bluuebunny/crossref_metadata_2025 huggingface dataset:
A preliminary examination of the thixotropy of some sedimentary rocks
Authors: Boswell Percy George Hamnall
Published: October 2009

Although the thixotropic behaviour of geological materials (made manifest by the isothermal, reversible, gel-sol-gel transformation has been utilized in many industries, the thixotropy of naturally occurring sediments appears to have been but little studied. The results of a preliminary examination of a representative series of unconsolidated rocks are therefore presented. Excepting coarse clean sands and gravel, and sediments prove to be capanble to assuming the thixotropic state, the degree of thixotropy depending on grain-size, grading, mineralogical composition and the presence of electrolytes. Thixotropic values and their range are given for a large selection of sediments from Britain and abroad, and notes are added on the problems presented by some of the more interesting materials.
On the spores of some Carboniferous plants; their development.
Authors: Moore L. R.
Published: October 2009

From
Dr. R. Crookall, F.G.S. :&

Over a number of years I have been accumulating data on the variations of the “microspore” designated C
1
-C
4
. One of the figures published in Dr. Moore's paper illustrated that type of spore, and Dr. Moore has kindly lent me not only the relevant slides to study, but also subsequently a number of others representative of other fructifications described in the paper.

The fundamental questions raised by Dr. Moore's paper are :—

(a) Is variation in Coal Measures spores principally due to relative maturity?

(b) Are the “Sporangia A and B” heterosporous?

The following conclusions are based on the detailed examination of Dr. Moore's slides and of his plates :—

(1) Many of the slides which I have examined (including those made from “Sporangia A and B”) show contamination, and therefore no affirmation to either question (a) or (b) can be reliably made in the absence of a complete spore-census.

(2) The ornamented spores in tetrads regarded by Dr. Moore as immature should not be so regarded in the absence of other evidence to that effect; they may be mature spores that have merely failed to separate from their sister-spores.

(3) “Sporangia A and B” are not heterosporous—they do not contain both microspores and megaspores.

(4) So far as my observations go, the degree of validity that may be accorded to the various correlations by spore-percentages is quite unaffected by Dr. Moore's evidence.

I would add that the work of others does not necessarily support
The form and distribution of dolerite masses in the Builth-Llandrindod inlier, Radnorshire
Authors: Jones O. T. , Pugh W. J.
Published: October 2009

The authors record a series of concordant dolerite intrusions in shales of the
Didymograptus bifidus
zone, at an horizon lying approximately 1000 feet below the top of the zone. A parallel occurrence would appear to be provided by certain intrusive dolerites of the Shelve Ordovician area of South Shropshire, described by the writer (
Q.J.G.S.
xcix, 1943, pp. 169–204). In that area, which lies some 25 to 30 miles to the north-north-east of the Builth-Llandrindod inlier, and along the general line of strike of the Ordovician rocks, concordant intrusions such as the Corndon phacolith occur in the Hope Shales, which form the lower part of the
D. bifidus
zone. The thickness of the zone in the Shelve area has been given as at least 1700 feet (W. F. Whittard,
Proc. Geol. Assoc.
xlii, 1931, pp. 322–44), of which the Hope Shales form the lower 800 feet. The top of the Corndon intrusion is estimated by the writer to have a cover of between 100 and 200 feet of Hope Shales, which are succeeded by massive tuffs of the Stapeley Volcanic Group. The dolerite therefore occupies an horizon between 1000 and 1100 feet below the top of the zone, on the above estimate of thickness—a very similar position to that given for the Builth-Llandrindod B dolerites.

The authors state that the Ordovician rocks of the inlier were probably “nearly, if not quite, horizontal over the greater part of the inlier when the dolerites were intruded”, and that the tilting of the rocks
Recent information concerning the evaporites and the pre-Permian floor of South-East Durham
Authors: Wood Frederick Wilfred
Published: October 2009

A description is given of the stratigraphical information obtained in the mining of anhydrite at Billingham and from exploratory boreholes in the immediate locality.

Details are given of an extraordinary crumpling of roof marl and anhydrite into the working seam, attributed to gravity movement on the sloping pre-Permian floor.

The existence of a high ridge of Carboniferous rocks forming the pre-Permian floor is postulated as an interpretation of available information in South-East Durham. The delineations of the westerly limits of the salt of the Tees-mouth area are discussed with reference to their probable correlation with the line of the Carboniferous ridge and the local limits of the seams of anhydrite. The existence of a gap in the Carboniferous ridge is inferred as correlating stratigraphical features found in the mine workings, underground boreholes and salt thicknesses.
The sheared porphyrite dykes of South Galloway
Authors: Blyth Francis G. H.
Published: October 2009

A group of more than 100 dykes, mainly porphyrites with some microdiorites, quartz-diorites, and lamprophyres, trends east-north-east from the Solway coast between Creetown and Gatehouse-of-Fleet; the dykes are intruded along the strike of the closely folded Lower Palaeozoic sediments, the belt in which they are emplaced being some eight miles in length and four miles wide. Most of the dykes possess directional textures, formerly described as foliation; these textures are partly of primary origin but mainly due to shearing. The shearing has taken place on vertical surfaces which lie either parallel to the length of the dykes or make small acute angles with their walls.

A feature shown by most of the dyke-rocks is the development of numerous flakes of white mica within their fabrics; in the sheared dykes the micas are oriented along the surfaces of shear. The mica-forming materials may have been derived from an internal source in the zone of shearing, or as emanations from subjacent granite masses.

The relationships between the shear directions, transverse joints, and quartz veins which cross the dykes are analysed, and experimental work due to Reidel is cited in support of the suggested origin of the structures in a belt of shearing. The attitude of the shear surfaces in relation to the ellipsoids of stress and strain is also examined.

The dykes are considered to fill tear (or transcurrent) fractures, on which lateral movement recurred after the emplacement of the igneous bodies. The implications of this mechanism in respect of a wider area are indicated.
Redescription of the Trilobite
Eoharpes
Raymond, 1905
Authors: Whittington H. B.
Published: October 2009

From Dr. Archie Lamont :—

Following Bancroft's example in dealing with Cryptolithinae, I have for some time considered applying a fringe-character classification to harpids. On this basis, in a manuscript prepared in 1947 I distinguished by name four apparently natural families : (1) with pits of fairly uniform size as in
Eoharpes primus
(Barrande); (2) with outer rows of larger pits grading into a finer inner pit complex as in
Metaharpes amibouéi
Lamont;
1
(3) with an outer row of large pits and inner complex of fine pits, but no gradation between the two, as in
Scotoharpes domina
Lamont;
2
and (4) Harpidae which show a combination of the characters of (2) and (3), as in
Harpes macrocephalus
Goldfuss.
3

Observations have also been made on the use of facial sutures in classification of Harpacea. In
Scotoharpes domina
a longitudinal suture has been described which meets a lateral transverse suture on the ala. This suggests a primitive arrangement whereby the longitudinal suture may have corresponded with the boundary between axial and pleural lobes and the lateral suture with the division between the anterior part of the cephalon and the occipital segment. If this is true, it seems likely that in Proparia the lateral suture is preserved, but in Opisthoparia the longitudinal suture only. In "
Harpes
"
flanaganni
(Portlock) (Hunterian Museum, Glasgow University, A.40), what seems to be a sensory tubercle occurs in the axial furrow, and from it a narrow suture runs outwards across the posterior half of the ala.
Note on the interbasaltic horizon in Northern Ireland
Authors: Eyles V. A.
Published: October 2009

In Mr. E. M. Patterson's “Preliminary Note on the Tertiary Lava Succession in North Antrim” (
Abs. Proc. Geol. Soc.
No. 1461, 28 March, 1950, p. 91) he claims that there are, in North Antrim,
two
interbasaltic horizons, characterized by the presence of laterite and separated by a Middle Lava Series consisting of tholeiitic basalts.

The writer of the present note spent much time during the war in examining the Antrim laterites, and has prepared an account of them which is about to go to press. This new conception of Mr. Patterson's is therefore a matter of particular interest to him. The development of a laterite horizon, as distinct from the frequent but less-prolonged minor interbasaltic periods whose existence is well known, implies a major time-break in the volcanic sequence. For this and other reasons stated below the writer considered that Mr. Patterson's claim required careful examination.

The Antrim lava plateau is built up of a succession of sub-aerial flows. Weathering of individual flows, marking, in most cases, minor interbasaltic periods, may be indicated by the presence of thin layers of red “bole”, by kaolinization of basalt, forming lithomarge, or by kaolinization
followed
by lateritization, i.e. by the formation of aluminous and ferruginous laterite (bauxite and iron ore).

The existence of one major interbasaltic horizon, with deposits subsequently recognized to be lateritic in origin, has been known for at least 150 years. It was mapped during the primary geological survey of Ireland. The bauxite and iron ore were mined for many
The gravitational and magnetic exploration of parts of the Mesozoic-covered areas of south-central England
Authors: Falcon Norman Leslie , Tarrant Leslie Hamilton
Published: October 2009

Gravity and magnetic anomaly maps for large areas of southern England are presented, and their geological implications are discussed. The geophysical results are interpreted in terms of the probable composition and structure of the hidden Palaeozoic floor, with particular reference to the possibility of the existence of appreciable thicknesses of Upper Carboniferous rocks in some parts of the area.
The stratigraphy of the Carboniferous rocks of the Weaver Hills district, North Staffordshire
Authors: Ludford Albert
Published: October 2009

The district described consists of the south-west corner of a large mass of Lower Carboniferous rocks stretching from the Weaver Hills in the south to the River Hamps valley in the north. The Carboniferous Limestone makes a tilted plateau while the lower ground is occupied by Churnet Shales.

The structure consists of a shallow anticline with numerous small folds super-imposed upon it. The Weaver Hills formed part of a basin lying to the south-west of the Derbyshire massif during Lower Carboniferous times. The limestones to limestones-with-shales.

The succession is very similar to that of Dovedale, Derbyshire, described by D. Parkinson. Over much of the area beds of a general S age are missing, having been removed by denudation prior to the deposition of D
1
limestones which rest on rocks varying in age from C
2
to S
2
. Evidence of this and faunal evidence as to the age of each of the formations is discussed in detail.
The movements of island arcs
Authors: Brouwer H. A.
Published: October 2009

Through geological time successive orogenic belts have shifted outward from central nuclei. Island arcs of the geosynclinal stage have often moved large distances in a horizontal direction. In the active zones of today movements continue, especially in association with the arcuate structure of the Pacific region, where the highest seismicity is reached.

There has been difference of opinion as to whether faulting or folding is the dominant structural feature in island arcs. Both are very important. The age of the faults may be considerable. Periods of thrusting have been genetically connected with tear-faulting and may have been followed by normal faulting. Relative horizontal displacements, which were not simultaneous or in the same direction, are supposed to have changed the position of areas of higher stability. Older strikes are often cut obliquely by the present coast-lines. There is continuity of structural control but the locus of tectonic activity has shifted. Definite conclusions as to the possible extension and maximum depth of the Tertiary seas cannot be derived from geological evidence.

The recent and earlier phases of deformation show different stages of growth. A number of non-homologous types can be distinguished. The future development of island arcs will be a complex process. Some arcs front toward the oceans and others toward continental areas, and the Pacific arcs do not all front with their convex sides toward the Pacific basin. Growth-stages of the present island arcs are discussed.
The pre-Torridonian metamorphic history of the Loch Torridon and Scourie areas in the North-West Highlands, and its bearing on the chronological classification of the Lewisian
Authors: Sutton John , Watson Janet
Published: October 2009

The paper describes the metamorphic history of two areas of Lewisian gneiss in the North-West Highlands of Scotland. Metamorphosed sedimentary rocks are described for the first time from the Loch Torridon area. It is shown that both in the Loch Torridon and the Scourie districts the gneisses have been produced in two separate periods of metamorphism, migmatization and deformation. These two metamorphic episodes, which are named the Scourian and Laxfordian episodes, are separated in time by a period of uplift and tension during which a series of uniform dolerite dykes was intruded. Since a very great interval of time appears to have elapsed between the two metamorphic episodes, it is suggested that the rocks produced during these episodes should be regarded as members, not of a single formation as heretofore, but of two distinct chronological units.
Llandovery brachiopods from Wales with special reference to the Llandovery district
Authors: Williams Alwyn
Published: October 2009

The paper is intended primarily as a palaeontological supplement to the stratigraphical studies of the Llandovery rocks in the type area (O. T. Jones 1925, 1949). The systematic revision is therefore based on collections obtained from the Llandovery district but material, in certain instances, has also been described from the Llandovery rocks of Meifod and Haverfordwest. Thus the basal beds (A
x
) of the Llandovery district are unfossiliferous, whereas the equivalent rocks in Meifod and Haverfordwest are richly fossiliferous and so provide important links between the Llandovery and the Ordovician brachiopods. Furthermore, some forms, especially those from the prolific Gasworks Sandstone of Haverfordwest, are better preserved than contemporaneous ones from Llandovery and have been used for specific descriptions.

The systematic study includes emended descriptions of nine species and the erection of two new genera, one new subgenus, eleven new species and fourteen new subspecies. Such a revision may seem radical, but it must be borne in mind that the fauna has received little attention in the past, and actually this work is intended only as the beginning of a much fuller investigation.

The paper concludes with a faunal list to show the stratigraphical distribution of Llandovery brachiopods. The chart emphasizes the fact that each of the lithological divisions established for the Llandovery district contains a diagnostic faunule.
The migmatites and felspar-porphyroblast rock of Glen Dessarry, Inverness-Shire
Authors: Harry William Trevelyan
Published: October 2009

In Glen Dessarry, Inverness-shire, the core of a sharp anticline affecting regionally injected Moine rocks is occupied by a hornblendic inlier petrographically comparable with the Lewisian of North-West Scotland and chiefly composed of a series of felspathic gneisses, with subordinate pyroxene-amphibole rocks originally sediments, later metasomatized, and abundant pink pegmatite. The felspathic gneisses include basic, dioritic and syenitic types, the last occupying the centre of the inlier. They are considered to have resulted from migmatization of pyroxene-amphibole rocks by pegmatitic material and constitute an evolutionary sequence of decreasing basicity. Movements within the gneisses during their formation impressed steeply inclined directional structures upon them, and are believed to be of post-Moine age.

With the decline of the stresses that accompanied migmatization the felspar mosaic of some gneisses recrystallized to form larger alkali-felspars of good outline, originating a series of porphyroblastic gneisses of varying basicity. The most striking of these is a rock with the appearance and chemical composition of a syenite, almost wholly composed of randomly orientated, large, grey alkali-felspars, and termed “felspar-porphyroblast rock”. The dominant factors in the formation of this rock are believed to have been stress decline, elevated temperatures and the promoting action of interstitial fluids residual from migmatization.
The Fuller's Earth of the Cotswolds, and its relation to the Great Oolite
Authors: Arkell William Joscelyn , Donovan Desmond Thomas
Published: October 2009

Lateral changes in the Fuller' Earth formation along the 50 miles of strike from the Avon valley at Bath to the Vale of Moreton at Stow-on-the-Wold are investigated by means of six-inch mapping of five selected areas.

It is shown that the Fuller' Earth Rock of the Bath district when traced northwards into the southern part of the South Cotswolds becomes two distinct rock bands separated by up to 30 feet of clay, so that there are two Fuller' Earth Rocks and three Fuller' Earth Clays.

In passing farther northwards, first the upper clay wedges out near Horton, then the upper rock passes laterally into Great Oolite “ White Limestone ” near Tresham, and false-bedded oolites come in below it; next the middle clay (which is the Upper Fuller' Earth of the northern part of the South Cotswolds and of the mid-Cotswolds) wedges out on approaching Nails worth; next the lower rock passes laterally into Great Oolite “ White Limestone ” near Nympsfield, and at the same time the false-bedded oolites of Minchinhampton come in below it; and finally the Lower Fuller' Earth Clay wedges out towards Stow-on-the-Wold and Burford and is at least partly replaced by the Chipping Norton Limestone.

The paper shows in detail that S. S. Buckman's correlation fifty years ago of the Fuller' Earth Rock of Somerset with part of the Great Oolite of Gloucestershire, made on the strength of the ammonites, was correct.

The lateral changes and alternations of facies are summarised in horizontal sections (Pl. XVI).
The results of a gravity survey in the country between the Clee Hills and Nuneaton
Authors: Cook Alan Hugh , Hospers Jan , Parasnis Dattatraya Shripad
Published: October 2009

Gravity observations have been made in te country between the Clee Hills and Nuneaton. It is found that the change of anomaly over the Warwickshire Coalfield is closely correlated with the thickness of Coal Measures, and over the Forest of Arden it is less closely correlated with the thickness of Trias. The corresponding differences of density agree with densities of rocks measured at the surface. Data are insufficient to establish definite correlations elsewhere.

The remaining anomalities indicate a considerable thickness of rather light rocks, probably Coal Measures, amounting to 4000 feet below the Trias in the Forest of Arden and a considerable thickness of Trias, about 2500 feet with perhaps also some Coal Measures, at Kidderminster.
The succession and structure of the north-eastern area of the South Wales Coalfield
Authors: Blundell Cecil Robert Knight
Published: October 2009

The paper deals with that portion of the South Wales Coalfield lying between Pontypool, Blaenavon and Tredegar : that is, the northern part of the East Crop and the eastern part of the North Crop. Although of much smaller thickness than farther west, the Coal Measures in the area have previously been regarded as constituting a full succession. It is now found that nowhere in the area is there a complete succession, the topmost beds of the Lower Coal Series and the lowermost beds of the Pennant Series being absent as a result of a major unconformity of Morganian age. The overlap and overstep developed by this unconformity increases in magnitude eastwards where the gradual disappearance of successive strata have been mapped; the major marine horizons of the Lower Coal Series have also been located and mapped across the area. The palaeontological evidence shows that the highly coloured beds below the Tillery Vein coal seam belong, not to the Lower Coal Series as previously thought, but to the Middle Pennant Group. The palaeontological and mapping evidence further shows that within the present area the Lower Pennant Group is completely absent along the East Crop, and in the south the Middle Pennant Group rests on the basal part of the upper
similis-pulchra
Zone of the Lower Coal Series.

The Coal Measures in the area have been affected by at least two periods of earth-movements, an earlier period of Morganian age and a later Hercynian (Armorican) period. Nevertheless, the folding due to these movements is very gentle, the strong monoclinal folding found in the south-eastern region of the coalfield being absent in the present area. The faults trend mainly in a north-westerly direction and are all tensional structures. They are regarded as accommodation fractures initiated and developed during Coal Measures times.
A Contribution to the Geology of the Kavirondo Rift Valley
Authors: Shackleton R. M.
Published: October 2009

From
Mr. J. Hospers :—

In Professor Shackleton's paper, as well as in Dr. Dixey's paper (1946) on “ Erosion and Tectonics in the East African rift system,” mention is made of Dr. Bullard's gravity measurements (Bullard 1946). Bullard found that the plateaus surrounding the rift valleys are very nearly isostatically compensated, but that over the rift valleys large negative isostatic anomalies occur. Not only are these rift valleys uncompensated, but there is even more light matter under them than if they were simply cut out of the plateau, leaving the compensation unchanged. Under the rift valley there is therefore an excess of light matter and the upward hydrostatic forces will, according to Bullard, exceed the downward pull of gravity; the floors of the rift valleys will therefore rise unless held under by some other force. Consequently, this settles the argument in favour of the compression theory, a wedge-shaped block (widening downwards) being forced down between reversed faults.

The crucial point in this reasoning is that if a part of the crust is not in isostatic equilibrium (that is, if the isostatic anomalies are not zero or very small) it cannot be in hydrostatic equilibrium.

This is true only for rectangular and not for wedge-shaped blocks. When wedge-shaped crustal blocks float on a denser substratum there is no isostatic equilibrium in the sense that the isostatic anomalies are zero, even though the block may be in hydrostatic equilibrium. In a recent paper F. A. Vening Meinesz (“ Les ‘ graben
The tectonics of the sub-Himalayan fault zone in the northern Potwar region and in the Kangra district of the Punjab
Authors: Gill William Daniel
Published: October 2009

The paper defines three major zones of deformation across the Nimadric (Tertiary freshwater) geosyncline between the foreland and the autochthonous folded belt in the North-West Himalaya:—

(1) A zone of open folding, affected to a varying degree by fold-faulting.

(2) A fault zone, displaying a number of reversed faults of steep northerly hade and great lateral extent with open folds between them in the west and, in places, gently dipping monoclines in the east.

(3) A zone with closely spaced strike-faults and severely compressed folds, referred to in the Potwar area as the isoclinal zone, terminating at the main boundary fault which forms the general northern limit of Nimadric rocks.

This succession of structural zones has a superficial resemblance to progressive deformation of the Jura type towards the nappe zone, and previous workers have regarded the tectonic pattern as reflecting tangential pressures from the north.

The author seeks to demonstrate that such an interpretation is denied by the evidence of the structures themselves. Two areas are chosen to illustrate in adequate detail the tectonics of all three zones, and in particular the crucial fault zone. In the west, the Jhamat-Khushalgar area of western Potwar typifies the fault zone of the area between the Indus and the Jhelum rivers. In this area there is clear evidence of the steep hade of the great strike-faults at the surface, and also important evidence of their continued steep hade in depth from the results of boreholes drilled by the Attock Oil Company. Analysis of the relationship of the faults to the fold structures leads to the conclusion that the faults have no genetic relationship to the fold axes. They are considered to be fractures due to shearing stresses principally with a vertical orientation, whilst the folding reflects the subsidiary compressive force. The Nadaun Dun area of Kangra district is some 200 miles to the southeast of the Potwar area, but lies across similar structural zones and typifies the relationships of the anticlinal zone and the fault zone in the region east of the Jhelum River. In this area the Gumber fault is seen to present all the features of the great strike-faults of the fault zone in the Potwar and is an upthrust structure produced by quasi-vertical movement. A feature not present in the Potwar is the marked contrast between the gently dipping monocline to the north of the fault and the strongly folded country to the south, providing a clearer distinction between the influence of tangential and vertical forces. It appears that the fault movement provided a block-line against which tangential forces from the south were directed. Important evidence of tangential pressure from the south is provided by the Barsa fault, which typifies the most common form of fold-fault in the anticlinal zone throughout the region. Gravity collapse structures are recorded in the form of severely overturned “ flaps ” of sandstone on the south side of the Sola Singhi ridge.
Lower Cretaceous ammonites in marine intercalations in the "Nubian Sandstone" of the Eastern Desert of Egypt
Authors: Attia Mahmoud Ibrahim , Murray George William
Published: October 2009

In 1910, the late Dr. W. F. Hume, Director of the Geological Survey of Egypt, reported Cretaceous fossils from limestones intercalating the “ Nubian Sandstones ” at the head of Wadi Qena, about 205 kilometres (128 miles) north of the town of that name in the Nile Valley. He divided the strata into three typical sandstone beds, namely (1) an upper Nubian at the base of the Campanian, (2) a middle Nubian above the Turonian ammonite bed, and (3) a lower Nubian below the Cenomanian strata and closely related to them (Hume 1911).

During the season 1950–51, while a topographical survey expedition was mapping an area lower down the same Wadi Qena, one of us (G. W. M.) noted a considerable extension of the fossiliferous limestones intercalating the Nubian Sandstones and brought in a good collection of specimens from them to the Geological Survey of Egypt.

The area covered by this note lies between latitudes 27° 00' and 27° 30' and longitudes 32° 35' and 32° 52'. The Nubian Sandstone in this area outcrops as a narrow stretch running roughly N.-S. and is overlaid on the west by Middle and Upper Cretaceous limestones etc., and rests in the east on granites etc. forming the Red Sea hills.

Fossils were collected from eight separate localities, four of which were near the base of the Nubian Sandstone where it rests on the granite while the rest were from higher horizons.

The four localities near the base yielded :—

Diplopodia cf. variolaris
The ammonite genera
Arcthoplites
Spath and
Tetrahoplites
gen. nov.
Authors: Casey Raymond
Published: October 2009

The type species of
Arcthoplites
Spath 1925 by original designation is
Hoplites jachromensis
Nikitin from the boreal Lower Cretaceous (Albian) of central Russia. Ammonites from the Mangyshlak Peninsula of Transcaspia identified with Nikitin's species by Sinzow have also been referred to
Arcthoplites
by Spath (1925, p. 77), while Breistroffer (1947, p. 69) has extended the genus to include the Mangyshlak species “
Sonneratia
”
subquadrata
Sinzow, and “
S.
”
latisulcata
Sinzow and “
Parahoplites
”
puzosianus
Jacob
non
d'Orbigny from the Albian of France. Discovery of the last-named two species in the English Albian has prompted a study of
Arcthoplites
. Through the courtesy of Dr. L. F. Spath and Dr. D. T. Donovan I have been privileged to examine a large series of
Arcthoplites
from East Greenland, where earlier investigations have shown the genus to occur (Spath 1946; Donovan 1949). This study has led to the view that the true
Arcthoplites
is as yet unknown outside the boreal province, and that the Transcaspian and European forms that have been referred to the genus belong to distinct groups. The Transcaspian species hitherto referred to
Arcthoplites
(excluding Sinzow 1907, pl. iii, fig. 11) are here described as
Tetrahoplites
gen. nov.

Type species.—Sonneratia subquadrata
Sinzow 1907, pi. iii, figs. 7–8.

Diagnosis
.—Moderately evolute, robustly ornamented hoplitids, having a subquadrate whorl-section with flattened sides and venter, but well-rounded umbilical and ventral margins. The sigmoidal or arcuate ribs proceed mostly in pairs from obtuse umbilical bullae and continue across the venter with a shallow sinus forwards. Suture-Hne with deep trind first
The structural history of Norway and its relation to Great Britain
Authors: Holtedahl Olaf
Published: October 2009

The rocks of Norway do not seem to afford evidence of any close geological relation to Great Britain during Archaean time. The birth of the Caledonian geosyncline initiated a fairly intimate connexion, especially with Scotland. A similarity in sedimentary facies and in volcanicity is especially marked in the Ordovician. The " Eocambrian " or " Sparagmite Formation " of Norway has been found to be of great importance in the history of the Caledonian zones of the North Atlantic region. This sedimentary complex, which consists principally of sandstones, with a tillite in its upper part, is stratigraphically and tectonically closely related to the Cambro-Silurian sediments, and equivalent formations are significant in the geology of Scotland. The unassorted " boulder-beds " of the Dalradian in Islay and at Schichallion in Perthshire may well be tillites of corresponding age. There appears to be a natural correlation, too, between the Moinian and the highly metamorphic Eocambrian rocks of Norway.

Old Red sediments of the coastal districts of southern Norway have been subjected to very strong compressive movements : this suggests that the Fennoscandian area at that time existed as a large, rigid block along the border of which broke the " waves " of this posthumous folding.

The structure of the igneous complexes of the Oslo region, of Permian age, with ring fractures as a dominant characteristic, show similarities to both Devonian and Tertiary plutonic centres of Scotland. The faulting just outside the plutonic masses of the Oslo region evidently has close genetic connexion with magmatic processes. The Tertiary uplift of the Scandinavian land-mass is discussed in connexion with submarine relief features off the Norwegian coast, believed to bear witness to marginal fracture-lines.
The supposed Lewisian inlier Of Scardroy, Central Ross-Shire, And its relations with the surrounding Moine rocks
Authors: Sutton John , Watson Janet
Published: October 2009

The Scardroy area lies east of the Moine thrust in central Ross-shire and is composed predominantly of metamorphosed sediments. Over considerable areas the rocks are gneissose in appearance, and these gneisses, together with associated striped hornblende-granulites and basic and ultrabasic minor intrusions, were regarded by the Geological Survey as representatives of the basement on which the sediments of the Moine Series were laid down, and were correlated with the Lewisian gneisses west of the Moine thrust.

The present paper brings forward evidence to show that the gneissose rocks were formed by recrystallization and felspathization of siliceous, semi-pelitic, calcareous and hornblendic rocks which are integral parts of the Moine Series. Detailed mapping shows that certain horizons can be traced continuously across the supposed line of unconformity.

Movements accompanying the metamorphism of the Moine rocks led to the production of an anticline and syncline, overturned towards the east and pitching east of south. The minor structures and the axes of quartz girdles determined by fabric analysis pitch in the same direction. On every scale, the same structural pattern characterizes both the Moine and the supposed Lewisian rocks, and no traces of older structures have been detected in the latter.

A tentative stratigraphical succession, established with the aid of sedimentary structures, suggests that the rocks hitherto regarded as Lewisian are younger than a belt of undoubtedly Moinian semi-pelitic granulites.

In view of the facts given above, the writers conclude that the rocks of the Scardroy area belong to a single series and that no rocks of Lewisian age are present.
Some features of Provençal tectonics
Authors: Bailey Edward B.
Published: October 2009

It is suggested that criticism of Marcel Bertrand's interpretations of Provençal tectonics has in certain cases overshot the mark. Besides the Beausset klippes the following items seem trustworthy : the Toulon thrust, the Ste. Baume thrust passing under Nans, and the Allauch window.
Notes on Gibraltar and the northern Rif
Authors: Bailey Edward , Muir-Wood Helen M. , Spath Leonard Frank , Chatwin Charles P.
Published: October 2009

Gibraltar consists of a Limestone and a Shale Group. Brachiopods long known in the Limestone Group are placed by Choffat and Dubar in the Lower Lias. Ammonites found in the passage beds of the Shale Group are determined as of Middle Liassic age. Radiolarian cherts found in the Shale Group suggest the Upper Jurassic. Since the Limestone Group has been found to overlie the Shale Group there appears to be a great inversion. The present paper revives an interpretation advanced by Gentil and Kober that Gibraltar is a nappe and argues also for an extension of the thrusting already recognized by Fallot in the Rif.
The geology of the Llandello district, Carmarthenshire
Authors: Williams Alwyn
Published: October 2009

The Ordovician and Silurian rocks of the Llandeilo area form the flanks and core of the Towy anticline. The oldest beds exposed are the
D. bifidus
Shales which pass upwards into a variable set of sediments, ashes and rhyolite lavas. These beds, with the Ffairfach Grit at the base, have hitherto been classified as Lower Llandeilo, but it now seems probable that they represent a facies variation of the
D. murchisoni
graptolitic shales and should be included in the Upper Llanvirn. The Llandeilo Flags are locally divisible into faunal and lithological units and are followed, with profound lithological and faunal change, by the
N. gracilis
Shales. The
Dicranograptus
Shales are poorly exposed but include towards the top the Crûg Limestone, apparently equivalent to the Robeston-Wathen Limestone of South-West Wales.

Important folding and faulting movements occured before the deposition of the Ashgillian rocks and resulted in the elevation of an important geographical barrier, the Towy anticline. Ashgillian deposition was limited to a basin west of the anticline, where at least 5000 feet of mudstones accumulated. The barrier persisted throughout most of the Silurian, but was breached by transverse troughs during Llandovery times and was subjected to sporadic sea invasions from the north-east, so that the Llandovery and Wenlock mudstones are involved in uncomformable overlaps and oversteps. The Towy anticline continued to exercise this geographical control until Upper Wenlock times, when it was completely inundated and buried in mudstones which were laid down far beyond the limits of the older Silurian rocks.
The major fault zone of central Vestspitsbergen
Authors: Mcwhae John Ross Hope
Published: October 2009

A deformation belt runs southwards from Wijdefjorden through the length of central Vestspitsbergen, a distance of over 190 miles.

From the stratigraphical summary several factors emerge that are relevant to the structural history.

1. The pre-Downtonian rocks are crystalline schists with a general N.-S. trend resulting from an earlier orogeny.

2. There was a basin of sedimentation in the Billefjorden area in Lower and Middle Carboniferous times.

3. The Carboniferous to Lower Permian succession is concordant in the central portion of this basin.

4. A strip of coarse conglomerates overlying an old fault-line suggests weak faulting activity in Middle Carboniferous times.

Fault activity occurred in Upper Devonian times, probably with a strong compressive phase in the earlier part which was followed by weaker gravity faulting
1
near the end of the period. Again in Tertiary times, either gravity faults or flexures formed, depending on the competence of the rocks affected.

Parallelism with the trend of the pre-Downtonian metamorphic rocks is striking and renewed dislocations along the Upper Devonian fractures seem to be common.

It is concluded that the major Upper Devonian fractures are not gravity faults. Two theories of genesis are possible : firstly, transcurrent faulting with associated upthrust wedges; secondly, high-angle thrusting with a later phase of gravity faulting. The data available appear to favour the second.
A pinnacle of chalk penetrating the Eocene on the floor of a buried river-channel at Ashford Hill, Near Newbury, Berkshire
Authors: Hawkins Herbert Leader
Published: October 2009

An isolated pinnacle of chalk,about 175 feet across and at least 150 feet above its normal level,rises through the Reading Beds and part of the London Clay near Ashford hill, and is associated with a drift-filled channel whose floor is, at its deepest proved point, 90 feet below the present ground-level. The channel reaches its greatest depth on the top of the chalk pinnacle, and seems not to extend beyond it. It is filled mostly with peaty silts with subordinate beds of gravel; and at depths of about 40 feet from the surface the pollen-content of the peats indicates a Lateglacial age. At the deepest point, almost 50 feet of alternating varves and Coombe Rock underlie the Late-glacial drift, in what appears to have been a swallow-hole.

The pinnacle of chalk into which this pit was excavated has evidently been driven up through the Eocene when in a plastic state; its elevation and exposure must have antedated the development of the deep channel which apparently ends at it. In an attempted explanation of these associated anomalies (both of which seem to have developed during the Glacial Period) it is suggested that the chalk at the point of convergence of two faults may have been subjected to deep freezing and subsequently to "eruption" as a tectonically localized "valley bulge".
The Interglacial at Clacton-On-Sea, Essex
Authors: Pike Kathleen , Godwin Harry
Published: October 2009

Pollen analyses through 18 feet of deposits in the Clacton channel show that the upper part of the freshwater beds falls within a warm-temperate forest period, whilst the overlying estuarine deposits formed in a period of declining warmth in which coniferous forests became dominant. The preponderance of pollen of
Abies
(silver fir) in these deposits is noteworthy.

The marine transgression thus took place in the middle to second half of an interglacial cycle, and it is suggested that this may have been due to an isostatic depression of the North Sea basin comparable with similar movements of other interglacial periods.

The pollen diagram shows little correspondence with British diagrams from the (older) Cromer Forest Bed, or from beds taken to belong to the Last Interglacial. Similarly, comparison with the range of West European interglacial pollen diagrams suggests the possibility that the Clacton deposits may relate to the Penultimate Interglacial.
The Interglacial Deposits at Histon Road, Cambridge
Authors: Walker Donald , Godwin H. , Sparks Bruce W.
Published: October 2009

A pollen diagram from the muds exposed in a sewer trench near Cambridge is presented, together with a record of the macroscopic plant remains obtained from the same deposits. The two zones of the diagram are correlated with zones
g
and
i
of the Last Interglacial period in Europe.
The migmatitic Older Granodiorite of Thorr district, Co. Donegal
Authors: Pitcher Wallace Spencer
Published: October 2009

The Donegal granite is emplaced in highly folded Dalradian strata. The meta-sediments comprise pelitic and semi-pelitic schists, siliceous granulites, calcareous rocks and quartzites; these rocks are intruded by numerous basic sills of pre-metamorphic age.

In the district of Thorr, on the northern margin of the granite, these strata are highly metamorphosed and sillimanite is the characteristic mineral of the pelitic types. This metamorphism is superimposed on one of low grade and is connected with the presence of heterogeneous rocks of tonalitic character; these are collectively called the " Older Granodiorite " and they contain many large enclaves of meta-sediment. Between such separated masses there is a concordance of structure, and the stratigraphical relationships are preserved. The presence of such a " ghost stratigraphy ", which indicates a considerable measure of replacement, has to be equated with the evidence of composition, which requires incorporation of country rock, and, again, with the evidence of sharp contacts and flow which suggests intrusion. A hypothesis requiring the partial mobilization of country rock granitized in place is contrasted with that of piecemeal stoping and marginal assimilation.

The Older Granodiorite is intruded by a series of microgranite sheets and dykes with associated aplites and pegmatites. These form the early phases of the relatively xenolith-free, sodi-potassic Newer Granites, which are of magmatic origin and constitute the greater part of the Donegal mass.

A wide belt of shearing enters the south-eastern part of the Thorr district and all the rocks suffer varying degrees of cataclasis. This may be a protoclastic deformation connected with the forceful intrusion of the Newer Granites. Late events in the geological history include the formation of a perfect joint system. The prominent north-north-westerly joints occasionally become faults, and they commonly afford the paths for numerous Tertiary dykes.
Hornblende-lamprophyre dykes of basaltic parentage from the Skaergaard area, East Greenland
Authors: Vincent Ewart Albert
Published: October 2009

In a complete sample of the Tertiary dykes in a small area of the Skaergaard peninsula, the majority of the forty specimens are ophitic olivine-bearing or olivine-free dolerites of a type prevalent in the East Greenland coastal dyke swarm as a whole. Some, however, are more alkaline dolerites, showing evidence of having crystallized from a magma fraction richer in volatile components and alkalis, and are later in the intrusion sequence. These oligoclase-dolerites are further seen to grade into camptonitic hornblende-lamprophyres.

A genetic lineage is traced from normal dolerites, through oligoclase-dolerites, to comptonites on the basis of textures, structures and mineralogical variations in the rocks, which have almost certainly all originated from the same parental basic magma.

Chemical analyses show the oligoclase-dolerites and camptonites to be poor in silica but somewhat enriched in alkalis, particularly in potash; and that there is little difference in chemical composition between oligoclase-dolerites and camptonites, the latter type being the result of crystallization at lower temperatures from a more watery magma.

An explanation of the genesis of the various types in terms of fractional crystallization and filter-press action in compatible with the field, petrographic and chemical evidence.
Linear structures and their relation to movement in the Caledonides of Scandinavia and Scotland
Authors: Kvale Anders
Published: October 2009

The author considers that, although Dr. D. B. McIntyre's geometrical reconstruction of the structures observed in mid-Strathspey (1951,
Q.J.G.S.
107
, 1–22) may be essentially correct, his kinematic interpretation of the structures is open to question. Dr. Mclntyre's evidence is discussed briefly. Sander's evidence for his theory of the relation of plane of symmetry to direction of movement is also reviewed. Structures in the Caledonides of Norway cannot be brought into agreement with Sander's theory, and it is concluded that the theory needs modification. A plane of symmetry may be formed at right angles to a lineation which is parallel to the direction of movement. Linear structures reflect local conditions of deformation and may under certain conditions be formed at any angle with the principal direction of movement. Brief remarks are given on the formation of a lineation and on the general picture of linear structures in the Caledonides. Comments are made on the occurrence of minor linear structures in the Scottish Highlands, and their importance. Variation in trend of linear structures in the Highlands is briefly discussed. It is suggested that when the linear structures of the Highlands are more completely known it may be possible to explain all structures as having been formed during the Caledonian orogeny. The Moinian and the Dalradian may both be Caledonian geosynclinal sediments, corresponding to the Norwegian Sparagmite Formation and Soros Group respectively.
The petrography and geological significance of the post-Cambrian minor intrusions of Assynt and the adjoining districts of North-West Scotland
1
Authors: Sabine Peter Aubrey
Published: October 2009

The post-Cambrian sills and dykes described occur mainly in the Assynt district of the North-West Highlands of Scotland. The principal types are grorudites, Canisp porphyry (biotite, albite-oligoclase, aegirine-augite porphyrite), hornblende-porphyrites, nordmarkitic rocks, vogesites and ledmorites and related rocks. They are emplaced in Lewisian Gneiss, Torridon Sandstone and Cambrian sediments, and some also occur in the Moine schists. The intrusions are affected by the Caledonian thrust movements. The tectonic distribution of the grorudites leads to the recognition of the Glencoul and Ben More thrust-masses as parts of a single tectonic unit. South of Conival the Benmore thrust-plane is of greater importance than to the north, and is renamed the Assynt thrust-plane. The sills in the Moine Series are metamorphosed and are thought to have been emplaced after the inception, but before the close, of the Caledonian thrust movements; some part at least of the Mo^ne metamorphism is thus of post-Cambrian age. Assimilation of limestone has probably no relation to the production of lime-magnesia pyroxene in the vogesites, nor to the production of highly alkaline rock types. A mechanism of differentiation of the post-Cambrian suite is suggested. Both major and minor intrusions have been emplaced by injection; in places the thickness of the sills amounted to several hundred feet, and had considerable effect in up-doming the strata over which the Moine schists were thrust.