bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Note on the Origin of Basic Xenoliths in Plutonic Rocks, with special reference to their Grain-size
Authors: Joplin Germaine A. 
Published: May 2009

SUMMARY AND CONCLUSIONSIt has been suggested that the grain-size of coarse basic plutonic rocks may be reduced in one or all of three ways:—
(1) If the temperature of the invading magma be sufficient, the reduction may be effected by the formation of a granoblastic structure. It is pointed out that recrystallized inclusions are found more often in basic plutonic masses, where the earlier crystalloblastic structures are not obliterated by superimposed hybridization. In 1933 (p. 156) the writer suggested that relict felspars with granular inclusions (or clouding) may be useful criteria of a recrystallization antedating hybridization.
(2) The grain-size may be reduced by the development of highly poikilitic crystals of hornblende and/or biotite, and by the final disruption of these. Such crystals may be formed as poikiloblasts in the initial recrystallization; but more often they may be attributed to hybridization, and in this process hornblende plays an important rôle.
(3) The grain-size may be reduced by the formation of granular masses of pyroxene or by criss-cross flakes of biotite during hybridization.
Thomas and Campbell Smith (1932) and Nockolds (1932) have discussed the development of large felspars within the fine grained xenolith and its final incorporation in the acid magma, but it is not the purpose of the present paper to deal with this stage. It is hoped that this discussion may have indicated a means by which coarse basic plutonic rocks may become fine grained xenoliths, and it is finally urged that it is not always necessary to postulate a fine grained origin for these inclusions.
On the Permian Coelacanth, Coelacanthus granulatus, Ag
Authors: Moy-Thomas J. A. , Westoll T. S. 
Published: May 2009

1.IntroductionAlthough the Permian species of Coelacanth, Coelacanthus granulatus, has been known since 1829, and although many authors have described specimens of it, it has remained unfortunately one of the lesser known of all Coelacanths. Since C. granulatus is the genotype of Coelacanthus, and since all the Carboniferous and some Triassic species have been assigned to this genus, it is surprising that further description has not been forthcoming. One of us (J. A. M. T.) has for some time been working on the Carboniferous Coelacanths, and it has been impossible to determine whether these really belong to the genus Coelacanthus. Accordingly it was hoped that by re-examining all the available material a more diagnostic description might be given. In doing this the authors have only been partly successful, as some of the most important generic characters—the dermal bones of the cheek and snout—were not preserved in any of the material examined. However, sufficient diagnostic characters have been provided by this research to distinguish the Carboniferous forms from this Permian genus.
A Search for the Mechanism of Earth Movements
Authors: Lewis R. G. 
Published: May 2009

SummaryThere is reason to suppose that a rise and fall of any part of the earth's surface may be due to anticlines travelling through the crust either (a) at the depth at which isostatic compensation becomes effective, which may be likened to the “surface” on which the crust “floats”, or (6) at a less depth, in a layer which becomes molten through the action of radioactivity.In the case of (a) the cause would seem to be mountain-building in the crust above and the anticlines are outflows of rock-material: the rise and fall may be about equal: there is also some slight reason to suppose that an oscillation, analogous to that occurring when a buoyant object is thrown into water, with the production of a series of waves of diminishing amplitude, has occurred, but it is not yet clear whether such an oscillation is possible.In the case of (6) the cause of the anticlines is the collapse of a portion of the crust which squeezes out plastic material below: a small rise is followed by a long, slow fall: a rise in one region is accompanied by a fall in an adjacent region : areas may be raised into domes by collapse of surrounding areas, in which case the central area will be a seat of vulcanicity.
Diorite-Limestone Reaction at Ben Bullen, New South Wales: A Study in Contamination
Authors: Joplin Germaine A. 
Published: May 2009

Summary and ConclusionsIt has been shown that diorite tongues invading limestone have given rise to a series of contaminated rocks in which definite mineral assemblages may be recognized. These assemblages are sharply defined and occur in rude concentric arrangement about the tongues.
On the Fossil Flora of the Bristol and Somerset Coalfield
Authors: Crookall Robert 
Published: May 2009

Summary(1) 510 plants are recorded from various localities in the coalfield, fossils having been collected from several new localities.(2) Fossil-plants are noted for the first time from the upper beds of the “Millstone Grit” of this district.(3) Two new species ofSigillariaare described and figured.(4) The known flora of the coalfield has been increased. Of the plants recorded—6 species have not been recorded previously from Britain.62 species have not been recorded previously from the coalfield, and290 species have not been recorded previously from various localities in the coalfield.Many of the species which have been previously recorded are here referred for the first time to definite horizons.(5) The known vertical distribution of 38 species is extended to the Staffordian Series.
Further Observations on the Clay Pebble Bed of Ancon (Ecuador)
Authors: Sheppard George 
Published: May 2009

Summary of Conclusions(1) The clay pebble bed of Ancon (Ecuador) is essentially a true deposit, probably formed, in the first place, by the denudation of an Eocene land surface under abnormal climatic conditions.It has not been formed primarily by overthrusting or shearing, although these tectonic phenomena have undoubtedly affected the deposit at a later stage of its history.(2) The clay pebble bed does not attain a thickness of more than three hundred feet, and it is included in about eighteen hundred feet of uniform clay shales and sandstones. The evidence collected from the drilling of boreholes suggests that recumbent folding has taken place in this area. No other explanation can satisfactorily account for the presence of two (or three) phases of the clay pebble bed in the same borehole. (Fig. 1.)(3) Whilst stratification is not usually present in the clay pebble bed, a certain linear arrangement of the constituent materials has been detected which indicates a flowage in the deposit prior to consolidation. Later folding, however, has obliterated most of the evidences of original accumulation.(4) Irregularities in the present attitude of the clay pebble bed and its associated strata (such as, for example, the upper limit of the clay pebble bed transgressing the bedding planes of the superincumbent strata, the upper limit apparently being a thrust plane from which minor thrusts branch into the upper block, the presence of transitional stages, etc., where the tearing away of the sole of the upper block is visible) can all be explained by an appreciation of the special tectonics of this area, which includes the theory of recumbent folding.
The Limestone of the Kinta Valley, Federated Malay States
Authors: Rastall R. H. 
Published: May 2009

Summary and ConclusionThe following is a very brief summary of the results of my investigation of the problems here dealt with:—(1) The limestone is Carboniferous or Permo-Carboniferous or more probably both.(2) All the limestone belongs to one continuous phase of deposition.(3) The “Schist Series” is above the limestone, and is of Triassic age.(4) The western boundary of the limestone is a great fault or system of faults.(5) The thickness of the limestone is indeterminable, but is probably to be measured by thousands of feet.(6) The limestone hills are due to overfolding from the west, modified by block-faulting and denudation.
The Petrology of the Avonian Rocks at Sodbury, Gloucestershire
Authors: Coysh A. W. 
Published: May 2009

Summary and Conclusions(a) The insoluble residues from the limestones contain detrital quartz, amorphous, cryptocrystalline and microcrystalline silica, siliceous pseudomorphs after organic remains, sponge spicules, fluor, magnetite, pyrites, zircon, ilmenite, tourmaline, muscovite, biotite, and felspar.(b) No megascopic chert occurs.(c) The succession contains more arenaceous and argillaceous rocks than occur in the Avon section. They contain magnetite, rutile, zircon, ilmenite, tourmaline, muscovite, and staurolite among the rarer constituents(d) Oolites have a notably small average percentage of insoluble residues, probably owing to their rapid formation, in clear water.(e) The detrital material in the Avonian rocks of Sodbury has probably been derived, directly or indirectly, from some Pre-cambrian complex to the north or north-west.
The Mineral Composition of the Modern Fenland Silt, with special reference to Carbonate Minerals
Authors: Hardy F. 
Published: May 2009

SUMMARY1. A sample of modern Fenland silt containing 8·98 per cent of carbonate was found on minaralogical examination to include dolomite as well as aragonite in its mineral assemblage.2. The dolomite is present in fresh angular crystal grains which suggest a secondary and recent origin of the mineral. It has possibly been deposited from sea-water which periodically covers the foreshore of the Fenland border of the Wash.3. The general mineral composition of the silt resembles closely that of certain geologically recent deposits of Cambridgeshire, and points to the boulder-clay left by the North Sea glacier as the chief source of the material of which the silt is composed. The silt has mainly been deposited by sea-currents which carry southwards the eroded glacial deposits of the South Yorkshire and North Licoln-shire coasts.4. An attempt is made to interpret the results of a chemical analysis of the silt in the light of its mineralogical composition, chiefly with regard to carbonate, potash, and phosphate. Muscovite, is found to be the main source of potash, and apatite of phosphate in the silt.
The Lower Carboniferous of the Skyreholme Anticline, Yorkshire
Authors: Anderson F. W. 
Published: May 2009

The area east of the Burnsall Knolls in the north-east Lowlands of Craven is occupied by limestones of the Northern facies type, apparently unaffected by the presence of the North Craven Fault.The beds are overlain unconformably by the Grassington Grit, which, overstepping the flanks of the Skyreholme anticlne, thus continues to the south the unconformity noticed north of the fault. It is suggested hat the line of the Skyreholme anticlne is the axis of uplift which gave rise to pre-Millstone Grit denudation. Passing westwards the beds become Reef-like in character and eventually grade into the Reef limestones of Burnsall.Finally, my best thanks are due to Mr. R. G. S. Hudson for much help and guidance during the progress of the above work.
Notes on the Brandesburton Kame, Yorkshire
Authors: Phemister James 
Published: May 2009

Summary1. The direction of the ridge is roughly parallel to the line of the moraine in Holderness as sketched by Carvill Lewis.
2. The material of the gravels is ice-collected, but is well waterworn though not rounded. The bulk of the pebbles are of northeastern England and Yorkshire origin, and a small proportion of Scandinavian rocks is present.
3. The stratification is horizontal and current bedding is frequent.
4. There is no seasonal banding nor any alternations of broad and narrow parts along the length of the ridge.
VII.—Belemnites of the Faringdon ‘Sponge-Gravels’
Authors: Lamplugh G. W. 
Published: May 2009

During a preliminary traverse of the Lower Cretaceous outcrop in the Midlands last June, I visited Faringdon for the first time, and examined the famous sections in the ‘Sponge-gravels.’ My chief aim was to obtain some evidence by which the relative position of these beds in the Lower Cretaceous series might be determined. The greater part of the fauna was so anomalous and peculiar that it afforded little or no assistance towards this purpose, and the only common fossil which gave definite promise of service was the fragmentary Belemnites, which I found in unexpected abundance. It is true that I had previously noticed a few specimens among the Faringdon fossils in the Natural History Museum (from the Caleb Evans’ Collection) and in other public collections, and had seen references to Belemnites in descriptions of the ‘Spongegravels’; but I went with the impression that its occurrence was rare and exceptional, whereas I found that it could be collected plentifully from every pit, though always in a more or less worn and fragmentary condition, and generally encrusted with small oysters, serpulæ and polyzoa, and perforated by marine borers. The scant attention which the fossil has hitherto received is probably due to the prevalent opinion that it is derivative from the Jurassics, but this opinion is almost certainly erroneous, as I shall now try to show.In the large number of specimens which I obtained only one species appears to be represented, and this species cannot, I think, be matched among Jurassic Belemnites.
VIII.—Quartz Dykes Near Foxdale, Isle of Man
Authors: Lomas J. 
Published: May 2009

In the neighbourhood of Foxdale, Isle of Man, and especially on Granite Mountain, the ground is strewn with numerous blocks of quartz. Many of them are of large size, 10 feet or more in diameter.On the slopes of South Barrule similar blocks are found in great profusion, and they can be traced across the hills to the west coast. North of Foxdale other bands are found, some of which are inserted in the geological map. They lie principally in the altered slates of the Barrule Series, and have a general trend corresponding with the main axis of the island, from north-east to south-west. In places they are seen to be in sitû, and where the granite mass of Foxdale intervenes the general direction changes, and is principally tangential to the intrusion.Numerous micro-granite dykes extend along the axis of the island in the same direction.In an old quarry at Renshent on the north margin of the granite several quartz veins are seen to traverse the granite itself. They can be traced along the floor of the quarry and up the vertical face about 30 feet high.One of these, about 3 feet in width, shows perfectly sharp margins when cutting through the granite, dips at 65° W., and strikes 10° E. of S. It consists mainly of quartz, some clear and some white and opaque, but on entering the granite it changes locally to a pegmatite. The pegmatite contains, in addition to the quartz, large felspars, some over 3 inches long, perfectly formed, and showing crystal faces, and mica in crystals over an inch in diameter.
I.—Eminent Living Geologists
Authors: Gaudey Albert Jean 
Published: May 2009

The recent retirement of Professor Albert Jean Gaudry, who for fifty years has been associated with the Jardin des Plantes, gives us an opportunity of presenting our readers with his portrait.Born in 1827, he started for Cyprus and Greece at the age of 25, on what was destined to prove an epoch-making visit, for while there he obtained satisfactory information about the rich deposit of vertebrata at Pikermi, which he afterwards visited. The results of his labours are embodied in the classic “Animaux fossiles et Géologie de l'Attique” (1862–67), and a new world of vertebrate life was fully opened to zoologists, of which the first glimpse had been obtained by Wagner. But perhaps the best known of Gaudry's writings is his “Enchainements du monde animal dans les temps géologiques” (1878), reprinted in 1895, a work which has had great influence on the younger school of thought (see Geol. Mag., 1878, pp. 221–227, and 1884, pp. 32–40).Appointed Assistant to Professor Alcide d'Orbigny (the first to hold the Chair of Palaeontology at the Jardin des Plantes) in 1853, while still in Cyprus, he succeeded Edouard Lartet in that Chair in 1872. He was Vice-Secretary of the Geological Society of France in 1852, Secretary in 1854, and President in 1863, 1878, and 1887; while in 1900 he presided over the Meetings of the Eighth International Congress of Geology, held in Paris.Gaudry's first published works dealt with Starfishes (1852) and the Origin of Flint (1852), but soon afterwards he confined himself to Vertebrate Palaeozoology, with a result that is known to even the most superficial student of the science throughout the world.
II.—Creechbarrow in Purbeck.—No. 2.
Authors: Hudleston W. H. 
Published: May 2009

Additional Points in Stratigraphy.In my paper published in the Proceedings of the Dorset Field Club (vol. xxiii), I dwelt at some length on certain borehole sections made towards the northern base of Creechbarrow with a view to the discovery of Pipeclay. This course was adopted in the hope that a study of these sections might throw some light on the stratigraphical relations between the Creechbarrow Beds on the hilltop and the Pipeclays lower down, if indeed there are any stratigraphical relations beyond a mere jumble of irregular deposits whose precise orientation can never be disentangled. Whether this latter supposition is the true one or not, the exceptional character of the Creechbarrow Beds, as a local feature, remains the same, even although we cannot decide whether they go under, over, or into the Pipeclay series. Before attempting any further speculation as to the possible stratigraphy of the region I will call attention, at any rate, to its topography as shown in the accompanying figure.
II.—Creechbarrow in Purbeck.—No. 2 (continued)
Authors: Hudleston W. H. 
Published: May 2009

Varieties of the Creechbarrow Limestone.—There are considerable extremes in this respect, ranging from a soft marly deposit, which soils the fingers like whitening, to a hard compact rock, which takes a good polish. Unquestionably the most dense and compact lime-stone is that near the summit, whilst the soft marly beds are on the northern slope, and especially near the 500 feet contour, where some of them are earthy and contain a considerable amount of impurity, so that they may at least be called marly limestones. On the other hand, there are compact white limestones, where nests of dog-tooth spar form no inconsiderable portion of the mass. Quartz grains may be noted on most of the weathered surfaces.The more compact and denser limestones, which prevail near the summit, may be roughly divided into non-pisolitic and pisolitic rocks. Thus, for instance, I have before me (Group 1) specimens of a very heavy and partially calcitic rock. It is a hard whitish limestone without pisolites, but largely interspersed with buff-coloured patches, not unlike some dolomites. Calcitic nests and strings occur, and also strings and stars of black oxide of manganese: the external surface is rough and somewhat honeycombed, and full of curious impressions, some of which may have had an organic origin.Group 2 comprises those specimens where the pisolitic character is indicated, but not very obviously. A characteristic specimen may be described as follows:—A large fragment of a creamy white tufaceous limestone, with specks and threads of black oxide of manganese in places: flattened pisolitic bodies in brownish calcite are numerous, but not very distinct.
IV.—Notes on a Collection of Bivalved Entomostraca and Other Microzoa from the Upper – Silurian Strata of the Shropshire District
Authors: Smith J. 
Published: May 2009

IntroductionDr. Harvey B. Holl, F.G.S., has obtained many very perfect Silurian Entomostraca, and the late Lieutenant Henry Adrian Wyatt-Edgell got some good specimens from the Border Counties; and indeed Dr. Holl made an extensive and valuable collection from the limestones and shales of the neighbourhood of Malvern; nor has his collection been fully described and illustrated as yet, although several selected forms have been published in the “Annals of Natural History,” for December, 1865, and March, 1869. The remarkably rich collection of Silurian Entomostraca, however, brought together by Mr. J. Smith, of Kilwinning, contains some of the finest specimens yet seen; and the following notes on the places where they were obtained, and a list of the species (although provisional only, and not fully worked out), must be of interest, and probably of some practical value both to the geologists of Shropshire and to palæontologists in general.—T. R. Jones.
V.—Contributions to Ceylon Geology: Occurrence of Corundum In Sitû Near Kandy, Ceylon
Authors: Coomáraswámy A. K 
Published: May 2009

The present notes are based on field observations made in 1900. The section described is now obscured.Corundum is abundant in the gem-bearing gravels of Ceylon, but with the exception of the case here described no localities are known where it occurs in sitû; the present occurrence is therefore of considerable interest, although not very satisfactory in itself.Crystals of corundum were found in the surface soil on a piece of land known as Tenna Hena, and situated east of Kandy, and three-quarters of a mile north-east of Talatnoya bridge. The exact spot is shown in a map accompanying a paper on the crystalline limestones of Ceylon (Quart. Journ. Geol. Soc, 1903, vol. lviii, pl. xiii). A small excavation had been made, and a few pounds of corundum extracted and sold for use as emery, before my visit to the spot. All the rock exposed was decomposed, and crumbled in the fingers, being in a condition resembling sand. I therefore carried on an excavation for two months, hoping to reach hard rock suitable for microscopic examination, but although a depth of about 30 feet was reached, no sufficiently hard rock was found.At the corundum pit the ‘beds’ of granulite dip northwards at a high angle. A conspicuous soft yellow micaceous band 7–3½ inches wide marks the position of the sapphire-bearing zone. The sapphires occur in fair abundance in a less decomposed felspathic rock occupying a few inches on either side of this yellow micaceous band in the upper part of the shaft, but on the south side only in the lower part. The associated types of granulite are chiefly acid leptynite.
VI.—River Curves Round Alluvial Plains
Authors: Ellis T. S. 
Published: May 2009

In the Geological Magazine for October, 1902, Dr. Callaway mentions the explanation of these curves that I gave in a paper printed twenty-one years ago. His quotation should be read with the immediate context—”These [the tributary streams] keep open a channel into which the larger stream falls.” This is the essence of my argument.Professor Phillips and Sir A. Geikie have remarked that an alluvial plain in the course of a river may be regarded as an old lake-bottom, now drained; the lake-like appearance being renewed in times of flood. Let us suppose ABCB (Fig. 1) to represent such an area with a river flowing through it in a straight line, and, on one side, a tributary stream, or, to use a shorter and more expressive term, an affluent, coming in at an angle. Such a condition, if it existed, would not continue even in consolidated alluvial soil; it is still less likely to have existed in the soft mud when the area was first drained. A succession of floods would certainly wash away the bank where the affluent, coming through it, had caused a break in its continuity. By this the river-bed opposite the affluent would be expanded beyond its requirements when at low water. At every flood the whole of the bed of the river and the adjoining area of land will be covered with water, the ordinary river channel being effaced. From this water suspended matter falls and forms a deposit, visible after the flood has subsided, but in greater quantity on the banks by the sides of the low-water channel than on the adjoining land.