bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Difference in Optics Between Volcanic and Plutonic Plagioclases, and its Bearing on the Granite Problem
Authors: Reynolds Doris L. 
Published: May 2009

AbstractThe 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

AbstractDetailed 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

AbstractDescription 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

AbstractThermal 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.
Limestone Blocks in the Lower Cretaceous Cuche Formation of the Central Range, Trinidad, B.W.I.
Authors: Barr K. W. 
Published: May 2009

AbstractThe occurrence of large blocks of fossiliferous Cretaceous limestone among the Lower Cretaceous shales of the Central Range area of Trinidad, B.W.I., has been known for many years, and several different modes of origin have been advanced. A critical exposure which shows the field relationships between the shales and limestone blocks is described, from which it is concluded that the limestone blocks were derived from the contemporaneous breaking up of limestone reefs, and the inclusion of such blocks, together with fore-reef breccia, in the adjacent shale deposits.
Illustrating the Laws of Morphometry
Authors: Chorley Richard J. 
Published: May 2009

AbstractThe new approach to quantitative morphometry, initiated by Horton (1945), has resulted in the recognition, measurement and comparison of the basic units of landscape geometry; the application to them of the principles governing the behaviour of open physical systems; and the testing and quantifying of the Davisian principles of landscape evolution. The laws of morphometry are here illustrated from three regions of maturely dissected sandstone terrain, lacking in differential gross structural control, and it is discovered that uniform, dimensionless ratios hold for their geometry.
The Taele Gravel near Thriplow, Cambridgeshire
Authors: Sparks B. W. 
Published: May 2009

AbstractThe erratics, weathering and surface relief of the Taele gravel south of Thriplow point to its being immediately post-Gipping (Saale) in age. On the other hand, its molluscan fauna is of a type usually considered to be characteristic of cold conditions associated with the last glaciation. It is concluded that this fauna is characteristic of a certain type of local conditions and not of a definite period in the Pleistocene.
Sutures and Septa in Jurassic Ammonite Systematics
Authors: Arkell W. J. 
Published: May 2009

AbstractIn the suborder Ammonitina the form of the septa and sutures is strongly influenced by whorl-shape and is often highly variable within the species and even the inidvidual. Claims that septa and sutures are specially significant because they are “internal characters” are refuted, as are also claims for overriding priority in classification for particular parts of the sutures, or for details of their early pntogenetic stages, or for the inner surfaces of the septa. Interpretation of the form of the septa and sutures as primarily conditioned by external water pressure is challenged. A recent revision of two superfamilies on the basis of septal form is held to involve unnatural groupings.
Notes on the Petrology and Mineralogy of the Barrovian Metamorphic Zones
Authors: Snelling N. J. 
Published: May 2009

AbstractThe antipathetic relation between chloritoid and biotite in the lower metamorphic grades of the Barrovian zones and the genesis of the index minerals in the higher metamorphic grades are briefly discussed. The observed mineral assemblages of 13 new analyses of peltic schists are compared with the assemblage required by the mineralogical phase rule; good agreement exists provided allowance is made for magnesia acting as a separate component. Six new biotite analyses covering all of the Barrovian zones show an increase in the degree of replacement of Si**** by Al*** with increase in metamorphic grade. The ratio of FeO: MgO varies according to the associated ferromagnesian minerals and shows no regular relation to metamorphic grade.
The Fuller's Earth of Whatley, Somerset
Authors: Sylvester-Bradley P. C. , Hodson Frank , Arkell W. J. 
Published: May 2009

AbstractThe Fuller's Earth Clay of the Whatley district nowhere rests directly on the Palaeozoic rocks, but is always underlain by Inferior Oolite. The Fuller's Earth Rock of the district contains two distinctive and successive faunas, the upper of which bears a suite of ammonites hitherto unknown from rocks of this age. It is correlated with the Wattonensis Beds of the Dorset Fuller's Earth.
Faulted Permian Dykes in the Highlands
Authors: Leedal G. P. 
Published: May 2009

AbstractIn the Arkaig district of Inverness-shire there is a well-defined suite of camptonite-monchiquite dykes, and several of them have been observed to be displaced laterally along sinistral faults. This provides direct evidence of transcurrent faulting in Permian or post-Permian times. Similar faulting may have occurred along the major northeasterly fracture lines of the Highlands.
Notes on the Geology of the Northern Part of the Ruwenzori Mountains
Authors: Johnson R. J. , McConnell R. B. 
Published: May 2009

AbstractA description is given of the geology of the northern portion of the Ruwenzori Mountains. The rocks consist chiefly of a migmatitic series of biotite-gneiss passing to plagioclase-amphibolite uncomformably overlying these are rare occurrences of a slightly metamorphosed series of conglomerates, grits, quartzites, and tale-schists. The area is bounded by rift faults which strike N.N.E.– S.S.W. and the strike of the gneiss series is in general parallel to that direction with a steep westerly dip. Major rift faults arc described and evidence given to show that they are rejuvenations of Pre-Cambrian fault lines. Dextral tear-fault movement is implied with superimposed vertical component. Evidence indicates that faulting took place under compressional stress in Pre-Cambrian times, but that tension supervened at the later stages under light load. A steeply dipping faulting system striking W.N.W.–E.S.E. is also present, and has resulted in the southern blocks rising relative to the northern: in this system also, early compressional stress has been superseded by tension.
The Insertion of Septa in the Later Growth Stages of Palaeosmilia murchisoni (Edwards and Haime)
Authors: Coope G. R. 
Published: May 2009

AbstractIn the later growth stages of Palaeosmilia, minor septa are inserted simultaneously on both sides of each newly added major septum and they originate high up near the growing crest of this major septum. Thus, a minor septum occupies the interseptal space in which the next major septum will be inserted. The next major septum develops directly upon the axial edge of this minor septum and it originates deep down in the calyx. The similarity is pointed out between the septal insertion in Palaeosmilia and in the more typical aulophyllid (clisiophyllid) corals.
The Hangnest Dolerite Sill, S.A
Authors: Walker F. , Poldervaart A. 
Published: May 2009

A 500 ft. sill of dolerite from Hangnest in the Calvinia division of the Cape Province (South Africa) exemplifies very clearly two well-marked features of the thicker Karroo sills:—(1) Very slight amount of crystallization-differentiation.(2) Marked tendency to mobilize and react with the associated shales and siltstones.A petrological and chemical study of this sill is given and the mechanism of the various processes discussed.
Shore Platforms
Authors: Hills E. Sherbon 
Published: May 2009

AbstractThe use of the terms “normal” and “abnormal” in relation to shore-platforms has led to confusion and should be discontinued. Processes operative in the formation of shore platforms are analysed from Victorian examples. The effects of water-layer weathering, growth of marine organisms, breakers, and waves of translation on sheltered and open coasts and on various rocks (including a special study of platforms in aeolianites) are discussed.
On the Genus Corynoides Nicholson
Authors: Strachan Isles 
Published: May 2009

AbstractThe Ordovician genus Corynoides Nicholson has until recently been very imperfectly known and generally neglected. Its development and peculiar morphology are discussed, but its systematic position amongst the graptolites remains doubtful. Four European species are here described and figured, one being new, and American species are briefly discussed.
An Early List of Strata by William Smith
Authors: Douglas J. A. , Cox L. R. 
Published: May 2009

AbstractAn account is here given of the recent discovery at Oxford of a hitherto unrecorded MS. in William Smith's handwriting, giving the list of Strata as known to him in 1797 and differing in some respects from the famous list dictated by him two years later at Bath to the Rev. B. Richardson and the Rev. Joseph Townsend, a copy of which is preserved in the Geological Society's collection. The list is reproduced here in its original form and spelling, together with a number of annotations.
Kyanite-Gneiss within a Thermal Aureole
Authors: MacKenzie W. S. 
Published: May 2009

AbstractThis preliminary note records two discoveries in the Ross of Mull. Kyanite is considerably more widespread in the Moine rocks than previous investigations have indicated. Where the kyanite-gneiss enters the thermal aureole of the granite, large andalusite paramorphs are formed from kyanite.
Evidence of Fissure Eruption in the Tertiary Lava Plateau of North-East Ireland
Authors: Patterson E. M. 
Published: May 2009

AbstractAn example is described of a dyke feeding a lava flow in the Tertiary basalt plateau of North-East Ireland. The dyke has an erratic course and branches into several veinlets, but otherwise it displays the usual characters of a dyke. Continuity between dyke and flow is seen in five places in the restricted area of outcrop of the flow. The possible relationship of the dykes and volcanic plugs of Antrim to the plateau lavas is briefly discussed.
Contact Metamorphism at Maddocks Hill near Wellington, Shropshire
Authors: Chapman Randolph W. 
Published: May 2009

AbstractA large basic sill intrudes the Shineton shale (Cambrian) at Maddocks Hill, east of the Wrekin, near Wellington, Shropshire. An old quarry exposes the contact and reveals that the shale close by has been recrystallized to a hard, compact hornfels, the intensity of alteration decreasing away from the contact. Thin sections show that the metamorphic effect was solely thermal, the rock having been completely recrystallized, and biotite having been generated under conditions of the amphibolite facies. The metamorphism is compared with that brought about by other basic hypabyssal intrusions.
Olivine-bearing and other Basic Hornfelses around the Insch Igneous Mass, Aberdeenshire
Authors: Sadashivaiah M. S. 
Published: May 2009

AbstractBasic hornfelses occurring at the contact of slates and olivinenorite are ascribed to influx of Ca, Mg, Fe, Ti, Mn, and P from the gabbro magma into the sedimentary rocks. This kind of basic front, unlike those postulated for acid bodies, has a basic back.
The Origin of the Fenland Meres: Fenland Homologues of the Norfolk Broads
Authors: Jennings J. N. 
Published: May 2009

AbstractA section from the extinct waterway of the Little Ouse to the former Red Mere in west Suffolk is described, which shows that the lake mans succeed the clay flanges extending from the roddon silts. Thus the Fenland Meres formed in the course of the Coastal or Upper Silts transgression of the Fenland Basin, during which raised banks of silt were built along the tidal waterways, and these ponded back the fresh water. The Meres are shown to be roughly similar in age and manner of formation to the Norfolk Broads.
On the Ages of Certain Upper Tertiary Beds of Peninsular India and Ceylon
Authors: Eames F. E. 
Published: May 2009

AbstractDuring the course of researches upon the Cainozoic faunas of Burma, Pakistan, India, and Ceylon, the writer has compiled a list of all the species that have been recorded, and has assessed the accuracy of the information from the points of view of both specific identification and age. As a consequence, he has been led to believe that current opinions as to the ages of certain horizons may have to be modified, and that in other cases the evidence of age is much less certain than was believed. The faunas here discussed are those of the Miocene beds of Ceylon, of the Quilon limestone, of the Pliocene of Karikal, and of the Cuddalore sandstones.
The Stratigraphy and Structure of the Arenaceous Formation of the Main Range Foothills, F.M.S
Authors: Richardson J. A. 
Published: May 2009

The evidence relating to the problems raised by the Arenaceous Formation of the Main Range Foothills may be summarized thus:—(i) The Foothills are built as a rule of predominantly arenaceous sediments; belts of quartzite-conglomerate occur and argillaceous types generally are interspersed with the coarser grained rocks.(ii) Lithological variations northwards and southwards along the strike of the Formation, and eastwards and westwards through its strati-graphical succession are very great.(iii) No fossils have been found anywhere in these rocks and their age is consequently not definitely known.(iv) The Foothills have obviously been the site of orogenic pressures and metamorphism, and they appear to have formed a buttress against which the Permocarboniferous rocks have been moulded by forces from east-south-east or east.(v) There is a persistent difference of 10° to 20° between the general strike of the Foothills Formation and that of the Permocarboniferous Formation along the eastern margin of the Foothills in the 35-mile tract examined by the writer. This fact cannot be accepted as proof that an angular unconformity exists because structural complexities dependent upon (iv) above can also afford a satisfactory explanation of this divergence of strike.(vi) Scrivenor has mapped the Foothills Formation as Triassic, so that its easterly dip below the Permocarboniferous must, on this hypothesis, be due to overfolding.(vii) Between the western margin of the Foothills and the Main Range granite, occur rocks, many of them strongly metamorphosed, which may originally have been calcareous shales, pyroclasts, and impure limestones, presumed, on lithological grounds, to be of Permocarboniferous age. Their alteration has been so profound that no transitional types have been discovered between thorough-going amphibole- and epidote-schists and the presumed parental calcareous sediments. Metamorphosed argillaceous and arenaceous rocks accompany them.
Structural Features of the Grey Granites of Aberdeenshire
Authors: Cameron James 
Published: May 2009

INTRODUCTIONThe area containing the quarries discussed in this paper extends inland from the City of Aberdeen for a distance of about twenty miles and is bounded on the north and south by the rivers Don and Dee. This is the area of the Newer Granites of Aberdeenshire, which C. B. Bisset has described in “A Contribution to the Study of Some Granites near Aberdeen” and has divided the acid igneous rocks into:—1. The Skene Complex: consisting of diorite, adamellite, grey granites, transition types and minor intrusions.2. Later Group: consisting of coarse red granites.
The Term Gotlandian and its Implications
Authors: Greenly Edward 
Published: May 2009

Some of us are old enough for our geological infancy to have been nourished on books which were written at a time when the “Silurian System” was threatening to annex the whole of the Lower Palaeozoic Rocks. Most of us welcomed Lapworth's arrangement, which now seems to have won general approbation. In the interim, however, the following compromises were proposed:Neither of them has been widely adopted. It is to be noted that De Lapparent's proposal of “Gotlandian” was made because he had already made use of “Silurian” as an inclusive designation. His selection of the term was of course founded upon the fact that the beds in question are finely developed in Gothland.
The Crystalline Metamorphic Rocks of South-Western Togoland
Authors: Robertson Thomas 
Published: May 2009

1. A belt of gneiss of dioritic composition lies along the west side of the Togo Range, and is exposed at intervals practically all the way from Pode to Atakpame.2. Associated with it are hornblende- and mica-schists, garnet-amphibolites, and hypersthene-gneisses resembling rocks of the charnockite series. These last form the greater part of Agu Mountain, and also occur at several places along the foot of the Togo scarp.3. The valley of the Dsawoë River appears to be in large part underlain by gabbro and dolerite types of rock, with associated dyke rocks.4. A tract of garnetiferous biotite-gneiss, partly granitic in composition, occupies that part of the basin of the Amu River due south of Atakpame. It is associated with schists similar to those accompanying the dioritic gneiss.5. Basic intrusions occur in the gneisses, e.g. serpentine at Djeti and pyroxenite north of Pode. A pyroxenite north of Akata is intrusive in rocks of the Togo series. No granitic intrusions were found.6. The rocks described form a basement upon which the rocks of the Togo series and other younger ones rest.
Note on Fossiliferous Strata on the Galapagos Islands explored by W. H. Ochsner of the Expedition of the California Academy of Sciences in 1905–6
Authors: Dall W. H. 
Published: May 2009

One of the most interesting results of the exploration of the Galapagos Islands by the Academy's expedition was the discovery of sedimentary fossiliferous strata on several of the islands. A report was prepared with descriptions of the fossils by the writer in 1916, but the publication so far, has been delayed.The interest attaching to this discovery is so great, the islands having been regarded hitherto as entirely eruptive, that it seems desirable to put on record a brief abstract of the results, as recorded by Mr. Ochsner.
Intrusion of Cone-Sheets
Authors: Kuenen Ph. H. 
Published: May 2009

SummaryEvidence from Mull and Ardnamurchan is brought forward to show that the injection of cone-sheets is accompanied by a vertical lifting of the upper wall. This confirms Anderson's explanation. It is argued that the fracturing and injection are of a quite sudden character and that it is in the nature of the process that no evidence from recent volcanoes has yet been obtained of contemporary cone-sheet injection.
On the Differentiation of the Glen More Ring-dyke, Mull
Authors: Koomans Cath , Kuenen Ph. H. 
Published: May 2009

SummaryNew analyses are given of the Glen More Ring-dyke. The basic end of the variation diagram is found to differ considerably from that of the Normal Magma Series. The magma variation is explained by gravitative sinking of augite and iron-ore (and plagioclase), the olivine of the Normal Series playing only a subordinate part. Various objections are brought forward to the explanation of the magmas by hybridization. The peculiar microscopic aspect of the intermediate rocks is tentatively attributed to pneumatolytic emanations from the lower reaches of the column. It is shown that a gradual transition from basic to acid already existed before the final consolidation of the magma took place.
The Evolution of the Granodioritic Rocks of the South-Eastern End of the Kopaonik Batholith, Yugoslavia
Authors: Wilson Gilbert 
Published: May 2009

Summary and ConclusionsThe composite granodiorite batholith of the Kopaonik Mountains forms one of the more southerly members of the peri-Adriatic tonalitic intrusions. In the area discussed in this paper it intrudes a series of sedimentary rocks which range from dominantly calcareous to pelitic types. Metamorphism of these rocks has produced crystalline limestones, skarns, and calc-silicate hornfelses, which grade downwards into mica-, amphibole-, epidote-, and locally cordierite-bearing rocks. The pelitic and amphibole-bearing hornfelses are in immediate proximity to the batholith on the surface. The amphibole-bearing types are mainly confined to a relatively small area, well within the zone of high-grade metamorphism and overlying the southerly pitching nose of the intrusion. With them are associated hornfelses which carry porphyroblasts of albitic feldspar. It appears that the persistence of the amphibole and the development of these feldspar porphyroblasts may have been caused by hydrous and probably sodic emanations which permeated the sediments above and ahead of the advancing igneous mass.
The Relative Age of Concretions
Authors: Richardson W. Alfred 
Published: May 2009

The age of a concretion, relative to that of the parent-rock, must be either:—1. Contemporaneous.—The concretion grew on the sea-floor at the same time, and at about the same rate, as the surrounding deposit was laid down.2. Penecontemporaneous.—The concretion segregated more or less close to the surface of recently deposited sediment.3. Subsequent.—The concretion formed after deposition had finished, and after the strata had largely consolidated, but, perhaps, before cementation had taken place to any noteworthy extent.