bluuebunny/crossref_metadata_2025_split huggingface dataset:
The problems and contributions of methods of absolute dating within the Pleistocene period
Authors: SHOTTON FREDERICK WILLIAM 
Published: October 2009

The basis of the radiocarbon method is discussed with special reference to sources of error in the estimations and their relative significance. Radiocarbon dates now indicate that the Würm Glaciation in the northern hemisphere has two stadia of approximately equal importance, one or other the more important in different localities, separated by a long cool interstadial. This concept is applied to an interpretation of some of the British deposits to which radiocarbon dates are applicable.
The potassium–argon method is next discussed. Age estimates for the beginning of the Pleistocene period indicate a considerable antiquity but range between 1.75 and 3.5 my. and it is still uncertain which estimate should be regarded as more nearly correct. In the later Pleistocene, K–Ar dates have been applied to the Rhine terraces, which have been correlated with the Alpine glacial stages, suggesting that the Günz Glaciation is less than 0.5 m.y. old, despite the much greater age given by the same method for the beginning of the Pleistocene.
The decay series of uranium-238 and uranium-235 provide several other methods of dating used either in deep-sea cores or in marine carbonate organisms. The maximum possibility of the best of these is of the order of 300 000 years. Figures that have been given to the early Pleistocene appear to be widely at variance with potassium–argon; but figures on deposits in southern Europe and the Mediterranean ranging from Günz–Mindel to Riss–Würm are in reasonable accord with potassium–argon figures on a similar stratigraphy.
Possible alternative dating methods of the future are mentioned.
Metamorphosed and deformed pegmatites and basic dykes in the Lewisian complex of the Outer Hebrides and their geological significance
Authors: DEARNLEY RAYMOND , DUNNING FREDERICK WEIR 
Published: October 2009

The central zone of the Outer Hebrides is composed of a gneissic (‘grey-gneiss’) complex containing evidence of the earliest as well as many of the later events in the history of the Lewisian. In northern South Uist, an old metamorphic complex is intruded by pegmatites which were strongly deformed by a tectogenesis equated here with the Scourian of more than 2600 m.y. ago. It is concluded that much of the original material of the greygneiss may represent the products of a pre-Scourian orogenic cycle of possible Katarchaean (>3000 m.y.) age.
Widespread post-Scourian basic (tholeiitic) dykes which cut the grey gneiss are thought to be equivalent to the Scourie dykes of the Scottish Mainland. These intrusions were subjected to granulite-facies metamorphism, regarded as Early Laxfordian, followed by retrogressive amphibolite-facies metamorphism with local folding and migmatization, all of Late Laxfordian date (1500 to 1600 m.y.). A number of dykes described from Benbecula and South Uist illustrate stages of Laxfordian deformation in which perfectly preserved cross-cutting relationships are progressively obliterated, the final products in the southern zone of South Uist being highly deformed and disrupted amphibolite masses with concordant margins in mobilized Laxfordian migmatitic gneiss.
The petrology of the metamorphosed syenite in Glen Dessarry, Inverness-shire
Authors: RICHARDSON STEPHEN WIGHAM 
Published: October 2009

The Glen Dessarry syenite is composed of two types of syenite which were intruded before or during a phase of almandine–amphibolite facies regional metamorphism. The chemistry. of the syenites, taken together with their field relations and mineralogy, suggests that they are derived from a parent magma crystallizing principally aegerine-augite, biotite and magnetite. The syenites themselves crystallized as alkali-feldspar, pyroxene, biotite, magnetite, spheric, apatite (calcite, allanite, zircon) rocks.
During metamorphism and deformation, the feldspar, by this time mesoperthite, unmixed into granular orthoclase and sodic plagioclase. A fluid phase entering the igneous rocks gave rise to disequilibrium pyroxene-hornblende bearing assemblages and equilibrium pyroxene-free assemblages (the criterion of equilibrium being regularity of distribution of Mn and Mg between co-existing phases); the same fluid effected an over-all reduction of the original rocks. On the assumption that the fluid contained only water and hydrogen, its composition is calculated to be at least as rich in hydrogen as 20mol per cent.
Probably during a later metamorphic episode, small amounts of epidote and quartz formed in the syenites at the margins of the complex.
Practical geology and the natural environment of Man—II Seas and oceans
Authors: DUNHAM KINGSLEY CHARLES 
Published: October 2009

Great advances in knowledge of the sea bed and ocean floor have been made during the past two decades; nevertheless, investigation of the usefulness of this part of the environment of Man is at an early stage of reconnaissance only. Elaborate techniques and expensive equipment are necessary to advance marine geophysics and geology and for these researchers must depend upon industrial or governmental support. The current theoretical results are exciting; some have practical significance. The continental terrace (slope, shelf and underlying crust) appears to contain on the average a higher proportion of thick, young sediments than the adjacent continents, and is correspondingly more important as a potential source of petroleum. The chances of finding workable solid mineral deposits such as occur in older rocks are less than in the continents.
These points are illustrated with reference to the terrace around the British Isles. The superficial sediments on the shelf may include concentrations of useful detrital minerals, submerged during the late Pleistocene–Holocene rise of sea level. The deep ocean bottoms may some day be a source of certain non-ferrous elements from ubiquitous manganese nodules, and of phosphates. Special concentrations of valuable elements may be found in ocean water, associated both with regions where upwelling promotes high biological activity and with restricted basins receiving hot hydrothermal fluids from below; but the feasibility of recovering these elements has not yet been demonstrated. The geology of the sea bed affects creatures living in the sea and thus influences Man's food supply.
The nature and possible origin of the pillow lavas and hyaloclastite breccias of King Island, Australia
Authors: SOLOMON MICHAEL 
Published: October 2009

Basaltic pillow lavas and breccias of possible Cambrian age are exposed in the south-east of King Island. Pillow flows and massive flows generally occur at the base of the succession and are overlain by hyaloclastite breccias. Studies of the cooling of pillows show that they must develop their globular form almost immediately the lava contacts the cold medium. At this stage surface tension could be important in determining the spherical shape if the magma was projected or was moving rapidly. Because of its high latent heat of vaporization, water is a far more efficient coolant than air and the cooling in water may be rapid enough to 'freeze' the pillow shape before it becomes unstable.
The hyaloclastite breccias consist of whole pillows, fragments of pillows, or parts of thin lava flows, within a tuff matrix of devitrified and metasomatized micro-globular particles and shard-like fragments. The components of the matrix were not derived from pillow or flow margins but formed by micro-globulation and shattering.
Two rock-types are represented: the spilite or albite-diopside type which forms massive or pillowy flows, and the picritic type (chlorite pseudomorphing olivine) which forms the hyaloclastite breccias and similar rocks.
Most of the volcanic activity was sub-aqueous, and judging by the proximity of tillite and varve-like rocks, may have taken place under or in ice.
Intraglacial volcanoes of the Laugarvatn region, south-west Iceland—I
Authors: JONES JOHN GILBERT 
Published: October 2009

The shape and structure of a group of basaltic volcanoes is described. It is concluded that these volcanoes grew within bodies of melt-water in an ice-sheet. The activity of some was limited to effusion in water, resulting in steep-sided piles of pillow lava. In others which mounted to a water surface activity culminated in explosions which mantled the pillow lava pile with vitric tuff. With still others explosive emergence was superseded by quiet effusion of lava in air. Flows advanced outwards into an encircling lake on deltas of breccia formed at their fronts, mantling and obscuring the products of the earlier phases of aquatic effusion and explosive emergence.
Details of the structure and structural interrelationships of the volcanoes are explained in terms of eruptions within an ice-sheet of continually increasing thickness.
Attention is drawn to the morphological contrast between intraglacial and extraglacial basaltic volcanoes.
Tertiary granites and associated rocks of the Marsco area, Isle of Skye
Authors: THOMPSON ROBERT NEVILLE 
Published: October 2009

The early Tertiary intrusive igneous rocks of the Marsco area, Skye, form part of the Western Redhills Complex. They are predominantly granitic in composition, but also include small amounts of gabbro and ferrodiorite. The intrusions are arcuate, steep-sided, dyke-like bodies. Portions of the roofs of several successive plutons are preserved on Marsco.
The margins, against granite, of the gabbro on top of the mountain give evidence of the chilling of basic against acid magma. Seven high-level granites are described. They show a considerable variety of textures and mineralogy; usually containing feldspar phenocrysts, and ground-mass fayalite, ferrohedenbergite, calciferous or alkali amphibole, biotite and numerous accessory minerals. Mineralogical data and twelve new whole-rock chemical analyses are presented. It is shown that the ferrodiorite is probably contaminated by acid magma.
Two granites south of Marsco are truncated by the Western Redhills intrusions, and appear to belong to a separate, possibly earlier, intrusive centre. The six major granites in the Marsco area are classified structurally into three pairs. The second members of each pair are very alike mineralogically and chemically. It is postulated that the acid magmas were produced by partial melting of Lewisian gneisses and Torridonian sediments in the thermal aureole of a large basic intrusion. The phase-chemical relationships of the granites to their supposed source rocks are discussed. A petrogenetic scheme is given, which attempts to explain the compositions and forms of the granitic dykes, and their emplacement in pairs. It is thought that intrusion took place during the tilting of a foundering crustal block.
The ecology and preservation of the Oxford Clay fauna at Woodham, Buckinghamshire
Authors: HUDSON JOHN DOUGLAS , PALFRAMAN DAVID FRANCIS BENEDICT 
Published: October 2009

The exposure of Oxford Clay at the Woodham Brick Company's Pit, near Akeman Street Station, Buckinghamshire, is described in detail. Macrofaunal bed-by-bed collections reveal that throughout the deposition of the Oxford Clay at this locality a wide range of ecological niches was inhabited.

There are no major ecological differences between the faunas of the main lithological units (the Spinosum Clays, the Lamberti Limestone, and the Mariae Clays). Such differences as do exist between the clays and the limestone are probably related mainly to differing rates of deposition. The authors have found no evidence to support the contentions of
Rutten (1956)
that waterblooms periodically killed off the clay faunas, nor that the limestone is a littoral deposit.

Many Woodham fossils are preserved as internal, pyritic moulds. There is abundant evidence that pyrite deposition occurred only in small, enclosed shell chambers which had not been invaded by mud. Hence the nuclei of ammonites are preserved as internal pyritic moulds, but beyond a diameter of about 20 mm the remaining whorls (with consequently larger chambers) are preserved as clay moulds. Other once-aragonitic shells not offering small, enclosed voids are preserved as composite clay moulds, whereas calcitic shells remain preserved as such, often with detailed micro-structure.
Sulphates dissolved in sea-water are considered to be the source of sulphide in pyrite formation, and from comparison with recent sediments the authors envisage pyritization as beginning beneath the mud-sea-water interface, possibly at a depth of several centimetres.
Forms of preservation not recorded at Woodham are briefly mentioned as occurring at other Oxford Clay localities. It is concluded that the Oxford Clay sea-bottom at Woodham was not stagnant and anaerobic, and that there is no evidence of dwarfed faunas. The relationship between original shell mineralogy and structure, and mode of preservation is stressed.
Near-shore marine and continental sediments of the Sirte basin, Libya
Authors: SELLEY RICHARD CURTIS 
Published: October 2009

At the end of the Cretaceous period the Sirte basin developed in North Africa between the Tethyan foredeep and the Sahara Shield. In-filling of the basin throughout the Tertiary era resulted in the deposition of a thick sequence of clastic rocks and carbonates with minor evaporites. The Sirte basin contains large quantities of oil and gas. This paper describes mixed carbonate and clastic Miocene shoreline deposits of a type which prevailed during much of the history of the Sirte basin. These rocks have been studied in the field using sedimentological logging techniques. Forty-seven detailed sections have been recorded totalling some 3000 m of sediment over an area of about 1500 sq km. Some 26000 field observations have been made. These have been used to interpret the depositional environments of these rocks by comparison with studies of recent sediments.
Five major facies have been recognized; each has been given a type section and is defined by five parameters, viz: geometry, lithology, sedimentary structures, palaeontology and palaeocurrent pattern. Four of these facies trend parallel to the shore of the Sirte basin. They are locally cross-cut by the fifth.

In the north bioclastic limestones were deposited by the shoreward migration of offshore bars and barrier beaches. These interfinger southwards with laminated lagoonal shales with oyster banks. The shales in turn pass shorewards into interlaminated fine sands, silts and shales with abundant bioturbation and micro-cross-lamination. These beds are cut by channels of inclined laminated sand and shale. This third facies is interpreted as inter-tidal, the channels originating as creeks which drained the mud flats. The most southerly (landward) of these four facies consists of crossbedded sands and shales, lignites, rootlet beds, with a spectacular fauna of continental vertebrates. These beds are thought to be the deposits of a fluviatile coastal plain. The four facies belts just described are replaced at two places by
n–s
trending calcareous sandstone shoe-string complexes interpreted as estuarine channels.

Palaeocurrent analysis shows that carbonate sediment, generated in the offshore zone, was transported up-slope towards the land, while clastic sediment was carried seawards from the Sahara Shield. Bipolar palaeocurrents in the calcareous sandstone channels indicate mixing of these two sediment types within the estuarine environment.
This Miocene shoreline was similar to the present-day coast of south west Texas, though in this analogue the barriers are made of non-carbonate sediment. The Miocene limestones are broadly comparable to the present-day barrier carbonates of the Trucial coast and have certain points of similarity with recent carbonate sands of the Bahamas.
A gravity survey of coastal areas of West Finnmark, northern Norway
Authors: BROOKS MICHAEL 
Published: October 2009

A gravity survey carried out in coastal regions of West Finnmark is described. The survey reveals a positive Bouguer anomaly with an amplitude of approximately 100 mgal centred over the island of Söröya and forming a culmination on a persistent positive anomaly axis extending along the entire coastal zone. The Söröya anomaly is similar in amplitude and width to a large anomaly overlying Lofoten-Vesterålen 300 km to the south-west.
These anomalies are interpreted as being caused by an underlying upper crustal zone of high density, formed either by a massive enrichment of the upper crust in basic and ultrabasic material or by a culmination of granulitic facies metamorphic rocks, perhaps containing abundant basic intrusions. The proposed crustal structure is similar in important respects to that of the Western Alps as indicated by recent geophysical surveys, and is consistent with modern Russian views on the role of asthenoliths in geosynclinal development.
The structural evolution of the Tollie antiform—a geometrically complex fold in the Lewisian north-east of Gairloch, Ross-shire
Authors: PARK ROBERT GRAHAM 
Published: October 2009

Five phases of deformation D1–5 are recognized in the Tollie gneisses. D1–2 are probably Scourian
(s.l.)
and ante-date a set of basic dykes. The pre-dyke metamorphism was highgrade, in part granulite facies.

D3 was accompanied by almandine–amphibolite facies metamorphism and caused minor folding F3 on
nnw–sse
axes with an associated penetrative foliation of variable dip. The basic dykes were intruded either before or during D3. D4 produced widely-developed steep penetrative foliation S4 with associated folds F4 and lineation L4 having a
nw–se
trend slightly oblique to that of F3 and causing widespread transposition of S3. The associated metamorphism was retrogressive over part of the area to lower almandine–amphibolite facies. D5 comprises late- or post-metamorphic structures without penetrative foliation.

The Tollie antiform hinge is an F4 fold superimposed on a pre-existing major structure the nature of which is investigated by analysing the variation in L4 attitude using lineation-pitch isogons, and by studying the geometry of the dykes. It is deduced that the F4 folds were superimposed on an upright box-shaped anti-form described by the S3 foliation in the gneisses and by the dykes.
Alternative hypotheses are proposed to account for the pre-F4 variation in attitude of the dykes.
Photogeology and structure of the Mozambique orogenic front near Kolo, north-east Tanzania
Authors: HEPWORTH JOHN VORD , KENNERLEY JOHN BRIAN 
Published: October 2009

A regional investigation into part of the Mozambique Orogenic Belt in north-east Tanzania is based on photogeological interpretation supported by ground work at selected localities. A 15-mile traverse was made, near Kolo, from the granitoid Tanganyika Shield towards the adjacent orogen in order to establish the structure and tectonic relationships across the front.
Three tectonic domains and two subsequent deformations were recognized. One of the domains (Kondoan) corresponds to the tectonically reworked margin of the Shield, which itself consists of a batholithic granite and a marginal series of gneisses (Parangan). Analysis of the structural data obtained on the ground shows that the tectonic domains which were postulated, in part photogeologically, on grounds of distinctive structural styles, display some degree of structural homogeneity.
The western domains, which constitute the foreland, are deformed by shearing. The onset of tectonic reworking in the Kondoan domain converts the pre-existing rocks into flaggy gneisses dipping to the east. The axial planes of all the imposed folds dip eastwards towards the orogenic belt and the axes of deformation plunge predominantly towards the east-southeast and south-east, i.e. transverse to the general north-south trend of the orogenic belt. Comparison with other regions suggests that at similar tectonic levels folding, with stretching in the axial direction transverse to the orogenic front, is a common feature in the development of mountain chains.
Lateritization and landscape development in Kyagwe, Uganda
Authors: McFARLANE MARGARET JOAN 
Published: October 2009

In Kyagwe the ‘high-level’ laterite capped mesas, the remnants of the Buganda Surface, do not belong to a monocyclic land surface. The nature of the ground-water laterite on the sloping summits of the remnants varies altitudinally. Vermiform laterite is followed downslope by spaced and then packed pisolithic laterite. Further downslope the sequence is repeated.
Study of the ‘low-level’ ground-water laterites suggests that (1) the pisolithic laterites are immature and form in association with a gently lowering water-table and (2) the vermiform variety is a mature formation associated with a stable water-table.
The development of the vermiform laterite of a planation surface is outlined.

The ‘high-level’ laterite sequence on the mesas is interpreted as belonging to two erosion cycles. The two laterite profiles, consisting of vermiform overlying spaced pisolithic laterite, have been truncated and reworked to form continuous sheets
•
The immature spaced pisolithic laterite and mottled zone which underlies the vermiform laterite of a planation surface is believed to form as the water-table commences lowering upon initiation of the succeeding cycle. Each profile is therefore bi-cyclic. The formation of the underlying pallid zone is discussed in terms of a post-incision modification by leaching through the carapace.

The two planation surfaces represented by the mesas of the Buganda Surface are discussed in relation to the denudation chronology of Uganda.
On the Geology of Cape Breton
Authors: Brown Richard 
Published: October 2009

In a letter to MK Lyell, dated Sydney Mines, Cape Breton, Oct. 20. 1843, the author stated—
“I have made a survey of some forty miles of coast on the eastern side of our coal-field; and have since devoted a few days to the examination of the shores of the Island of Boularderie, which is four miles wide, and twenty-six miles long, and exhibits natural sections on both sides from end to end. Nothing can be more definite than the position of the masses of gypsum in this island. I have examined them this summer in four different places, scores of miles apart, and find the following, with little variation, to be a section of the accompanying strata:
Appendix to Professor Henslow's Paper, consisting of a Description of the Fossil Tympanic Bones referable to four distinct Species of
Balæna
Authors: Owen Richard 
Published: October 2009

The fossils from the Crag at Felixstow, which have been submitted to my inspection by Professor Henslow, are the tympanic portions of the petro-tympanic bones of large Cetacea.
The tympanic adhering to the petrous portion by only two small surfaces is easily detached, and may be recognised by its conchoidal shape and peculiarly dense texture; the recent bone breaking with almost as sharp a fracture as the petrified fossils.

None of these are entire: the thin brittle outer plate which bends over the thick, rounded, and, as it were, involuted part, like the outer lip of such simple univalves as the
Buliæ
and
Leptoconchi
, is broken or worn away in the best specimens, all of which are rolled and waterworn.

We are led by the size of the specimens to the largest of the existing Cetacea for the subjects of comparison, as the Grampus, the Hyperoodon, the Cachalots (
Physeter
) and the true whales (
Balænoptera
and
Balæna
)

Two or three of the specimens are fortunately sufficiently entire to show the form of the tympanic cavity bounded by the overarching plate, with the proportion and direction of its anterior or Eustachian outlet, and most of them have the opposite or hinder extremity entire.