bluuebunny/crossref_metadata_2025 huggingface dataset:
A forward look for the Institute of Geological Sciences in Scotland
Authors: DUNHAM KINGSLEY , ROBBIE JAMES
Published: December 2007

A
hundred years
ago, Andrew Crombie Ramsey as Director-General of the Geological Survey and Archibald Geikie as Director for Scotland, had a great prospect before them. The progress of the survey in Scotland as indicated by the publication of one-inch geological maps, had lagged considerably behind that in England, Wales and Ireland where primary one-inch publication was already half completed. In Scotland, only the sheets around the Firth of Forth, and two sheets (one mainly sea) south of the Clyde had been issued. The survey of the western part of the Midland Valley was in progress, to be extended south across the Southern Uplands; the Highlands remained virtually untouched until after 1880.

Geikie was, however, already well acquainted with the two great problems with the solution of which his name and general directorate will always be associated: the tectonic history of the North-West Highlands and the volcanic history of its west and midland regions. If these formed the major items in Geikie’s forward programme, there were a host of other major discoveries to come: the metamorphic zones in the Central Highlands (George Barrow); the unravelling of the structure of the slate and greywacke country of south Scotland, strongly influenced by Lapworth’s great work at Moffat and Girvan; the interplay of facies, structure and volcanism in the central rift valley; the cauldron subsidence and ring structures of Glencoe and the volcanic centres of Arran and the Inner Hebrides (Gunn, Maufe, Bailey, Thomas, Richey); the spectacular transcurrent shift of the Great
Palaeocology: has the study of past life got a future?
Authors: AGER DEREK
Published: December 2007

F
or students
and staff alike, palaeontology is probably the least popular subject taught in university geology departments. The bewildering babel of binomens and the frustrating flood of facts produce an antipathy that is both understandable and, in a sense, unavoidable. What is more, this all belongs in the unfashionable realms of observational science, which is not science at all. The inevitable temptation for the lecturer, therefore, is to play to the audience, to pick out the titillating titbits, the exciting ideas, however shallow their roots may be in the subsoil of scientific fact.

It is largely for this reason that palaeoecology has become very popular in the last decade. It brings the fossils to life; coupled with its aura of scientific method it encourages field studies, it seems to be all the more interesting and
easier
than the slow and patient study of morphology and systematics. Ay, there's the rub, for along that primrose path lies the trend towards the everlasting bonfire of super-ficial, airy-fairy hypotheses and over-generalization. As one who has done his best to encourage the study of palaeoecology, I cannot help but feel somewhat guilty about this trend. But to defend myself, let me quote a passage from the introduction to my book on palaeoecology (1963, p. 5):

“I maintain strongly that every young palaeontologist should have fundamental training in the careful examination and description of fossils. This is essential not only for altruistically taking one's share of the vast task still before us but also because
Geomorphology—a study which spans the geology/geography interface
Authors: CLAYTON KEITH MARTIN
Published: December 2007

T
he interfaces
between disciplines blossom out from time to time as major fields of development, growing at times into subjects in their own right, on other occasions as less formal areas of interdisciplinary activity. At other times these appear to be frontiers rather than interfaces, shunned by all but the colonizers of the pioneer fringe as each of the subjects involved draws in on it self, seeking strength through a focus of activity within the core of its academic field.

At the beginning of the century, the study of geomorphology was developing from an intellectually sound basis in the work of G. K. Gilbert and others who had been able to gain an adequate understanding of landscape development from their exploration of the American west. In addition, at the school and under- graduate level, W. M. Davis devised a clever abstraction of reality which he called the Geographical Cycle. Whatever later abuse may have been heaped on Davis, his approach was timely and effective and aided the creation of an interesting and stimulating subject, widely taught within the curriculum of both geography and geology for perhaps a quarter of a century. For a number of reasons, the study of geomorphology gradually declined in the geology curriculum in the United Kingdom and many countries in Europe, and in geography in the United States. This abandonment of geomorphology has been paralleled by a corresponding decline in the relative significance of the subjects at University level. The connection is unlikely to have been a direct, causal one, but it is suggested that the neglect of geomorphology is one symptom of a general withdrawal from the frontiers of a subject, and that as the discipline becomes more restricted in scope, so its attraction to a wide group of potential students declines. After all, in the United Kingdom the withdrawal from geomorphology has been matched by a neglect of geophysics and by repeated emphasis of the virtues of the central concern of a ‘pure’ geology. In the same way, in the United States, geography lost interest in field evidence as well as turning its back on geomorphology, and sought strength from the core material of cultural landscape and natural region. This neglect of the intellectual ground between geography and geology has been to the disadvantage of the subjects themselves, and has seriously affected progress in geomorphology. Here is a most difficult topic, one in which it is extremely easy to make major errors of interpretation which then persist un- checked for decades. Through neglect by at least one of the adjacent subjects, the number of people that might have been involved in geomorphological research has been cut almost by half. Further, when geomorphology is introduced into teaching or applied in research by those who do not treat it as a main concern, it is often treated superficially and inaccurately, its complexities unrecognised
The oceanic affinities of some alpine mafic rocks based on their Ti-Zr-Y contents
Authors: BICKLE MICHAEL JAMES , NISBET EUAN
Published: December 2007

Ophiolite-Chert complexes containing ultramafics, mafic dykes and pillow lavas, overlain by radiolarian cherts and other pelagic sediments are significant features of mountain belts, especially in the Alpine-Himalayan chain (Vine & Hess 1970), and in the Caledonides (

Bird
et al.
1971

). The sedimentology and fauna of the cherts and the similarity of the igneous succession with inferred oceanic igneous structure are consistent with the hypothesis that these complexes are tectonically emplaced fragments of oceanic crust and upper mantle (Vine & Hess 1970). Elsewhere in orogenic belts, mafic rocks of oceanic aspect are frequently found without the full ophiolite succession being present. Although these are broadly similar to oceanic mafic lavas it has not proved possible to establish the genetic affinities of such rocks by their major element chemistry (
Vallance 1969
).

It has recently been proposed that the genetic affinities of basaltic rocks may be distinguished by the ratios of the three elements, Ti, Zr and Y which have been shown to be insensitive to alteration affecting major elements during metamorphism up to greenschist facies (
Cann 1971
; Pearce &
Cann 1971
). Five magma types (number of analyses given in parentheses) have been considered by Pearce & Cann; island arc andesites (12), island arc tholeiites (14), ocean island alkali basalts (8), ocean island tholeiite basalts (13) and mid-ocean ridge basalts (39). Using discriminant analysis they constructed functions in Ti, Zr and Y which distinguished these lava types. Analyses were by X-ray fluorescence on pressed powder pellets. On this basis, samples of supposed oceanic rocks
Wealden detrital tourmaline: implications for northwestern Europe
Authors: ALLEN PERCIVAL
Published: December 2007

Wealden detritus in S England and NW France suggests ultimate derivation from an ancient complex. This had affinities with present-day Cornubia, Armorica and NW Iberia, which apparently represent its relict flanks. Westwards, lay a Cadomian-Caledonian core. Repeated tourmalinizations occurred from pre-Cambrian times onward. These were postdeformational and may have followed separate orogenies. Geographically, the massif probably focussed on what is now the continental margin, over the Southwestern Aproaches. Structurally, it was the Cadomian-Hercynian-Galician-Caledonian convergence. Eastwards the hills diverged to encompass a lowland depression, divided into northern and southern basins by the Cornubian island. After the first sediment arrived in the ?Permian there were important fluctuations of supply and composition during the late Trias/early Jurassic, late Jurassic/early Cretaceous and Hastings Beds/Weald Clay. These may have been related to movements of the massif generated by changes in North Atlantic spreading rates and opening of Biscay.
The Mozambique orogenic belt and its foreland in northeast Tanzania: a photogeologically-based study
Authors: HEPWORTH JOHN VORD
Published: December 2007

The tectonic relationships within a rather large part (130,000 sq. km) of the Mozambique orogenic belt in N.E. Tanzania were investigated by photogeological interpretation and ground control Within the granitoid foreland (part of the Tanganyika Shield) the Dodoman and Nyanzian Greenstone belts, and charnockitie granulites are recognized. These were intruded and replaced by the chelogenie Katarchaean granite.

Within the orogenic belt pre-Mozambiquian gneisses (termed Parangan) are exposed at the western margin, and in the floor of the orogen. These were tectonically reworked and transformed into L-tectonites and flaggy gneisses in the main Mozambiquian tectonism (termed Kondoan): this took place by strong folding about south-easterly-plunging axes, the folds being characteristically reclined.

It is observed that structures transverse to the regional trend are a feature of other orogenic fronts such as the Grenville and Caledonian. In Tanzania they are succeeded by flexure folds on nne axes (termed Bongan), which locally become the predominant structures, parallel to the regional trend. In the north they are overturned towards the foreland and over-ride it.

The Mozambiquian tectonism deforms the margin of the Shield and may penetrate it for considerable distances, perhaps contributing to the deformation in the Greenstone belts.
The Gipping Till: a reappraisal of East Anglian glacial stratigraphy
Authors: BRISTOW CLEMENT ROGER , COX FRANK CHARLES
Published: December 2007

The proposed interpretation of Pleistocene stratigraphy, which results from recent 6-inch geological surveys in the Chelmsford and Norwich areas is at variance with generally accepted correlations relating to the drift deposits of East Anglia. The evidence for the existence of the Gipping Till and its associated glaciation is critically examined. It is concluded that widespread chalky boulder clay was formed during only one glacial episode. It is also suggested that the Hoxnian and Ipswichian deposits in East Anglia are closer in time than has been thought hitherto, and that the main glaciation of East Anglia is the penultimate (Wolstonian).
Heterogeneous deformation in the development of the Laxfordian complex of South Uist, Outer Hebrides
Authors: COWARD MICHAEL P.
Published: December 2007

Four phases of heterogeneous deformation (
f
1
to
f
4
) are distinguished within the Laxfordian episode of regeneration of the Lewisian gneiss complex of South Uist. The variation in amount of deformation has been examined with respect to three of the Laxfordian fold phases, especially
f
3
and
f
4
, and apparent relationships between the strain heterogeneities and both the original nature of the rock and the syntectonic metamorphic conditions have been observed. The heterogeneities of the
f
3
deformation appear to be related to the forms of the large scale
f
3
structures that are characterized by broad open antiforms and tight synforms. These owe their form, in part, to the strains set up during the buckling of an interface between competent rocks below and less competent rocks above. Heterogeneities in the
f
4
deformation are closely related to variations in the intensity of the syntectonic metamorphism; intense
f
4
deformation is closely associated with migmatisation and granitisation. Possibly intense
f
4
strain may result from localised variations in ductility caused by a local thermal high.
The biostratigraphy of the Silurian rocks of the Girvan District, Scotland
Authors: COCKS LEONARD R. M. , TOGHILL PETER
Published: December 2007

The Silurian biostratigraphy of the Girvan area is reviewed. Of the 23 Silurian formations, 7 have abundant shells and 14 have common graptolites. The Silurian is nearly 3000 m thick and was chiefly deposited in a turbidite environment. All the Llandovery zones from
cyphus
to
crenulata
inclusive are represented by graptolite faunas. In the Rhuddanian (prior to the
cyphus
Zone) the Lady Burn Conglomerate, Mulloch Hill Formation and Woodland Formation are shelly facies laid down by a marine transgression. There are two stratigraphical breaks, the unconformity at the base of the Silurian sequence and in the Fronian, where there is a paraconformity underneath the Lower Camregan Grits, both breaks with a transgressive sequence of animal communities above them. At the top of the succession Lower Wenlock turbidites, bearing shells at their bases, are followed by a sparse ostracodbivalve assemblage representing brackish or even fresh water conditions, culminating in ‘Old Red Sandstone’ facies beds of presumably Wenlock age, all representing the marine regression seen in other inliers in the Midland Valley of Scotland. Remarkable fossil finds from the Llandovery include
Stomatograptus grandis girvanensis
subsp, nov.,
Monodimacis crenulata
itself, and the only chonetid brachiopod known anywhere from the Rhuddanian or Idwlan.
The geological interpretation of a gravity survey of the Bristol Channel
Authors: BROOKS MICHAEL , THOMPSON MARTIN S.
Published: December 2007

A Bouguer anomaly map of the Channel and surrounding land areas is presented and interpreted. The main features of the map are: (1) a negative anomaly approaching –20 m-gal trending
wnw
across the southern half of the Channel and adjacent areas of west Somerset and north Devon; (2) a broad flanking area of weak positive anomaly in the northern part of the Channel which may extend southeastwards across the Cothelstone fault into Bridgwater Bay; and (3) a local positive anomaly of over +20 mgal around Lundy Island. These anomalies are all superimposed on a strong regional gradient of +0.38 mgal km
−1
to the southwest.

The negative anomaly in the southern part of the Channel is due partly to Mesozoic strata in the Bristol Channel syncline but partly to underlying, low density, Upper Palaeozoic rocks which are probably preserved in a structural basin similar to the South Wales coal basin but overthrust by the Devonian succession of Exmoor. The parallel belt of positive anomaly in the northern half of the Channel is interpreted as overlying an anticlinorial zone, characterized by Old Red Sandstone at shallow depth, separating the South Wales coal basin to the north from the postulated basin to the south. The positive anomaly around Lundy Island is attributed to the effect of a large basic pluton of Tertiary age occurring at shallow depth, and the gravity field of Lundy is compared with that of other Tertiary igneous centres. A sketch structural section across the Bristol Channel is presented.
Geochronological investigation of the quartzofeldspathic rocks of the Lewisian of Rona, Inner Hebrides
Authors: LYON THOMAS D. B. , PIDGEON ROBERT T. , BOWES DONALD R. , HOPGOOD ALARIG M.
Published: December 2007

Rona Island consists of Lewisian quartzofeldspathic gneisses and amphibolites that show the effects of polyphase deformation. The age of the gneisses, from a six point Rb-Sr whole rock isochron, with λ
87
Rb 1.39 × 10
−11
yr
−1,
is 2790 ± 210 m.y. This is not significantly different from the age of 2710 ± 20 m.y. determined from zircon fractions from a single block of the gneiss. These results are interpreted as reflecting amphibolite facies metamorphism and gneiss formation, associated with the first recognized fold phase, during the Scourian orogenic episode

A Rb-Sr age for unaltered muscovite books from a pegmatite emplaced in the hinge zone of a fold of the third deformational phase is 1740 ± 10m.y. and a Rb-Sr whole rock isochron for a later granite sheet, emplaced between the fifth and sixth fold phases is 1680 ± 170 m.y. These igneous events, and the fold phases between them, belong to the later part of the Laxfordian orogenic episode. No isotopic disturbance of the Rb-Sr whole rock systems of the analysed gneisses has taken place during the Laxfordian episode and no isotopic events between the
c
2700 m.y. and
c
1700 m.y. episodes have been found in the quartzo, feldspathic rocks. K-Ar ages on the muscovite samples suggest minor opening of minerals to argon loss sometime after 1740 m.y.
Structural zones of the Variscan fold belt in SW England, their location and development
Authors: SANDERSON DAVID J. , DEARMAN WILLIAM R.
Published: December 2007

The D
evonian
and Carboniferous strata of SW England were deformed during the Variscan orogeny. Differing amounts of polyphase deformation imposed upon rocks of differing rheological character gave rise to a variety of attitudes and styles of folding. The present account attempts to outline the location and development of structural zones within which the attitudes of folds are constant.

Dearman (1969a)
suggested a zonal scheme based on the recognition of areas of upright primary folds passing southwards into inclined and recumbent folds on the north Cornish coast between Bude and Padstow. Continuity of this arrangement of structures eastwards to the western margins of Dartmoor can be demonstrated (Dearman 1971a). The zone of recumbent folding was extended, without subdivision, into south Cornwall.
Simpson (1970)
, recognising a zone of upright folding to the south of Brixham in south Devon, correlated this with the inclined folding in the Newquay area and thus subdivided the southern zone of recumbent folds. A line between Brixham and Newquay separates recumbent folding to the north from upright or inclined folding to the south, but this simple subdivision is unsatisfactory as recumbent first phase folds (
F
1
) are common in the Mylor and Gramscatho Beds to the south of Perranporth (
Smith 1965
). Neither zonal scheme, based solely on the attitude of fold axial planes, attempts to separate the north facing primary folds of south Cornwall and south Devon from the south facing primary folds of north Cornwall.

In a discussion of the spatial relationships of the folding the following criteria
Siluro-Devonian thelodonts from the Welsh Borderland
Authors: TURNER SUSAN
Published: December 2007

Silurian, Downtonian and Dittonian strata from the Welsh Borderland contain a succession of thelodonts (Agnatha). Isolated scales have been identified and a new species,
Apalolepis toombsi,
is described. Four scale assemblages are recognized:
Turinia pagei
in Dittonian;
Goniporus/Katoporus
in U. Red Downton Group; Acanthodians (thelodonts absent) in Holdgate Sandstones Group and
Thelodus parvidens
in the Silurian—Lower Red Downton Group.

The
Thelodus parvidens
assemblage occurs above and below the Ludlow Bone Bed, which, on the basis of the thelodonts, does not correspond to a major break in the succession. The incoming of the
Turinia pagei
assemblage at the beginning of the Dittonian marks a principal faunal change, and this can be correlated with the N. German Beyrichienkalk erratics, and the Polish-Lithuanian and Spitsbergen sequences.

Comparison of the Welsh Borderland thelodont succession with that of Scotland, Europe, Russia and Canada suggests the existence of distinct faunal provinces, influenced by palaeogeography.
The Lewisian of Lochinver, Sutherland; the type area for the Inverian metamorphism
Authors: EVANS CALVIN R. , LAMBERT RICHARD ST J.
Published: December 2007

The Lochinver district contains gneisses, pegmatites and dykes generated in five main episodes: (1) pre-2600 m.y, garnet pyroxene granulite facies gneisses with low angle dips, formed in their final state by the Badcallian metamorphism; (2) potash-rich pegmatites of age range 2540 to 2310 m.y.; (3) 2310–2200 m.y. amphibolite facies gneisses occurring in vertical WNW zones, produced by a broadly isochemical metamorphic event; (4) vertical NW-trending dykes emplaced at 2200 m.y. and perhaps down to 1900 m.y. and (5) epidoteamphibolite facies gneisses produced in narrow, discontinuous NW shear zones during the succeeding Laxfordian events. The petrographic and structural features of each sector of the complex are described and new whole rock Rb–Sr ages given for the pegmatite suite, suggesting a maximum age of 2540 m.y. for the suite (plus intrusion of a further suite at 2310 m.y. or recrystallisation of the first suite at 2310 m.y.). Other pegmatite ages confirm the presence of pre-2000 m.y. activity NE of Scourie and at Gruinard. Field and petrographic evidence at Lochinver demonstrates the existence of amphibolite facies metamorphism in post pegmatite pre-dyke times, which produced well-defned rock types and WNW vertical structures, and is defined as the Inverian metamorphic event.
The emplacement of a high temperature peridotite in the Seiland Province of the Norwegian Caledonides
Authors: BENNETT MICHAEL C.
Published: December 2007

The Reinfjord ultramafic complex, an orogenic peridotite, was emplaced near the margin of an extensive sheet of two pyroxene gabbro during an early phase of the Caledonian orogeny. The complex is cylindrically zoned and consists of a dunite core with high Mg/Fe ratios which is separated from lherzolitic marginal zones with relatively low Mg/Fe ratios by a series of layered wehrlites with intermediate Mg/Fe ratios. Igneous textures are developed throughout, and the layering is shown to be of magmatic origin. Contact relationships confirm the high temperature of the intrusion and show that melting and assimilation of both metasediment and gabbro occurred. The composition of hybrids so formed, the formation of sills consisting of layered peridotite and the development of coeval ultrabasic veins all suggest that the rocks crystallized from melts of ultrabasic composition. Multiple intrusion of ultrabasic magmas and reaction with wall rocks explain the evolution of the complex. Confining pressures of 6–8 kb (20–30 km depth) were operative during intrusion and the magmas involved could have existed at temperatures as low as 1300°C. The implications of this for the evolution of the Seiland province are discussed.
Silurian microfossils from west of the Leinster Granite
Authors: BRÜCK PETER M. , DOWNIE CHARLES
Published: December 2007

The upper part of the Lower Palaeozoic sequence west of the Leinster Granite in eastern Ireland is shown, by means of chitinozoa, to be Llandovery in age, with some of it perhaps younger. These Silurian rocks are part of a turbidite succession which extends down to the lower Ordovician west of the granite and down to the lower Cambrian on the east.
The development of vein and rock textures by tensile strain crystallization
Authors: PHILLIPS WILLIAM J.
Published: December 2007

The characteristics of fibrous veins of gypsum and other minerals are described and it is concluded that the growth of the fibres kept pace with the dilation of the veins because fluid pressures were in excess of lithostatic pressures but less than the combined lithostatic pressures and tensile strengths of the fibres. Crystallization in the regions of greatest tensile strain in the fibres would be promoted by the greater probability of atoms being accommodated in the crystal structure. The free energy associated with the crystal dislocations which are likely to be concentrated in these regions would contribute to the crystallization process and allow it to proceed at very low levels of supersaturation. Crystallization during tensile strain explains the common occurrence of strain effects such as undulose extinction and dislocation planes in fibrous crystals.

It is suggested that polycrystalline aggregates may deform under triaxial stress by pressure solution of the grains on planes approximately perpendicular to the direction of greatest stress and simultaneous crystallization of elongate crystals in the direction of maximum extension from the points of concentrated tensile strain. Tensile strain crystallization may be an important mechanism in the development of penetrative preferred orientations in metamorphic rocks.
Geological structure of the Malin Sea
Authors: DOBSON MAXWELL R. , EVANS DANIEL
Published: December 2007

Geophysical surveys in the Malin Sea have revealed the presence of two asymmetric fault bounded basins, here termed the Loch Indaal basin and the Rathlin trough. They extend in a NE–SW direction between Northern Ireland and Western Scotland, and are thought to be largely Permo-Triassic in age. Four major fault belts have also been identified, together with a large number of igneous bodies, the latter having been confirmed by dredge sampling. In addition the offshore extents of the Fanad and Thorr Plutons have been delineated.
Precambrian and Palaeozoic pegmatites in the Moines of northern Scotland
Authors: VAN BREEMEN O. , PIDGEON R. T. , JOHNSON M. R. W.
Published: December 2007

Thirty-four Rb-Sr isotope dilution analyses on muscovite books as well as four U-Pb zircon and monazite analyses demonstrate two distinct episodes of pegmatite emplacement in the Moines at 730 ± 20 m.y. and 450 ±10 m.y. (λ
87
Rb = 1.39 x 10
−11
y
−1
)
. Confirmation of the Precambrian episode comes from a detailed Rb-Sr study on muscovite books from the Carn Gorm pegmatite in Central Ross-shire and from the concordance of Rb-Sr muscovite and U-Pb zircon ages from two pre-F2 pegmatites from the hornblende anorthite zone of
Kennedy (1949)
11 km west of Glenfinnan in western Inverness-shire. Palaeozoic pegmatites were measured from Loch Monar in central Ross-shire and from occurences in the Moines east of the western tip of Loch Eilt in the Glenfinnan area.

Near Glenfinnan Rb-Sr analyses on cross-cutting pegmatites yield an age of 445 ± 10 m.y. for a suite of post F3 lamprophyres. An older age limit for the F3 deformation is provided by a 450 ±10 m.y. monazite age from a post F2 to pre-F3 pegmatite. Both isotopic and geological evidence is presented for a post Arenig pre-450 ± 10 m.y. age for the second deformation in the Moines. Structural correlations in the Moines are briefly discussed as well as the evidence for two orogenic events corresponding in age to the episodes of pegmatite emplacement.
New isotopic age data on rocks from the Long Mynd, Shropshire
Authors: BATH ADRIAN H.
Published: December 2007

New Rb–Sr isotope data on fine-grained sediments from the Long Mynd, west of the Church Stretton Fault in Shropshire, indicate a much younger age for these rocks than has been assumed in recent literature. Well-defined isochrons, one of which corresponds to an age of 529 ± 6 m.y. with an initial
87
Sr/
86
Sr ratio of 0.7061 ± 0.0001, put the depositional age of the Stretton Series (the stratigraphically lowest part of the sequence) at a maximum of 600 m.y.
Sediment distribution and Quaternary history
Authors: HAILS JOHN R.
Published: December 2007

The superficial sediments in Start Bay consist of three discrete lithological units, know as
barrier, bay
and
bank
deposits. Flint and quartz are the dominant constituents of the barrier deposits with small quantities of rhyolite, felsite and grantie. The bay deposits are mainly fine-grained sediments varying in thickness from about 1 m in the nearshore zone, as a result of winnowing by tidal currents and waves, to a maximum of 28 m in the middle of the Bay. The bank deposits consist of coarse shelly sand, are up to 18 m thick and are located within the general vicinity of the Skerries Bank.

Sedimentological and foraminiferal studies, together with C–
14
dates, show that barrier-estuarine-lagoonal environments existed seaward of the modern shoreline in the past and that barriers migrated landward in response to oscillations of sea level during the later stages of the Flandrian transgression.

Available evidence indicates that Start Bay is a
closed system
under present-day conditions. The influence of the Skerries Bank on wave refraction and energy dissipation along the coast has been assessed. The Hallsands disaster can be attributed to the legacy of dredging shingle from the inter-tidal zone, combined with a critical combination of storm waves, gales and spring tides.
Foraminiferida from Holocene sediments in Start Bay
Authors: LEES BARBARA J.
Published: December 2007

Two hundred and fifty two samples from 40 cores and 40 seafloor samples have been analysed using sedimentological and foraminiferid techniques. The results have been used to interpret the sedimentological history of Start Bay during the later phases of the Holocene marine transgression. They indicate the existence of a barrier–lagoon complex, with associated tidal marshes and rivers and an open sea environment c. 8000 years BP. With a continuing rise in sea level and accompanying barrier migration shoreward the Bay and coastline with enclosed freshwater lagoons were established. Geophysical evidence supports this hypothesis.
Quartile deviation-median diameter analysis of surface and core sediments from Start Bay
Authors: McMANUS JOHN
Published: December 2007

Quartile deviation-median diameter analysis is sufficiently sensitive to permit sectors of bed characterized by wave or current dominant sediments to be recognized. These may be related to modern conditions or to erosion of buried sub-recent deposits which cores indicate exist beneath the present seabed. Although only approximately 45% of the samples are unequivocally related to either set of dynamic conditions the divisions achieved suggest that the analysis technique has a value in the shallow marine environment.
A new concept of the evolution of the British Tertiary intrusive centres
Authors: WALKER GEORGE P. L.
Published: December 2007

An early event in the history of most or all of the intrusive centres in the British Tertiary province was probably the uprise to a high level of an acid diapir. This fact, combined with the idea that the relative densities of magmas and crust play a major role in the localisation of igneous intrusions, forms the basis for a new interpretation of the mechanism of formation of the intrusions and enables a model to be developed for the evolution of each centre.

Firstly it is postulated that the emplacement of cone sheets is governed by a tendency of rising magma to move in the direction of maximum excess hydrostatic pressure, P
He
(this being the amount by which the hydrostatic pressure in the magma exceeds the lithostatic pressure). It is suggested that the perturbation of surfaces of equal P
He
near a high level diapir of low-density acid magma can cause uprising magma to be diverted to form cone sheets instead of dykes. Secondly by a similar mechanism some batches of basaltic magma are diverted into a magma trap situated at the base of each diapir and there they gradually build up the great cylinder of basic intrusions the existence of which has been inferred from gravity anomalies. This cylinder marks the upward course of the diapir, and heat supplied by this basic magma aided its uprise.

A late stage in the development of an intrusive centre is the elimination of the diapir because of the escape of successive batches of acid magma from it in a near-surface environment. Subsidence then takes over as a dominant process and ring dykes are emplaced. Intrusions of bell-jar or “curved flange” type also occur and a mechanism involving downsagging of the basic cylinder is invoked for their emplacement.
Isotopic evidence for the age and origin of the “grey gneiss” complex of the southern Outer Hebrides, Scotland
Authors: MOORBATH STEPHEN , POWELL JAMES L. , TAYLOR PAUL N.
Published: December 2007

Rb-Sr and Pb/Pb whole rock isochrons for the “grey gneiss” complex yield typical Scourian ages of 2690 ± 140 m.y. and 2640 ± 120 m.y. respectively, probably dating Scourian metamorphism. Subsequent events (< 2100 m.y.) produced complete or partial loss of radiogenic
40
Ar from minerals, but left the whole rock samples closed systems to Rb, Sr, U and Pb. The suggestion of an early Laxfordian granulite facies event followed by regional retrogression to amphibolite facies is thereby rendered most unlikely.

Consideration of the initial
87
Sr/
86
Sr ratio for the grey gneiss complex of 0.7014 ± 0.0007, as well as of the Pb isotope ratios, strongly suggests that the precursors of the “grey gneiss’ complex were derived from upper mantle source regions not more than 100–200 m.y. prior to the Scourian metamorphism, and rule out the possibility that the complex represents the reworking of a significantly older gneissic basement complex with anything like normal crustal Rb/Sr ratios.
A new Tertiary basin east of Lundy Island
Authors: FLETCHER B. N.
Published: December 2007

Seismic profiling in the outer Bristol Channel has enabled the Sticklepath-Lustleigh fault zone of Devon to be traced offshore from Barnstaple Bay for at least 52 km to the NW. This fault, which passes 4·5 km E of Lundy Island forms the western margin of a large sedimentary basin. Five boreholes into this basin proved silts, mudstones, lignitic clays and lignites of middle to upper Oligocene age.
Geomagnetic reconnaissance on the continental margin of the British Isles between 54° and 57°
N
Authors: BAILEY R. J. , BUCKLEY J. S. , KIELMAS M. M.
Published: December 2007

Marine magnetic surveys reveal two important positive magnetic anomalies, coincident n location and trend with the continental margin. The form and spatial relationship of these and other positive anomalies suggest thay they represent two buried marginal ridges of metamorphic basement rocks with an intervening E.-W. fault at 56°N. The southern ridge is believed to terminate at 54° 50’N along an ENE.-WSW. line which could represent the offshore course of the Great Glen Fault. To the S., a subdued and generally negative anomaly pattern possibly implies a fault-bounded depositional trough occupying Donegal Bay.
Major early folds at the southern margin of the Culm synclinorium
Authors: HOBSON DAVID M. , SANDERSON DAVID J.
Published: December 2007

In N. Cornwall and mid-Devon major southerly facing recumbent F1 folds cause repetition of upper Devonian and lower Carboniferous stratigraphical sequences along the southern margin of the Culm synclinorium. At Tintagel on the N. coast, and near Lydford, close toDartmoor, there is evidence that large F1 folds, modified by later low-angle faults, control the outcrop pattern. Recognition of these folds demonstrates a continuity in structural style throughout N. Cornwall and mid-Devon
The stratigraphic distribution of conodonts in the British Silurian
Authors: ALDRIDGE R. J.
Published: December 2007

Llandovery and early Wenlock conodont faunas show high diversity and rapid evolution, and conodonts provide a valuable biostratigraphic tool for this interval. Wenlock, Ludlow and Downtonian faunas are of lower diversity and variability, but, with the exception of the lower Ludlow, abundances are fairly high and several species are useful in local correlation. The local geographic distribution of conodonts is affected by facies variation, and this is particularly marked in the upper Llandovery and lower Wenlock. Geographic restrictions on distribution are also evident on an international scale, and of the ten conodont zones defined in the Silurian of Europe only four
(the celloni, amorphognathoides, sagitta and eosteinhornensis
Zones) have been identified in Britain. However, several species that are of value in Britain have been widely recognized, and with further work, the promise shown by eonodonts for international correlation should be fulfilled.
Seismic pumping—a hydrothermal fluid transport mechanism
Authors: SIBSON R. H. , MOORE J. Mc. M. , RANKIN A. H.
Published: December 2007

A consequence of the dilatancy/fluid-diffusion mechanism for shallow earthquakes is that considerable volumes of fluid are rapidly redistributed in the crust following seismic faulting. This is borne out by the outpourings of warm groundwater which have been observed along fault traces following some moderate (M5–M7) earthquakes. The quantities of fluid involved are such that significant hydrothermal mineralisation may result from each seismically induced fluid pulse, and the mechanism provides an explanation for the textures of hydrothermal vein deposits associated with ancient faults, which almost invariably indicate that mineralisation was episodic.
A geophysical survey of the Turriff basin of Old Red Sandstone, Aberdeenshire
Authors: ASHCROFT W. A. , WILSON C. D. V.
Published: December 2007

A gravity survey of some 300 stations has been made over the Turriff outlier of Old Red Sandstone, Aberdeenshire. Two reversed seismic refraction lines, each 4 km long, were shot in the northern part of the basin. Density and velocity contrasts were found with the underlying Dalradian rocks, enabling estimates to be made of the depth of the basin fill.

The southern half of the basin is structurally simple: N.-S. faulting, partly concealed, drops the basin floor to a depth of
c.
1000–1500 m. Gravity anomalies in the northern part of the basin have been corrected for the effects of the Longmanhill and Strichen granites and offshore gabbros. The remaining anomalies, due to the O.R.S., have been coordinated with the seismic results. In the centre the floor is fairly flat with a depth of 1 km, but near the margins it rises by concealed faults to less than 500 m depth.

Tectonically, the long axis of the basin has been modified at the northern end by NE.-SW. trending faults along which movements were initiated by granite intrusions in the late Ordovician and continued until after the deposition of the O.R.S. The fault trends are considered in their regional context.
A simple-shear model for the ductile deformation of high-level intrusions in South Greenland
Authors: STEPHENSON DAVID
Published: December 2007

Major ring-intrusions in the Gardar Province are frequently elliptical in cross-section and are located at the intersections of regional dyke swarms with sinistral wrench-fault systems. Fault movement was contemporaneous with igneous intrusion and the ellipticity may be explained by ductile deformation of hot intrusions undergoing large-scale simple-shear.

Geometrical measurements on four of the intrusions give shear-strain values (
γ
) ranging from 0.6–1.2. Away from the intrusions, deformation is entirely by brittle fracture and the amount of fault movement correlates well with the sum of brittle and ductile movement within the intrusions.
Recrystallization textures in metals and alloys
Authors: Cahn R . W .
Published: December 2007

When a rod is drawn into wire, a bar is forged, or a sheet is rolled, the grains acquire a preferred orientation or deformation
texture.
When any of these are subsequently heated to a temperature high enough to create a new population of grains, this population also possesses a texture, usually though not always different from the deformation texture. The process of creation of a population of new grains is called
recrystallization
(since there is no change of phase, this usage differs from geologists' common usage), the treatment is called
annealing
and the texture is termed an
annealing texture.
Most annealing textures are statistically diffuse, but some (especially the (100) [001]
cube texture in
copper and its alloys) can be so sharp as to verge on single-crystal status.

There has long been conflict between two categories of interpretation:
oriented nucleation
hypotheses and
oriented growth
hypotheses. The former assert that nuclei are generated only in particular orientations and all then grow; the latter assert that nucleation is random and that only certain orientations are able to grow fast. For a long time, attempts to decide between these were based on statistical arguments, depending on close analysis of pole figures before and after annealing. There is plenty of experimental evidence pointing to
mechanisms
that lead to oriented nuclei (polygonization, strain-induced grain-boundarymig-ration); and to mechanisms for oriented growth, based on the differential segregation of soluble impurities to various kinds of grain boundaries. It has become quite clear that to get an understanding of
Diagenesis of carbonate rocks
Authors: Bathurst R. G. C.
Published: December 2007

The mineralogy and textures of sedimentary carbonate rocks suggest two stages of diagenesis. The stabilization of skeletal fragments from aragonite, high magnesian calcite and calcite, to calcite is the first stage and generally pre-compactive grain fracture. The formation of cements and consequent reduction in porosity is the second stage and is generally post compactive grain fracture. Both stages involve reaction and equilibration with pore waters. Stable isotopes and trace element ratios indicate compositional variations between rain water and marine brines for these fluids. The role of organic reactions and clay minerals is important. Pressure solution may occur at any stage and varies from grain to grain to through rock stylolites.
The complex microstructural evolution of the Kittelfjall peridotite, Central Swedish Caledonides
Authors: Calon T. J.
Published: December 2007

The Kittelfjall peridotite located in the Eastern Belt of the Seve Complex (
Zwart 1974
) has been involved in four deformation events under low-medium grade amphibolite facies metamorphism. A progression of olivine microtextures related to the two oldest deformation events is observed: a) large olivine porphyroclasts, kinked and showing a strong planar–plano-linear fabric surrounded by fine grained foam textured olivines, b) various mortar textures related to local shear zone development. The last two deformation events affected mainly the rim of the peridotite. Dislocation substructures indicating high energy deformation environments have been found in both types of microtexture (Boland & Buiskool Toxopeus 1974) and it is suggested that these reflect only the last deformation event.
A model for the formation of ignimbrite by gravitational column collapse
Authors: SPARKS R. S. J. , WILSON L.
Published: December 2007

Eruption columns consist of two components. The lower
gas thrust
component results from decompression of the gas phase, and decelerates rapidly to near zero velocity at heights of 1.5–4.5 km for initial gas velocities of 400–600 m/s. The upper
convective thrust
component is due to the column having a lower density than the atmosphere, and can transport the column to heights of 30–40 km.

At the base, the effective density of a column is considerably greater than that of the atmosphere and is very sensitive to changes of gas content. Fall out of clasts and incorporation and heating of air reduce the density substantially during the gas thrust part. It is shown that columns formed from magmas with high water contents (5%) are likely to show convective motion. Magmas with low water contents (

1
2

%) or high proportions of CO
2
will form a column with an effective density greater than the atmosphere, and gravitational column collapse can occur to generate ignimbrite-forming pyroclastic flows. In magmas with intermediate gas contents, the occurrence of convection (plinian case) or collapse (ignimbrite-forming) depends on vent radius, proportion of ash and gas content.

The model presented here can explain: the sharp transition from plinian to ignimbrite-forming activity; the increase of temperature with time shown by some ignimbrites; the common association of low temperature ignimbrites with preceding plinian eruptions, and the apparent mobility of pyroclastic flows.
The Currywongaun-Doughruagh syntectonic intrusion, Connemara, Ireland
Authors: KANARIS-SOTIRIOU R. , ANGUS NORMAN S.
Published: December 2007

The Currywongaun–Doughruagh intrusion comprises a folded sequence of ultrabasic cumulates, anorthosites–norites-pyroxenites, all with plagioclase more calcic than An
80
. Acid gneisses and granite dykes and pegmatites occur in intimate association with the ultrabasic rocks. Due to faulting the intrusion is separated into two masses: Gurrywongaun constitutes the lower, layered parts of the intrusion; Doughruagh forms the higher levels and consists of massive norites that are in places extensively replaced by acid gneiss. Within each part there is a progressive Fe-enrichment towards the axial planes of the major structures (inverted synclines), with the overall trend in Currywongaun continued by a similar trend in Doughruagh.

Early crystallizing cumulates of the basic magma are thought to be represented in the nearby Dawros peridotite that was tectonically separated during strong F
2
movements. Subsequently the magma crystallized the Currywongaun cumulates and during later folding (F
3
) the remaining magma was squeezed out and ultimately crystallized as the Doughruagh norites. Accompanying crystallization of the ultrabasic rocks, upward migration of acid components and water culminated in the segregation of acid magma in the uppermost levels of the intrusion. Silica-rich hydrous phases emanating from this acid residuum metasomatised the Doughruagh norites, while renewed F
3
deformation imparted the acid gneiss foliation. Finally the acid residuum injected and agmatised the ultrabasic rocks.
Upper Cretaceous and Cenozoic carbonates from the margins of Rockall Trough, N. Atlantic
Authors: DOBSON M. R. , GARRETT P. , HAYNES J. R. , JENKINS D. GRAHAM , MEDANI A. H.
Published: December 2007

Dredged carbonates from the margins of Rockall Trough mostly represent hard grounds made up of outer shelf benthonic skeletal assemblages and pelagic ooze. Chertification and occasional iron impregnation either as a crust or dominant association, are particular features of these rocks which have frequently suffered a complex history of cementation.

Further micropalaeontological work allows the dating to be refined and the Tertiary carbonates are shown to contain upper Eocene microfaunas that have been transported and rolled prior to final lithification, probably during the post-Eocene erosion interval widely reported in the Northeast Atlantic, Reflector R4.
Middle Pleistocene stratigraphy in south-east Suffolk
Authors: ROSE J. , ALLEN P.
Published: December 2007

A conspicuous horizon of rubification, clay and iron enrichment, involutions and ice-wedge casts is attributed to two stages of soil formation. It comprises a rubified sol lessivé formed in warm temperate conditions, which was altered to an arctic structure soil by periglacial processes. These palaeosols indicate that the sand and gravel deposits beneath the Lowestoft Till comprise two units, and provide the basis of a revised Middle Pleistocene stratigraphy. The Kesgrave Sands and Gravels were formed during the Beestonian in a periglacial environment by a major river which drained towards the north-east. Subsequently the Valley Farm Rubified Sol Lessivé was formed during the Cromerian Interglacial, and the Barham Arctic Structure Soil and the associated Barham Loess were formed during the early Anglian Glacial. Both soils and the wind-blown sediments were formed on low relief terrace topography and are the remnants of a formerly extensive land surface. This feature was subsequently trimmed by meltwater rivers, then overlain by the Barham (outwash) Sands and Gravels and the Lowestoft Till which were deposited during the Anglian Glaciation.