bluuebunny/crossref_metadata_2025 huggingface dataset:
The transformation of tillite by migmatization at Mount Fitton, South Australia
Authors: Bowes Donald Ralph
Published: October 2009

This paper gives an account of the transformation of tillite by migmatization in the vicinity of Mount Fitton, South Australia. The mineralogical and chemical changes invplved are described and discussed.

During an orogeny in the early Palaeozoic some of the tillites, slates and quartzites, which are stratigraphically part of the Sturtian section of the Adelaide System (late Pre-Cambrian), were altered to migmatites. Large granitic migmatite complexes were formed by granitization and small patches of epidiorite-like rocks were formed by basification.

The tillite contains erratics of varying type, shape and size set in a semi-pelitic matrix made up essentially of quartz and biotite and with a composition generally falling within the subgreywacke range. The tillite at Mount Fitton is similar to late Pre-Cambrian tillites found in many parts of South Australia.

The transformation of tillite by granitization involved an increase in the amount of potash-felspar, acid plagioclase, quartz (in the case of the more pelitic rocks) and in grain-size and a decrease in the amount of biotite. K and Na and, in most cases, Si increased and Fe, Mg, Ca, Ti, P and Mn decreased. Granitization altered the rocks by direct replacement, except in one area where the rocks were agmatized.

The transformation of tillite by basification involved a considerable decrease in the amount of quartz, the disappearance of biotite and the development of actinolitic hornblende, labradorite and ilmenite as well as an increase in grain-size. Si and K decreased and Fe, Mg, Ca, Ti, Mn and Cr were introduced. These introduced constituents are the same as those expelled during the granitization of tillite and the processes of granitization and basification are considered to be complementary.
The Evolution of Vertebrate Organization
Authors: Young John Z.
Published: October 2009

No generally satisfactory system has been devised by which the organization of an animal or plant type can be described and related to the environment in which it survives. Differences of terminology and method of approach to this problem have been responsible for many of the disagreements between zoologists and palaeontologists, and among the latter, on such matters as the direction and significance of evolutionary changes.

Even in the case of the vertebrates progress in the study of the evolution of organization has been slow and perhaps the situation is worse in other phyla. It is possible that progress has been held up for lack of a model that can be used to provide an exact terminology for the subject. It may be that palaeontology would profit from bold attempts to find analogies between the evolution of populations and the performance of man-made machines.

The task of description is never simple in any science. We all use analogies every day throughout our work. In describing the shape of a fossil we may say that it is “boatlike” or “whorled”, “cruciate” or a thousand other things. These are small and superficial analogies, serving to call attention to particular features and to explain what is meant. Perhaps all sciences begin in this way with a multiplicity of lesser comparisons. The brain operates by the process of comparison, selecting for attention certain attributes of each situation that are already associated as a result of previous experience. The maturity and efficiency of a science
The Structure of the Jebel Hagab Area, Trucial Oman
Authors: Hudson Robert George Spencer , McGugan Alan , Morton Douglas Michael
Published: October 2009

The authors describe and discuss the structure of an area on the western front of the Oman Mountains and east of Ras al Kheima, Trucial Oman, an area of foothills dominated by Jebel Hagab, 1450 m. high. The outcropping strata consist of an upper and a lower series: the former, exposed over most of the area, ranges from Permian to Lower Cretaceous, is almost entirely limestone, and has a total thickness of 3408 m.; the latter is a series of several hundred metres of Jurassic and Lower Cretaceous tuffs and radiolarian cherts, about 50 m. of Aptian limestones, and about 15 m. of conglomeratic Maestrichtian marls: the junction between the two series is well exposed and is a thrust-plane. The overriding sheet, thrust from the northeast in Neogene times, has a series of N.-S. frontal folds with steep or slightly overturned west limbs. Below the thrust of the Jebel Hagab area, exposed in the window of Wadi Hagil, contorted radiolarites are overlain unconformably, partly by Aptian and partly by Maestrichtian, both with basal breccia-conglomerates which include fragments of weathered serpentine. Their closely packed folding is considered to be partly due to submarine gravity slip following uplift. There was also pre-Aptian metamorphism and emplacement of serpentinites.

Both the limestone and radiolarite successions of Jurassic and Lower Cretaceous age are facies expressions of the sedimentation in the Persian Gulf embayment of southern Tethys extending southwards between, and overlapping on to, the Arabo-Ethiopian and Indian massifs. The limestones are considered to be a
The Plutonic History of the Maas Area, Co. Donegal
Authors: Iyengar Sosale V. P. , Pitcher Wallace Spencer , Read Herbert Harold
Published: October 2009

The paper describes the plutonic geology of part of the envelope of the Donegal granite . In the Maas area a thick and varied series of Dalradian rocks is displayed in a relatively simple anticline, the southern limb of which is buckled into smaller folds. After the folding, which was accompanied by regional metamorphism, there followed three successive plutonic events, each differing in the nature of the introduced material, the manner of its emplacement and the associated metamorphic effects. Migmatization in the highest levels of the structure is associated with mobilization and the production of sillimanite-hornfelses. The later intrusion of the composite granodiorite pluton of Ardara was clearly accompanied by the shouldering and pushing aside of the country rocks by a hot plastic body. Early fold structures were tightened and dislocated during the formation of a zoned aureole characterized by sillimanite-garnet and andalusite-staurolite associations. Alongside what was probably the feeding channel of the pluton, migmatization and mobilization of a special kind, concentrated in action, have resulted in flow tectonics; involved in these operations are metasediments of varying properties, amphibolites of appinitic types and many kinds of migmatitic derivatives. Lastly, these rocks are truncated by the pegmatitic fringe of part of the main body of the Donegal granite and as this consolidated it recorded an intense shear deformation, possibly produced by its own upward pressure.

I. Introduction

The investigation of the plutonic geology of the Maas district is of considerable importance in the general study of North-West Donegal. There is here
The Ard Bheinn Area of the Central Igneous Complex of Arran
Authors: King Basil Charles
Published: October 2009

The complex is largely surrounded by Old Red Sandstone formations, which were evidently domed up at an early stage in its development. A succession of sediments ranging in age from Permian to Cretaceous, surmounted by Tertiary lavas, is represented within the complex as “remanié masses” which are interpreted as relics of a block that foundered during the formation of a volcanic caldera, the main subsidence being estimated at 3000 feet.

Subsequently there arose on the caldera floor a series of volcanic cones, characterized in general by the sequence andesite-dacite-rhyolite, but also showing a great diversity of pyroclastic formations. The position of the various centres is recognized by the disposition of concentric and radial structures. Quasi-horizontal formations in the most elevated parts of the Ard Bheinn area are considered to correspond to remnants of the basal portions of the volcanic superstructures. The andesites and andesitic breccias are evidently extrusive in character, but the later dacites and rhyolites are represented only by their intrusive equivalents.

Finally, granites were emplaced, mainly in conformity with the general structure of the caldera, and in all but the Ard Bheinn area are the prevalent formations at the present level of erosion.

I. Introduction

The complex occupies an oval area about three miles from north to south and nearly four miles from east to west almost in tne centre of the Isle of Arran and is emplaced within strata ranging in age from Old Red Sandstone to Permian.

Topographically the area is a dissected plateau, the highest
The Tectonics of the Morar Anticline and the Problem of the North-West Caledonian Front
Authors: Kennedy William Quarrier
Published: October 2009

Within the Morar region of western Inverness-shire, the schists of the Moine Series, adjacent to the North-West Caledonian Front, are disposed in a great N.-S.-trending anticlinal fold—the Morar anticline—which consists of a simple discordant envelope of normal Moine Schists in continuous stratigraphical succession, and a complex core of highly folded and deformed Moine-like rocks with associated, tectonically incorporated gneisses of basement (Lewisian) type. A reinvestigation of the area leads to the conclusion that the lower part of the Moine succession has been reduplicated within the core of the Morar anticline and that the structure provides an example of a window opened by erosion on a pitch culmination. The simple envelope is identifled as an upper Moine or Morar nappe which has been driven westwards across a much broken, autochthonous basement, with partial reduplication of the Moine succession. This structural interpretation applies also to the homologous Loch Hourn—Glenelg anticline to the north and is shown to be comparable in style with the type of relationship which exists between the autochthonous Hercynian massifs and the Helvetic ang Subalpine zones of the Alps. The structures in the Morar area are correlated with those of the North-West Caledonian Front to the west of the Moine thrust, and two orogenic phases of Caledonian movement are distinguished, (a) an earlier (mid-Ordovician) phase of folding and thrusting, followed by regional injection and regional metamorphism of the Moine Series, and (b) a later (late-Silurian=Erian) phase of clean-cut thrusting—the Moine thrust phase. The region is regarded, therefore, as a
The Eocene Succession in the Eastern Part of the Enborne Valley, on the Borders of Berkshire and Hampshire
Authors: Hawkins Herbert Leader
Published: October 2009

Records obtained from trial borings with a combined penetration of over 8000 feet of strata are analysed, and an account is given of the Eocene succession revealed. This ranges from the Lutetian to the Sparnacian, comprising the Bracklesham, Bagshot, London and Reading formations. Their maximum proved thickness is 436 feet. The Chalk next beneath the Eocene is that of the
Marsupites
Zone except in the most northerly boring, where the
Uintacrinus
Zone was proved. Evidence is adduced suggesting that local variations in the thickness of the Reading Beds may be due to original irregularities on the surface of the Chalk.

The Reading Beds, averaging 69 feet thick, have a marine “bottom bed” which varies in thickness from 6 to 25 feet; in one case this facies seems to persist to within 10 feet of the top of the series, foraminiferal glauconitic sand there replacing the mottled clay of nearby borings. Several seams of lignite were found, one of them resting on a seat-earth full of pyritized rootlets.

The lithology of the rest of the succession resembles Wat of the Hampshire Basin rather than that of the London Basin of which it forms a tectonic part. Alternations of marine and estuarine episodes recur throughout; banks of shingle are common and beach-deposits occur; lignite, scattered or in actual seams, pervades the whole.

The London Clay rests on a plane of erosion at the top of the Reading Beds; it falls into three main sections, the Lower Silts, Stiff Clays and Upper Silts.
The Post-Silurian Pre-Marine Carboniferous Sedimentary Rocks of the Eastern Side of the English Lake District
Authors: Capewell Joseph Gerald
Published: October 2009

The post-Silurian, pre-marine Carboniferous rocks of the eastern side of the Lake District comprise a variety of clastic sediments, mainly red conglomerates. They consist of two main groups, the older—the Mell Fell Conglomerate—being unconformably overlain by Carboniferous Limestone and possibly therefore of Lower Old Red Sandstone age. The Mell Fell Conglomerate is some 5000 feet thick, the lower part being mainly greywacke-cobble-conglomerate, the higher beds being finer conglomerates and coarse sandstone with a mixed assemblage of derived pebbles. It is probably a piedmont deposit of locally derived material in a region of pronounced relief.

The younger group is best developed in the Birk Beck valley, where three divisions are recognized—a lower local subaqueous fan conglomerate, a middle group of red sandstones and an upper yellow conglomerate. These Carboniferous (probably Z), though a break exists at the base of the red sandstones. These sandstones are composed of wind-rounded grains, laid down under water, probably in a flood-plain that periodically dried out. In the Ravenstonedale district, the Pinskey Gill Beds may be contemporaneous with the lower conglomerates of Birk Beck, both being deposited in saline water.
The Geological Results of Measurements of Gravity in the Welsh Borders
Authors: Cook Alan Hugh , Thirlaway Henry Ivison Shipley
Published: October 2009

The gravity measurements made by members of the Department of Geodesy and Geophysics of Cambridge University in the Welsh Borders from 1947 bo 1950 are described and the geological results discussed. The methods of measurement and the calculation of the gravity anomalies are not given in detail since they have already been discussed elsewhere. The data given in the paper in the form of a map of the Bouger anomalies are probably consistent to within ±0–25 mgl.

At the Malvern Hills the Bouguer anomalies change rapidly from about —25 mgl. on the east to about -(-5 mgl. on the west. A probable interpretation is that there is a deep basin east of the Malverns, filled mostly with Triassic rocks, reaching a depth of nearly 10,000 feet near Worcester and bounded on the west by a surface sloping down at about 45° from the Malvern Hills. It is suggested that the basin was formed by faults, the movement along which began in late Carboniferous times and ended in late Triassic times.

Large variations of anomaly in the Welsh Borders appear to have no relation to the known geology and are probably due to heavy Pre-Cambrian masses, particularly in the Black Mountains and near Leominster. The Church Stretton disturbance appears to be marked only by a slight maximum anomaly.
The Geology of the May Hill Inlier
Authors: Lawson James Dixon
Published: October 2009

The May Hill inlier displays a calcareous and shelly development of Silurian rocks. The Upper Llandovery and Wenlock strata are similar, in general, to the corresponding beds of the Malvern and Woolhope area. The Ludlow beds, however, are remarkably thin (maximum thickness 250 feet); they are here divided into six divisions based mainly on faunal changes, and a correlation with the succession at divisions based attempted. Only the basal and the uppermost separated by an unconformity. The Aymestry Limestone is cut out by an unconformity at the base of the
Dayia
Beds, marked by a thin development of limestone-conglomerates. A phosphatized fragment-bed in the Upper Ludlow strata marks yet another important break in deposition. A distinctive faunal horizon at the base of the Upper Ludlow division, characterized by an abundance of the brachiopod
Shaleria
[
Brachyprion
]
ornatella
, has been traced throughout the Welsh Borderland and has been found most valuable for correlation.

Structurally, the May Hill inlier is a complex pericline situated at the junction of the Malvern and Woolhope axes; the main folding movements probably occurred in post-Westphalian—pre-Triassic times, with subsidiary and intra-Morganian movements.
The Pleistocene Epoch in England
Authors: King William Bernard Robinson
Published: October 2009

A review of the evidence on the position of the boundary line between the Pliocene and Pleistocene is given. This leads to the acceptance of a boundary in England berween the Coralline Crag and the Waltonian division of the Red Crag. A plea is made for basing the boundary on stratigraphical rather than climatographical considerations. Since the evidence from the Midlands appears to be much more clear-cut than that in East Anglia, the former is taken as a starting point. The stratigraphy in the Thames basin is then considered in the light of the Midland deposits; the question of the succession and age of the oldest drifts raises problems clearly needing elucidation. These are further considered in connexion with the East Anglian drifts, where the importance of recent work is emphasized. The problems of the Newer Drift in the northern parts of England are reviewed. It is suggested that in the Midlands and northern England the
Corbicula-Hippopotamus
fauna probably occurs at only one horizon and that this lies between the Older and the Newer Drifts.

It is suggested that more objective thinking would be possible if the Alpine nomenclature of Penck & Brückner were not used in Britain, and that it might help if a committee were set up, not to try to formulate correlations, but to propound an agreed nomenclature for the English divisions of the Pleistocene deposits.
On the Geological Distribution of Carboniferous Blastoids in the Craven Area, Based on a Study of Their Occurrence in the Yoredale Series of Grassington, Yorkshire
Authors: Joysey Kenneth Alan
Published: October 2009

An abundant Carboniferous blastoid faunain the Middle Limestone of the Grassington area, Yorkshire, has been used as the basis of a study of the geological factors which influence the distribution of blastoids.

In this area, Lower Carboniferous sedimentation was influenced by the craven fault-belt, which separated a shelf-sea over the Askrigg massif to the north from the rapidly subsiding craven basin to the south. In the northern part of the Grassington area the Cockleshell division of the Middle Limestone is characterized by bands of the brachiopod
Gigantoproductus
. When traced in the direction of the basin,
Gigantoproductus
decreases in abundance and finally disappears. The lower beds pass laterally into the knoll-bearing marginal facies. The knoll phase is succeeded by a crinoid-bank phase, which, on the massif side of the knoll region, contains abundant blastoids (
Orbitremites
and
Codaster
). An Orbitremites band has been traced northwards into the area characterized by
Gigantoproductus
.

The association between the occurrence of
Orbitremites
and the knoll-forming limestones is confirmed by other blastoid localities in the Craven area. Blastoids are abundant in the crinoid-bank deposits which cap the clitheroe knolls (C
2
), and also in the upper pat of the Whitewell knolls (C
2
). In the Slaidburn anticline
Orbitremites
has been found in shales (C
2
) which are the lateral equivalent of nearby knoll limestones.
Orbitremites, Codaster
and
Zygocrinus
have also been found in the marginal facies (D
2
) of the Malham area.
Plant Remains from the Gravels of the Summertown-Radley Terrace Near Dorchester, Oxfordshire
Authors: Duigan Suzanne L.
Published: October 2009

Plant remains have been found at the base of gravels attributed to the lower part of the Summertown-Radley stage of the upper Thames Pleistocene succession, with which a mammoth fauna and Middle Acheulean implements are associated. The flora, which on the whole is similar to that of the district at the present time, includes a few species now restricted to northern or alpine regions, thus indicating a colder, although by no means an arctic, climate. In the Oxford district the lower gravels of the Summertown-Radley stage are succeeded by others containing an
Elephas antiquus
fauna; there is evidence of a later cold period, with which Acheulean implements are not associated.
The Disturbed Strata on the Fox Earth Coal and its Equivalents in the East Pennine Coal-Field
Authors: Shirley Jack
Published: October 2009

During the course of outcrop-coal working occurrences of disturbed strata were noticed at Swallow Nest, near Sheffield. These were in the roof strata of the Fox Earth Coal, which is in the Lower
similis-pulchra
Zone of the Middle Coal Measures. The relations of the disturbed strata showed that they owed their structures to contemporaneous phenomena and that the disturbances were completed before the deposition of the next coal seam 32 feet higher in the sequence. The strata are cut by numerous thrusts and are contorted, folded and broken in a complex manner. The mudstones have been converted into a typical " clod ", i.e. a relatively finegrained rock which breaks continuously into small pieces and is very difficult to support in either a cliff face or underground. The underlying Fox Earth Coal is almost undisturbed. Various lines of argument led to the suggestion that the structures of these strata were due to earthquake disturbance rather than to slumping as usually understood. By reason of the detailed knowledge of the stratigraphy of the Middle Coal Measures of the East Pennine Coalfield it was possible to demonstrate that disturbed strata occur at several other localities on this horizon through the length of the coalfield. At two localities sandstone dykes cut through the underlying coal. The widespread occurrence of these phenomena at exactly the same horizon supports the suggestion that they are due to earthquake disturbance.
Gravity and Magnetic Anomalies in North Wales
Authors: Powell David Williamson , Griffiths Donald Harrison , King Roy Favell
Published: October 2009

Bouguer anomalies in North Wales have been calculated from a network of gravity stations in which the standard deviation of a gravity difference is about 0·2 mgl. Magnetic anomalies have been surveyed in part of the area. Rock densities have been measured in the laboratory and in the field.

The depth to the Pre-Cambrian geosynclinal floor in North Wales is thought to influence the gravity anomalies in some areas, but may control the magnetic anomalies more directly. The regional gravity gradients are due to deeper density contrasts, possibly those involved in crustal warping.

At the head of the Vale of Clwyd, 2500 feet of Upper Carboniferous is inferred; farther south, 2000 feet of Trias. The possibility of a Triassic basin under Cardigan Bay is discussed. Structures within the Flint Coalfield are reflected in the gravity anomalies.
The energy of earthquakes
Authors: Gutenberg Beno
Published: October 2009

Calculation of the energy released during earthquakes, including all great shocks from 1904 to 1954, indicates that the average annual release of energy in earthquakes is roughly 10
25
ergs. Since this is only about 0–1 per cent of the energy produced by disintegration of radioactive matter in the earth, processes maintained by the generation of heat could furnish the earthquake energy. In each of the three major depth ranges, (a) shallow shocks, depth
h
≤ 60 km., (b) intermediate shocks, 60 <
h
≤300 km., (c) deep shocks,
h
> 300 km., the frequency of earthquakes increases about exponentially with decreasing earthquake magnitude
m
down to at least
m
= 2, and in each the average energy release between 1904 and 1913 was greater than that in later decades. The largest energy calculated for a single shock during the 51 years, about 2 X 10
25
ergs, was found for two shallow shocks. With increasing focal depth h the maximum energy of a single shock decreases to about 6 X 10
23
ergs at h = 650 ± km. and to about 4 X 10
22
at 720 ± km. No deeper earthquakes are known. The rapid decrease in energy release near 700 km. could be caused by flow processes if the apparent coefficient of viscosity decreases to the order of 10
20
poises at a depth of about 700 km.
Seismic Prospecting in the Western Approaches of the English Channel
Authors: Day Alan Arthur , Hill Maurice Neville , Laughton Anthony Seymour , Swallow John Crossley
Published: October 2009

On the basis of the measured seismic velocities, the layering found at 25 seismic stations in the area of the Western Approaches of the English Channel is divided into four classes which are respectively correlated with semi-consolidated Cretaceo-Tertiary sediments, the New Red system, the Palaeozoic system, and a metamorphic basement. The last of these appears to form a long, deep trough. The Palaeozoic floor is depressed in a trough of somewhat variable depth, bounded on the north by an outcrop of the metamorphic basement which is possibly a westward extension of the upthrust Lizard-Start metamorphic belt. Contour maps of the layering are produced.
The Boyndie syncline of the Dalradian of the Banffshire Coast
Authors: Sutton John , Watson Janet
Published: October 2009

The paper deals with the great fold affecting the Dalradian rocks exposed on the Banffshire coast, for which the name Boyndie syncline is now proposed. It is a large asymmetrical syncline whose axis runs north-north-east and emerges on the coast west of Banff. Its western limb is steeply inclined and, as Read showed, youngs eastward; over short stretches the rocks of this limb are intensely corrugated by subsidiary folds. The eastern limb is, as a whole, very gently inclined and is flexed to form the shallow Turriff syncline. Much of this limb is violently corrugated on a small scale. Variations in the attitude of the axial planes of small folds within the Boyndie syncline are described and discussed. It is suggested that the corrugation of the eastern limb is due to the squeezing out of incompetent beds from the core of the major fold.

The central part of the steep western limb of the syncline has been intensely deformed and boudinage, mullioning and allied processes have led to the formation in this zone of a tectonic melange in which elonaated or lenticular masses of rock are enclosed in a less competent matrix. The axiil plunge of small-scale structures in this zone is very variable and is often steep. Preliminary petrofabric studies show that the preferred orientation of quartz is much stronger here than elsewhere in the fold. An oblique cleavage is imposed on rocks to the east and west of the intensely deformed sector.

The possible significance of the structures seen on the Banffshire coast is discussed and their bearing on current views on the tectonics of North-East Scotland is debated.
A sedimentary study of the Fell Sandstones of the Coquet Valley, Northumberland
Authors: Robson Douglas Arthur
Published: October 2009

The Fell sandstones are about 1000 feet thick in the Coquet valley. They form the upper part of the Tuedian, which is the lower division of the Lower Carboniferous in Northumberland. Current-bedding is generally present, and occasionally shows deformation structures. Directions of current-bedding indicate a source lying to the north-east.

The heavy mineral content of the underlying Cementstone Group is distinct from that of the Fell Sandstones. The lower part of the latter, described as the mixed zone, contains a mineral assemblage common to both groups.

The results of mechanical analysis show a marked degree of uniformity of grade-size throughout the Fell Sandstones. Coarser beds occur only very occasionally. Careful sampling from individual units of current-bedding indicates that all parts of a single unit generally yield almost coincident cumulative curves. Adjacent units of current-bedding often differ from one another in grade-size, evidently in response to the varying strengths of tho depositing currents. To the same cause may be ascribed the variations in the percentages of heavy minerals in samples taken from adjacent current-bedded units.
The two great breaks in the history of life
Authors: Watson David Meredith Seares
Published: October 2009

Very early in the history of geology it became recognized that past time, so far as the history of life was concerned, fell into three periods: Primary, Secondary and Tertiary. Each contained fossils, easily recognized—trilobites, ammonites and mammals—which as groups characterized the periods, coming in with them, dying out at their ends. When evolution became the accepted explanation of the successive series of animals and plants the existence of “ gaps ” between the faunas of the three periods implied evolutionary events not easily understood, and their nature and significance have often been discussed. Most of such discussions have been based on the history of marine invertebrates, and are inconclusive. Thus some study of the events through their effects on land-living vertebrates throws further light on the phenomenon and its evolutionary significance.
On the trace-fossil
Chondrites
Authors: Simpson Scott
Published: October 2009

The problematical fossil
Chondrites
, well known from the Flysch of the Alps, Carpathians and Apennines, and from the Lias of Germany, is shown to be common in various Palaeozoic formations of the British Isles and also in the English Lias. The varying forms taken by the fossil are described and explained and shown to be primarily the result of different modes of preservation and not of taxonomic significance. A consideration of the different modes of preservation, as well as of the morphology of the fossil, permits its interpretation as a trace-fossil resulting from the driving of a system of branching tunnels in the sea-bed sediment. A new reconstruction of the fossil has been made. It is tentatively explained as the product of a sipunculoid worm feeding on sediment by means of its extensible proboscis. Various implications of the mode of occurrence of the fossil in particular circumstances are considered.
The Dawros peridotite, Connemara, Eire
Authors: Rothstein, Andrew T. V.
Published: October 2009

The Dawros peridotites are characterized by a strong banding and evidence of thermal metamorphism exists in the enclosing schists. The banding arises from a rhythmic crystal accumulation ranging through a sequence of dunites and pyroxenites in which the assemblage olivine and orthopyroxene at one extreme passes into the assemblage olivine, clinopyroxene and subordinate orthopyroxene at the other.

Felspar is absent. There is evidence of gravity stratification and the action of magmatic currents in the chrome—spinel horizon which occurs at the transition between the two principal mineral groups.

The textures vary from primary igneous to secondary metamorphic, the primary minerals having frequently recrystallized under conditions of high-temperature dynamic metamorphism. There is also evidence in the country rocks of a period of deformation subsequent to the thermal metamorphism.

The pyroxenes show a primary variation within the solid solution series, of an iron enrichment over a restricted magnesium-rich range; the orthopyroxenes lie in the onstatite-bronzite series and the clinopyroxenes within a similar diopsidic range. There occurs among the recrystallized rocks a hypersthene-pyroxenite of charnockitic type.

The conclusions drawn are that the Dawros mass is a peridotite formed as a deep-soatod magmatic crystal accumulate, subsequently dynamically metamorphosed, possibly while being emplaced into higher levels of the earth's crust, and later undergoing serpent inization.
The stratigraphy and structure of part of the Kintail district of southern Ross-shire : Its relation to the Northern Highlands
Authors: Clifford Tom Neville
Published: October 2009

The portion of southern Ross-shire dealt with in this paper lies between the two recently redescribed districts of Fannich Forest (Sutton & Watson 1954) on the north, and Morar, Inverness-shire (Kennedy 1955), on the south. This paper provides the first detailed geological survey of the area.

The district is composed essentially of crystalline schists and gneisses of the Lewisian Gneiss and Moine Series disposed in north-easterly and north-north-easterly trending major isoclinal folds. Within the most important of these, the Sgùrr an Airgid syncline, the following structural succession has been established :—

The upper element is regarded as composed of exotic representatives of the lower element repeated at higher levels by thrusting ; in view of the disposition of this element as a structural outlier it is termed the Kintail klippe. The question of a root-zone is discussed.

The major post-Moinian structural events in southern Ross-shire have been recognized as thrusting and the emplacement of the Kintail nappe, folding along NE.—SW. (Caledonide) axes and the development of WNW.—ESE. trending " crossfolds." These phases were followed by post-metamorphic faulting as exemplified in the Strathconon fault plexus. The regional implications of the now map area are discussed.
The geological interpretation of a gravity survey of the Alston Block and the Durham Coalfield
Authors: Bott Martin Harold Phillips , Masson-Smith David
Published: October 2009

Problems of the deep structure of the Alston Block and the Durham Coalfield are outlined in relation to previous geophysical work. The gravity survey planned as the most expedient approach to these problems is briefly described. The results of a density survey undertaken in conjunction with the gravity survey are stated.

The main feature of the gravity survey is a large negative anomaly over the Alston Block. The earlier conclusion, that it is caused by an unexposed granite, is upheld by the detailed physical and geological interpretation. The postulated granite approaches closest to the surface in five bosses, some of which almost certainly reach within 5000 feet of the surface. The shape of the gravity anomalies bears remarkable resemblance to the zones of mineralization and the volatile content of the coal seams, and for these reasons a post-Carboniferous age seems likely. Possible modes of origin of the postulated granite are discussed.

The northward decrease of anomaly across the Stublick fault system is caused by fairly rapid thickening of the Lower Carboniferous succession, which continues eastwards across the line of the Ninety Fathom Dyke. A southward Bouguer decrease- across the Butterknowle fault is similarly interpreted as a southward thickening of Lower Carboniferous rocks. The internal structural features of the Alston Block are interpreted in relation to the assumed granite below.

A study of the background Bouguer anomaly suggests a North Pennine crustal mass deficiency in addition to the granite. It is considered that the granite mass deficiency, if accompanied by an additional crustal deficiency, could account iso-statically for the present North Pennine uplift, and for the general stability since the Lower Carboniferous.
Interpretation of a vertical field magnetic survey in North-East England
Authors: Bott Martin Harold Phillips , Masson-Smith David
Published: October 2009

A vertical field magnetic survey of Durham and South Northumberland supplements the gravity survey described in the previous paper. The field survey and its reduction are described and some of the problems of interpretation are mentioned.

A negative magnetic anomaly over the Alston Block is interpreted as another manifestation of a concealed granite under Weardale. Similar anomalies occur over exposed mineralized granites elsewhere, and arise from granite with low polarization existing in country rocks with higher polarization. The magnetic minima are displaced to the south-east of the corresponding gravity minima, and it is thought that this is caused by permanent polarization directed westwards in the country rocks. A violent positive anomaly lies immediately to the north at Blanchland and is tentatively interpreted as a marginal feature of the assumed granite.

A magnetic anomaly of Caledonian strike in Northumberland probably marks the southern limit of low-polarization basement rocks. This may well represent the south-eastern limit of the sub-Carboniferous outcrop of the Southern Uplands Upper Ordovician and Silurian rocks.
The Middle Lias of the Dorset coast
Authors: Howarth Michael Kingsley
Published: October 2009

The two zones of the Middle Lias of the Dorset coast are remarkably different. The
spinatum
Zone at the top has a maximum thickness of only two feef, consisting of ferruginous sandstones or limestones containing species of
Pleuroceras
. The
margaritatus
Zone is more than two hundred times thick, consisting of loams, clays and sands, wit hard sandstone and limestone bands, containing species of
Amaltheus
and
Amauroceras
.

In the palaeontological section of the paper, remarks on the amaltheid ammonites are confined to their stratigraphical distribution, and more detailed treatment is given to representatives of
Metacymbites, Dactylioceras
, and the Middle Liassic hildoceratids
Leptaleoceras
and
Paltarpites
.

Finally, a comparison is made with the stratigraphy and ammonite faunas of the Middle Lias on the Yorkshire coast, and the conclusion is drawn that differences between the two areas were greater in
spinatum
Zone times than in
margaritatus
Zone times.
The Pleistocene Geology of the South Birmingham Area
Authors: Pickering Raymond
Published: October 2009

The Older Drift of South Birmingham has been shown to include three levels of lacustrine sediments. Their disposition and lithological variation is discussed. They are interpreted as due to the advance of the Riss (Saale) glacier which, impounding glacial Lake Harrison between Leicester and Bredon Hill, produced also a branch at the same height, the Tame valley arm (Shotton 1953). The lowest lake of South Birmingham is part of this arm but the two higher levels are due to smaller stretches of water impounded in a proto-Rea valley by the ice as it advanced southward against the high land in front of the Clent-Lickey Hills. Eventually this ice completely overrode its own lacustrine deposits.

Post-Riss erosion has cut the Rea valley east of its drift-filled ancestor, so that the lake deposits and associated beds are now largely preserved below the higher ground.
The Structural Geology of the Moine Thrust Zone in Coulin Forest, Wester Ross
Authors: Johnson Michael Raymond Walter
Published: October 2009

In the Coulin Forest psammitic schists some 6000 feet thick, with infrequent politic horizons, overlie the Moine thrust : the rocks are the right way up and dip gently eastwards. The Moine outcrop has been divided into an eastern zone in which the rocks owe their structure and texture to regional metamorphism and a western zone in which the rocks exhibit the structural and metamorphic effects of the thrust movements. The structures in the western zone of the Moine and in the Torridonian and Lewisian below the Moine thrust are alike in style and orientation ; they are related to the thrust movements. The following movement history has been recognized in the rocks of the thrust zone :—

1. The formation of folds and linear structures trending E.-W. and generally plunging gently eastwards. The folds, which indicate some movement on N.-S. lines, are not consistently overturned in a single direction. These movements were accompanied by granulation, recrystallization and the formation of. orthorhombic fabrics. The relation of the E.-W. structures to the major transport along the thrusts is discussed.

2. The formation of folds and linear structures trending NNE.-SSW. and generally plunging to the north. These structures were produced by late shearing movements in zones of intense sliding. During this phase, the previously formed and folded mylonites were transported to the west-north-west.
Some Apects of the Progress in Geology in the Last Fifty Years. I.
Authors: Hawkes Leonard
Published: October 2009

The interpretation of the record of the rocks current fifty years ago has been modified as a result of new evidence and the realization of the immensity of geological time. There is as yet no good reason to doubt that conditions under which the rocks available for examination were formed have remained the same throughout geological time. The hypothesis of a world-wide rhythm in the intensity of crustal movement remains unproved. On present evidence, Lyellian uniformitarianism is applicable to the whole of geological history.
The Petrochemistry of the Ardara Aureole
Authors: Pitcher Wallace Spencer , Sinha Ram Chandra
Published: October 2009

The chemical variation in a single horizon of pelitic schists, both within and without the contact aureole of the granodioritic diapir of Ardara in County Donegal, is given in detail. In both environments the schists have been carefully sampled and some 50 analyses made by using rapid spectrophotometric methods.

By establishing an original compositional variation across this horizon it is shown that the contact metamorphism is largely isochemical. Close to the pluton, however, certain slightly higher values for potassium and sodium are recorded and, throughout the aureole, the water content is significantly reduced. The variations in the chemical composition of the rocks are clearly reflected by changes in the mode ; most important are the appearance of a new muscovite and a progressive change in the composition of the ferromagnesian micas.

The results of this study make it quite clear that a knowledge of the original chemical variation of the sediments is a necessary prerequisite to the petrochemical study of their metamorphic derivatives.

Certain of the contact aureoles of the Donegal Granite Complex in North-West Ireland provide excellent opportunities for the geochemical investigation of metamorphic processes. Almost ideal sites for such researches are given by the beautifully exposed aureole surrounding the diapiric pluton of Ardara. The Dalradian country rocks include a thick horizon of pelitic schists which can be followed into this contact zone, thus providing a single medium in which to determine and compare any changes in chemical composition. This study is concerned with a comparison of the composition of
The Investigation of a peat moor at Rodbaston, Penkridge, Staffordshire
Authors: Shotton Frederick William , Strachan Isles
Published: October 2009

The form and stratigraphy of an oval peat-filled area north of Wolverhampton is investigated and interpreted as the filling of a kettle-hole formed during the retreat of the Irish Sea glacier. The fauna of the basal silt and the flora of this and the overlying gyttja and peat suggest that the infilling of the hollow did not commence until about zone III of Late-glacial time (some 11,000 years before the present) and that about 30,000 years elapsed after the retreat of the Irish Sea glacier before the kettle-hole received its first sediments.
The structure of the Lower Palaeozoic rocks of the Arklow district (Ireland)
1
Authors: Tremlett W. Edward
Published: October 2009

The Lower Palaeozoic succession consists mostly of slates but contains a large volcanic series, apparently of Bala age. This is composed essentially of rhyolitic pyroclasts but contains some basic lavas in parts. It reaches a thickness of more than 8000 feet of virtually uninterrupted volcanic rocks in the north-east, but fades out rapidly towards the west.

The basic structure of the area is a fold of synclinal type. In the north-east this is sharply overturned towards the north-west, but it changes south-westwards to a shallow, symmetrical synclinorium. This fold has been cut through by numerous thrust-planes with displacements averaging two to three miles and by many high-angle faults, some of considerable dimensions.

Evidence on the relative ages of intrusions and faults is abundant and allows the complex Caledonian history to be largely deciphered. The initial formation of the synclinorium was succeeded by numerous phases of faulting and a variety of igneous intrusions. Metasomatic events and periods of mineralization are also found in this history.
Problems and principles of Tertiary and Quaternary Stratigraphy
Authors: Van Der Vlerk I. M.
Published: October 2009

Stratigraphy, both in western Europe and in the Far East, began on the principle of the so-called percentages method. Applied to long-range correlations, however, and hence to the establishment of a valid worldwide succession, this method raises great problems. The use of index fossils for the same purpose makes too high demands on these fossils, which are suitable only for local use. Genera-assemblages of worldwide occurrence may establish correlations, but for a few stratigraphical series only. The use of bio-series may be more successful. Provisional morphogenetic investigations of the foraminiferal genus
Lepidocyclina
look promising.

The period is too short for the evolution of organisms to serve as a basis for a detailed subdivision of the Quaternary. The only reliable basis seems to be climatic fluctuations, and recent progress in palynological research has enabled these fluctuations to be traced in non-glaciated regions. The use of provisional local geological names in Quaternary stratigraphy has been advocated; the succession drawn up for the Pleistocene of the Netherlands is an example. Persistent attempts to force a worldwide succession into a Günz-Mindel-Riss-Würm frame will only increase the present confusion.

A great problem in Quaternary stratigraphy is the distinction between a “glacial” and a “cool oscillation”, an “interglacial” and an “interstadial”.
The Pleistocene succession in the Stockport and South Manchester area
Authors: Simpson Ian Morven
Published: October 2009

The Pleistocene history of the Stockport-South Manchester area commences with the spread of an ice-sheet over an undulating surface. This ice-sheet deposited the Lower Boulder-clay. After the ice had retreated a layer of sand accumulated over much of the area to form the Middle Sand. Later a second ice-sheet deposited the Upper Boulder-clay over the whole area. During the retreat of this ice the Upper Sand and Gravel was deposited on the clay. A period of erosion followed in which the present drainage system was established. Subsequently, oscillating conditions caused the formation of a series of terraces in the main river valleys.

A description is given of the lithology and distribution of the various deposits. The nature of the sub-drift surface in the Stockport area is described. The ages of the deposits and their modes of origin are discussed.
The Cader Idris granophyre and its associated rocks
Authors: Davies Rhys Glynn
Published: October 2009

The Cader Idris granophyre and its surroundings have been remapped, using vertical aerial photographs on the scale of 18 inches to the mile, and the information recompiled on the scale of six inches to the mile. A petrographic study has been made of the rocks present, and a selection of these analysed for major elements. The results suggest that the granophyre was emplaced as magma but caused some mobilization and metasomatism of country rocks near its contacts, as well as in xenoliths and rafts of country rock trapped and surrounded by granophyre in a discordant vent-like portion of the intrusion on Mynydd Moel.

It is believed that the associated quartz-diabase sill and certain rocks of intermediate composition occurring within the Upper Acid Group originated at depth by such processes of thermal mobilization and metasomatism. It is shown that the granophyre lifted its roof more than 1500 feet and that it is physically connected with the uppermost rhyolites of the Upper Acid Group. This fixes the age of the granophyre and suggests that its intrusion was associated with earth-movements of pre-Bala age.
Fossil calcareous algal floras of the Middle East with a note on a Cretaceous problematicum,
Hensonella cylindrica
gen. et sp. nov.
Authors: Elliott Graham F.
Published: October 2009

In the Middle East predominantly calcareous sedimentation from Permian to Miocene has preserved rich algal micro-floras: these are listed in detail for Iraq, Qatar, Oman and the Hadhramaut, and compared with other Tethyan floras in the Mediterranean area and elsewhere. The family Chaetangiaceae (Rhodophyta or red algae) is traced from Permian to Recent, being well represented in the Permian, Cretaceous and Eocene of the Middle East. A new genus of problematicum,
Hensonella
, is described.