摘要:

AbstractThe Pleistocene deposits in the area of the village of Beckford, in the Carrant Valley, Worcestershire are described. A radio‐carbon date of 27,650±250 years B.P. has been obtained from plant material in the terrace deposits in the valley. Detailed studies have been made of the terrace sediments and of the remains of Mollusca and Coleoptera in fossiliferous layers. Frost structures are described and their stratigraphy considered. The nature of the local environment and regional climate in the final stages of the Upton Warren Interstadial period is reconstructed in detail. The terrace appears to have aggraded in a periglacial environment, dominated initially by solifluction processes. Extensive solifluction may have led to local diversions of drainage. In time, the climate deteriorated, becoming cooler and somewhat less continental with the onset of the main Devensian glaciation. This latter stage was characterised by extensive ice‐wedge growth, aeolian activity and, subsequently, by river inci

ISSN:0072-1050    

DOI:10.1002/gj.3350100101

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe Lower Carboniferous conglomerate at Lligwy Bay, Anglesey, is shown to be underlain as well as overlain by limestones of D1age so that the conglomerate is of intra‐D1age. It is considered to have been deposited very close to a coastlin

ISSN:0072-1050    

DOI:10.1002/gj.3350100102

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractInvolutions are reported for the first time from northwest England. They occur in ‘head’ deposits of reworked mudstone, shale, sandstone and breccia soliflucted over glacio‐fluvial sands and gravels in the Poaka Beck valley. The involutions were developed in the late Devensian period and most present a strongly festooned cross‐section. Excavation of these features showed that the regular form was a result of chance sectioning and that the cryoturbate structures were a cellular or pocket type of feature. Frost heave, ice segregation and a reversed density stratification all probably contributed to the development of the involutions, but an important factor was the ground water hydrology which gave especially favourable conditions for strong cryergic activity at th

ISSN:0072-1050    

DOI:10.1002/gj.3350100103

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe Cambrian sediments in Howth and Ireland's Eye to the northeast of Dublin have been mapped and the submarine deltaic Censure Group and the overlying Nose of Howth Group, which consists of interbedded turbidites and olistostromes, have been distinguished. Large scale sedimentary disruption has accompanied detachment of quartzitic sandstone beds in the Censure Group, where the bases of detached blocks have slump features while their tops generally do not. This contrasts with the chaotic sedimentary breccias in the olistostromes of the Nose of Howth Group. Blocks in the Censure and Nose of Howth Groups are up to 450 m and 700 m across respectively. The turbidies have come from the southeast and east whereas the slumping appears to have been generated from the southwest.Slumping during sedimentation was followed closely by large‐scale folding and sliding of sedimentary or tectono‐sedimentary origin, and the bulk appearance of the sediments is due to these sedimentary and tectono‐sedimentary mechanisms. The main structure is an easterly facing, steep plunging syncline which locally is associated with a poorly preserved cleavage. This structure predated the main penetrative cleavage which is not axial planar

ISSN:0072-1050    

DOI:10.1002/gj.3350100104

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractTwo phases of deformation are described from the area. D1 is related to the first phase movements widely recognised in the Dalradian; D2 is related to more localised modifications of the D1 fold pattern.Four major D2 folds are recognised from the evidence of minor structures. Three of these, the Beinn Chuirn, the Ben Lui and the Ra Chreag Folds, had previously been considered as D1 structures, whilst the fourth, the Dalmally Fold, was unrecognised. These folds provide continuity between the southeast facing of the D1 folds of the Moine and Ballachulish Succession of Glen Orchy (Thomas and Treagus 1968) and the southeast facing of the D1 Jay Nappe (Shacketon 1958) in the Iltay Succession above. The D2 deformation reaches a climax at the junction between the two Successions, the Iltay Boundary Slide, which is now regarded as a D2 structure. The regional implications of these results are briefly considered.

ISSN:0072-1050    

DOI:10.1002/gj.3350100105

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe Swansea Valley Disturbance is one of four NE‐SW belts of faulting and folding which cross the northern limb of the South Wales Coalfield syncline at variance with the normal E‐W Variscan structures. The Disturbance extends from Hay‐on‐Wye (Herefordshire) southwestwards to Clydach (near Swansea) and may extend northeastwards to Titterstone Clee Hill (near Ludlow) and southwestwards along the Tircanol Fault to Swansea Bay.The main structural elements of the Disturbance are: impersistent NE‐SW folds; NE‐SW normal faults; and NE‐SW and NNW‐SSE wrench faults. The NE‐SW structures are confined to a narrow zone which seldom exceeds two kilometres in width.It is suggested that this narrow belt of faulting and folding has been controlled mainly by sub‐Devonian basement structures, which involve faulting and/or folding. The effect of the Variscan compression was to reactivate the basement structure, which had the effect of resolving this compression along the disturbed zone to produce sinistral wrench movements. The structure of the Disturbance has been complicated by folding, produced by the Variscan force driving the Upper Palaeozoic rocks against the Lower Palaeozoic block.It is concluded that the main movements are of Variscan age and that vertical movements may have taken place in post‐Carboniferous a

ISSN:0072-1050    

DOI:10.1002/gj.3350100106

出版商:John Wiley&Sons Ltd    

年代:1975

数据来源: WILEY