bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Greywacke problem
Authors: Cummins W. A. 
Published: July 2010

AbstractGreywacke is a kind of sandstone in which the sand grains are set in a fine “muddy” matrix. The fine grained matrix is at once the essential characteristic of greywacke and the essence of the greywacke problem. The mode and environment of deposition of greywackes can be inferred from their sedimentary structures and from their lithological and palaeontological associations. Many greywackes are recognised as deep water marine turbidites; others are shallow water marine sediments; and yet others are fluviatile. Modern sediments of comparable origin, whether found in nature or produced experimentally, are not greywackes. Thus, if the principle of uniformitarianism is applied, the peculiar texture of greywackes cannot be an original detrital feature, but must be the result of post‐depositional alteration of “normal sand”. Several independent lines of evidence support the post‐depositional alteration hypothesis for the origin of greywacke.
Cross‐strata of the Rough Rock (Millstone Grit Series) in the pennines
Authors: Shackleton J. S. 
Published: July 2010

AbstractThe Rough Rock is the highest sandstone horizon in the Millstone Grit Series (Namurian) in northern England. It is about 70 feet thick and outcrops over an area of some 4,000 square miles. Modal analyses show that it is an arkose, with about 20% of felspar (mainly microcline perthite) and many quartzose rock pebbles. Cross‐stratification is very common, occurring in sets mostly between one and three feet in thickness. The orientations of 1738 cross‐strata, measured at 301 localities, show that the currents flowed mainly southwestwards.It is suggested that the arkoses were deposited on an extensive and nearly horizontal floor just above sea level, and that sediment was distributed not by one but by many rivers, perhaps aided by flash floods.
The geology of the Nefyn‐Llanaelhaiarn area of north Wales
Authors: Tremlett W. E. 
Published: July 2010

AbstractA detailed geological map of this northeastern part of the Lleyn peninsula is provided for the first time. The area consists largely of a suite of Caledonian intrusions, in which many distinctive rock‐types can be recognised, but the majority are of granodioritic affinities. These rocks are described in detail and eighteen chemical analyses of them are given. The relations of intrusions to the structural features of the area are discussed and the probable geological history described.
Asymmetrical ripple marks and the origin of water‐laid Cosets of Cross‐Strata
Authors: Allen J. R. L. 
Published: July 2010

AbstractAsymmetrical ripple marks formed by flowing water are described and classified on geometrical form, physical size, and hydrodynamic conditions of origin. By analysing models it is demonstrated that the character of cosets of cross‐strata resulting from the migration of asymmetrical ripple marks is dependent on ripple geometry and sediment supply. Predicted cross‐stratification patterns are shown to agree well with those described from water‐laid sediments. The use of cross‐strata in deducing sedimentation rates and depths of deposition is pointed out. Models are developed from natural situations for interpreting cross‐stratal dip direction patterns in shallow marine and deltaic sediments.
A tectonic profile across the caledonides of south Mayo
Authors: Dewey J. F. , Phillips W. E. A. 
Published: July 2010

AbstractA composite tectonic profile, from Clew Bay to central Murrisk is constructed and the sequence of structural events from the Upper Cambrian to post‐Wenlock—pre‐Viséan (C2 S2) times is outlined. Four main structural episodes affected the Dalradian rocks in pre‐Arenig times. ‘Taconic’ thrusting and concentric folding were important, and finally a complex sequence of structures were variably imprinted on the Dalradian, Ordovician and Silurian rocks during post‐Wenlock, pre Viséan (C2 S2) times.
On the statistical analysis of fabric diagrams
Authors: Flinn Derek 
Published: July 2010

AbstractIn his book “Structural Diagrams” (1958 Academy of Sciences of the U.S.S.R.) Vistelius proposes a scheme for the statistical analysis of fabric diagrams. The scheme is critically examined in this paper and found to be statistically invalid, largely due to a misunderstanding of the nature of the pole distribution in random diagrams.
Facies patterns in the Ludlovian of Wales and the Welsh Borderland
Authors: Holland C. H. , Lawson J. D. 
Published: July 2010

AbstractA series of facies distribution maps with accompanying discussion is given for nine divisions of the Ludlovian; significant information on faunas and sedimentary features is incorporated. Isopachyte maps are presented for the whole of the Ludlovian and for its four component stages. Two sections are drawn across the area of sedimentation from northwest to southeast and northeast to southwest respectively. From the evidence assembled in these maps and sections deductions are made as to the probable palaeogeography of the Welsh Borderland area in Ludlovian times.
The dolerite plug at Slemish, Co. Antrim, Ireland
Authors: Preston J. 
Published: July 2010

AbstractThree olivine dolentes D1, D2, and D3 form a multiple intrusion of Tertiary age. The earlier intrusions, D1 and D2, fill the conduit in the lower part of the hill. The final intrusion D3 broke through the solid plug of D1 and D2 along restricted channels to fill the conduit in the upper part of the hill. The intrusions are exposed at the present erosion level of the Upper Basalts and near the top of the original lava‐plateau. D1 contains layers full of cognate platy xenoliths; D3, at the south end of the hill, is crowded with cognate xenolithic sheets, and similar sheets settled on to the floor of the D3 intrusion elsewhere. The xenolithic sheets are considered to be surface crusts formed at the top of the magma column and carried to their present place by the circulatory system of a lava‐lake.
The ordovician and other post‐rosslare series Rocks in Southeast Co. Wexford
Authors: Baker J. W. 
Published: July 2010

AbstractOrdovician sediments at Tagoat and Rosslare Harbour are re‐described and their relationship to the underlying Rosslare Series discussed. A brief outline of their petrology is given, but it is shown that the fauna is in need of revision before reliable correlations can be made. Similar rocks are recorded near Tomhaggard; amongst these, spotted mudstones imply Ordovician or later intrusions. Undeformec dykes intrusive into the Rosslare Series are believed to be representatives of this phase.
A survey of the age relations of Shetland Rocks
Authors: Miller John A. , Flinn Derek 
Published: July 2010

AbstractThe survey is based on field work by Flinn, on forty‐two K‐Ar age determinations by Miller, and on previously published work on Shetland. Most of the metamorphic rocks give K‐Ar ages of about 420 m.y. It is clear from petrological and stratigraphical evidence that this age is not the age of the metamorphisms and migmatizations responsible for the more obvious features of the rocks, and also that the metamorphic rocks in different areas have had different histories of development. Ages up to 515 m.y. have been found in various areas, and these may be more closely related to the main metamorphisms than the more common 420 m.y. ages. In the Mainland the 420 m.y. age may be related to a late porphyroblast metamorphism: in Unst and Fetlar it seems to be the age of Read's second metamorphism which accompanied the emplacement of nappes and the formation of orogenic sediments. About 400 m.y. ago a series of postorogenic granitic and appinitic complexes were emplaced in the southern part of Shetland. By 380 m.y. ago erosion had reached migmatitic rocks and they were being buried again beneath Old Red sediments and contemporaneous volcanics. Later still, possibly 350 m.y. ago, in Upper Devonian times, granites were emplaced in the west of Shetland cutting the Old Red rocks. Finally the Walls Boundary Fault (Great Glen Fault ?) cut one of these late granites.
The problem of origin, deformation and recrystallization of calcite‐quartz bodies
Authors: Nicholson R. 
Published: July 2010

AbstractThe calcite‐quartz bodies which occur in the Upper Wenlock slaty succession of Llangollen have a distinctive fabric of platy calcite crystals and coarse, sometimes euhedral, quartz. The calcite internal deformation lamellae and folds and boudins formed in the bodies during the production of the folds and cleavage of the country rock are described together with the recrystallization fabrics of some of the calcite. Note is made of similar rocks from Ribblesdale and Coniston and their origin discussed.
On the correlation of certain lower Dalradian successions in northwest Donegal
Authors: Pitcher W. S. , Shackleton R. M. 
Published: July 2010

AbstractWithin the Dalradian Series of Donegal, the Creeslough, Maas and Fintown successions, which have hitherto been regarded as stratigraphically distinct, are correlated. A standard terminology for this sequence is proposed and a detailed correlation is made with the Ballachulish Succession, which thus forms all the country around the Donegal Granites, northwest of the faults and thrusts which separate it from the Islay Succession.
Ignimbrite eruptions in the volcanic history of the glencoe Cauldron subsidence
Authors: Roberts John L. 
Published: July 2010

AbstractThe field relations and petrography of two thick ignimbrite horizons are described from the volcanic pile within the Glencoe Cauldron and are correlated with two pyroclastic horizons in the Lorne Plateau lavas. Their recognition enables two cycles in the volcanic history, culminating in cauldron‐subsidence and caldera formation to be discerned. The role of variation in gas pressure in depth is discussed in relation to the formation of the ring‐faults bounding the Cauldron‐Subsidence, and the volcanic history of the Glencoe Cauldron Subsidence reviewed.
Some aspects of a horizontal schistosity
Authors: Shelley David 
Published: July 2010

AbstractA Pre‐Cambrian horizontal schistosity was formed in regionally metamorphosed rocks around Lannilis, Finistére, during repeated fold movements. Only horizontal movement occurred since the superimposed load due to deep burial was great. Biotite crystallisation along horizontal planes resulted in a schistosity except in the principal thrust zones where decussate biotite textures and large garnets developed. During the early movements, ‘ac’ girdles of quartz axes were formed but these girdles were rotated during the later movements along the schistosity. The degree of rotation and the form of the associated structures cannot be interpreted easily either by ‘Sow’ on planes perpendicular to a compression axis or by ‘slip’ along the schistosity.
A late pleistocene marine molluscan fauna from the Drifts of the Cheshire plain
Authors: Thompson D. B. , Worsley P. 
Published: July 2010

AbstractSome recent finds from two working pits in the outwash sands of the Cheshire Plain are recorded.The opportunity is taken to discuss the dating and ecology of the fauna in relation to past and present theories of environment in the late Pleistocene, and their relationship to the fauna of the Macclesfield New Cemetery Beds.
The geology of ordovician rocks at Balbriggan, County Dublin, Eire
Authors: France D. S. 
Published: July 2010

AbstractA thick series of Caradocian volcanics is described. The volcanics are basic‐intermediate and it is own that they have a number of characteristics which are peculiar to emplacement in a subaqueous environment. A new interpretation of the stratigraphy results from a consideration of the folding of the succession.
The stratigraphy and tectonics of the Skiddaw slates and the relationship of the overlying borrowdale volcanic series in part of the Lake District
Authors: Simpson Alexander 
Published: July 2010

AbstractThe Skiddaw Slates consist of eight formations with the substantial thickness of about 30,000 ft. This geosynclinal sequence is of Arenig age though the highest formation may continue into the Lower Llanvirn.The polyphase tectonics of the Skiddaw Slates and the relationship of the overlying Borrowdale Volcanic Series are discussed. It is concluded that the Caledonian tectonic history of this part of Britain contains two paroxysms of orogenic activity. In addition to the orthodox end‐Silurian orogenesis there was also an intra‐Lower Ordovician orogenic episode which took place towards the close of the Llanvirn.During the earlier tectonic climax the Skiddaw Slates were deformed by two phases of folding. Their structure is, therefore, largely of pre‐Borrowdale age and bears little relation to that of the overlying cover. After this dual deformation the slaty basement was truncated by erosion and is separated from the overlying Borrowdale Volcanic Series by an angular unconformity. Only the end‐Silurian folding affects the volcanic superstructure and the younger Lower Palaeozoic sequence.
The periglacial origin of the drifts at Morfa‐Bychan, near Aberystwyth
Authors: Edward  , Watson Sybil 
Published: July 2010

AbstractThe superficial deposits at Morfa‐bychan have previously been interpreted as deposited by Welsh ice. A reconsideration, including: stone orientation analysis, suggests however that they consist of screes and solifluction deposits with subordinate rain‐wash gravels, and a thin loess—the whole laid down under periglacial conditions, when the Irish Sea ice no longer reached the area. There is no direct evidence for dating but their volume and field relations suggest they represent the deposits of the last glaciation.
The geological results of gravity and magnetic surveys in the Malvern Hills and adjacent districts
Authors: Brooks Michael 
Published: July 2010

AbstractDetailed gravity and vertical force magnetic surveys in and around the Malvern Hills are described, and the results of determinations of densities and magnetic properties of local rocks are presented. The geophysical surveys indicate that the Malvern axis is a broad anticline involving basement rocks and that the folded basement extends northwards at shallow depth under the Storridge anticline; it cannot be traced further north under the Abberley Hills. Areas of surface Pre‐Cambrian rock are interpreted as comprising intensely folded and faulted axial portions of the major fold, which is assumed to be of Armorican age. On the basis of the shallow depth to basement directly north of the Hills, and by analogy with the situation in the southern Malverns where Llandovery strata overstep the Local Cambrian succession, it is concluded that the Cambrian rocks were largely removed from the Storridge area as well as from the Malvern Hills area following a period of pre‐Llandovery tectonism. To the west, the basement surface dips at about 30° to a depth of at least 5,000 ft.Cook and Thirlaway's (1955) suggestion that the Eastern Boundary Fault is part of a step‐fault complex is accepted, and their interpretation of the configuration of the Worcestershire Triassic basin is not significantly amended in the present account.
The caradoc rocks around llyn cowlyd, North Wales
Authors: Diggens J. N. , Romano M. 
Published: July 2010

AbstractA thick succession of Middle Caradoc sediments (Glanrafon Beds) with occasional volcanic horizons is described. Faunas found within the succession prove a Soudleyan to Lower Longvillian age for these sediments. Detailed mapping has shown the presence of an unconformity between the Glanrafon Beds and the overlying Lower Rhyolite Tuff of the Snowdon Volcanic Series. A new fauna from the sediments within the Capel Curig Volcanic Series proves a Soudleyan (?Lower) age for this period of vulcanicity.
Studies of andean uplift part I‐post‐cretaceous evolution of the San Bartolo Area, North Chile
Authors: Hollingworth S. E. , Rutland R. W. R. 
Published: July 2010

AbstractOn the eastern side of the Atacama Desert an early Tertiary planation surface may be recognised across the major structures. Subsequent tectonic activity has taken place along particular lineaments and each episode has induced a period of dissection. The tectonic activity and associated dissection can be correlated with a period of ignimbrite deposition, and by inference with the period of Andean uplift. Isotopic ages on the ignimbrites can therefore be used to date Andean uplift. They suggest that uplift began in late Miocene times. Important later phases can be dated as mid‐Pliocene and Late Pliocene or Pleistocene.
The faunal‐stratigraphy of the ludlovian rocks between Craven Arms and Bourton, near Much Wenlock, Shropshire
Authors: Shergold J. H. , Shirley J. 
Published: July 2010

AbstractThe Ludlovian Series has been mapped between the River Onny at Craven Arms and the village of Bourton which lies 2½ miles SW of Much Wenlock. Ten subdivisions are recognised on biostratigraphical and lithostratigraphical criteria. For these divisions the stratigraphical terminology established by Holland, Lawson and Walmsley (1959, 1963) in the Ludlow area has been utilised. Two breaks occur in the otherwise continuous succession of variable calcareous sediments: there is lithological and faunal discontinuity at the base of the Leintwardine Beds and within the Upper Leintwardine Beds. The latter can be recognised over a wide area of the Ludlovian shelf. Accordingly alternative correlations, to those presently accepted, are proposed for the Leintwardine Beds.
folding and slumping in a layered gabbro
Authors: Thompson R. N. , Patrick D. J. 
Published: July 2010

AbstractThe layered gabbroic intrusion of Sarqata qaqa, Ubekendt Ejland, West Greenland contains numerous xenoliths of thermally metamorphosed picrite‐basalt. Folding and slumping of the layering occurs adjacent to some of these blocks. It is postulated that the structures were formed by sloped lava xenoliths hitting the unconsolidated layers of crystals forming the floor of the magma chamber during the cooling history of the intrusion. The settling velocities of the xenoliths, and thickness and viscosity of the crystal mush are estimated and discussed.
Geophysical investigations of buried river valleys around Cardigan Bay
Authors: Blundell D. J. , Griffiths D. H. , King R. F. 
Published: July 2010

AbstractGravity and seismic surveys over the estuaries of the rivers Dovey, Dysynni, Glaslyn and Mawddach have indicated that the rock floor lies at depths of from 100 to 1,250 ft (30 m to 380 m) below the present surface. The methods of survey and difficulties of interpretation are discussed, and the significance of the results is assessed in conjunction with those already published for the Teifi estuary and with preliminary results obtained by seismic reflection profiling in. Cardigan Bay. It is concluded that all the valleys with the exception of the Glaslyn could have been carved during Pleistocene times, but that the much deeper buried valley of the Glaslyn, extending south of Portmadoc across Morfa Harlech, is probably of earlier origin.
Carboniferous lithofacies, Halkyn Mountain, North Wales
Authors: Oldershaw Alan E. 
Published: July 2010

AbstractA brief description of the carboniferous succession on Halkyn Mountain, North Wales, together with a map illustrating the areal distribution of upper Viséan carbonate and Namurian non‐carbonate lithologies, is presented. The upper Vistan carbonates have been divided into four major units termed in ascending order: A1 (pelsparites and biopelsparites); A2 (alternating biopelmicsparites, non‐argillaceous biomicrites and micrites); B1 (argillaceous calcite siltstones); B2 (alternating non‐argillaceous and argillaceous biomicrites and micrites). Analysis of the distribution of microfacies within each unit indicates that during upper V i s h times, deposition of shallow water, off‐shore, carbonate sand banks alternated with, and finally gave way to, the deposition of in‐shore, lagoonal carbonate muds. The presence of an erosional surface at the top of Unit B2 suggests that a period of emergence took place prior to the deposition of the succeeding Namurian bedded cherts. The cherts can be differentiated into three major lithologies which exhibit characteristics that are consistent with cyclic deposition in a marginal, restricted basin.
PHYSIOGRAPHY, FORAMINIFERA AND SEDIMENTATION IN THE Dovey Estuary (Wales)
Authors: Haynes John , Dobson Max 
Published: July 2010

AbstractA study of the chemistry, circulation and sedimentation is followed by an outline account of the living and dead communities (particularly foraminifera) characteristic of the main physiographic subenvironments. On the basis of the relationships established these results are used in an interpretation of the vertical sequence.
The namurian succession between Tenby and Waterwynch, Pembrokeshire
Authors: Jones D. G. , Eagar R. M. C. 
Published: July 2010

AbstractNamurian cliff sections are described in detail. A minimum thickness of about 76 m is ascribed to Namurian A and 198 m and 104 m respectively to Namurian B and C. Faunal marker bands enable the Chokierian, Marsdenian and Yeadonian Stages to be recognised and the detailed structure to be worked out and this confirms the structural interpretation of Dixon. The succession is correlated and compared with adjacent areas in Pembrokeshire and South Wales. The Marsdenian includes a fauna of highly variable Sanguinolites. S. ovalis Hind is redescribed and a lectotype chosen.
The upper cretaceous ophiolite complex of Masirah Island, Oman
Authors: Moseley F. 
Published: July 2010

AbstractMasirah Island is almost entirely composed of a highly faulted and unmetamorphosed folded ophiolite complex which is unconformably overlain by unfolded Eocene limestone and is correlated with the Upper Cretaceous Semail Complex of the Oman Mainland. The ophiolites include serpentine, basalt, pyroclastics and some radiolarite, and intrusive complexes largely composed of serpentine, peridotite, picrite, anorthosite, gabbro and granite, with transitional varieties. Emplacement structures within the intrusions are extremely complicated, with the gabbros full of blocks mostly of serpentine up to 1 km or more in diameter. There are also late stage veins, lenses and irregular bodies of granite. Ophiolites, probably derived from the mantle, are ultrabasic differentiates with soda metasomatism. Tectonic structures are largely pre‐Eocene. They include fractures, some of which are parallel to the late Tertiary submarine Masirah fault which is related to continental drift.
Sedimentology and petrography of three tuff horizons in the Caradocian sequence of the Bala area (North Wales)
Authors: Schiener E. J. 
Published: July 2010

AbstractThree interstratified pyroclastic deposits in the Caradocian marine sequence around Bala (N. Wales) are investigated. Their petrology is used for identification and correlation.The Cefn Gwyn Ash is a vitric tuff, locally indicating subaerial deposition. The Frondderw Ash is the product of subaqueous pyroclastic flows, giying evidence of very short‐lived volcanic activity. The Pont‐y‐Ceunant Ash is a waterlaid vitric crystal tuff. Lateral changes in lithology allow a north‐easterly source‐area to be inferred for the former two members. Sedimentary structures show partial emergence of the area during Soudleyan times.The highest member, the Pont‐y‐Ceunant Ash, is restricted to the south‐west of the area.
The imprint of structural grain on the micro‐relief of the Welsh uplands
Authors: Thomas T. M. 
Published: July 2010

AbstractStructural lineations of varying orders have been mapped for the full extent of the Welsh uplands where in some areas their clear impress in the micro‐relief has revealed minor structures not previously described in geological literature. Although significant variations in the strike of these structurally induced breaks of slope may be noted they display the more typical Caledonoid alignments (NE—SW or NNE—SSW) in nearly 60 per cent of the total area of the country. The dominance of these trends has been somewhat accentuated by the fact that even along the northern edge of “Armorican” South Wales, where low dips are a feature, a NE–SW grain is also evident in extensive tracts of the prevalent scarplands.