bluuebunny/crossref_metadata_2025 huggingface dataset:
The Geology of the Prescelly Hills, North Pembrokeshire
Authors: Evans William David
Published: October 2009

The Ordovician rocks of this district range from the Arenig to the Bala, with the succession generally ascending northwards. The rocks usually possess a Caledonoid strike and are disposed about two eastwardly pitching anticlines and a complementary syncline, which are dislocated by faults and overthrusts to the south-east. The Sealyham Volcanic Series is composed of rhyolites and tuffs in the western part of the area, but in the east the formation is almost entirely represented by trachytes. The
Didymograptus bifidus
beds occupy nearly the whole of the Prescelly Hills and they are mainly composed of shales and mudstones. The Fishguard Volcanic Series consists of fine-grained spherulitic and flow-brecciated rhyolites with thick beds of tuffs and local developments of ashy shales and mudstones. Sills of quartz-dolerites (among them the “spotted dolerite” which has been described as the analogue of the blue-stones of Stonehenge) and a single intrusion of a keratophyria rock occur in the Arenig and Llanvirn rocks but do not penetrate the shales, mudstones and sandstones of the Llandeilo and Bala formations. Petrographic descriptions of the igneous rocks are given, as well as a figure illustrating the stratigraphical correlation of the beds with those of other areas.
The Stratigraphy, Structure and Mineralization of the Greenhow Mining Area, Yorkshire.
Authors: Dunham K. C. , Stubblefield C. J.
Published: October 2009

From Dr. R. G. S. H
udson
:—

The Horizos of
Eumorphoceras bisulcatum
s.l.

The comparison in this paper of
Eumorphoceras bisulcatum
Girty mut.
grassingtonense
Stubblefield with other forms of
E. bisulcatum
s.1. found in the Lower Namurian is a valuable contribution to the palaeontology of Carboniferous goniatites. Dr. Stubblefield would, however, have added to its value if he had included in it that form of
Eumorphoceras
occurring in the Weston marine band near the base of the Weston Shales and above the Weston Grit, and exposed, for instance, in the Washburn variation within the species-group at particular horizons ; this failure is to some extent due to the lack of " solid " specimens in collections from British localities ; it is hoped that suites of well-preserved specimens may be collected and studied and the results made available to assist in correlation work, not only in Britain but in North America and elsewhere.

I regret to find that in Dunham and Stubblefield (1945), two errors have arisen in my measurements of previously published figures of the species
E. bisulcatum
and I should like to rectify these.

The number of ribs in Girty's type specimen from locality 2082 in Oklahoma, according to his illustration, is approximately 18 in half a whorl (not 23 as stated by me) ; this form seems closer to
E. bisulcutum grassingtonensis
than does Girty's figure of the same species from his locality 2075 in which there are 11 or 12 ribs in half a whorl at
The gabbroic complex of Belhelvie in Aberdeenshire
Authors: Stewart Frederick Henry
Published: October 2009

The Belhelvie igneous complex is a mass of basic and ultrabasic rocks, exposed over an area of about seven square miles, which intrudes and metamorphoses sillimanite-cordierite-gneisses and quartzose gneisses of the Dalradian Series. It is younger than the regional metamorphism of the gneisses and older than a patch of Old Red Sandstone conglomerate exposed near the intrusion. The general succession of rock types from west to east is : dunite-serpentine and peridotite, troctolite, hypersthene-gabbro, olivine-gabbro, and end-stage derivatives of olivine-gabbro and hypersthene-gabbro. The main conclusions reached in this paper have been derived from a study of this succession and of small-scale rhythmic banding and allied structures shown by many of these rocks. The evidence indicates that the various rock types have been formed largely by differentiation in place by crystal settling under the influence of gravity, and that at Belhelvie a section is exposed through a layered concordant mass similar in many respects to the large layered intrusions of Bushveld type. Study of the primary banding has led to the conclusion that the mass may have been tilted considerably since its consolidation, so that the bands have a nearly vertical dip. An alternative suggestion—gravity differentiation in another chamber and intrusion in a mushy state—is not supported by the petrological evidence, but the question must remain open until more knowledge is available of the structures of the gneisses of this part of Scotland.

At the eastern side of the complex is a large area of uralitized derivatives of olivine-gabbro and hypersthene-gabbro, and the more normal rocks to the west have been uralitized in many places. This uralitization is considered to have been due to the action of end-stage liquids or vapours (introducing water and silica) from the basic magma. Serpentinization of olivines is widespread, and microscopic evidence indicates that the main serpentinization took place before the main uralitization, and that both were preceded by the development of hornblende-spinel reaction rims round the olivines.
Intraformational Contorted Rocks in the Upper Carboniferous of the Southern Pennines
Authors: Cope F. W.
Published: October 2009

An occurrence in Ireland similar to those described by Mr. Cope from the southern Pennines seems worthy to be placed on record. In the face of the large quarry at Noughaval, Co. Clare (1-inch sheet 123, 6-inch Clare 9) there is a band of contorted shale about nine to twelve inches in thickness lying between beds of undisturbed black shale some three feet above a bed of phosphorite, which in turn is a few feet above the top of the Carboniferous Limestone. The phosphorite is supposed, from the associated goniatites, to lie very near the R and H zones of the Millstone Grit; so that the stratigraphical position of this bed is comparable with that of some of Mr. Cope's examples. The general dip of the beds is about 5° the strike of the intraformational shear-planes being essentially that of the major formations. The feature provided a considerable puzzle before Mr. Cope's explanation was published. A tectonic origin in this case is not, however, altogether convincing, since the regional dips are as a rule less than 50° and much lower than those generally encountered by Mr. Cope.

A subsequent attempt at detailed description by the writer was frustrated by the filling.in of the quarry section without previous notice, so that it is no longer visible. There is one photograph, but this is unfortunately not good enough to provide a satisfying record.
Erosion and tectonics in the East African Rift System
Authors: Dixey F.
Published: October 2009

Perhaps I may be allowed to suggest as additions to the list of references appended to Dr. Dixey's paper, J. E. S. Moore's
The Tanganyika Problem
(London, 1903) and E. Parson's important paper, “The origin of the Great Rift-Valleys as evidenced by the geology of coastal Kenya” (Trans. Geol. Soc. S. Afr. xxxi, 1929, pp. 63-96). The map accompanying my own paper on the “Karroo System in East and Central Africa” (
C.R. Int. Geol. Congr. xv
, 1929,
S. Aft.
ii, 1930, pp. 263-87) gives some idea of what may be termed the paulo-post-Karroo faulting, which, as Dr. Dixey points out, has often been confused ~rith the later “Rift” system. As it was the result of going over much of the area on foot, the paper contains details about various definite points, and attention may be drawn to the fact that both alongside Lake Tanganyika and in the Zambesi Valley all the faulting I saw had the downthrows the wrong way for the depressions to be ascribed to its influence. The fact that the faulting does not completely neutralize the effect of the general dip seems to show that Moore was not so far out, after all, with his “eurycolpic folds”.

A point touched upon as long ago as 1903 in the Geological Magazine (1903, p. 548) may be again emphasized here. It is not by any means as certain as seems to be generally assumed that the southern half of Africa has had its present shape for any great length
The petrology of two granite-slate contacts at Cape Town, South Africa
Authors: Walker F. , Mathias M.
Published: October 2009

Most geologists acquainted with the wonderfully clear contact sections of the Cape Town granite will doubtless be inclined, like Sir Lewis Fermor, to follow Darwin and Lyell in regarding them as typical examples of igneous intrusion. This does not, of cmirse, mean that there is nothing more to be learnt about the process which they illustrate. I have spent a considerable amount of time in the area since I first described cordierite from it, having ranged much farther afield on the granite than the paper takes us. I was particularly interested in the problem of the large felspars, to the occurrence of which attention was first drawn by A. W. Rogers. Their similarity to the pseudo-porphyritic crystals seen in the granite, not only here, but in the part of Dartmoor with which I am familiar, is most marked. They also closely resemble the large microclines in the Matopo granite, near which I am writing, this being part of a mass of “ Old Granite ” so big that it extends beyond the boundaries of Rhodesia, in spite of the fact that the country is much larger than Britain. The Cape granite does not belong to this ancient group, but is one of a younger series to which the well-known Bushveld Complex is probably related, a point which is certainly worthy of attention.

At the Cape contact, though the margin of the altered sediments is often felspathized, just as it is on the north side of Dartmoor, this does not appear
The form and distribution of dolerite masses in the Builth-Llandrindod Inlier, Radnorshire
Authors: Jones Owen Thomas , Pugh William John
Published: October 2009

Numerous albite-dolerite masses occur within the inlier of Ordovician rocks which extends between Builth Wells, Breconshire, and Llandrindod Wells, Radnorshire. These are surrounded by Silurian rocks which in many places rest unconformably upon them. Nearly all the dolerites are intruded into shales and show a tendency to occur at nearly constant levels. The lowest horizon belongs to the zone of
Didymograptus bifidus
, which is succeeded by the zone of
D. murchisoni
; this is followed by the
Glyptograptus teretiusculus
zone and this in turn by the zone of
Nemagraptus gracilis
and the
Dicranograptus
shales. Each of these has dolerites at one level, except that in the
G. teretiusculus
shales there are two levels. It has been found that the largest and most continuous bodies occur at the lowest horizon, and at each successive horizon upwards the dolerite masses become more and more divided, culminating in the remarkable set of intrusions near Llandrindod described in the previous communication. Below the upper
G. teretiusculus
horizon, the masses appear to be concordant and their feeders are unknown. At and above that horizon many of the masses are very small and grouped in clusters which suggest comparison with the plug-like feeders of the Llandrindod laccolith; they are associated with large oval masses of concordant habit. The mechanism of the intrusion, the probable temperature of the magma and the effect of depth on the form and distribution of the dolerite masses is discussed.
Slumping in the Carboniferous rocks of Pembrokeshire
Authors: Kuenen Philip Henry
Published: October 2009

The coastal cliffs between Tenby and Telpyn Point afford a fine section through part of the Carboniferous strata of southern Wales. Here the writer came across some thirty localities showing evidence of slumping. The evidence takes several forms : (1) contortion and slip-bedding; (2) slump-ball structures of a few inches to 24 feet across, generally composed of sandstone and embedded in mudstone. Lumps of clay-ironstone, resembling concretions, appear to have a similar origin; (3) crumpled balls, resembling the slump balls, but of a less compact structure, of only a few inches across and occurring embedded in sandy shale; (4) slipped blocks, giving the appearance of cross-bedding. These occur amongst other slump structures, as separate masses, generally a few feet across, which have slid without much internal distortion; (5) pseudo-ripple marks, which are regular slight folds measuring a few inches from crest to crest, each crest persisting only a short distance along the strike. They resemble ripple marks, but through a thickness of a few feet all laminae are bent in “similar folds” with the crests directly above each other.

The thickness of the slump sheets varies from a foot or less to about 15 feet. For each sheet the thickness remains almost constant over large areas. The most extensive sheet is exposed for a mile along the coast around Telpyn Point and for 200 or 300 yards at right angles to this direction. At Waterwynch Bay four sheets are superposed. These larger sheets are composed of slump balls embedded in mudstone. They alternate with undisturbed beds. The slopes on the sea-floor during the slumping must have been exceedingly slight, since there is plentiful evidence of shallow water. Moreover, most individual, undisturbed beds can be traced for considerable distances, each showing a constant thickness.

The slump balls are explained by quasi-turbulent motion of the sliding mud. An experimental investigation of the mechanics is being conducted in conjunction with Dr. van Straaten.

Difficulty is sometimes found in distinguishing between slump structures and buckling in anticlinal cores, the two features frequently being closely associated in the field. Although it is not deemed probable, the possibility must be admitted that the so-called buckling is due, at least in part, to slumping. Anticlines, also, may have tended to form where slumping had previously caused irregularity in the bedding.
The geology of the Llandovery district: Part II. the Northern Area
Authors: Jones Owen Thomas
Published: October 2009

The area described lies north-east of Llandovery and within about seven miles of that town; it is largely exposed, heather-clad upland. The adjoining area to the south was dealt with by the same author in a paper published in 1925.

The three divisions (A) Lower, (B) Middle and (C) Upper Llandovery, established in the south, are recognized in the Northern Area, but here they vary greatly in thickness and some even disappear locally.

Along the western boundary the Lower Llandovery rocks are faulted against Upper Bala mudstones with thin grits. Due east of the town only the lower part of the Lower Llandovery occurs between the Western Boundary Fault and the Upper Llandovery, but farther north, in the Crychan valley, the higher parts of the formation appear for a short distance. East of Noethgrug the whole subdivision is overstepped by the Upper Llandovery.

The Middle Llandovery first appears in the Crychan valley about three miles northeast of the town, and after trending to the north and then the south disappears under the Upper Llandovery three miles east of the place where it first appears. North of these two points the subdivision is represented probably to its full thickness and in places yields many graptolites.

The Upper Llandovery maintains its general characters through Cefn-y-gareg and Noethgrug, but near Craig-wyddon thinning sets in and within about three miles the main development is reduced to only 40 feet of
Pentamerus oblongus
sandstones. The uppermost part of the formation consists of green mudstones with some thin siliceous bands. The Upper Llandovery below these mudstones near Llandovery consists largely of greenish, sheared-looking mudstones but becomes more sandy to the north-east. It is significant that not only the Upper Llandovery but also the Middle and Lower Llandovery in the Noethgrug area develop coarse sandy and pebbly beds. At the extreme north-east of the district the base of the Upper Llandovery can be seen resting on Upper Bala mudstones.

The structure of the area is relatively simple; to the east of the Western Boundary Fault the Lower Llandovery rocks dip with few exceptions very steeply, or are even vertical. In the succeeding Middle and Upper Llandovery of Gefn-y-gareg the dip lessens, and between Cefn-y-gareg and Noethgrug the beds turn over in an impressive pitching syncline.

On Noethgrug the rocks dip west at moderate angles, but south of that region they turn over in a broad anticline with a southerly pitch. On the eastern limb of the anticline in the Craig-wyddon ridge they again become vertical. The core of the Noethgrug anticline is occupied by Upper Bala mudstones which are partially surrounded by a strong escarpment of Lower Llandovery rocks. The dips in the folds suggest a push from the north-west.
An early Ordovician shore-line in Radnorshire, near Builth Wells
Authors: Jones Owen Thomas , Pugh William John
Published: October 2009

This paper deals mainly with the western margin of the Builth-Llandrindod Ordovician inlier and is concerned with the phenomena associated with the unconformity between the Newmead Series and the underlying Builth Volcanic Series. The rocks dip westwards and strike approximately north and south. They are extensively faulted and, in particular, the outcrops are displaced by powerful tear-faults.

The Newmead Series consists of Grey Felspar Sands, Pyritous Felspar Sands and the flinty mudstones of Tan-lan. Within the sands, and especially in the lower part of them, there are many impersistent boulder-beds; both these rocks are beach deposits. There is progressive overlap within the Newmead Series, so that ultimately the flinty mudstone rest directly upon the Builth Volcanic Series. The Newmead Series is followed unconformably by the
Glyptograptus teretiusculus
shales. A rhyolitic series emerges from beneath the
G. teretiusculus
shales near Cwm-amliw and can be traced into the northern part of the inlier.

The Newmead Series oversteps different divisions of the Builth Volcanic Series, the succession in the latter being most completely developed in the southern part of the inlier. The contact between the two series reveals the characteristics features of a coast-line, with wave-worn surfaces, sea-cliffs, screes and stacks as well as the beach deposits which occur in the Newmead Series. It is possible to reconstruct in detail the features of the area exposed to sub-aerial and marine erosion which was subsequently buried beneath the Newmead sediments. It consisted of horizontal layers of spilitic rocks, making trap topography, and in one locality this was overlooked by rounded hills of keratophyre. The presence of several outliers of Newmead sands to the east of the main outcrop indicates that the deposition of the Newmead sediments was probably widespread over most of the southern half of the inlier.

From our observations, it is possible to interpret the general sequence of events, in particular of elevation, erosion and depression. It is shown that all these events took place within a relatively restricted part of the time-interval represented by the
Didymograptus murchisoni
zone. Finally, attention is called to the remarkable preservation of these ancient Ordovician physiographical features.
The Lower Carboniferous reef limestones of Cracoe, Yorkshire
Authors: Bond Geoffrey
Published: October 2009

The limestones forming the " reef-knolls " in the Cracoe district of Yorkshire lie at the eastern end of a belt of similar limestones which stretches westwards across the Central Province of the Carboniferous Limestone Series. This " reef belt " separates areas of contrasted sedimentation, the strata to the north being of massif (Great Scar) facies, while to the south lies the much thicker basin facies, of impure limestone with much interbedded shale. The Cracoe knolls have attracted much attention in the past, owing to their peculiar topography and the abundance of their fossils. Theories on their origin were based either upon supposed quaquaversal dips of original deposition or upon more normal deposition, followed by tectonic deformation and subsequent erosion.

It is now shown that the limestones in the Cracoe area are divisible into local faunal and lithological subdivisions, which can be mapped by the usual methods. These subdivisions are correlated with the coral-brachiopod zones and goniatite succession of the Viséan, and extend from S
2
to D
2
. The peculiar facies is due to the beds having been laid down against a long narrow ridge which kept the basin and massif areas of sedimentation apart until it was finally submerged in D
2
times, when sedimentation became continuous across it.

The reef limestones are, in fact, the marginal facies of the Great Scar Limestone, and the lateral change of each member of the local subdivision is traced through the marginal facies into the normal Great Scar Limestone.

The structure consists of a series of anticlines and broader synclines, arranged in echelon, which pass obliquely across the facies belts and die out north-eastwards. They were formed by pressure from the south impinging obliquely on a ridge of older rocks. The folding took place under exceptionally light cover and was completed before the Bowland Shales were deposited. The knoll topography was blocked out by faults which cut across the fold axes. The knolls themselves were eroded to very much their present shapes before the Bowland Shales, which lie with strong unconformity on the limestones, were laid down. The removal of these shales is now proceeding, and is re-exposing the buried topography of the knolls.
A tectonic window in south-western Iran
Authors: Gray Kenneth Washington
Published: October 2009

The paper presents evidence of large-scale overthrusting during Upper Cretaceous times in part of the Zagros Mountains in south-western Iran. Thrust-sheets made up mainly of radiolarian cherts and serpentinous igneous rocks, and including fossiliferous rocks of Triassic age, are shown to have been extensively overthrust upon Cretaceous rocks, including Cenomanian limestones and marlstones probably of Senonian age. Marine Maestrichtian and younger rocks were deposited upon the thrust-sheets and were later folded, together with the sheets themselves and the underlying autochthonous rocks. Subsequent erosion of the cover has exposed the thrust-sheets over wide areas and in places has exposed the underlying autochthonous rocks in tectonic windows of which a striking example, the Dalnashin Window, is described in the paper.
Foraminifera from the Upper Lias of Byfield, Northamptonshire
Authors: Barnard Tom
Published: October 2009

The paper, which for the most part is a systematic description of the foraminifera, is an attempt to unravel the somewhat complicated taxonomy of the species present. The foraminiferal fauna is unlike that of the preceding Lower and Middle Lias, being typically Upper Lias in appearance, except for several long-range species.

In the chapter on systematics the variation of several species is dealt with. On the whole, the foraminifera are very variable and some abnormal specimens occur.
Some aspects of magmatic evolution
Authors: Tilley C. E.
Published: October 2009

The address is concerned with some aspects of magmatic evolution in volcanic successions, and includes particularly a discussion of the nature and genetic relations of primary and derivative basic and intermediate magmas.

Among the volcanic associations of the oceanic areas, those of the Hawaiian archipelago provide data of critical importance in the study of basaltic evolution. The established chronological succession of magmas in these islands makes it probable that the alkali-poor tholeiites to be recognized in the lavas of the primitive shield volcanoes form the closest approach to the primary magma of the ocean basins, and from them derive by fractional crystallization processes the Hawaiian alkali magma series of alkali olivine-basalt, mugearite (so-called andesite) and trachyte.

The course of volcanic variation there exhibited provides a new orientation to the study of the genetic evolution of the Tertiary igneous Brito-Icelandic province, and leads to the conception that the Hebridean alkali magma series derives through tholeiites as an alternative line of descent.

The course of fractional crystallization of tholeiite magma in the great layered intrusion with its final product of granophyre is illustrative of the great flexibility in line of descent which fractionation processes permit. Derivation by crystallization differentiation in a convecting system comparable to that demonstrated in layered intrusions seems, indeed, the most likely mechanism for the genesis of the primitive sialic layer of the crust itself.

The problem of intermediate magma in the volcanic successions of the orogenic belts is critical in petrogenic theory. Though fractionation processes appear most competent to give a liquid line of descent through andesite to rhyolite, normal andesite magma does not reflect in its chemistry the course of basaltic (tholeiitic) differentiation.

Consideration is devoted to the conception that andesites, though ultimately of basaltic parentage, have derived in part by sialic contamination.

The testing of the genetic relations of assemblages within the basalt-andesite range of the volcanic suites of the orogens remains one of the most important problems of volcanic petrogenesis.

Systematic attack through intimate phase analysis and geochemical study may provide the data which will go far to solve, not only the status of the voluminous andesite, but of intermediate magma in general in igneous rock evolution.
Graptolites from the
Dictyonema
Shales of Quebec
Authors: Bulman Oliver Meredith Boone
Published: October 2009

The fossiliferous
Dictyonema
Shales of Matane are represented in older collections by a rich graptolite fauna which is here fully described on the basis of material sent to Lapworth at the end of last century, and the Richardson collection and other material from McGill University, Montreal. Included in this fauna is
Dictyonema canadense
(figured but not described by Lapworth) and four new species of
Dictyonema
, together with six species and varieties of
Anisograptus, Triograptus
and
Staurograptus,
and a species of
Didymograptus
. From other less fossiliferous localities spread along the south shore of the St. Lawrence River come some of the above, with another new species of
Dictyonema
, a
Bryograptus
and a monotypic new genus
Radiograptus
, intermediate between
Anisograptus
and
Dictyonema
. The stratigraphical relations of these various localities are unknown, but the whole constitutes a fauna of Tremadoc age which is assigned either to the highest part of the
Dictyonema
Shales (of Scandinavia) or the lower part of the Upper Tremadoc.

Structurally, all the species of
Anisograptus
, the
Bryograptus
and the
Staurograptus
are shown to possess stolothecae, and bithecae can be identified in most of them; the occurrence of this dendroid branch structure is also believed to characterize
Triograptus
and
Radiograptus
. Accordingly, all these genera, together with
Clonograptus
and
Adelograpius
, are separated from the Dichograptidae where they were previously placed, and united into a new family, the Anisograptidae, which is transferred to the Dendroidea. No phylogeny can be indicated with any assurance, but the whole group seems to constitute a plexus intermediate between the Dendroidea and the Graptoloidea.
The study of the world's plainlands: a new approach in geomorphology
Authors: King Lester C.
Published: October 2009

A review of the older plainlands and plateaus of the earth reveals a similarity in age and elevation sufficient to suggest that their independent origin and development in their present situation is unlikely. It is claimed that continent-wide bevelled surfaces have been produced by " pediplanation ". A world-wide correlation of pediplaned surfaces now standing at varying levels above O.D. is suggested by the following grouping : (a) pre-Cretaceous super-continental cycles of erosion (" Gond-wana " and " Laurasia " surfaces); (b) pre-Miocene intermediate continental cycles (" African ", " Prairie " etc. surfaces); (c) modern continental cycles. The difference in elevation between the fundamental surface (a) and the plains of the continental early-Tertiary cycle (b) is attributed largely to the altitude of the twin Gondwana-Laurasia super-continents at the time of their break-up. It is suggested that global forces, and probably continental drift, must be invoked in explanation of these world-wide pediplaned surfaces.
Note on the gravel deposit from which the Piltdown skull was obtained
Authors: Edmunds Francis H.
Published: October 2009

The age of the Piltdown skull has long been a subject of intermittent controversy and it is a question which can only be determined from palaeontological data or other evidence inherent in the fossil itself, such as that provided by fluorine fixation; details of river-terrace forms and levels as related to the present-day
thalweg
of the River Ouse, and of materials comprising the gravel in which the skull was found, offer little assistance.

In the literature on the subject some misunderstanding has arisen as to the height of the gravel deposit in which the skull was found relative to the present-day River Ouse; height above the river having to some extent been used to date the fossil.

According to levels taken from the six-inch scale Ordnance Survey map, Sussex 40 NE., the 100-foot contour above Ordnance Datum cuts the surface of the gravel spread, the highest part of which lies about 103 feet O.D. while the lowest part is about 97 feet O.D. The nearest part of the River Ouse, at Gold Bridge, is between 45 and 50 feet O.D. Thus the terrace is is about 50–55 feet above the nearest part of the river.

Dawson (1913, p. 119), however, stated that the terrace lies on a plateau above the 100-foot contour, with an average height of about 120 feet above O.D.; a statement true of the plateau, but not of the gravel terrace, which is the thing that matters. Again, he gave the height of the gravel spread above
Notes on the geology of the St. Elias Range, Alaska-Yukon Territory, North America
Authors: Odell N. E.
Published: October 2009

The following notes are a preliminary record of geological results of work in the Yukon-Alaska boundary region by the writer with the expedition of the Arctic Institute of North America (project " Snow Cornice ") during the summer of 1949.

Field-work was mainly along the northern border of the great inter-montane basin occupied by the Seward Glacier (or firn-field), which lies intrenched behind, and immediately north of, the main St. Elias Range, of which Mt. St. Elias itself, 18,008 feet, is the dominant peak. During flights from the coast at Yakutat to and from this basin, and on other occasions over neighbouring localities, visual observations of structure and morphology were also made. Chiefly, however, field-work was a matter of climbing (as in the case of a pioneer ascent of Mt. Vancouver, 15,800 feet), or of skiing over the immense spaces of the Seward firn-field (750 square miles in area) in order to visit scattered island outcrops or mountain cliffs flanking the firn-field.

The region is underlain by a metamorphic series of sedimentary origin, mainly pelitic, with subordinate psammitic elements and marked calc beds. The pelitic series consists mostly of biotite-schists and gneisses, rarely garnetiferous; the calc beds are composed of fairly pure marbles, which occupy no regular stratigraphical position within the pelites, but occur in mountain walls as conspicuous elongated or irregular masses, having suffered severe deformation during orogenesis. The thickness of this whole series, whose dip is variable and locally vertical, was not determinable. Into the series has been
A tectonic window in south-western Iran.
Authors: Gray K. W. , Lehner E.
Published: October 2009

From
Dr. E. Lehner :—

The peculiar conditions in the Niriz region, and especially at Kuh-i-Dalnashin, afford apparently unassailable evidence of the existence of a nappe of radiolarites and green rocks which was formed in Upper Cretaceous time. From my knowledge of published papers and of unpublished reports by the geologists of the Anglo-Iranian Oil Company I believe that, for the whole disputed zone from Oman to the Mediteranean, no other case of equal merit has been made out in favour of such a nappe. It is therefore desirable that Dr. Gray's conclusions be put to every test.

The paper does not explicitly deal with the roots of the composite radiolarite-green igneous nappe. It describes, however, in some detail the stratigraphical succession in the “Late Tertiary Overthrust Zone” and its south-eastern extension at Aghirq. Here the radiolarites are only thinly developed, as intercalations in the sandstones which mark the coming in of the Kirman facies of plant-bearing Jurassic. It would, therefore, seem obvious that the roots of the nappe must be looked for to the south of this zone, either in the Dehbid valley, which is covered by Neogene or Quaternary, or in a region now overridden by the late Tertiary thrusts. Yet in the sections (pl. ix) the Dehbid valley is shown as a gently folded monocline, and the drawing of the thrust zone does not admit the probability of a root zone underneath. Where does Dr. Gray assume the root to be ?

The paper tentatively suggests a
The mineralogy of some Nile sediments.
Authors: Shukri N. M.
Published: October 2009

Dr. Shukri's reply to the discussion (pp. 530-4) ::—

The author thanks the speakers for their kind remarks and for their interest in the work. He also thanks Dr. Sandford for his answers to the questions raised. He fully agrees with Dr. Sandford that the Blue Nile and Atbara sediments were not added suddenly to the Nile system. Their material appeared for the first time in Lower Palaeolithic terraces and were absent in Pliocene and Plio-Pleistocene sediments.

In reference to Dr. Wiseman's remarks, the author states that local contamination is observed at present along the course of the Nile and is not restricted to the cataracts. Some of the Nile sediments in Egypt, for example, contain Nummulites and other fossils derived from the sedimentary formations north of the first or Aswan cataract. These, and any other material brought from the neighbouring deserts by wind or by casual torrents, are, however,of negligible importance in the recent sediments, as can be seen at present. The mechanical constitution of the sediments was determined and the clay fractions were investigated and the results will be given elsewhere.

In reply to Mr. Edmonds, the genetic significance of the uncommon minerals which are liable to spice the assemblages of the commoner minerals was taken into consideration in the paper. Some of these very scarce minerals are recorded as one grain in one slide out of five. On the other hand, the author sees no objection to the use of the more abundant minerals as evidence in
A contribution to the study of the Eocene in western Pakistan and western India: A. The geology of standard sections in the western Punjab and in the Kohat district
Authors: Eames Frank Evelyn
Published: October 2009

Detailed descriptions are given of the geological successions in the Eocene of standard sections in the Rakhi Nala and at Zinda Pir in the western Punjab, and at Tarkhobi, Panoba, the Shekhan Nala and Sirki Paila in the Kohat district. The work forms the first stage in the reinvestigation of the classification and correlation of the Eocene in western Pakistan and western India. Comprehensive collections of fossils were made.
A contribution to the study of the Eocene in western Pakistan and western India: D. Discussion of the faunas of the certain standard sections, and their bearing on the classification and correlation of the Eocene in western Pakistan and western India
Authors: Eames Frank Evelyn
Published: October 2009

Local palaeontologieal subdivisions are established for the Eocene of the Rakhi Nala, Zinda Pir and Kohat areas as a result of the examination of extensive collections of fossils recently made in these areas. The distribution of the different phyla in various facies developments is discussed. Comparison is made with the pre-existing major subdivisions of the Eocene in western Pakistan and western India. In the Rakhi Nala and Zinda Pir area, it is concluded that the Khirthar-Laki boundary has previously been taken at too low a horizon, and that beds previously referred to as lower Middle Khirthar include representatives of the upper Middle Khirthar, the Upper Khirthar, and still younger horizons of Upper Eocene age.

The lithological and mapping evidence and the palaeontologieal evidence from the Rakhi Nala and Zinda Pir areas are each considered separately and finally synthesized in order to arrive at as precise a correlation as is possible. The evidence from the Kohat Eocene beds has been synthesized with that from the Rakhi Nala-Zinda Pir area in like manner, and it is evident that only the major palaeontological subdivisions can be correlated.

The present investigations have confirmed the usefulness of the terms “Ranikot Series”, “Laki Series” and “Khirthar Series” for subdivisions of the Eocene in western Pakistan and western India. The writer considers that the basic and fundamental soundness of these terms is not affected by the fact that beds and faunas have occasionally been incorrectly allocated to one or other of them.

Certain beds, which are here named the “ Tapti Series ”, and which are not of very widespread occurrence, contain a fauna which is distinct from that of the Khirthar Series below and is of Upper Eocene age. The fauna of this series, in addition to several species of Upper Eocene age and a number of new species, includes the genus
Pellatispira
, which is also of Upper Eocene age and has not yet been unquestionably recorded from horizons as low as those containing the genus
Assilina
.

A consideration of all the available evidence indicates that published information concerning the ranges of some species is incomplete and that in some cases the existing conception of a species requires modification. The author is of the opinion that the “ zones ” which have been previously proposed within the Ranikot, Laki and Khirthar Series are of local rather than regional value, and that there has been too great a readiness to assign regional chronological significance to local facies faunas. It is evident that further work is necessary before regional zoning of the series can profitably be attempted.
The geology of the Arnage district (Aberdeen-Shire) : a reinterpretation
Authors: Read Herbert Harold , Farquhar Oswald Cornell
Published: October 2009

In 1923, Read considered that in the Arnage district an initial gabbroic magma had been contaminated by country-rock material to produce on consolidation quartz-biotite-oligoclase-cordierite rocks (Arnage Type), pseudo-dioritic rocks (Kinharrachie Type) and finally granitic rocks (Ardlethen Type). Detailed field investigation leads to a new interpretation. The continuous magmatic series proposed by Read has been broken into two parts :—

1. An older part, consisting of the Arnage-Kinharrachie-Ardlethen types, produced by migmatization and comparable with migmatitic complexes of “ Older Granite ” age developed elsewhere in Aberdeenshire.

2. A newer part, gabbroic in character and belonging to the basic phase of the “ Newer Granite ” igneous activity of North-East Scotland.

The “ Older Granite ” migmatites of Arnage have characters, such as the hornfelsic nature of their enclaves and their richness in cordierite, that are appropriate to their setting in the metamorphic zones of North-East Scotland. They present a contrast to the Cromar type of migmatites set in the Barrovian metamorphic zones of the South-East Highlands.
A note on a small ammonoid fauna from the Northern Range of Trinidad, British West Indies
Authors: Barr Kenneth William
Published: October 2009

During the course of an investigation of the Toco district at the eastern end of the Northern Range a small number of poorly preserved pyritized ammonites have been found. They occur in low-grade sericite phyllites which are the dominant rock type of the area. The first specimens were observed in deeply weathered rock near Cumana village at the 24¼-mile post on the Toco road. They were too fragile for extraction and preservation but were seen to be slender, uncoiled forms, with a maximum length of 25 mm. Subsequently, a number of incomplete specimens, including coiled and uncoiled forms, were found in fresh rock at Cumana Bay. In all, 14 pyritized specimens were collected but the majority were too poorly preserved to allow determination. In spite of continued search very few other fossils have yet been found. In a thin limestone band at Balandra River, some five miles to the south of Cumana Bay, however, scattered
Aptychi
were collected; and at the mouth of the Tompire River, in a calc-phyllite, minute limonitic casts of embryonic ammonites were found.

The collection was shown to Dr. Spath, who identified the following forms :
Protancyloceras
sp. ind.,
?Bochianites
sp. ind., phylloceratid or desmoceratid type,
Lamellaptychus
sp. ind.

This fauna is too poor to allow more than a very broad indication of the age to be given. According to Dr. Spath, it may range from Upper Jurassic (Tithonian) to Lower Cretaceous (Neocomian), and such a range would be consistent with the sparse information that is
The Cluanie igneous intrusion, Inverness-Shire And Ross-Shire
Authors: Leedal Geoffrey Philip
Published: October 2009

Rocks of the Moine Series occurring in the Cluanie area are divided into three main groups, namely : Upper Psammitic, Pelitic, and Lower Psammitic. This general succession is similar to that in the Morar area and maintains throughout the southern portion of the Northern Highlands.

Most of the country in the vicinity and to the east of the Cluanie intrusion is composed of rocks of the Upper Psammitic Group which almost invariably show gentle dips. To the west of the intrusion the Moine rocks are generally highly inclined. Nappe structures are present.

Prior to or during early Caledonian folding the Moine Series was intruded by basic sheets and dykes now represented by amphibolites and hornblende-schists. Regional injection by trondhjemitic material, and, slightly later, localized intrusion of granodioritic to adamellitic orthogneiss, occurred contemporaneously with the folding.

The Cluanie igneous intrusion is one of the “Newer Granites”. It cuts the regional injection and is clearly later than it. The intrusion consists of only one major rock type, namely a porphyritic hornblende-biotite-granodiorite which is cut by E.-W. trending dykes of microdiorite, quartz-microdiorite and trondhjemite-porphyrite and aplite. Round much of the margin of the intrusion the strike and dip of the Moine rocks conforms to the attitude of the igneous contact. This is a characteristic feature of other Caledonian “granites” and indicates that strong magma pressure accompanied their intrusion.

The granodiorite and other minor intrusions have been metasomatically altered by hydro thermal solutions rich in alkalis. During the alteration, which may be described as albitization, quartz was replaced by felspar and the plagioclase became progressively more sodic. Cleavelandite was commonly formed at a late stage in the albitization. Solutions causing the albitization in the main followed lines of intense jointing trending between north-north-east and north-north-west, though in some cases no such relationship between jointing and albitization occurs, the solutions having apparently percolated upwards through solid granodiorite or trondhjemite.

The injection complex and the Cluanie granodiorite are considered to have been formed by the rise of granitic material and magma consequent upon melting of the acid crust at depth during the Caledonian orogeny.
The Entomoconchacea; a new superfamily of macroscopic ostracods of Upper Palaeozoic Age
Authors: Sylvester-Bradley Peter Colley
Published: October 2009

The morphology of the type species of the ostracod genera
Entomoconchus
McCoy (Carboniferous) and
Cyprosina
Jones (Devonian) is discussed and reinterpreted. Their characters are compared with those of recent and fossil Myodocopa. The family Entomoconchidae Brady is retained within the Myodocopa but referred to a new superfamily. The family Cyprosonidae Whidborne is also retained in the Myodocopa, and tentatively assigned to the same superfamily.
Arenaceous Foraminifera from the Upper Cretaceous of England
1
Authors: Barnard Tom , Banner Frederick T.
Published: October 2009

A study of the arenaceous Foraminifera from the Chalk of England shows them to be useful stratigraphically. A range chart indicates that some species are of diagnostic value in age determination.

The problems of nomenclature and synonymy have been studied in an endeavour to delimit more precisely the stratigraphical range of the species. The internal structures of certain species have been studied in detail. Study of the structure of the initial part of the test and of the internal structure of later chambers has yielded information with a significant bearing on the relationship and the evolution of the various genera.
Problems and progress in volcanology
Authors: Williams Howel
Published: October 2009

Volcanoes are, and always have been, concentrated chiefly along continental edges and within ocean basins. Volcanism is most nearly continuous in orogenic belts, other than those of Alpine-Himalayan type, and in the oceans; it is intermittent and short-lived adjoining orogenic belts and ceases for vey long periods only in continetal nuclei. More information is needed concerning the shapes and depths of volcanic reservoirs. Wedging, stoping and fluxing rather than explosive churning are the chief means by which vents are opened. The source and maintenance of heat are largely unsolved problems, but much of the requisite thermal energy probably comes from ascending juvenile gases. Among the factors that control volcanic behaviour one of the chief is the rate of vesiculation; magma composition, degree of crystallization, retrograde boiling and depth of magma chambers appear to be relatively unimportant. The origin of the water vapour given off by volcanoes remains in dispute, but in certain kinds of eruptions groundwater plays an important part. Many calderas and volcano-tectonic depressions owe their formation chiefly to large-scale subterranean migration of magma. methods of prediction are being improved; seismic and tilt measurements now offer the most reliable information, but magnetic and electric methods merit further trial.
The structure of the Neath disturbance between Bryniau Gleision and Glynneath, South Wales
Authors: Owen Thomas Richard
Published: October 2009

The Neath disturbance is one of a number of compression belts which occur on the northern limb of the South Wales syncline, and caledonoid directions of which are at variance with the normal armoricanoid trend characteristic of South Wales structures.

The main structural elements of the disturbance are (1) impersistent, caledonoid folds; (2) charnoid shear-faults which separate areas of contrasting fold pattern; (3) normal charnoid faults, some of which do not break the continuity of the folds; (4) a caledonoid, sinistral, shear-fault—the Dinas fault; (5) a caledonoid, normal fault—the Coed-Hir fault.

In general, the caledonoid folds and accompanying charnoid shear-faults appear to have been formed before the Dinas fault. But local reversals of this general sequence and the partial or complete overlap of the phases indicate that they belong to a single period of earth-movement, believed to be of Armorican age. Subsequent vertical movements resulted in the formation of the Coed-Hir fault and some charnoid faults, and occurred also along the Dinas fault and many of the existing charnoid shear-faults.

The Neath disturbance is a product of the resolution of a major Armorican force from the south-south-west into a compressional force directed towards the north-north-west and a sinistral shearing force along the Dinas fault. Such a resolution was probably due to a control exerted by the sub-Devonian foundation. A similar control was being exerted during late Avonian times along part of the disturbed area.