摘要:

AbstractA soil overlying Carboniferous calcarenites in Anglesey has a clay fraction dominantly of kaolinite in contrast to the illite‐chlorite assemblages generally characteristic of North Wales soils. From the mineralogy and field evidence this soil is interpreted as resulting from Late Glacialin situweathering of the underlying rock

ISSN:0072-1050    

DOI:10.1002/gj.3350060102

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractA tuff filled volcanic vent which outcrops among Tremadocian rocks about 2 miles southwest of Blaenau Ffestiniog is described. The vent is correlated with the lower Caradocian Moelwyn Volcanic Series. Comparisons are drawn between this vent and the fissures from which the dominantly ignimbritic rocks of the Snowdon Volcanic Series were erupted and these are extended to account for lithological differences between the Snowdon and Moelwyn volcanic rocks.

ISSN:0072-1050    

DOI:10.1002/gj.3350060103

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

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 a

ISSN:0072-1050    

DOI:10.1002/gj.3350060104

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

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.

ISSN:0072-1050    

DOI:10.1002/gj.3350060105

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

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 Pleistocen

ISSN:0072-1050    

DOI:10.1002/gj.3350060106

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350060107

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe Coniston Grits and Bannisdale Slates south of Shap are folded into the major Bannisdale Syncline, an asymmetrical fold with a longer northwest limb, a half wave length exceeding 5 miles, and numerous minor parasitic folds with half wave lengths ranging from 200 yds to 2 or 3 yds. These minor folds generally plunge from 5° to 10° to the northeast and occur in belts of tight folds which alternate with belts of steeply, uniformly dipping strata. It is notable that the axial planes of the folds are not parallel to the cleavage and in fact the trend of the former (005°) is about 5° oblique to the latter (060°). There are also complementary dextral and sinistral wrench faults and numerous sets of joints related both to the folds and the faults. The joints present distinctly different patterns on opposing limbs of the minor folds and it is suggested that they formed at different stages of the orogeny. The earliest phase, shortly after initiation of folding, is thought to have been “wrench type” joints, subsequently folded and succeeded by post folding dextral and sinistral “wrench” joints accompanied by Reidel shear and kink bands, and then finally by high and low angle tension joints at a late stage in

ISSN:0072-1050    

DOI:10.1002/gj.3350060108

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe Pre‐Betic Alpine ranges of southeast Spain consist of a series of ENE trending folds developed mostly in Mesozoic and Tertiary limestones. One of these folds, the Mongo Syncline is described here and is of interest because of firstly its anomalous ESE trend, secondly the clearly demonstrable conical form and thirdly theen‐echelonarrangement of the minor fold axes which comprise the axial zone of the main syncline. To facilitate interpretation of this structure a considerable number of bedding and fracture orientations were taken (the latter mostly joints) over an area of 3 sq. km. The fractures related to the structure of the syncline, reveal particularly important sets of ENE “sinistral” joints and northerly “dextral” joints. The origin of the fold is debatable but the interpretation favoured here is that of a second order drag fold to a major wrench fault in the pre‐Triassic basement. In both cases diapiric squeezing of the incompetent Trias, which outcrops as an elongated (NW‐SE) inlier adjacent to the Mongo structu

ISSN:0072-1050    

DOI:10.1002/gj.3350060109

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractAn analysis of the preferred orientation of the long axes of erratics contained within the superficial deposits of the Lleyn Peninsula indicates that during the two recorded glacial advances the area was invaded by ice from two source regions—the Irish Sea ice‐sheet and local Welsh ice‐bodies. An attempt is made to re‐construct the pattern of ice movement during both glacial advances, to determine the extent to which ice from each source region penetrated Lleyn, and to interpret the environment under which the tills were de

ISSN:0072-1050    

DOI:10.1002/gj.3350060110

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY

摘要:

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

ISSN:0072-1050    

DOI:10.1002/gj.3350060111

出版商:John Wiley&Sons Ltd    

年代:1968

数据来源: WILEY