bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quaternary deposits of the Ballaugh and Kirkmichael districts, Isle of Man
Authors: MITCHELL GEORGE FRANCIS
Published: October 2009

During the Last Glaciation ice advanced against the Isle of Man from the north, depositing in the north-west of the island large amounts of drift up to an altitude of 150 ft, and smaller isolated amounts of drift up to an altitude of 650 ft. These deposits are well seen in section at Orrisdale Head, and are described as an Orrisdale Series of deposits. Much of the island projected above the ice of the Last Glaciation as a nunatak.

In the coastal cliffs west of Kirkmichael another series of drifts, also derived from the north, is seen below the Orrisdale Series, and since these drifts are similar to the glacial deposits of Gipping age known farther south in the Irish Sea basin, they are regarded as Gipping in age. They are well exposed at Jurby Head and at Ballateare, and are described as a Ballateare Series. The whole island may have been overridden by ice during the Gipping Glaciation.

During the retreat of the Orrisdale ice, marginal lakes, outwash fans, and morainic ridges were formed. Late-glacial deposits accumulated in enclosed basins on the ridges, and these have been given carbon-14 dates ranging from 10 200 to 8300
b.c
.

When the permafrost melted at the end of late-glacial time, large quantities of sand and gravel, which had been built up into terraces in a marginal lake impounded in Glen Wyllin, south of Kirkmichael, were set free. These sands and gravels moved down and built up an early post-glacial alluvial fan at the mouth of the Glen, burying the late-glacial deposits to a depth of 40 ft.
Environmental history of quartz sand grains from the Lower and Middle Pleistocene of Norfolk, England
Authors: KRINSLEY DAVID HENRY , FUNNELL BRIAN MICHAEL
Published: October 2009

Criteria aresuggested for the distinction of glacial, glacio-fluvial, dune, beach, and deeper-water or estuarine environments on the basis of electron-microscopic examination of surface textures of quartz sand grains. In favourable circumstances a sequence of events representing a succession of environments may be recorded on a single sand grain or group of grains. Textures resulting from chemical action are also recognized.

Application of the technique to the Lower and Middle Pleistocene (Norwich Crag to North Sea Drift) deposits of Norfolk, England, has confirmed the origin of deposits previously interpreted on the basis of their contained faunas and general sedimentary characteristics, and has provided new evidence on the origin of others. On the basis of these studies it is concluded that the Norwich Crag is of littoral and sublittoral origin with occasional incorporation of dune sand, that the quartz–quartzite–flint gravels of the upper part of the Norwich Crag Series
s.l.,
the Weybourne Crag, and the Estuarine Bed of the Cromer Forest Bed Series each show initial glacial and sometimes glacio-fluvial action, followed by turbulent (beach) or less turbulent (estuarine or deeper-water) action, and that the Norwich Brickearth and Cromer Till both appear to have incorporated large quantities of mainly marine sand into relatively stoneless till, probably near the margins of an ice-sheet.
The formation of a palagonite breccia mass beneath a valley glacier in Iceland
Authors: WALKER GEORGE PATRICK LEONARD , BLAKE DAVID HENRY
Published: October 2009

A mass of palagonite breccia, with associated palagonite tuffs, basalt pillows, and large bodies of columnar basalt, is described from southeastern Iceland. It rests upon a glacially striated surface, with or without a thin intervening tillite layer. The mass is probably of early Pleistocene age and the evidence shows that the basalt which gave rise to it flowed down a valley beneath a valley-glacier. The mass has a present volume of 1.5 km
3
(the original volume must have been several time
s
this) and the basalt flowed certainly for 22 km, and probably for 35 km, beneath the ice. It is believed to have flowed through a central conduit along the valley bottom, and the breccia and contained pillows mainly developed by escape of the basalt upwards and sideways from this conduit into the glacier or its melt-waters.
Cretaceous outliers in south-west Ireland and their implications for Cretaceous palaeogeography
Authors: WALSH PETER THOMAS
Published: October 2009

An investigation of the Gweestin Valley, near Killarney, Co. Kerry, has revealed the presence of datable deposits of Chalk at an elevation of about 300 to 400 ft
o.d.
The Chalk forms the matrix in a breccia of Namurian shale fragments, the breccia apparently occurring as a pocket in surrounding unbrecciated Namurian shales. The faunal content indicates a Senonian age for at least some of the Chalk, whereas the lithology and texture of the breccia and a knowledge of the local Carboniferous succession and structure strongly suggest that the deposit originated as a rapid submarine intra-Cretaceous karstic subsidence. Evidence is presented bearing upon the size of the existing pocket, the elevation of the local Chalk sea bed, and the sequence of events leading to the collapse.

The Chalk–shale deposit is termed the
Ballydeenlea outlier.
Two other karstic-subsidence outliers occur nearby at Kilkneedan and Ballyhar; though neither contains chalk sediment, they are thought to be genetically related to the Ballydeenlea outlier.

The existence of the Chalk sea floor not far above 400 ft
o.d.
in the centre of the Dingle Bay synclinorium suggests, from one point of view, that the contemporary physiography of mid-Kerry is essentially an exhumed pre-Senonian landscape, or, from an alternative point of view, that the Old Red Sandstone ranges of Iveragh and Slieve Mish have been uplifted by at least 2500 ft during Tertiary times. The evidence, which is inconclusive, is presented in review of these postulates. The Gweestin valley deposits are briefly compared with other British karstic subsidence phenomena.
The distribution of pressure and temperature during Dalradian metamorphism
Authors: CHINNER GRAHAM ALAN
Published: October 2009

The formation of sillimanite in association with the development of gneisses and migmatites in the Grampian Highlands and north-eastern Scotland is interpreted as a later superimposition upon a slightly earlier metamorphic pattern characterized in its higher grades by andalusite and kyanite. This earlier pattern is subdivided by three significant isograds: (i) the
andalusite isograd,
along which andalusite developed from hydrous mineral assemblages; (ii) a
kyanite isograd,
along which kyanite developed from hydrous mineral assemblages; and (iii) an
andalusite–kyanite isograd,
dividing the andalusite and kyanite zones, (i) and (ii) are interpreted as dehydration isograds, virtually isothermal; (iii) represents the polymorphic inversion of kyanite to andalusite, with a
P/T
slope of approximately 12.8 bars/degC.

For some 50km southwards from the coastline along the Moray Firth on the western limb of the post-metamorphic Boyndie syncline, the andalusite and andalusite–kyanite isograds form virtually parallel traces; parallelism of isograds with such disparate
P/T
slopes suggests that isobars and isotherms in this region were parallel.

In central Aberdeenshire the inversion isograd diverges from the andalusite isograd, and appears to run along Deeside to meet the kyanite isograd in the south. This is interpreted as indicating a divergence between isobars and isotherms; an antiformal monocline with approximately
ne–sw
axes is deduced for the thermal surface. To explain this disposition synmetamorphic monoclinal folding is suggested, in which pressure adjustment was instantaneous as sediments were depressed to deeper levels, but the heat content enabled pre-existing isothermal surfaces to be preserved.
The Dartmouth Beds of Bigbury Bay, south Devon
Authors: DINELEY DAVID LAWRENCE
Published: October 2009

The oldest datable Devonian rocks of south Devon are the Dartmouth Beds. They have been examined in the coastal sections between Plymouth and Bigbury Bay and in Slapton (=Start) Bay, where the following successive units are proposed: Warren Sandstones, Yealm Formation, Scobbiscombe Sandstones, and Wembury Siltstones. The Warren Sandstones are similar to the Dittonian rocks of Wales and the Welsh borderlands. The Yealm Formation contains considerable amounts of pyroclastic rocks. The succeeding Scobbiscombe Sandstones occur only at Beacon Point and along the strike inland, and are regarded as a local fluvial grit deposit. Rapidly alternating sandstones and siltstones dominate the Wembury Siltstones succession.

Plant remains, vertebrates, and molluscs occur, abundantly in places, but are generally poorly preserved. Most common are pteraspid fragments (
Pteraspis cornubica
), and it seems that at least two species are present. A correlation with the Dittonian and Breconian stages is highly probable.

The rocks constitute a continental depositional initial phase in this part of the Cornubian section of the geosyncline. No base is seen, but the phase may be analogous to similar red beds in the Lower Devonian of western Europe, notably Germany, where they precede the mass of marine geosynclinal sediments. The material in south Devon may have come from either the north or the south but there is no conclusive evidence of the southern land-mass postulated by some authors.

During the Variscan earth–movements the rocks were compressed, cleaved, and folded to give a shallow anticlinorial structure. Strike-faulting has been detected only on a minor scale but larger displacements along faults striking
nnw–sse
may be present. The early impression that the Dartmouth Beds comprise many thousands of feet of sediments is erroneous. No evidence is produced to show that the Dartmouth Beds and the Meadfoot Beds are at least in part coeval, but the Geological Survey’s (i.e., W. A. E. Ussher’s) basic succession and outcrop-pattern are confirmed.
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.
Practical geology and the natural environment of Man—I Continents and islands
Authors: DUNHAM KINGSLEY CHARLES
Published: October 2009

The recent grouping of geology and the related disciplines as environmental sciences for official purposes suggests a closer relationship to human ecology than is sometimes recognized. The events leading up to the formation of the Natural Environment Research Council are reviewed. Note is taken of the revolution in instrumentation and research which has flowed from Government support, and of the substantial increases in the staffs of universities and research establishments. It is claimed that support for the earth sciences can be justified in terms of practical results. Theoretical and practical advances are still largely based on geological and geophysical surveys, yet a consideration of the published map cover shows how inadequate is knowledge of the world environment on any but the smallest scale. Practical achievements of geology, geophysics and geochemistry are briefly reviewed as applied to ground-water, fuels, ores, industrial minerals and engineering. It is suggested that the role of the Society should be to provide a forum for discussion of useful as well as fundamental research.
The structural and metamorphic history of the Lower Palaeozoic rocks of central Murrisk, County Mayo, Eire
Authors: DEWEY JOHN FREDERICK
Published: October 2009

The Ordovician and Silurian rocks of central Murrisk possess a common post-Wenlock, pre-Viséan metamorphic and tectonic sequence, during the development of which a complex history of recrystallization and deformation was associated with the growth of a relatively simple major structure. Five phases of deformation, excluding faulting, affected the region. An early phase of buckling, flattening and variable stretching with the development of slides and great fold-plunge variation was succeeded by a phase of essentially plane strain during which a complex plunge and facing geometry was developed. The third deformation consisted of the growth of generative folds with vertical east–west axial surfaces and was succeeded by the development of strain-slip and crenulation cleavages. The fifth phase of deformation was an east–west axial shortening with the development of steeply plunging kink-bands.
Some aspects of the Caledonian geosyncline and foreland west of the Baltic Shield
Authors: STØRMER LEIF
Published: October 2009

In the Scandinavian Caledonides a eugeosyncline is well developed while a miogeosyncline is only known in a few localities, possibly because this structure is concealed by covering nappes from the eugeosyncline. Both in the western and eastern facies of the eugeosyncline faunas with an American (Appalachian) aspect prevail. The foreland sediments, well demonstrated in the Oslo Region, show repeated invasions of arenaceous sediments apparently from the western part of the foreland and from the geosyncline. Certain sedimentary cycles are suggested. The floras and faunas are partly Baltic, British and American. A considerable thickness of sediments towards the end of the Silurian indicate the formation of a syneclise reaching from the Oslo Region via Scania to the Baltic. The ‘Faltungsgraben’ and Devonian ‘cuvettes’ in western Norway and Scotland are interpreted as similar, but more trough-like depressions (Aulacogenes).
The felsites, granophyre, explosion breccias and tuffisites of the north-eastern margin of the Tertiary igneous complex of Rhum, Inverness-shire
Authors: DUNHAM ANSEL CHARLES
Published: October 2009

The explosion breccia of the north-eastern margin of the Tertiary complex has a steep northern contact but turns into a sheet to the south. It consists of blocks of either Torridonian or Lewisian age set in a groundmass of the same comminuted material. The tuffisites occur as thin sheets with varying attitude and consist of Torridonian fragments set in a comminuted matrix with blebs of devitrified glass. The felsites are closely associated with the explosion breccia whereas the granophyre cuts unbrecciated country rocks. The mineralogy and chemistry of the felsites and granophyre are shown to be very similar, and are believed to have crystallized from the same magma intruded into different environments. The evolution of the explosion breccias, tuffisites, felsites and granophyres is believed to be closely connected. Firstly it is suggested that the acid magma was generated by partial fusion of the Lewisian country rock; evidence coming from the nature of the thermal metamorphism in the presently exposed Lewisian, the general composition of the gneiss and the presence of a suitable heat source (the basic magma chamber responsible for the accumulative ultrabasic rocks). Secondly, the country rock is believed to have sunk slightly on an underground cauldron subsidence. The escape of volatiles from the acid magma into the breccia zone formed the explosion breccia. The tuffisites may have originated by a fluidization process within cone-sheet-like fractures, the transporting medium being largely water vapour from the acid magma chamber. Finally, the felsites and granophyre are probably different portions of the same magma. The felsite magmas were intruded into the explosion breccias, where they quickly lost their volatiles and chilled, whereas the granophyres were intruded into unbrecciated country rocks and cooled more slowly. Identical oscillatory zoning in plagioclase in both granophyre and felsite, is believed to have formed by relief of pressure, possibly when volatiles were escaping from the magma chamber to form the explosion breccias and tuffisites.
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.
Isotopic age-determinations of rocks and minerals from the British Isles, 1966
Authors: SABINE PETER AUBREY , WATSON JANET VIDA
Published: October 2009

This publication is the third of a series providing abstracts of recent papers dealing with isotopic age-determinations of rocks and minerals from the British Isles. Abstracts of seventeen papers are given, including records of the localities and geological relationships of the dated samples, together with details of the methods employed and the authors’ conclusions. A brief introduction and indexes (by P. A. Sabine & J. V. Watson) are supplied.
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.
Compositional variation of minor intrusions and the form of a volcano magma chamber
Authors: BAKER I. A. N.
Published: October 2009

A number of highly alkaline parasitic bodies and dykes within the south-western basaltic shield volcano on Saint Helena belong to a late intrusive phase. The rocks exhibit systematic compositional variation from phonolite in the central area, outwards through trachyte to trachybasalt. This variation is interpreted as resulting from the tapping of a differentiated magma chamber by a number of independent dykes and parasitic intrusions. The chamber was tapped at varying depths dependent upon the horizontal distance of the individual intrusion or dyke from the apex. The most basic intrusive rocks therefore occur furthest from the centre. The dimensions and volume of the chamber are estimated.
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.
Palaeontological and geochemical facies in the
Gastrioceras subcrenatum
marine-band and associated rocks from the North Crop of the South Wales Coalfield
Authors: BLOXAM THOMAS WALLACE , THOMAS RICHARD LYNN
Published: October 2009

Vertical sections through the
Gastrioceras subcrenatum
marine-band and associated shales exposed at three different localities on the North Crop of the South Wales Coalfield have been studied palaeontologically and geochemically. On the basis of quantitative palaeontology four palaeoecological phases are distinguished which are related to marine transgression and regression.
Lingula
can be divided into two types: those associated with goniatites and bivalves are considered to be marine, and the other type, without goniatites or bivalves, brackish. Differences in the chemical composition of the shales, after correcting for detrital quartz, can be correlated with the palaeoecological phases. Offshore sediments are characterized by higher amounts of organic carbon, carbonate, sulphur, phosphorus and uranium, together with smaller amounts of quartz. Most of the uranium is contained in organic material and collophane, while thorium occurs mainly in the clay fraction. Boron exibits a poor correlation with the palaeosalinities based on palaeontological criteria. The reasons for this are discussed. The amounts of detrital quartz, organic carbon, and the ratios of quartz to carbon, thorium to uranium, and sodium to potassium are shown to provide useful indicators of relative sedimentation rates. The quantitative distribution and type of fauna is mainly controlled by the sedimentation rate. Marine bivalve populations, like their modern representatives, exhibit a close relationship to the organic carbon content of the associated bottom sediments. While absolute values of redox potential during deposition of the shales cannot be determined, present variations in the ferric to ferrous iron and thorium to uranium ratios give some indication of relative differences. The depositional and post-depositional geochemical evolution of the shales has been controlled to a large extent by their organic carbon content.
The evolution of the volcanoes of Aden and Little Aden, South Arabia
Authors: COX KEITH GORDON , GASS IAN GRAHAM , MALLICK DONALD IVOR JOHN
Published: October 2009

Along the south coast of Arabia, between the town of Aden and the southern entrance to the Red Sea, there are six central-vent volcanoes of Miocene-Pliocene age. The degree of erosion is ideal, and the abundance of exposures makes detailed structural and evolutionary studies possible; data are presented for the three easternmost cones, those of Aden, Little Aden and Ras Imran. Each volcano evolved through a complex cone-building stage during which the predominant rock types were trachybasalt, trachyte and peralkaline rhyolite. This was followed by periods of caldera formation during which trachyandesites, trachytes, and peralkaline rhyolites were erupted. A final stage of parasitic activity included small amounts of olivine-tholeiite amongst the eruptive products.
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.
The sedimentology and palaeoecology of the Devonian of the Ferques inlier, northern France
Authors: WALLACE PEIGI
Published: October 2009

The geology and environmental history of the Devonian of the Ferques inlier are discussed. The basal Devonian is of Givetian age and lies unconformably on Upper Silurian black shales. It is of Old Red Sandstone facies, but passes upwards into the marine deposits of a shallow shelf, in which an alternation of biostromal and lagoonal sediments occur. The sea shallowed towards the end of the Devonian, with the uppermost Frasnian and the Famennian represented by mud and sand flats. The changing environments of this region of the Devonian shelf are discussed in detail.
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.
Quaternary sediments off south-east Devon
Authors: CLARKE RICHARD HEDLEY
Published: October 2009

Non-marine, intertidal and inshore-marine deposits have been recognized in 43 gravity cores collected from the sea-bed off south-east Devon; at least eight of these cores end in bedrock (New Red Sandstone). Foraminiferal assemblages were used as criteria to distinguish several depositional environments. Pollen analyses of intertidal muds, which were apparently deposited along the margins of a now-submerged extension of the Exe river channel, have dated the Flandrian transgression in the region between —140 ft and —55 ft
o.d.
(zones IV-V to VIc). The rate of sea-level rise was about 5 ft/century during zone VI. An extensive deposit of muddy sand covers the intertidal deposits and the old land surface, and was probably laid down in the sublittoral zone, seawards of the transgressive Flandrian shoreline. Authigenic pyrite and glauconite are found in several sedimentary types; their distribution in the muddy sand indicates that the glauconite is syngenetic, while the pyrite has formed during the early stages of diagenesis.
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.
The consolidation of clays by gravitational compaction
Authors: SKEMPTON ALEC WESTLEY
Published: October 2009

Sedimentation compression curves, relating void ratio to effective overburden pressure, are presented for a wide lithological range of argillaceous deposits. These curves show the progressive changes from recently deposited muds on the sea floor, to Quaternary clays at depths of several tens of metres, and finally to hard clays and mudstones of Pliocene age at depths extending to about 3 000 m. Twelve localities are examined in some detail and information is also given from another eight previously published sites. In all cases the data are derived from ‘normally-consolidated’ deposits, strata which have never been under greater pressures than those existing at the present time. This procedure eliminates the difficulties of estimating the effect of pressure reduction by erosion. Clays containing high proportions of carbonates and organic matter are not included in this study.

The water content (or void ratio or porosity) of any particular clay in the normally-consolidated condition is controlled by the effective overburden pressure
p
0
, given by Terzaghi's law
p
0
=
σ − u,
where
σ
is the total vertical pressure exerted by all the material (particles and water) above the point considered, and
u
is the pore water pressure at that point. This law is shown to hold good even at porosities as low as 15 per cent.

At any particular effective overburden pressure the water content of a normally-consolidated clay is directly related to the amount of clay minerals present and to their colloidal activity. The combined influence of these two factors can be indicated quantitatively by the Atterberg limits; and at a given value of
p
the water content is found to be a function of the Atterberg (liquid and plastic) limits for all inorganic non-calcareous clays except those with an extremely unstable microstructure, such as the so-called ‘quick clays’ of Scandinavia. Moreover, the water contents of muds on the sea bed or in tidal flats can also be expressed approximately by single-value parameters in terms of these limits. Thus if the water content, effective overburden pressure and Atterberg limits are known for an individual layer of normally-consolidated clay, it is possible to reconstruct the entire sedimentation compression curve for that clay with a reasonable degree of certainty; and hence an estimate can be made of the compaction which has occurred in the clay under its own weight and under the load of any overlying strata.

At some of the sites, in addition to data relating to compaction, information is given on the increase in strength with depth and the rate of deposition as deduced from radiometric dating.
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.
Correlation of the younger Triassic rocks across eastern England
Authors: BALCHIN DAVID ALAN , RIDD MICHAEL FREDERICK
Published: October 2009

The younger Triassic rocks of eastern England, traditionally called the Keuper Series, have been correlated in boreholes between Tetney Lock, on the Lincolnshire coast, and the South Nottinghamshire outcrop. In addition the correlation has been extended to Burton-upon-Stather in North Lincolnshire. Wire-line geophysical logs have been the chief means of correlation. The log markers are sub-parallel to the base of the Rhaetic and, excepting the onlapping Keuper-Bunter contact, they are believed to be close approximations to synchronous horizons. The Keuper Sandstone (
Sherlock 1947
) of the Nottingham area dies out toward the north-east and it is markedly diachronous. A dolomitic facies in more north-easterly boreholes pinches out toward the outcrop and it also is diachronous.

The Muschelkalk time-equivalent recognized by Geiger & Hopping (1968) in the Tetney Lock borehole correlates with at least the upper part of the Waterstones, the Radcliffe and the lower half of the Carlton Formations at outcrop
•
Thus the lowermost beds of the British Keuper Series—the Woodthorpe Formation and possibly part of the Waterstones Formation—are the correlatives of the upper Buntsandstein of Germany, whilst the correlative of the German Keuper is restricted to that part of the British Keuper Series above the middle of the Carlton Formation. A new rock-stratigraphical unit, the Nottingham Group, is proposed to replace the name Keuper Series in eastern England.
The Triassic succession in the central Midlands in its regional setting
Authors: WILLS LEONARD JOHNSTON
Published: October 2009

Recent deep boreholes in a small area near Bromsgrove and Droitwich in the Worcester Basin of Triassic times have provided a virtually complete Triassic succession, 3350 ft thick, which displays cyclic desert-sedimentation throughout, although the cyclothems differ in the three main rock groups. The sequences proved in many other borings in Worcestershire, Birmingham and Warwickshire, and a few in other parts of the central Midlands, are taken into account, subjected to cyclic analysis, and the results collated
•

The implications of cyclic sedimentation for local and regional correlation are discussed in the light of known flora and fauna, and the outcome is illustrated by palaeogeographical maps of Britain and also of north-west Europe.