and sodium to form a marginal zone rich in plagioclase, has left the magma enriched in potassium.
On the presence of the Upper Dibunophyllum Zone (D3) near Glynneath, South Wales
Authors: Owen T. R. , Jones D. G.
Published: May 2009

Beds near Glynneath previously believed to be of Middle Dibunophyllum Zone (D2) age are claimed to belong to the Upper Dibunophyllum Zone (D3). These beds are described, and the implications of the position of this new locality on the Neath Disturbance are discussed.
The Western Longmyndian Rocks of the Shrewsbury District
Authors: Whitehead T. H.
Published: May 2009

Evidence from graded bedding and other sedimentary structures has shown that in the eastern outcrop of the Western Longmyndian rocks of the Shrewsbury area the stratigraphical base lies towards the east. Since in the western outcrop of these rocks the base is believed to lie towards the west, Professor Whittard's suggestion that the Western Longmyndian rocks are folded into a syncline, with the “ Oakswood Group ” representing a repetition of the “ Bayston Group ”, is accepted. The form and age of the fold are briefly discussed.
A Probable Organic Structure from the Dalradian of Ben Vrackie, Perthshire
Authors: Pantin H. M.
Published: May 2009

Globular bodies, which may represent organic remains, are found in the Dalradian at a locality on the south-west side of Ben Vrackie. Their mode of occurrence, composition, and form are here described and their possible affinities are discussed.
The Occurrence and Significance of Pre-Cambrian Algal Forms at Kabwer Hill, Bukoba District, Tanganyika, and in Singo, Uganda
Authors: Pallister J. W.
Published: May 2009

Stromatolites found in Karagwe-Ankolean rocks on the Tanganyika-Uganda border occur in siliceous beds associated with cherty and ferruginous breccia without trace of calcareous material. Somewhat similar conditions prevail in beds of the Singo Series of Uganda from which Collenia-type structures have been recorded. Little stratigraphical value can be ascribed to the structures, but they are significant in pointing to the replacement character of some fine-grained siliceous beds which may explain the scarcity of limestone in the Pre-Cambrian sequence of Uganda.
The Structure of the Plastron of the Echinoid Somaliaster Hawkins
Authors: Joysey Kenneth A.
Published: May 2009

Previous descriptions of the plastron of Somaliaster Hawkins have been conflicting and, in consequence, there has been some doubt regarding the systematic position of this genus. The type-material has been re-examined and the plastron found to be meridosternous. Somaliaster is here referred to the family Stenonasteridae, where it has close affinities with Iraniaster Cotteau and Gauthier.
The Occurrence of Orthoclase and Microcline in the Granitic Gneisses of the Carn Chuinneag-Inchbae Complex, E. Ross-shire
Authors: Harker R. I.
Published: May 2009

Optical examination of the potash feldspars in the granitic gneisses of the Carn Chuinneag-Inchbae complex suggests that both ortho-clase and microcline occur together—not infrequently in the same crystal. Optic axial and extinction angles, intermediate in value between those characteristic of the two polymorphs, have been recorded and plotted graphically. X-ray powder diffraction patterns confirm that both orthoclase and microcline are present together in these rocks. It is believed that most of the microcline developed from orthoclase during the regional metamorphism of the area, which permitted recrystallization at a lower temperature than that at which the orthoclase was formed.
The Form of the Eastern End of the Insch Igneous Mass, Aberdeenshire
Authors: Sadashivaiah M. S.
Published: May 2009

Peridotite, troctolite, and olivine-gabbro are exposed in the Bourtie area at the eastern end of the Insch igneous mass. The distribution of outcrops suggests that the rocks are disposed in bands running north and south and a smaller-scale north-south banding can be seen in some exposures. The earlier view that the ultrabasic rocks form an east-west lens on the floor of a northerly-dipping gabbro sheet is therefore abandoned and both the northern and southern contacts are believed to be part of the roof of the igneous body.
Idosocrinus gen. nov. and other Crinoids from Thornton Burn, East Lothian
Authors: Wright James
Published: May 2009

The new genus Idosocrinus is proposed for a remarkable type of crinoid occurring in the Thornton Burn section of the Calciferous Sandstone Series (Lower Carboniferous) of East Lothian, and two species are recognized. In general habitus the new genus resembles Phanocrinus Kirk, but differs in the character of the left and right posterior primibrachs, which extend outward from the cup in the form of strongly developed spines. Two new specimens of Anemetocrinus wilsoni Wright are also figured.
A New Ampthill Clay Fauna from Knapwell, Cambridgeshire
Authors: Hancock J. M.
Published: May 2009

A new ammonite assemblage from the Ampthill Clay is recorded. Its correlation with the Trigonia clavellata beds of Dorset indicates that these condensed beds are represented by two distinct horizons in the Ampthill Clay—the Boxworth Rock below and the Knapwell Ditch horizon above.
A New Palaeechinus from Alberta
Authors: Kier Porter M.
Published: May 2009

A new species of Palaeechinus from the Lower Carboniferous of Alberta is described.
Petrofabric Analysis of Marbles from Mid-Strathspey and Strathavon
Authors: McIntyre Donald B. , Turner Francis J.
Published: May 2009

Petrofabric analyses of marble specimens from three widely separated localities in Mid-Strathspey and Strathavon are recorded. Preferred orientation of [0001] in the constituent grains of calcite conforms to a B-tectonite pattern, the symmetry axis (B) of which coincides with the b axis of the megascopic fabric (lineation and fold axis) at each locality. Development of {011¯2} lamellae in calcite grains is attributed to late minor compression, the direction of which is more or less horizontal and trends between N.E.–S.W. and E.N.E.–W.S.W.
Critical Sections in a Carboniferous Reef Knoll
Authors: Black W. W.
Published: May 2009

A study of the structure and petrography of the limestones exposed at Hall Hill, in Bowland, enables the geometry of part of a Carboniferous reef knoll to be defined. The main features are a central mound-like core of unbedded, poorly fossiliferous calcite mudstone and a peripheral area of bedded calcite mudstones with original, depositional dips. Thick, well-bedded coarse crinoidal limestones were subsequently bedded over the underlying knoll.
The Miocene/Oligocene Boundary and the Use of the Term Aquitanian
Authors: Eames F. E.
Published: May 2009

It is considered that some fossils, e.g. Orbulina and Miogypsina, are good indicators that beds containing them are of post-Oligocene age, and that the ages of some beds in certain parts of the world require reconsideration; mention is made of successions in Morocco, Venezuela, and Peru. It is recommended that the use of the term “Aquitanian” be restricted to beds of basal Miocene age.
Breconian: a Stage Name of the Old Red Sandstone
Authors: Croft W. N.
Published: May 2009

The Breconian stage of the Anglo-Welsh Old Red Sandstone is defined. The Breconian follows the Dittonian and precedes the Farlovian. In Breconshire, the Breconian comprises the Senni Beds and the overlying Brownstones. The Senni Beds have yielded a fauna and flora of Siegenian-Emsian age; the Brownstones are apparently unfossiliferous.
Fausto de Elhuyar (1755–1833), A Spanish Mining Geologist
Authors: Eyles Joan M.
Published: May 2009

Elhuyar, born in Spain in 1755, received a thorough training in mining geology at several of the leading European mining schools. He was appointed to an important post in New Spain (Mexico), where he arrived in 1788. There he devoted himself to reorganizing the administration of the mining industry and then to founding a School of Mines in Mexico City. This was opened in 1792, and in 1811 moved into the magnificent new building known as El Palacio de Minería, which now houses the Engineering School of the University. When an independent government was set up in Mexico in 1821, Elhuyar returned to Spain, where he continued to work for the government as a mining consultant. He prepared a report on the Rio Tinto mines and was responsible for the planning of the School of Mining Engineering in Madrid.
Shear-Folding in the Mylor Slates, near Porthleven, Cornwall
Authors: Stone M. , Lambert J. L. M.
Published: May 2009

Recumbent shear folds and their related structures in the Mylor Slates are briefly described. It is concluded that folding has been produced by subhorizontal shearing stresses acting in a northwesterly or south-easterly direction.
Some “Uniserial” Membraniporine Polyzoan Genera and a New American Albian Species
Authors: Thomas H. Dighton , Larwood G. P.
Published: May 2009

Herpetopora Lang is considered to be a junior synonym of Pyripora d'Orbigny, from which Rhammatopora Lang is distinguished by possessing apertural spines. A new species of Pyripora is described from the Albian of Texas.
The Horizon of the Tillery Vein in Monmouthshire
Authors: Sullivan H. J. , Moore L. R.
Published: May 2009

The discovery of a hitherto unrecorded non-marine lamellibranch fauna from the Tillery Vein of Monmouthshire indicates that this coal represents a horizon at, or near, the junction of the Phillipsii and Tenuis Zones. The characteristics of the seam in a small portion of the North Crop of the South Wales Coalfield are described in an attempt to account for the limited occurrence of these shells.
Contact Phenomena from N.W. Jersey, C.I
Authors: Henson F. A.
Published: May 2009

The field relationships between the Armorican granite of North-West Jersey and the Precambrian sediments in the Le Pulec and L'Etacq areas are described together with the petrography of the contact rocks. Trace-element determinations on rocks from two traverses across contacts in the area, and upon control specimens of granite and sediments supplement the petrography. The mechanism of granite emplacement in this area is discussed.
On certain geological similarities between North-East Shetland and the Jotunheim area of Norway
Authors: Flinn Derek
Published: May 2009

In a recent account of the geology of North-east Shetland (Flinn, 1958, Quart. Jour. Geol. Soc.) two nappes of crystalline rocks lying one above the other on a base of meta-sedimentary rocks were recognised. Comparison with the Norwegian geological literature followed by field investigations in Norway has shown many similarities with the Jotunheim area of Norway. In both areas two relatively rigid nappes were thrust one after the other over the surface of the earth to their present positions. In both areas the lower of the two nappes was emplaced first and was subjected to erosion giving rise to sediments which were deposited on the nappes (Phyllite Group of Shetland and the Valdres Sparagmites of Norway). These sedimentary groups had a similar history of formation, deformation, and metamorphism, but differed somewhat in materials because the source rocks were different, although several strikingly similar rock types are present as pebbles in both areas. The remains of the first nappe and the newly deposited sediments were overrun by the second nappe in both areas. The emplacement of these nappes gave rise to considerable deformation and metamorphism in the underlying rocks. If the metamorphic rocks of Shetland are of Caledonian age, as seems likely, then it is possible that the Valdres Sparagmites and the Phyllite Group are stratigraphically equivalent: they are certainly tectonically equivalent.
Cyclic Sedimentation of the Rough Rock (Millstone Grit) as illustrated by a section near Eakring, Nottinghamshire
Authors: Bond K. W.
Published: May 2009

The section described is a well section, 20 miles from the nearest Millstone Grit outcrop. Attention is drawn to the rhythmic sedimentation resulting from the intermittent subsidence that was occurring at the time.
Cyclic Resection of Headlands by Marine Erosion
Authors: Cotton C. A.
Published: May 2009

Though good examples of plunging cliffs surviving as such are now rare, this form of shoreline was probably commoner in the initial stages of the current (postglacial) cycle of marine erosion. Most cliffs now bordering the sea, whether developed from initially plunging cliffs or not, have already receded some distance from the initial shoreline.

As plunging cliffs may, because of reflection of waves from them, enjoy some immunity from direct frontal attack, the headlands which they truncate may be more vulnerable to marine erosion on the flanks, where the slopes partially submerged by shift of ocean level are less steep. Flank attack may lead to resection of the headland in such a way that eventually it will again end distally in a straight line of cliff; but at an intermediate stage of this resection cycle the terminations of headlands are characteristically scalloped, while at a penultimate stage of resection the salient of submaturity may be reduced to a row of stacks, the “needles” stage
The Difference in Optics Between Volcanic and Plutonic Plagioclases, and its Bearing on the Granite Problem
Authors: Reynolds Doris L.
Published: May 2009

The orientation of the optical indicatrix in synthetic and volcanic plagioclases differs from that in plutonic and metamorphic plagioclases, the former “optics” being commonly known as “high-temperature”, and the latter as “low-temperature”. The difference between the two series is most marked at the sodic end and decreases towards An70. The conclusion that the difference, though small, still persists in the range An70to An100is shown to be unwarranted on the evidence available. Grave doubt is thrown on the supposition that temperature is the controlling factor in determining the type of optics by Tuttle and Bowen's failure to synthesize low-temperature albite, even at low temperatures. It is known, however, that some low-temperature plagioclases (e.g. in albite-schists) have grown without the intervention of melt. The real antithesis may therefore be between plagioclases crystallized from melts, and those developed during the metamorphic reconstitution of rocks.

From the fact that the plagioclase, quartz, and alkali feldspar of undoubted magmatic rocks such as quartz-porphyry and rhyolite are respectively systematically different from those of granite it is concluded that the latter is a metamorphic rock
The Lochaber Series South of Loch Leven, Argyllshire
Authors: Hardie W. G.
Published: May 2009

Detailed mapping of a small area has shown that the Eilde Schist undergoes marked variations of facies when traced southwards from Loch Leven. Through the appearance of interbedded quartzite the normal schist of the western outcrop passes into a banded facies, while much of the banded facies of the eastern outcrop is believed to pass into massive quartzite mapped as Elide Quartzite. This sedimentary transition, rather than tectonic causes, probably accounts for the rapid variations in thickness of the two stratigraphical units. An additional factor controlling the thickness of the Elide Schist belonging to the eastern outcrop is the existence of an erosional surface at the base of the succeeding Binnenian Quartzite. The possible significance of these factors in the geology of the country north of Loch Leven is discussed briefly with special reference to some of the minor slides.
Volcanic Ash from the Hekla Eruption of 1947
Authors: Henson Frederick A.
Published: May 2009

Description of ash which fell on a trawler, fishing off Iceland, during the first hours of the 1947 Hekla eruption. Discussion of the probable track of the ash from the volcano to the ship and the factors affecting sorting involving upper wind velocities, terminal velocities of the various sizes of pumice and mineral fragments which constitute the ash, and weather conditions.
Basic hornfels at a gabbro contact near Carlingford, Eire
Authors: Harry W. T.
Published: May 2009

Thermal metamorphism of Silurian sediments at a gabbro contact took place under pyroxene-hornfels facies conditions. The most common hornfels is essentially composed of pyroxene and labradorite; its chemical composition compares with that of average gabbro. The hornfels is believed to have been metasomatically altered, probably basified, during metamorphism.