摘要:

AbstractI. Two quarries show Tertiary dolerites of the Carlingford Complex traversed by granophyric veins against which the dolerites chill. The veins have almost certainly resulted from remelting.II. A picritic sill in Ubekendt Ejland, West Greenland, can be harmoniously interpreted as owing much of its character to pre‐intrusion sinking of olivine in an underlying supply‐reservoir. It also shows repeated evidence of marginal magmatic erosion during intrusion, and this has affected its post‐intrusion co

ISSN:0072-1050    

DOI:10.1002/gj.3350020202

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe cast of a Coal Measures tree seen in position of growth is described. The cast is about 13 feet long, and evidence is given that the original tree trunk was probably at least 38 feet long before it became completely buried in sediment. The precise history of the tree is unknown but the rate of sedimentation round about it must have been very high.

ISSN:0072-1050    

DOI:10.1002/gj.3350020203

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe Nantglyn Flags consist of very thinly interbedded mudstones and laminated muddy siltstones with less frequent thin beds of calcareous siltstone. The lithology, sedimentary structures and fauna of these three rock types are described and discussed. It is concluded that the calcareous siltstones bed were deposited by turbidity currents.

ISSN:0072-1050    

DOI:10.1002/gj.3350020204

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractDevelopments of arenaceous beds in different parts of North and Central Wales are shown to be contemporaneous and are grouped together as the Lower Ludlow Grits. Directions of transport based mainly on flute cast measurements are recorded. It is shown that the Welsh Basin was divided into two distinct troughs. In the northern, Denbigh Trough, greywackes were deposited by currents flowing from west to east. In the southern, Montgomery Trough, no greywackes are found, but calcareous siltstones were deposited by currents flowing from south to north. Turbidity current flow was along the lengths of the troughs. Contemporaneous slumping was down the sides of the troughs.

ISSN:0072-1050    

DOI:10.1002/gj.3350020205

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350020206

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe combination of geological and botanical evidence with meteorological reasoning leads to the conclusion that in the ninth millenium B.C. small glaciers became re‐established in corries and in the heads of the wetter Lake District valleys, and also in a number of Pennine corries north of Bowland Forest. The meteorological factors giving rise to their distribution and comparative extent are discussed. It is inferred that the amount and distribution of precipitation during this episode resembled that of today. Quantitative estimates are given of the characteristics of the climate during this post‐Alleröd recession, which from the meteorological standpoint appears to be similar to the minor recessions during the post‐Glacial

ISSN:0072-1050    

DOI:10.1002/gj.3350020207

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe succession of Cambrian and Ordovician rocks in the area between Snowdon and Tremadoc is described. The Upper Cambrian includes Ffestiniog Beds with theLingulellaBand, and part of the Dolgelly Beds. The unfossiliferous Pennant Slates and Quartzites may be Upper Cambrian or Lower Ordovician. Many localities for Llanvirn graptolites are recorded. The Caradoc includes graptolitic slates below, and sediments and volcanic rocks with several shelly faunas above. The Snowdon Volcanic Series includes basalts and basaltic agglomerates. Some intrusions are related to the Snowdonian vulcanicity, others to the Caledonian deformation.

ISSN:0072-1050    

DOI:10.1002/gj.3350020208

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractA seismic refraction survey has shown three layers below the drift, correlated with Trias, Upper Carboniferous and Carboniferous Limestone, respectively. The thicknesses of the first two have been estimated. A detailed gravity survey has been co‐ordinated with three of the four seismic lines. One of the faults on the west of the Vale has been traced by the gravity survey for 11/2 miles and identified on a seismic line. It is shown to be either a single fault of 700 feet throw and approximately 45° hade, or else two or more step‐faults. The first arrival times at this line can all be explained on the simple ray theory with the assumption of wave diffraction. The significance of the later arrivals is discussed.The Vale is shown to be divided into basins of Trias by the faults on the west side, but the Vale of Clwyd fault on the east side is contin

ISSN:0072-1050    

DOI:10.1002/gj.3350020209

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe coastline from Borth to New Quay is described. Three points of general interest emerge. The coastal bevel (hogs back cliffs, fausses falaises) is shown to be the remains of cliffs cut by marine erosion, and degraded by sub‐aerial weathering, at several times in the past. Raised beach platforms occur at different levels, each being backed by degraded cliffs, which merge laterally with the coastal bevel. Later than these, but earlier than the spread of the latest boulder clay in this area by solifluction seawards, are steep “fossil cliffs” cut during apparently two periods of lowered sea‐level. Where the beach platform is cut in solid rocks its outer edge is coincident with the course of one or other of these fossil

ISSN:0072-1050    

DOI:10.1002/gj.3350020210

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350020212

出版商:John Wiley&Sons Ltd    

年代:1961

数据来源: WILEY