bluuebunny/crossref_metadata_2025 huggingface dataset:
The Carboniferous Limestone of the Manifold Valley region, North Staffordshire
1
Authors: Prentice John Edward
Published: October 2009

The region comprises the extreme south-western portion of the Dinantian outcrop in the southern Pennines. A survey on the 1/10,560 scale has revealed a succession ranging from Tournaisian to Namurian. The beds are of marginal facies, lying between the Derbyshire Rigid Block and the Cheshire basin; they contain both reef and bedded limestones. A lower series consists of an upward sequence of cement-stones, massive limestones, and black cherty limestones. The major reef limestones and the cementstones contain a pericyclid fauna equal to a C
1
age, and the higher beds are referred, with a little evidence, to C
2
-S
1
horizons. The upper series overlies these with unconformity, and represents the D
1
P
2
zones. Facies changes from north to south, related to a central reef belt, occur in both D
2
and P horizons, in the following fashion :—

Minor unconformities occur at the base of the “
crassiventer
” beds and the base of the P zone. In the west, early Namurian beds rest with slight transgression upon P
2
; this discordance increases eastwards, and it is clear that the main folding movements were pre-Namurian. Two periods of folding have been recognized, one of pre-D
1
age along north-west and south-east lines; the main late-Viséan folding has a north-and-south trend. The reef limestones have been little affected by the folding, the less competent bedded limestones being folded and shattered against them.
The Glenelg-Ratagain igneous complex
Authors: Nicholls Geoffrey Dennis
Published: October 2009

The Glenelg&Ratagain complex is situated approximately six miles east of Glenelg, Inverness-shire, and is the most north-westerly of the Newer Granites of Scotland. Like other intrusions of that age, it is composite in character, though differing from most in the presence of biotite-pyroxenite and nordmarkitic syenite. To the northeast the igneous rocks intrude paragneisses similar to those of Lewisian age farther west; elsewhere, the country rock is acidic gneiss of Moine type with sporadic politic bands.

Four intrusions have been recognized. The first, of granitic composition, is only sparsely represented, forming small discontinuous outcrops around the western side of the complex. The second, a diorite, was closely followed by one of syenitic material and, at a somewhat later date, by a fourth of adamellitic composition.

Around the margins of the complex the diorite carries quartz and, on the western side, passes, apparently by gradation, into rocks of granodioritic composition. It seems likely that assimilation of the earlier “ granite ” has led to marginal acidification of the diorite.

Considerable variation is seen in the diorite, the following varieties having been noted as well as the normal rock : fine-grained pyroxene-mica-diorite, brown horn-blende-mica-diorite and a coarse hornblende-diorite. Masses of biotite-pyroxenite and “ appinite ” occurring in the diorite area are probably xenolithic.

Late magmatic liquors, possibly augmented by the assimilation of the earlier acidic rock, have attacked the crystallized material, with the replacement of andesine by more sodic plagioclase, the formation of potash felspar and the conversion of pyroxene to a green hornblende, thus giving rise to a variety of so-called “ modified diorites ”.

The succeeding intrusion of syenitic magma, following rapidly upon the emplacement of diorite, probably before its final consolidation, has, by extensive hybridization, given rise to a wide range of monzonitic and similar rocks.

The adamellite of the fourth intrusion is richer in alkalis than most comparable Scottish granites and is believed to have originated by hybridism at depth between the syenites and a more normal calc-alkaline granodiorite.

The nordmarkitic syenite is comparable both chemically and mineralogically with similar rocks from Ben Loyal and Loch Ailsh and was probably derived from the same source at depth. The emplacement of such a magma between two intrusions of distinctly calc-alkaline affinities indicates the co-existence of alkaline and calc-alkaline magma beneath the Highland region during Caledonian times.
A contributon to the geology of the Kavirondon Rift Valley
Authors: Shacleton Robert Millner
Published: October 2009

The paper describes some of the geological work of the 1947 British-Kenya Expedition to Rusinga Island and other sites in western Kenya where Miocene anthropoids have been found.

The pre-Miocene floor of the region consists of gneisses (Basement System) in the east, separated by the Nandi fault from altered basic igneous rocks (Nyanzian System) and post-Nyanzian granitic rocks in the west.

Relics of a peneplain supposed to be Mesozoic are preserved on high residuals; about 1300–1500 feet lower is another surface, the sub-Miocene peneplain, which is correlated with the main (Buganda) peneplain of Uganda. In early Miocene times this surface was gently warped (there was no great pre-Miocene Kavirondo Valley) and extensive shallow lakes were formed. In the region of the present Kavirondo Rift Valley, normal sedimentation was soon augmented by the explosive eruption of carbonatite, ijolite and granitoid blocks, lamprophyric tuffs, melanite-nephelinite-agglomerate, and nephelinite-agglomerate. Nepheline-basalts were erupted from great volcanoes; phonolite flooded the area from the east. During these times normal faulting and earthquake shocks led to sub-lacustrine landslips and slumping. Local erosion is proved by intra-Miocene unconformities, formerly supposed to be thrusts.

Another period of erosion followed, when the “ end-Tertiary peneplain ” was developed on the softer beds. In late Pliocene or earliest Pleistocene times the region was dislocated by powerful rift movements. The Kavirondo Rift Valley was depressed between faults and flexures, relatively to the regions to the north and south, while these regions were uplifted and tilted. The peneplains now slope away from the shoulder of the Eastern or Gregory Rift Valley towards the basin of Lake Victoria, where the waters were impounded by a transverse warp. These great movements do not seem to have caused any local structures suggestive of lateral compression; normal faulting is the rule. Yet a considerable negative isostatic anomaly was determined at Kisumu by Bullard.

On the Elgeyo escarpment, which forms part of the western wall of the Gregory Rift Valley, Miocene beds are again exposed. They are intermediate in facies between those of Kavirondo and Turkana. The Elgeyo escarpment, like those bounding the Kavirondo Rift Valley, is a fault-scarp due to post-Miocene faulting.
The tectonics of the Tintagel area, North Cornwall
Authors: Wilson Gilbert
Published: October 2009

The paper describes the structure of the coastal region of North Cornwall in the neighbourhood of Boscastle, Tintagel and Trebarwith Strand. The area has been remapped, and the tectonics originally outlined by Dewey (1909) have been reinterpreted. The revision has shown that the epidiorite at Tintagel is more extensive than hitherto believed. Massive epidiorite grades into chlorite-schist which is often very similar in appearance to the sheared volcanic rocks of the area; but the schist derived from the intrusive rock can be identified by its local thermal metamorphism of the phyllites which lie above it.

The important tectonic episode in the area was that of thrusting, in which the upper beds moved from the south-south-east towards the north-north-west. The direction and sense of the translation is indicated by various minor structures, e.g. slickenside striations, elongations of lava pillows, amygdules etc., in a (the movement direction); and by drag-folds, zig-zag folds, boudinage structure, tension fractures etc. in
b
(normal to
a
). Three main thrust-zones are recognized, and they separate the rocks into three tectonic units or thrust-slices which lie on an autochtonous foundation. The higher thrust-slices lie to the west of the lower ones because they have been preserved from erosion by the local westerly dip aided by normal faulting which downthrows to the west-north-west.

The more important of these normal faults pass through Tintagel Haven and form,
inter alia
, the great fault complex seen in the cliffs of the Island. Similar faulting occurs at Trebarwith Strand, Lill Cove and Hole Beach. In each case the downthrow is such that the flat thrust-plane there is dropped to the west. The general direction of strike in the area is controlled by the gentle doming due to the Davidstow Anticline. This hemidome pitches north-westerly, and it developed later than the thrusting episode. The evidence shows that there is no connexion between the thrust movements which carried the beds forward at least 2½ miles (or more) and the warping of the anticline. The tectonics at Tintagel are thus no longer to be considered the result of thrusting from the west-north-west, but are rather the result of a major movement from the south-south-east, and so become an integral part of the Hercynian tectonic pattern of Cornwall.
The Glen Banvie igneous complex
Authors: Holgate Norman
Published: October 2009

The Glen Banvie complex consists of appinitic diorites, tonalite and granodiorite, emplaced in that order in Moine type country rocks; they have mutual contacts at the present level of erosion. The appinitic diorites represent original pyroxene-mica-diorite modified in situ under the influence of later-intruded magmas, and are now dominantly hornblendic. The tonalite and granodiorite magmas appear to have engendered distinctive variants within the diorite, and have each suffered modification by reciprocal reaction and by gain of solid phases from the rocks already emplaced. All three masses were effectively fluid when intruded to the level exposed; their chemical compositions show near conformity to the trend of chemical composition revealed by the intrusive rock suites of the Scottish Caledonian province.
Observations on the geology of the northern part of North-East Land (Spitsbergen)
Authors: Sandford K. S. , Fairbaim P.E.
Published: October 2009

From Mr. P. E. Fairbairn :—

Dr. Sandford's demonstration that in North-East Land a gneissic-granitic core is older than the Cape Hansteen Formation will come as a considerable relief to those Spitsbergen workers who have never felt quite comfortable about deriving all metamorphic types in the archipelago from the Hecla Hoek sediments by dynamic metamorphism and granitiz-ation.

During my brief visit to the upper portion of the Lomme Bay Glacier in 1932 I was struck by the same point that Dr. G. W. Tyrrell has raised in his contribution to the discussion (p. 491) on Dr. Sandford's paper: namely the close proximity (two miles) of the eastern sedimentary to the western metamorphic rocks without any sign of transition. It was tantalizing to find that, for as far north as I was able to search for it, the contact zone was effectively concealed by the glacier. Evidence in favour of a transitional relationship in this area rests on Odell's observations in the neighbourhood of Mt. Irvine, which agree with those of Fleming and Edmonds on the Gullfaxe Glacier, 30 miles to the north. That metamorphosed representatives of the Hecla Hoek sediments do occur is proved beyond doubt, but I agree with Dr. Tyrrell that until further detailed work has been carried out in the upper part of the Lomme Bay Glacier, and until continuity of structure along the west wall of the glacier has been proved, we are safer in assuming a faulted or unconformable contact there.

I wonder whether Dr.
The study of the world's plainlands
Authors: King L. C. , Arkell W. J.
Published: October 2009

From
Dr. W. J. Arkell :—

Since a world-wide synthesis such as Professor King states that he has in preparation (the “ major work ” of which this paper is “ merely a preliminary statement ”) should depend on accurate, critical, and unbiased analysis of each individual area, I would like to ask for elucidation of some of the data mentioned in the preliminary statement. My questions all relate to North-East Africa, part of the “ central locking-piece of the Gondwana super-continent ”.

1. On p. 104 Professor King states that the same “ cyclic landscapes ” form the Abyssinian highlands and the mountains of western Arabia, and that these surfaces are of “ Gondwana ” age; i.e. they were above sea in the Jurassic and Cretaceous. Since published maps show the high plateau of Abyssinia as consisting of hundreds of metres of lavas, which rest in places of thick water-laid sandstones probably Creataceous date and in other places of hundreds of metres of marine Jurassic sediments,beginning with Bathonian and probably earlier stages, would Professor King explain how he arrives at the conclusion that this “ cyclic landscape ” was above sea in the Jurassic and Cretaceous? Further, since published maps shows the mountains of all western Arabia north of the Yemen as consisting of crystalline Pre-Cambrian rocks,I would ask what basis there is for comparing the present surface with that of the Abyssinian highlands?

2. on p. 104 it is stated that “ In eastern Arabia a later, possibly
The tectonics of the area between Grantown and Tomintoul (Mid-Strathspey)
Authors: McIntyre Donald Bertram
Published: October 2009

The region is homo-axial; the plunge of the fold-axes is to the south-east at nearly 30°. A profile nearly seven miles deep has been constructed by the use of the axial method of tectonic analysis developed by Lugeon, Argand, Wegmann, and others. This profile shows the tectonic relations of the Grantown Series, the Moine, and the Dalradian. Given the profile and the plunge, the general dips can be predicted; these coincide with the observed data. Metamorphism grades from phyllites to migmatites from the highest levels to the deepest. The majority, if not all, of the contacts are tectonic. Gigantic tectonic inclusions of Moine swim in the Dalradian; it is possible that similar inclusions of Dalradian occur in the Moine. The Moine and Dalradian suffered the same movement, the sense of which appears to have been towards the south-west. Lineation is perpendicular to this direction.
A revision of the sequence and correlation of the Lower Coal Measures west of Wigan
Authors: Eagar Richard Michael Cardwell
Published: October 2009

The Geological Survey in 1938 concluded that the Lower Coal Measures westward of Wigan showed considerable expansion in their lower part, abnormal lithological developments and a number of new faunal horizons, including Gerrard's marine band. The present paper is based on numerous non-marine lamellibranch studies and on field-work in the drift-free areas of Parbold-Harrock Hill and Upholland. In both districts the author demonstrates the presence of the Bassy Mine faunal succession and the Six Inch Mine “ mussel ” band. Their positions permit a decisive interpretation of the Tunley borehole section and, with other new sections and evidence, necessitate a correlation of the Upholland sequence in which the Lower Coal Measures diminish slightly in thickness west of Wigan, notable attenuation taking place in their lowest part in the Harrock Hill area. There are shown to be neither new marine nor non-marine bands (except above the Sand Rock Mine) westward of Wigan, the lithological and palaeontological sequence remaining essentially the same. Minor differences are seen in the development and disappearance of grits, with phases of erosion below them both at Harrock Hill and Upholland. In the light of the recorrelation W. B. Wright's sequence of non-marine faunas in Lancashire is drastically revised, and the unsatisfactory position of
Gastrioceras
in the Lower Coal Measures of Lancashire and Yorkshire is briefly reviewed.
The distribution of coal volatiles in the South Wales Coalfield and its probable signifinance
Authors: Jones Owen Thomas
Published: October 2009

The variation of volatile contents in seams in a horizontal sense is shown on an isovol map constructed by the Fuel Research Board following on a coal survey of the South Wales Coalfield. Nine vertical sequences of seams were also assembled, giving the volatile contents of each seam and its depth below a top seam assumed as a datum. For each of these sequences the constants and coefficients in each of four hypothetical relations were found by the least-squares method; these four hypotheses are: Hilt's law, the square-root relationship proposed by F. M. Trotter, the exponential relation suggested by H. W. Wellman between the ratio of the volatiles to fixed carbon and the depth, and another exponential relation between the volatiles and the depth. When applied to calculate the volatile contents of the other seams in the sequences all these relations gave results which did not differ significantly. The sequences cannot therefore give a verdict in favour of or against any one of the above hypotheses. The fact of greatest interest that emerged is that the coefficients for each expression vary so widely from one part of the field to another that no expression which uses a fixed value for its coefficient can be applied successfully to the coalfield as a whole. A surprising empirical relation was found, however, between these varying values and the mean volatile contents over which they hold, and from this expressions were derived which enable the volatile contents of any seam to be calculated or predicted if its depth below any other seam of known volatile content is given. These calculations are independent of any theory and the same value is obtained whichever of the above expressions is used if its coefficient and constant are determined by standard methods. The intimate relation between volatile contents and depth has been used to construct a contour map showing the depth of the Nine Feet Seam below an assumed datum of a seam with a 40 per cent volatile content. It is considered that this extremely intimate relation between volatile content and depth can be explained only by the hypothesis that the changing conditions which obtained when the seam was buried to varying depths are responsible for the variation of volatile contents.

These relations are applied to certain problematic areas in the coalfield.
The drainage systems of Wales and the adjacent regions
Authors: Jones Owen Thomas
Published: October 2009

The streams of Wales have been incised in a surface of considerable relief. From the summit-levels shown on the one-inch Ordnance Survey map their means and standard deviations were calculated for each 10 kilometres square of the National Grid. From these data the main physiographic elements can be picked out, such as the mountain area, the high plateau and two major surfaces at lower levels. The numerical distribution of summits on each of these surfaces appears to be wholly random.

Strahan's hypothesis of superposition from a Cretaceous cover is adopted with some modifications, but certain difficulties in accepting it are discussed.

WALES and the adjacent regions are drained by many streams belonging to several systems; a map of these streams, based upon those shown on the quarter-inch map of the Ordnance Survey, is given as Pl. XII; it has the appearance of a complicated mosaic. A large part of the surface of the region consists of an extensive tableland in which the streams are deeply incised.

Ramsay (1876, p. 223) gave a graphic description of the great extent of this tableland, “ all intersected by unnumbered valleys,” and recognized that its relief was due to “ fluviatile erosions that have scooped out the valleys ”.
A gravimeter survey in the Bristol and Somerset coalfields
Authors: Cook Allan Hugh , Thirlaway Henry Ivison Shipley
Published: October 2009

Gravity measurements in the Bristol and Somerset coalfields are described and discussed. Accounts are given of the methods of measuring gravity, of calculating the gravity anomalies and estimating the densities of rocks. It is shown that the variations of gravity correspond in a general way to the geological structure of the coalfields but that discrepancies in detail indicate that the anomalies are partly due to structures lying below the coalfields which may have controlled the development of sedimentation and deformation in the region. Detailed studies were made in the neighbourhoods of Bitton, Chew Stoke, Ston Easton and Avonmouth with a view to assisting the planning of a boring programme for the development of the coalfields in these areas.
The Carboniferous Limestone of the Manifold Valley Region
Authors: Prentice J. E.
Published: October 2009

Note by the
Author :—

My attention has been drawn to certain statements in the above paper which need clarification. These are mainly concerned with correlation and misplaced lines in Fig. 11. None of the fossils of the Cementstone and Lower Reef Series (pp. 176 and 181) is truly diagnostic of the C
1
subzone, and these beds should be ascribed to C
2
; the possibility of a lower horizon being present is suggested solely on the abundance of
Productus
aff.
mesolobus
Phillips, though the species also occurs in C
2
and higher beds. The correct alignment of the Manifold column in Fig. 11 will be made if the whole lower portion (Ca, Cb, Cc and Lower Reef) is moved upwards so that the base of Ca aligns with the base of Pe2. The Manifold Limestones-with-Shales (Cc) should then be aligned with S
1
; there is no evidence of their extension into S
2
. A black triangle should be added to Cb. In the upper series, the Lower Waterhouses Limestone (Da) and the Warslow Limestones (Dl) are probably D
1
, and all the beds above, D
2
, including the Apestor Limestone (Dk) and the Upper Waterhouses Limestone (Db); the “
crassiventer
” beds (Dc) are B
2
-P
1a
and the
Goniatites crenistria
band is P
1a
. On Fig. 11, Dn should be eliminated, the top of Dc & m raised, and the top of Db & 1 raised slightly. The fauna at Under Wetton Farm (p. 189) is probably low D
2
; latissimoid gigantoproductids range from D
1
, though the true
Gigantoproductus
The Study of the World's Plainlands
Authors: King L. C.
Published: October 2009

From
Mr. G. W. Murray, lately Director, Desert Survey of Egypt :—

My attention has been caught by a discussion in the
Journal
(106, 108, 470) as to the origin of the Qattara depression, in which Dr. Arkell questions Professor L. C. King's assertion that this was tectonic. During 1927–31, the depression was surveyed by my colleagues and myself of the Desert Survey of Egypt on the 1 : 100,000 scale with 5-metre contours and the scarp to the north of it examined in detail at the four points of emergence of as many projected tunnels designed by the late John Ball to connect the sea with the depression. (The results of our survey were given in abstract by Ball in the
Geographical Journal
for October, 1933.) At the eastern end of the depression, two vertical lithological sections were compiled in the field quite independently by the late H. J. Ll. Beadnell and myself. Two hundred miles farther west, Siwa Oasis, another depression at the foot of the same scarp was mapped geologically (though not published) by Dr. O. H. Little, the then Director of the Geological Survey of Egypt. During the four years of our survey, and during many discussions since with geologists who have had personal knowledge of the region, I had not, until I read Professor King's reply to Dr. Arkell, either seen in the field or heard in the office any suggestion of either faulting or folding in the area. My former colleagues may, perhaps, differ
The Stratigraphy of the Siwalik Series in the Northern Potwar, Punjab, Pakistan
Authors: Gill William Daniel
Published: October 2009

Detailed mapping of the Jhamat area in the west and of the Soan syncline in the east forms the basis of revision of the stratigraphy of the Siwalik Series in the northern Potwar region. The succession is here affected by facies changes of regional significance :—

1. Near the Indus River the uppermost 3000 feet of the Middle Siwalik sequence (Upper Nagri and Dhok Pathan stages) contain thick beds of conglomerate which die out eastwards and south-eastwards into sandstones and clays. Farther eastwards, across the Soan syncline, a clay facies develops at progressively lower horizons in the Nagri Stage, replacing a considerable portion of the massive sandstones of the type area. The facies change is accompanied by a reduction in thickness. The facies variation in the Middle Siwalik rocks is indicative of a channel environment in the west at Jhamat, clearly coinciding with the line of the present Indus River and grading eastwards into deposits of “ flood-plain ” type.

2. The Lower Siwalik rocks show a development of coarser facies in the opposite direction to that noted in the Middle Siwalik. At the eastern end of the Soan syncline the lowest 1500 feet of the Chinji Stage, which in the west is almost entirely of clay-shale facies, contain thick beds of hard sandstone and the sequence is very similar to that of the underlying Kamlial Stage.

In the Soan area, the complete Siwalik succession from the Kamlial Stage to the Pinjor Stage (Villafranchian) is free from any marked unconformities but is overlain with strong unconformity by post-Siwalik Pleistocene beds—the Lei Conglomerates. This interpretation differs greatly from that of de Terra (1936, 1939), who placed the first great unconformity of the area at the base of the Tatrot Stage. The revision explains Pilgrim's reluctance to include the Villafranchian in the Pleistocene, since in the Indian Siwalik belt this stage forms the highest member of a conformable succession which was intensely folded and subjected to peneplanation before the next deposition took place. The decision at the International Congress in 1948 to adopt the Villafranchian as the base of the Pleistocene places the Siwalik phase of Himalayan orogenesis within the Pleistocene System.
Acerocarina
, new name for
Cyclognathus
Linnarsson,
non
St. Hilaire
Authors: Poulsen Christian
Published: October 2009

The name
Cyclognathus
, proposed by Linnarsson for a monotypic genus of Cambrian trilobites (
Geol. Fören. Stockholm Förh
.
2
, 1875, 500), has been used by previously by Geoffroy St. Hilaire, 1833 for a mammalian genus. I therefore substitute for
Cyclognathus
Linnarsson,
non
St. Hilaire, the new generic name
Acerocarina
, the type species being
Cyclognathus micropygus
Linnarsson, 1875.
Note on a Pleistocene coral-rock in Jamaica, altered into material resembling bauxite of laterite
Authors: Trechmann Charles Taylor
Published: October 2009

On long stretches of the north coast of Jamaica there is a platform of Pleistocene raised coral-rock at an elevation of 10 to 25 feet. At some places, notably near the sea-water end of Folly Point (lighthouse), Tichfield Peninsula, and of Navy Island, all at the entrance of the two harbours of Port Antonio, this coral-rock has been altered in patches to a dark brown material for a depth of one or two feet and over a distance of about 100 feet from the edge of the cliff. Both massive and branched coral has been altered in this way and pieces of unaltered coral-rock often remain embedded in the brown mass and stems of altered branched coral in the white coral-rock. This material retains roughly the structure of the coral and where the two parts are joined the coral takes on a crystalline nature and the brown material penetrates along the structure of the coral. This peculiar alteration is found where the sea splashes over the rock and particularly in depressions where the sea-water evaporates and forms small salt pans. It is not seen beyond the reach of the sea spray, nor on the late Tertiary rocks against which the coral-rock rests. The coral-rock has not been overlain by any other formation. The water that washes over has covered the living reef growing on the late Tertiary and Eocene argillaceous rocks that form the bed of the bay and the off-shore slope. I have not seen this coastal bauxite or
Foreland folding
Authors: Lees George Martin
Published: October 2009

A study of foreland fold zones indicates that the cover of sedimentary rocks plays a passive role and accommodates itself to movements of the basement beneath. Lateral pressure exerted along a sedimentary cover from a thrust mountain front, such as is implied by the
Abscherung
theory of Buxtorf to explain the Jura Mountains structures, is not regarded as probable. Mountain building is the consequence of contraction of the interior of the earth and crustal compression from this cause has been dominant throughout revealed geological time. Examples of compression structures in shield areas far distant from active mountain fronts, as in Nigeria, are described. The Gulf of Suez and the Dead Sea rift valleys show evidence of both compressional and tensional features, but the former is the more important.

A crystalline basement complex can flexure and form the cores of anticlines with, in some cases, little or no faulting. Oil exploration borings in Venezuela, Sumatra and elsewhere have reached basement rocks in the core of anticlines and have shown that the active principle is movement of the basement and not sheared, rootless folding in the sedimentary cover produced by lateral pressure.

Examples of different types of foreland folding are described. The Jura Mountains structures are ascribed to steep folding or fault-slices in the basement below, the sedimentary cover having become detached as a result of the lubricating effect of the Triassic salt and folded into an independent pattern. The South-West Persian mountain belt is taken as an example of simple folding with long anticlines of up to 250 miles in individual length. Assam is described as an example of imbric folding— strongly thrust-faulted anticlines arising from thrust-folds in the basement below. The great flexure on the south flank of the Shillong plateau. between the Himalayan front and the Assam ranges, shows how an apparently rigid crystalline complex can be bent into a steep flexure and an erosion surface down-warped to a depth of about 30,000 feet.

Clay diapir anticlines in Trinidad are the surface expression of steep folding below a cover of soft incompetent clays, with high-pressure water and gas acting as agents to promote the upward extrusion of the clay core. Salt diapir anticlines, as distinct from circular salt plugs, also owe their origin to compressional movements in their substratum.

The degree to which basement rocks have been faulted, folded or flexed in some foreland zones is in marked contrast to more rigid behaviour in others. The great thrust-anticlines along the Rocky Mountain front in Alberta, such as Turner Valley, are the consequence of fault-slices in the basement. This complex zone is thrust on to the sedimentary cover of an unyielding foreland zone extending for hundreds of miles to the eventual outcrop of the basement rocks.
Some geological results from the exploration for potash in North-East Yorkshire
Authors: Raymond Leo Richard
Published: October 2009

The paper deals with the geology of the Permian, Triassic and Jurassic rocks penetrated by the Eskdale No. 3 (Sleights), Eskdale No. 4 (Sneaton), Eskdale No. 5 (Eskdalegate), Eskdale No. 6 (Upgang) and Eskdale No. 7 (Rockhead) borings, put down by Imperial Chemical Industries Limited in search of workable deposits of potassium salts. An account of sedimentary structures in the Permian evaporite succession is given and this succession is shown to result from a series of cycles of evaporation. Correlation with the Permian succession of South-East Durham is attempted.
The structure of the granite massif of Flamanville, Manche, North-West France
Authors: Martin Norman Roy
Published: October 2009

The present structural study of the small granite massif of Flamanville, based on the field technique originated by Hans Cloos, provides critical data from which to reconstruct the tectonic episodes, and the mode of emplacement of the granite.

The folding in the region results from two earth-movements. Firstly, the Caledonian (Mesodevonian in the Cotentin) on NE.–SW. axes, and secondly, the Hercynian (Sudeten?) on axes a few degrees south of due west. Superimposed on these tectonic trends are the folds due to the emplacement of the granite.

The granite appears to be diapiric in form, and to have risen into place by thrusting aside the country rocks. The primary flow-planes of the minerals in the granite and the foliation in the hornfels of the aureole are due to the same movements. Their form is consistent with the conception of a pluton expanding like a balloon, within its plastic cover. The joint patterns clearly demonstrate the tectonic unity of the granite with its immediate environment, and they cannot be envisaged as resulting from regional movements.

It is concluded that, though metamorphism, metasomatism, felspathization, and assimilation of the stoped country rocks have taken place along the contact, these processes were incidental to the emplacement of the magma. This is in contra-distinction to the previous conclusion, that the granite was created in situ by the granitization of the country rocks.
Early stages in the physiographic evolution of a portion of the East Midlands
Authors: Kellaway Geoffrey Arthur , Taylor James Haward
Published: October 2009

The paper deals with an area of over 600 square miles falling largely within the drainage basins of the rivers Nene and Welland. Formations present comprise a succession from the Lower Lias to the Oxford Clay and Pleistocene-Recent drifts.

Six-inch mapping, supplemented by numerous borehole records, discloses differences between the present and the sub-boulder-clay topography. The significance of these differences is discussed. Relics of the surface on which the present cycle of erosion was initiated are preserved as bevels on the solid formation. This surface, which falls from 750 feet O.D. in the west to below 250 feet in the east, is believed to have been tilted toward the North Sea basin.

Study of the stages of river diversion and capture provides strong evidence of an original W.-E. consequent drainage. The controlling effect of structure on river development is clearly shown. Certain lines of drainage are believed to have existed as subsequent streams before the start of the present cycle of erosion.

The origin of the large-scale superficial structures of the region is reconsidered. It is claimed that they were produced under periglacial conditions. The authors suggest that an important part was played by perennially frozen ground in the physiographic evolution of the region.
The plutonic history of the district around Trawenach Bay, Co. Donegal
Authors: Gindy Amin Riad
Published: October 2009

The metamorphic and granitic rocks of north-western Donegal are being investigated by a research group, mainly from the Geology Department of Imperial College, London. The present paper is the first of a series in which the detailed geology will be described and material assembled to provide eventually a synthesis of the geological history of one of the most interesting plutonic regions of the world. In these investigations all mapping is of outcrop type, the minimum scale being six inches to the mile.

This first communication gives the pattern of the plutonic history of a key-area characterized by a long sequence of granitic manifestations varying with time and crustal environment. The position of the area is shown in Fig. 1. It falls within sheet 15, published in 1890, of the one-inch Geological Survey map; the description of the geology of this sheet is included in the memoir for North-West and central Donegal, published in 1891. The rocks encountered are a varied series of folded metamorphosed sedimentary rocks, presumably Dalradian, with associated basic igneous intrusions that become involved in migmatitic and granitic complexes of diverse characters.

Earlier work on this small area will be most approriately dealt with in the final synthesis, where the development of ideas on the whole Donegal research field will be considered. Two aspects of this earlier work may, however, be mentioned. First, the attempts to determine the succession of the sedimentary strata are of little value in the absence of modern sedimentation techniques. Second, the opinions on
Seismic prospecting in the English Channel and its geological interpretation
Authors: Hill Maurice Neville , King William Bernard Robinson
Published: October 2009

Recent geological information obtained by core sampling in the English Channel off the South Devon coast is set forth. This information has been combined with the results obtained from a seismic survey along a line southwards from Plymouth.

The evidence from these two sources points to the existence of a trough filled with New Red Sandstone deposits which extends from within a few miles of the English coastline to a point south of the middle of the Channel. The thickness of these deposits reaches approximately 3000 feet.

The line of reefs formed of metamorphic rocks extending from Bolt Tail to the west of the Eddystone projects through the New Red Sandstone formations, which appear to be swamping an irregular topography.

Southwards from the Eddystone the breccias and sandstones of the Permian and Trias are followed by Keuper Marl and a small thickness of Lower Jurassic formations. These in turn are covered unconformably by a few hundred feet of Chalk.
A contribution to the geology of Rusinga Island, Kenya
Authors: Whitworth Thomas
Published: October 2009

The paper describes the results of geological mapping and palaeontological collecting in the Gumba peninsula, at the south-western end of Rusinga Island, Lake Victoria, Kenya.

A description of the rocks is given, with discussion of the conditions under which they were formed. The sediments seem to represent deposits of shallow, impersistent lakes and flood-plains in a semi-arid region which was subjected to continued volcanicity, often violently explosive. The stratigraphical sequence at Gumba closely resembles that described by R. M. Shackleton at Kiahera in western Rusinga.

Structurally the Gumba peninsula conforms to the simple plan established elsewhere in Rusinga. No evidence of violent post-Miocene compressive activity emerges, although minor fractures occur, which may represent local squeeze, dependent on major faulting of normal type.

An account is given of early Miocene vertebrates collected at Gumba, and of recent additions to the Rusinga fauna.
Variation in the Terebratulacea of the Fuller's Earth Rock
Authors: Mckerrow William Stuart
Published: October 2009

Over 3800 brachiopods have been collected from 15 localities along the 40 miles of the outcrop of the Fuller's Earth Rock. They consist largely of the terebratellid genera
Ornithella
and
Rugitela
; terebratulids and rhynchonelloids are also present.

The
Ornithella
populations are shown to be homogeneous in both external and internal characters. Their variation is generally symmetrical about the Mendips; one exception is a population containing dwarfs at the south end of the outcrop.

Statistical examination of the omithellids from four localities north of the Mendips shows that significant differences occur in the measurements of length, breadth, thickness and periphery, and in their ratios. The small omithellids are all broad forms with a rounded anterior, and changes in variation are entirely due to differences developed in the adults. The slopes of the growth-curves have been examined statistically : significant differences between these are not obvious.

Rugitela
is shown to be distinct from
Ornithella
by internal characters, and a bimodal histogram for T/L indicates that
Rugitela bullata
belongs to a different Linnaean species from the remainder of this genus in the Fuller's Earth Rock.

Environmental factors are considered to be the causes of many lateral changes: for example, obese forms of many genera occur near the Mendips.
Palaeoscolex piscatorum
gen. et sp. nov., a worm from the Tremadocian of Shropshire
Authors: Whittard Walter Frederick
Published: October 2009

The unique preservation among fossil annelids of a worm from the Tremadocian has retained the form of the gut, the jaw apparatus and the minute detail of the surface of the skin. The new genus cannot confidently be placed in any known division of the annelids.
The evolution of a shrinking earth
Authors: Lees George Martin
Published: October 2009

Fold and thrust mountain structures are the consequence of compression of the earth's crust, but beyond that simple fact there has been wide divergence of opinion on the causal mechanism. The seen geological evidence of the compression zones which weave intricate patterns through all continental areas, and the presumptive evidence that they continue into the oceans, have been undervalued and, instead, deductions drawn from geophysical observations—seismic, gravity and magnetic— have unduly influenced geological opinion. The Mohorovičić seismic discontinuity at about 35 km. depth, where there is a velocity increase to 8-1 km./sec, has been interpreted as a change in composition from a “granitic” layer to a “peridotitic” layer because at the surface these rocks give corresponding velocities. The continents are said to float on this mobile layer and hence the assumption of the isostatic principle.

Geological evidence shows the extreme improbability that there can be a layered arrangement of this type and that the observed compression structures can terminate downwards within such a thin crust. An alternative explanation of the seismic facts, more acceptable geologically, is that the discontinuities result from phase modifications at critical pressure levels with consequent marked changes in density and elastic characteristics. The compressed rocky crust with the same pattern as seen at the surface, though with increasing metamorphism downwards, may have a thickness of many hundreds of kilometres; and there is now no reason to assume any important change in chemical composition even at deeper levels. The old theory of a nickel-iron core is no longer necessary to explain the physical data.

Contraction of the earth's surface due to shrinkage of the interior is the only adequate explanation of the compression zones, but the amount attributable to cooling is thought to be inadequate. Estimates of the extent of compression during the Alpine, Hercynian, Caledonian and at least three Pre-Cambrian phases give a contraction of the earth's circumference of at least 3000 km. and perhaps much more. The processes of compression, mountain-forming and erosion were already an established regime at the time of the oldest exposed Archaean rocks, and in consequence there is no geological evidence on the nature of the primordial crust and certainly no hint that it was at one time molten. Assuming no important change in the mass of the earth since the Archaean, the average density at that, already advanced, stage of compression may have been about 4–5 g/cm
3
compared with the present value of 5–517. Adiabatic compression may have generated more heat than has been lost by radiation and hence the basis of the assumption of a cooling earth is very insecure. The planetesimal theory of Chamberlin and Moulton for the formation of the earth is the most acceptable geologically. The present-day moon may illustrate the appearance of the earth at some pre-Archaean stage, the moon's craters being interpreted as infall craters of meteorites.
The structure and petrology of the hypersthene-gabbro intrusion, Ardnamurchan, Argyllshire
Authors: Wells Maurice Kingsley
Published: October 2009

The hypersthene-gabbro intrusion has an unusually broad outcrop compared with related ring-dykes. The outer wall has a moderate inclination away from centre 2, dipping in the same direction as the overlying sediments and lavas and to a similar degree. In contrast to this, banding in the gabbro is inclined in towards centre 2, with increasing steepness as the centre is approached. The banding or layer surfaces have therefore a roughly conical shape, and since there is some evidence that gravity accumulation of crystals was a factor in the production of layering it is suggested that the lower part of the intrusion has a conical form. The hypersthene-gabbro was probably forcefully intruded, and appears to bear little relationship to ring-dykes.

The petrography of the hypersthene-gabbro and its varieties is described. A quartz-gabbro marginal variety may have consolidated from some magma remaining from a pre-hypersthene-gabbro phase of cone-sheet injection, this magma having been driven towards the upper surface of the hypersthene-gabbro intrusion during the forceful injection of the latter.

The origin of various types of granular basic pyroxene-hornfels intrusions is discussed and criteria are suggested by means of which the types may be distinguished.
The Pre-Carboniferous rocks of the Slieve League promontory, Co. Donegal
Authors: Anderson John Graham Comrie
Published: October 2009

The metamorphic rocks of the Slieve League promontory, in South-West Donegal, are shown to form a conformable succession consisting of the Killybegs Pelitic and Calcareous Group (oldest), the Glencolumbkille Limestone Group, a boulder-bed with granite boulders and the Slieve Tooey Quartzitic Group. Both pre- and post-metamorphic intrusions are also described; in places there is an unconformable cover of Lower Carboniferous sediments.

Structurally, the Quartzitic Group forms several synclines in the older schists. Overfolding and thrusting have taken place towards the north; parts of the folds have been bent sideways through angles of up to 90°. The effects of post-Lower Carboniferous folding and faulting are also discussed; the faults are mainly of the strike-slip type with sinistral displacement.

Most of the schists fall within the biotite zone of metamorphism, but garnet occurs in the west of the promontory. The garnets are largely replaced by chlorite, suggesting retrograde metamorphism.

A connexion is established between the schists of the promontory and those of Lough Derg, described in an earlier paper. The present work supports the view that the Lough Derg rocks are of Moinian age.

The schists succession in southern Donegal is correlated with the Moinian and Dalradian succession of the Scottish Highlands, and particularly with that of Islay.
The Namurian of the Lancaster Fells
Authors: Moseley Frank
Published: October 2009

The Lancaster Fells are situated in the northern part of the Central Province and the Namurian sequence resembles that of the similarly placed Rombalds Moor region.

The marine Upper Bowland Shales are at the base and rest conformably on the Lower Bowland Shales (Lower Carboniferous). Together with the succeeding Bowland Grit Group, 1200 feet thick, they make up the Pendleian Stage (E
1
).

The
E. bisulcatum
marine band marks the base of the Arnsbergian (E
2
) and is followed by the Roeburndale Grit Group, 600 feet thick, which is in turn succeeded by the important Caton Shales (
Ct.
nitidus Zone).

The upper part of the sequence is much thinner than in other areas. The Sabdenian (H) has but one marine band (
H. beyrichianum
) and a succeeding thin sandstone. The Kinderscoutian (R
1
) starts with brachiopod beds, follows with two Reticuloceras marine bands and has red sandstones near the top. The Marsdenian (R
2
), with
R. gracile
at the base, has similar red sandstones, whilst the Yeadonian (G
1
), only exposed farther north in the Greta valley, contains the
G. cancellatum
and
G. cumbriense
marine bands.

The structure consists of a broad asymmetric synclinal area with steep dips on the flanks and gentle northerly dips in the axial regions. The dominant trend of the faults is north-westerly and the downthrows south-westerly.