bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isotopic age-determinations of rocks from the British Isles, 1955–64
Authors: SABINE PETER AUBREY , WATSON JANET VIDA 
Published: October 2009

Over 475 individual age-determinations of British rocks, recorded in some sixty papers, have appeared during 1955–64, the decade in which isotopic dating reached practical maturity and began to have great effect in establishing the scale of events in historical geology, including that of the Pre-Cambrian. The willing co-operation of all the British laboratories in which isotopic ages are determined has enabled abstracts of these papers to be prepared for publication; the emphasis of the abstracts lies in the geological implications.
In an introductory section (by P. A. Sabine& J. Watson), the number of determinations of British rocks is plotted against apparent ages. The resulting histograms are broadly similar to those derived from world-wide sources and from other countries, showing that they record not only the incidence of laboratory determinations but fundamentally significant geological events. Major peaks of activity are indicated, the implications of which are reviewed. Periods of plutonic activity are shown in the Lewisian at 2600 to 2200m.y. (Scourian) and 1600 to 1450m.y. (Laxfordian). Metamorphic rocks, migmatites, and granites from the Caledonian Belt are spread from about 750 to 360 m.y. with a weak maximum at 750 to 650 m.y. and a stronger one at 450 to 360 m.y. In south-west England metamorphic activity yields dates from 400 to 350m.y., and Hercynian granites dates from 300 to 250 m.y. Tertiary granites and allied rocks are mainly 65 to 50 m.y. old.
In each abstract an attempt is made to include geographical locality, character and geological relationships of specimens investigated, method employed, and constants used, ages obtained, and conclusions drawn. Full indexes are provided.
Intrusive tuffs of west Cork, Ireland
Authors: COE KENNETH 
Published: October 2009

Minor intrusions in west Cork include pipes and dykes believed to have originated by a process of fluidization. These bodies are described, emphasis being placed on features known to be characteristic of fluidization. The intrusions are pipes or dykes with sharp contacts with the country-rock, which plunge vertically or at high angles. Some show a zonal form based on the xenolith content; xenoliths moved upwards in the central zones but there is evidence of downward movement in some of the outer zones. Matrices are devoid of igneous material. The west Cork bodies are distinctive in occurring between phases of deformation of a fold-belt and in having their positions controlled by pre-existing structures. Petrologically they are distinguished by having a carbonate content that is variable but attains a maximum of 95 per cent.
The bodies are compared with certain carbonatites that are held to be high-level developments of kimberlite pipes.
Clay fractions and colours of some Devonian red beds in the Catskill Mountains, U.S.A
Authors: FRIEND PETER FURNEAUX 
Published: October 2009

The fine fractions of samples from a cyclothemic section in the Catskill facies, Appalachian region, have been analysed by X-ray diffraction and determinations of iron content made. All the samples contain both illite and chlorite, and some contain kaolinite. Two of the cyclothems are richer throughout in kaolinite. This is attributed to a change in provenance and demonstrates the relative unimportance of diagenetic alteration of the clays.
The redness is due to the presence of fine-grained hematite, much of it in hexagonal crystalline form. The clay content does not vary with the red or non-red state of the rocks, and this colour differentiation did not therefore involve alteration of the clays. A hypothesis to explain the red-non-red differentiation within the cyclothems is put forward.
Erosion-surfaces, tectonics and volcanic activity in Uganda
Authors: BISHOP WALTER WILLIAM , TRENDALL ALEC FRANCIS 
Published: October 2009

The historical development of the erosion-surface nomenclature previously used in Uganda is reviewed briefly. Several surfaces are defined, or re-defined, and together with their component physiographic units are described and given local names referring to areas in eastern and central Uganda.
For eastern Uganda the sub-volcanic (broadly early Miocene) topography is reconstructed in detail and its subsequent modification is described. In central Uganda two major erosion-surfaces are recognized. Post-formational amendments to these former landscapes are discussed in relation to the present drainage-pattern and to tectonic deformation associated with the development of the Lake Albert-Edward graben. The stratigraphical-geomorphological history of the Western Rift south of the Murchison Falls is summarized.
Sequences of events in the formation of the present landscape are outlined for eastern, central and western Uganda, and extrapolation is made from the eastern region into adjacent areas of Kenya. Some recasting of established sequences is suggested. It is concluded that insufficient attention has been paid previously to the local physiographic setting (often dominated by the form of the sub-volcanic landscape) controlling the stratigraphical relations and lithology of the fossiliferous Miocene volcanic and other sediments. The extent of late Tertiary and Quaternary tectonic deformation of erosion-surfaces has in the past been underestimated.
Aegirine-gneisses in central Malawi
Authors: BLOOMFIELD KEITH 
Published: October 2009

A sixty-mile-long zone of interbanded psammites and aegirine-gneisses occurs within the paragneisses of the Mozambique belt in central Malawi at about the 13°30's parallel. The typical mineral assemblages are quartz-micro-cline-oligoclase/andesine-magnetite-zircon and aegirine-(Na amphibole)-quartz-microcline-oli-oclase/andesine-zircon-magnetite. Two chemical analyses show that the Fe/Mg ratios are very high and that Ca is present in only small amounts.
A syngenetic origin from glauconite-rich feldspathic sandstones is suggested, the sedimentary environment being near-shore deltaic or marine.
Gravity and magnetic surveys of the younger gabbros of Aberdeenshire
Authors: McGREGOR DAVID MARSHALL , WILSON CHARLES DOUGLAS VERNON 
Published: October 2009

About 700 gravity and 1200 magnetic measurements have been made in north-east Aberdeenshire in order to find the attitudes of the basic intrusions. The surveys have covered the younger gabbros, the Bennachie granite and the intervening areas. A marine magnetic survey has covered an area about 40 × 30 km offshore from Banff.
The Bouguer anomalies are positive over almost the whole area except the Bennachie granite; together with prominent magnetic anomalies these indicate that the exposed gabbros form part of a continuous basic sheet. This sheet varies in thickness from 1 or 2 km near Huntly to 7 km at Cabrach.
Positive magnetic and negative gravity anomalies are found from Dufftown to the Moray Firth, suggesting that there are extensive granite intrusions in this area. Hidden extensions of the Cabrach mass and the Bennachie granite have been approximately delineated. Positive gravity anomalies extend from Cabrach over the northern part of the Morven mass.
Models have been constructed which fit the anomalies over the Insch and Belhelvie masses; these suggest that there has been post-consolidation folding at Belhelvie.
In five localities the gravity and magnetic anomalies are closely correlated and the direction of magnetization has been computed for each of these areas. These are compared with the directions found by Blundell & Read (1958) and the deformation of the basic intrusions is discussed. Gravity and magnetic anomalies at the east end of the Insch mass suggest that this mass also has been deformed.
Pleistocene deposits of the north-western Allegheny Plateau, U.S.A
Authors: WHITE GEORGE WILLARD 
Published: October 2009

In North America Pleistocene ice sheets entered the lowland now occupied in part by Lake Erie and expanded far southward in several lobes in the Interior Plains, but less far in two lobes in the Allegheny Plateau to the east in north-eastern Ohio, north-western Pennsylvania and western New York. This maturely dissected plateau, composed of essentially horizontal Carboniferous strata, has a summit level ranging from about 1200 ft in the west to about 1800 ft in the east.
In recent years excavations as deep as 135 ft for strip mines (coal), highways and quarries (limestone) in that part of the plateau in Ohio and Pennsylvania have exposed complete sections as much as a mile in length, which reveal lower drifts, mainly till, that have been previously almost unknown. Each till sheet has a characteristic texture and mineral composition and separate sheets can be traced for more than 100 miles, and treated as rock stratigraphical units. The younger tills are much higher in clay than the older tills. The feldspar content of the sand fraction ranges from about 5 per cent in the oldest till to 30 per cent in the youngest till. Carbonates range from less than one per cent in the oldest till to about 15 per cent in the youngest.
Within each till sheet there is a decrease in feldspar and an increase in quartz toward the margin. Statistical studies, in part by trend-surface analysis by computer methods, confirm the regularity of this variation, which is ascribed to dilution by local feldspar-poor sandstone. The dilution is much greater in the older tills; at their margins 90 per cent of the quartz content may be locally derived.

The lowest till, of pre-Illinoian age, entirely a sub-surface unit, is everywhere thoroughly weathered. The overlying till of probable Illinoian age, consists of two sheets, the upper one of which has a thick palaeosol. The bulk of the drift is early Wisconsinan in age and consists of three or more till sheets. It is named (in Pennsylvania) the Titusville Till and has a
14
C age of about 40 000 years. It is sandy, very compact and oxidizes to a distinct olive-brown colour. The weathering on it is not as intense as that of the two lower tills. The oldest till of late Wisconsinan age, the Kent Till, is a distinctive coarse yellow-brown, sandy till. It is overlain by the chocolate-brown, silty, more highly calcareous Lavery Till, which in turn is overlain by the brown, silty-clayey Hiram Till.

Each of the older tills, except the pre-Illinoian, extends farther south and south-east than the later tills, so that each forms the surface drift in a belt, ranging from 2 to 20 miles in width, in which its surface morphology and soil characteristics can be studied and its general character compared with that in the sub-surface.
Geosynclinal theory and the organizational pattern of the North-west Borneo Geosyncline
Authors: HAILE NEVILLE SEYMOUR 
Published: October 2009

The North-west Borneo Geosyncline occupied most of Sarawak, Brunei and western Sabah, extending over a distance of about 800 km in a ne–sw direction. The very thick sequence of strata deposited in the geosyncline ranges in age from late Cretaceous to late Cainozoic; over thirty formations have been defined and these may be classified into four groups:
(i) Rajang Group (late Cretaceous to early Miocene): thick intensely folded typical flysch with chert-ophiolite at or near the base.
(ii) Baram Group (late Eocene to late Miocene): predominantly argillaceous, with some sandstones and thick limestones.
(iii) Plateau Group (late Cretaceous to? Miocene): thick molasse-type continental deposits in the south.
(iv) Brunei Group (Oligocene to Recent): estuarine and marine deposits with molasse affinities in the north.
Previous syntheses have regarded western Borneo, lying to the south, as the probable foreland, but the author seeks to show that this region acted as a eugeanticlinal ridge and intermediate hinterland. The main eugeosynclinal furrow occupied the present outcrop of the Rajang Group, whereas the later miogeosynclinal furrow lay further north; a submerged miogeanticlinal ridge, not so clearly defined, separated the furrows. The Baram Group was deposited mainly in the miogeosynclinal furrow. A marked dynamic polarity is shown by migration of flysch deposition, orogeny, and molasse deposition, from south to north across the geosyncline; these processes also seem to have migrated along the geosyncline from west to east and north-east.
The distribution of the main chert-ophiolite belt along the internal side of the eugeosynclinal furrow and of the late-geosynclinal and post-geosynclinal lavas and acid intrusions in western Sarawak and western Kalimantan follows the typical pattern, with some minor exceptions. A terminal volcanic phase is represented by late Cainozoic lavas on the eugeosynclinal deposits.
A gravity survey of a region of the Highland Boundary Fault in Scotland
Authors: QURESHI IFTIKHAR RASUL 
Published: October 2009

The results of 1591 gravity measurements made in parts of the Midland Valley and the Grampian Highlands of Scotland, flanking the Highland Boundary Fault-zone between Callander and Cowal are described and density units in the Palaeozoic rocks of the area distinguished on the basis of some 800 laboratory measurements.
Steep gravity gradients across the Highland Boundary Fault at Callander and Aberfoyle show that its small hade to the north-west, observed at surface, is maintained to a depth of 2400 ft below sea-level, indicating that the fault behaved as a high-angle reversed fault in mid-Devonian times. West of Loch Lomond, the fault continues in general alignment with its course to the east and is inferred to underlie the Carboniferous cover in the Greenock–Inverkip region.
The existence of a deep sedimentary basin bounded to the north-west by three step faults and to the south-east by the Highland Boundary Fault is revealed by a gravity low west of Loch Lomond. The basin is probably partly filled by Lower Old Red Sandstone.
The maximum thickness of the Lower Old Red Sandstone sediments in the surveyed area is between 5000 and 6000 ft and the formation thins south-eastwards in the region of the Ochil Fault.
On the flanks of the Highland Boundary Fault, the survey has provided information of regional importance: the slate-belt probably occupies a downfolded synform within the Dalradian rocks; the Ochil Fault can have only a small magnitude in the surveyed area; the maximum thickness of the Lower Old Red Sandstone sediments in the area is between 5000 and 6000 ft and the formation thins south-eastwards in the region of the Ochil Fault.
The Triassic salt deposits of north-western England
Authors: EVANS WYNDHAM BOWEN 
Published: October 2009

A brief account is given of the present state of knowledge regarding the stratigraphy of the salt-fields in north-western England. It is stressed that salt solution has taken place on a considerable scale, and that old and shallow provings can be most misleading.
Interpretations of the British Keuper as a desertic continental deposit have been based largely on condensed non-saliferous sequences. In contrast the evidence in the salt-fields is capable of being interpreted differently. It is contended (i) that the clastic and chemical rocks of the salt-fields were deposited beneath water; (ii) that this water is likely to have been deep; (iii) that it was in continuous contact with the open ocean across a shallow shelf area occupying much of west-central Europe.
It is further contended that the importance of local factors in each salt basin so outweighed that of surface climatic fluctuations that it is unwise to assume that a particular salt formation in a particular basin necessarily correlates with a salt formation in another basin. Consequently it is argued that, away from the shelf-areas, no sound basis yet exists for long-range lithological correlations of the British Keuper.
The stratigraphy and palaeontology of the 'Keuper' Series of the central Midlands of England
Authors: WARRINGTON GEOFFREY 
Published: October 2009

A reappraisal of the stratigraphical status of the formations constituting the series traditionally termed 'Keuper' in central England is given, based on palaeontological and sedimentological evidence. The 'Keuper' Sandstone is a fluvial facies representing a sub-aerial deltaic environment and is of upper Scythian and Anisian age. At the base of the 'Keuper' Sandstone is a significant disconformity which is probably equivalent to the Hardegsen Disconformity of Germany.
The 'Keuper' Waterstones are a marine or semi-marine facies of transgressive nature and represent the distal facies belt of the delta complex. The Waterstones facies is of lower Ladinian age in the central Midlands but is probably older in more northerly districts (Cheshire, Yorkshire, etc).
The Keuper Marl is of Keuper age, representing at least the upper Ladinian and Carnian stages of the European Keuper, and is largely the deposit of a hypersaline epeiric sea.
A correlation chart and a series of palaeographical maps, based on the new evidence provided in this paper, are presented.
On the Older Palæozoic (Protozoic) Rocks of North Wales
Authors: Sedgwick A. 
Published: October 2009

Introduction

In a paper read before the Geological Society in June, 1843, and intituled, “ An Outline of the Geological Structure of North Wales,” the author gave a description of those stratified rocks in the northern counties of the principality which are of anterior date to the mountain limestone. Those rocks he separated into the following three principal groups:—

1.
Chlorite-slate and mica-slate. These form a band along the north-western side of the promontory of Carnarvonshire from Porth Dilleyn to Bardsea island.

2.

Greywacke and roofing slate, often containing calcareous bands, and alternating with Plutonic rocks of cotemporaneous formation: and these rocks the author terms, in his present paper, the
Protozoic
, group. They extend in an east and west direction, from the borders of Shropshire to the western coast of Carnarvonshire; and their north-western boundary, from the confines of Shropshire to Yspytty Evan, coincides nearly with the Holyhead road; and from Yspytty Evan to Conway, with the Conway river.

3.
An overlying and sometimes unconformable deposit of flagstone, &c., coterminous along the Holyhead road and Conway river with the last-mentioned principal group; but bounded towards the north-west by an overlying range of mountain limestone.
On the Trap-rock of Bleadon-hill, in Somersetshire
Authors: Williams D. 
Published: October 2009

Since the author's last communication on this subject, the completion of the Railway cutting through the western point of Bleadon Hill has disclosed several new and remarkable facts; and these have so materially changed his views respecting the origin of trap and other rocks, that he has been led to draw up a supplement to his former papers.
The Mountain Limestone of Bleadon Hill and that of Uphill have been disconnected by two great downcast faults since the lias was deposited, that on the Bleadon side ranging E. by N. and W. by S., and that on the Uphill side N. E. and S. W. In the space between them, which is about a quarter of a mile broad, the surface consists of lias and new red sandstone.
In the cutting the Bleadon fault is finely exposed, and its southern side presents a great slickenside wall of limestone and trap, which dips to the south at an angle of 70°. On the northern side of the fault, the lias is seen, curiously faulted, to some little distance; it then dips considerably towards the fault, the inclination increasing, and the beds at last going down with the fault, the lias inclining towards it at an angle of 45°. The lias, where abutting against the trap, has no appearance of having been altered, by it.
On the
Permian
System as developed in Russia and other Parts of Europe
Authors: Murchison Roderick Impey , de Verneuil M. E. 
Published: October 2009

On the part of his associates, M. de Verneuil and Count Keyserling, and himself, Mr. Murchison has previously explained in the Proceedings of the Geol. Soc. the nature of the various deposits which constitute the subsoil of European Russia. As in all other parts of the world which have been adequately examined, the Silurian rocks are those which contain the earliest forms of animal life, and in Russia they are overlaid by Devonian and carboniferous deposits, each of which is there singularly well defined by its organic remains and regular superposition.
In common with many other geologists, Mr. Murchison was formerly of opinion that the above-mentioned three systems constituted the whole Palæozoic series, but the examination of Russia and Germany has led him to include also therein the next group in ascending order, or that to which he had assigned the name of Permian.
When two or more conterminous formations are shown to have a community of fossils, it has recently been deemed essential to group them under one name; and following the practice of assigning to any such newly classed group a geographical name derived from the region where the strata are best developed, the term “Permian” was employed. This system was first proposed to embrace the deposits known in Germany as the Rothe-todteliegende, Zechstein, Kupferschiefer, &c., and in England as Lower New Red Sandstone, Magnesian limestone, &c.
On the Occurrence of Fossils in the Boulder Clay
Authors: Harkness Robert 
Published: October 2009

There can be no doubt that the presence or absence of fossils in different formations is owing to other causes than the actual existence of animals and vegetables on the spot and at the time of deposition, and is, indeed, generally the result of local circumstances; but the “boulder clay,” the formation of which the author of the present paper endeavours to explain the cause, presents similar characters in districts widely distant, and is also remarkable for the paucity of its organic remains.
The deposit in question belongs to the geological period immediately antecedent to the existing epoch, and consists of clay containing boulders of various kinds of rock, scattered without order through its whole mass. It occurs on various parts of the coast both of Great Britain and Ireland, but appears to be most fully developed in the basin of the Clyde, where it overlies a series of beds of fine clay containing numerous remains of shells. Similar remains have been found in many elevated sea beaches; and it has been concluded from the examination of them by competent naturalists, that the climate must have been more arctic at the time of their deposition than it is now in the places where they are found.
On the Cliffs of Northern Drift on the Coast of Norfolk, between Weybourne and Happisburgh
Authors: Trimmer Joshua 
Published: October 2009

In this paper the author proposes to describe certain changes that have taken place in these cliffs, comparing the appearances they present with those of raised beaches in North Wales.
With regard to the former subject, he notices first, the condition of a pinnacle of chalk at Old Hythe Point. The cavity at the summit of this pinnacle is now exposed to a greater depth than in Mr. Lyell's drawing, and the sand and gravel with which it was filled are removed. No vertical strata of sand to the N.E. of the pinnacle are now visible, and these must have been removed by denudation. Mr. Lyell's statement that this pinnacle is separated from the great mass of the chalk by the crag deposits, is, in the opinion of the author, confirmed by the position in which the chalk rests.
Of the protuberances of chalk near Trimmingham, the northern and middle seem now little changed, but the southernmost has undergone some alteration. Its length is still the same as when visited by Mr. Lyell, but it is reduced to nearly half its height, and the waves have washed away a portion of the overlying gravel at one extremity. The next fall of the cliff will probably bury this end of the protuberance entirely. The chalk inland seems tilted, and is covered with a breccia of the crag.