摘要:

AbstractScoured surfaces occur in the upper part of the Lower Old Red Sandstone of the Anglo‐Welsh cuvette between cyclothems consisting of intraformational conglomerate→sandstone→siltstone. The conglomerates are formed chiefly of rocks which can be matched in the deposits of the cuvette, and contain little or no gravel from more distant sources. The scoured surfaces persist laterally and are preserved typically as casts. They discordantly cut earlier beds, and show a variety of discordantly‐filled minor structures (sole marks) due to current scour: flute‐like and lobate forms, current crescents, sack‐like bulges, terraces and small flat‐bottomed channels. Large channels are also known. Scoured surfaces occur also in the Lower Old Red Sandstone amongst sandstones, within which they may delineate major groups of sedimentation units as well as individual units in trough cross‐stratified compilations.The basal features of the cyclothems (scoured surfaces, intraformational conglomerates) record periods when sediments of the cuvette were reworked. This probably took place as the rivers instrumental in deposition of the Lower Old Red Sandstone underwent major changes in their courses, perhaps as the result of crevassing directly onto their floodplains. By reference to modern river sands, the trough cross‐stratified sandstones appear to have accumulated on sandbanks in the stream channels of the cuvette through the acti

ISSN:0072-1050    

DOI:10.1002/gj.3350030101

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractCertain ostracod species in the Upper Purbeck of England show a succession of morphological changes which correspond to those described by Wolburg from the Wealden of North‐West Germany. Thus stage by stage correlation is possible between the deposits in the two countries, and it is shown that the Upper Purbeck Beds in England correspond to most of the German Wealden W3 together with all of W

ISSN:0072-1050    

DOI:10.1002/gj.3350030102

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350030103

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractUsing techniques applied by Eagar and by Broadhurst to investigate sedimentary environments of Westphalian non‐marine shell beds, an attempt is made to assess the palaeoecology of the earliest recorded Carboniferous non‐marine lamellibranchs. The latter pose a special problem of ecology by virtue of their antiquity and presumed closeness in time to a marine ancestry. Since the species under discussion occur with few other fossils the usual recourse to a study of faunal relationships provides only limited evidence of ecol

ISSN:0072-1050    

DOI:10.1002/gj.3350030104

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

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 o

ISSN:0072-1050    

DOI:10.1002/gj.3350030105

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractA group of alternating shale and limestone beds in theDibunophyllumZone of the Carboniferous Limestone at a quarry near Carnforth, Lancashire, shows an interesting variety of well‐preserved trace‐fossils. These include exceptionally large tracks ofHelminthopsistype, burrows of a tubular character which give rise to the characteristic “Stick Bed” structures, “cauda‐galli” markings and piles of worm castings. The new ichnogenusChomatichnusis proposed for the

ISSN:0072-1050    

DOI:10.1002/gj.3350030106

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractMuch of the lower hill‐country of the Lake District had a continuous ice‐cover during the Main Irish Sea glaciation, as probably also in the earlier glaciations, and there are many indications of ice‐action at considerable altitudes. The later phases of the Newer glaciation, however, made a great contribution to the present topography, in respect both of valley erosion and lowland deposition. The main Coniston glacier bifurcated south of Coniston town, and the eastern portion itself divided into three at Blawith and Lowick Green. A further triple sub‐division also occurred north of Ulverston. The drumlin display formed by the piedmont glaciers is correlated with the Scottish re‐advance, and with an end moraine at Kirkham, Lancashire. They are very similar to drumlins forming an extensive field of the same age between the Antrim and Kells moraines in Ireland. A substantial terminal moraine was formed at Haverthwaite and a multiple one at Nibthwaite. These are correlated with terminal moraines at Newby Bridge and Church Town, and with the Highland re‐advance and the Antrim coast glaciation. The sculpturing of the cirques to the form seen today belongs to the last, post‐Alleröd phase, the Cir

ISSN:0072-1050    

DOI:10.1002/gj.3350030107

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractDespite the large number of recent papers on ignimbrites, their origin is still debatable. Textural features of ignimbrites are considered and certain deductions are made as to the origin of these rocks.

ISSN:0072-1050    

DOI:10.1002/gj.3350030108

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

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 flo

ISSN:0072-1050    

DOI:10.1002/gj.3350030109

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractThe marine Mollusca are named and their relative numbers given in the stratigraphical section, which is described. From known facts of their habitat and resistance to changes of salinity in their environment, the geological history of the Holocene strata at this locality is attempted.

ISSN:0072-1050    

DOI:10.1002/gj.3350030110

出版商:John Wiley&Sons Ltd    

年代:1962

数据来源: WILEY