bluuebunny/crossref_metadata_2025_split huggingface dataset:
A contribution to the geology of Rusinga Island, Kenya
Authors: Whitworth Thomas 
Published: October 2009

Summary
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

Summary

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

Summary
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

Summary
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

Summary
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

Summary
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

Summary
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.
The transformation of tillite by migmatization at Mount Fitton, South Australia
Authors: Bowes Donald Ralph 
Published: October 2009

Summary
This paper gives an account of the transformation of tillite by migmatization in the vicinity of Mount Fitton, South Australia. The mineralogical and chemical changes invplved are described and discussed.
During an orogeny in the early Palaeozoic some of the tillites, slates and quartzites, which are stratigraphically part of the Sturtian section of the Adelaide System (late Pre-Cambrian), were altered to migmatites. Large granitic migmatite complexes were formed by granitization and small patches of epidiorite-like rocks were formed by basification.
The tillite contains erratics of varying type, shape and size set in a semi-pelitic matrix made up essentially of quartz and biotite and with a composition generally falling within the subgreywacke range. The tillite at Mount Fitton is similar to late Pre-Cambrian tillites found in many parts of South Australia.
The transformation of tillite by granitization involved an increase in the amount of potash-felspar, acid plagioclase, quartz (in the case of the more pelitic rocks) and in grain-size and a decrease in the amount of biotite. K and Na and, in most cases, Si increased and Fe, Mg, Ca, Ti, P and Mn decreased. Granitization altered the rocks by direct replacement, except in one area where the rocks were agmatized.
The transformation of tillite by basification involved a considerable decrease in the amount of quartz, the disappearance of biotite and the development of actinolitic hornblende, labradorite and ilmenite as well as an increase in grain-size. Si and K decreased and Fe, Mg, Ca, Ti, Mn and Cr were introduced. These introduced constituents are the same as those expelled during the granitization of tillite and the processes of granitization and basification are considered to be complementary.
The Evolution of Vertebrate Organization
Authors: Young John Z. 
Published: October 2009

No generally satisfactory system has been devised by which the organization of an animal or plant type can be described and related to the environment in which it survives. Differences of terminology and method of approach to this problem have been responsible for many of the disagreements between zoologists and palaeontologists, and among the latter, on such matters as the direction and significance of evolutionary changes.
Even in the case of the vertebrates progress in the study of the evolution of organization has been slow and perhaps the situation is worse in other phyla. It is possible that progress has been held up for lack of a model that can be used to provide an exact terminology for the subject. It may be that palaeontology would profit from bold attempts to find analogies between the evolution of populations and the performance of man-made machines.
The task of description is never simple in any science. We all use analogies every day throughout our work. In describing the shape of a fossil we may say that it is “boatlike” or “whorled”, “cruciate” or a thousand other things. These are small and superficial analogies, serving to call attention to particular features and to explain what is meant. Perhaps all sciences begin in this way with a multiplicity of lesser comparisons. The brain operates by the process of comparison, selecting for attention certain attributes of each situation that are already associated as a result of previous experience. The maturity and efficiency of a science
The Structure of the Jebel Hagab Area, Trucial Oman
Authors: Hudson Robert George Spencer , McGugan Alan , Morton Douglas Michael 
Published: October 2009

Summary
The authors describe and discuss the structure of an area on the western front of the Oman Mountains and east of Ras al Kheima, Trucial Oman, an area of foothills dominated by Jebel Hagab, 1450 m. high. The outcropping strata consist of an upper and a lower series: the former, exposed over most of the area, ranges from Permian to Lower Cretaceous, is almost entirely limestone, and has a total thickness of 3408 m.; the latter is a series of several hundred metres of Jurassic and Lower Cretaceous tuffs and radiolarian cherts, about 50 m. of Aptian limestones, and about 15 m. of conglomeratic Maestrichtian marls: the junction between the two series is well exposed and is a thrust-plane. The overriding sheet, thrust from the northeast in Neogene times, has a series of N.-S. frontal folds with steep or slightly overturned west limbs. Below the thrust of the Jebel Hagab area, exposed in the window of Wadi Hagil, contorted radiolarites are overlain unconformably, partly by Aptian and partly by Maestrichtian, both with basal breccia-conglomerates which include fragments of weathered serpentine. Their closely packed folding is considered to be partly due to submarine gravity slip following uplift. There was also pre-Aptian metamorphism and emplacement of serpentinites.
Both the limestone and radiolarite successions of Jurassic and Lower Cretaceous age are facies expressions of the sedimentation in the Persian Gulf embayment of southern Tethys extending southwards between, and overlapping on to, the Arabo-Ethiopian and Indian massifs. The limestones are considered to be a
The Plutonic History of the Maas Area, Co. Donegal
Authors: Iyengar Sosale V. P. , Pitcher Wallace Spencer , Read Herbert Harold 
Published: October 2009

Summary
The paper describes the plutonic geology of part of the envelope of the Donegal granite . In the Maas area a thick and varied series of Dalradian rocks is displayed in a relatively simple anticline, the southern limb of which is buckled into smaller folds. After the folding, which was accompanied by regional metamorphism, there followed three successive plutonic events, each differing in the nature of the introduced material, the manner of its emplacement and the associated metamorphic effects. Migmatization in the highest levels of the structure is associated with mobilization and the production of sillimanite-hornfelses. The later intrusion of the composite granodiorite pluton of Ardara was clearly accompanied by the shouldering and pushing aside of the country rocks by a hot plastic body. Early fold structures were tightened and dislocated during the formation of a zoned aureole characterized by sillimanite-garnet and andalusite-staurolite associations. Alongside what was probably the feeding channel of the pluton, migmatization and mobilization of a special kind, concentrated in action, have resulted in flow tectonics; involved in these operations are metasediments of varying properties, amphibolites of appinitic types and many kinds of migmatitic derivatives. Lastly, these rocks are truncated by the pegmatitic fringe of part of the main body of the Donegal granite and as this consolidated it recorded an intense shear deformation, possibly produced by its own upward pressure.
I. Introduction
The investigation of the plutonic geology of the Maas district is of considerable importance in the general study of North-West Donegal. There is here
The Ard Bheinn Area of the Central Igneous Complex of Arran
Authors: King Basil Charles 
Published: October 2009

Summary
The complex is largely surrounded by Old Red Sandstone formations, which were evidently domed up at an early stage in its development. A succession of sediments ranging in age from Permian to Cretaceous, surmounted by Tertiary lavas, is represented within the complex as “remanié masses” which are interpreted as relics of a block that foundered during the formation of a volcanic caldera, the main subsidence being estimated at 3000 feet.
Subsequently there arose on the caldera floor a series of volcanic cones, characterized in general by the sequence andesite-dacite-rhyolite, but also showing a great diversity of pyroclastic formations. The position of the various centres is recognized by the disposition of concentric and radial structures. Quasi-horizontal formations in the most elevated parts of the Ard Bheinn area are considered to correspond to remnants of the basal portions of the volcanic superstructures. The andesites and andesitic breccias are evidently extrusive in character, but the later dacites and rhyolites are represented only by their intrusive equivalents.
Finally, granites were emplaced, mainly in conformity with the general structure of the caldera, and in all but the Ard Bheinn area are the prevalent formations at the present level of erosion.
I. Introduction
The complex occupies an oval area about three miles from north to south and nearly four miles from east to west almost in tne centre of the Isle of Arran and is emplaced within strata ranging in age from Old Red Sandstone to Permian.
Topographically the area is a dissected plateau, the highest
The Tectonics of the Morar Anticline and the Problem of the North-West Caledonian Front
Authors: Kennedy William Quarrier 
Published: October 2009

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

Summary

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

The Reading Beds, averaging 69 feet thick, have a marine “bottom bed” which varies in thickness from 6 to 25 feet; in one case this facies seems to persist to within 10 feet of the top of the series, foraminiferal glauconitic sand there replacing the mottled clay of nearby borings. Several seams of lignite were found, one of them resting on a seat-earth full of pyritized rootlets.
The lithology of the rest of the succession resembles Wat of the Hampshire Basin rather than that of the London Basin of which it forms a tectonic part. Alternations of marine and estuarine episodes recur throughout; banks of shingle are common and beach-deposits occur; lignite, scattered or in actual seams, pervades the whole.
The London Clay rests on a plane of erosion at the top of the Reading Beds; it falls into three main sections, the Lower Silts, Stiff Clays and Upper Silts.
The Post-Silurian Pre-Marine Carboniferous Sedimentary Rocks of the Eastern Side of the English Lake District
Authors: Capewell Joseph Gerald 
Published: October 2009

Summary
The post-Silurian, pre-marine Carboniferous rocks of the eastern side of the Lake District comprise a variety of clastic sediments, mainly red conglomerates. They consist of two main groups, the older—the Mell Fell Conglomerate—being unconformably overlain by Carboniferous Limestone and possibly therefore of Lower Old Red Sandstone age. The Mell Fell Conglomerate is some 5000 feet thick, the lower part being mainly greywacke-cobble-conglomerate, the higher beds being finer conglomerates and coarse sandstone with a mixed assemblage of derived pebbles. It is probably a piedmont deposit of locally derived material in a region of pronounced relief.
The younger group is best developed in the Birk Beck valley, where three divisions are recognized—a lower local subaqueous fan conglomerate, a middle group of red sandstones and an upper yellow conglomerate. These Carboniferous (probably Z), though a break exists at the base of the red sandstones. These sandstones are composed of wind-rounded grains, laid down under water, probably in a flood-plain that periodically dried out. In the Ravenstonedale district, the Pinskey Gill Beds may be contemporaneous with the lower conglomerates of Birk Beck, both being deposited in saline water.