摘要:

AbstractEfforts to determine the highest thixotropic values that may be reached by sediments have shown that the manner of preparation of the systems is of considerable importance. In particular, the preliminary shaking of the system, instead of the usual procedure of stirring only, results in the production of substantially higher values, even in the case of but moderately thixotropic calcareous and sandy materials. The increase varies from 5 per cent. with weakly thixotropic systems to more than 70 per cent. with fat clays. The significance of the increase, in relation to the theory of thixotropy, is discussed.It has become evident that the lower thixotropic limit cannot be determined by the inverted‐tube method, although its approximate magnitude can be estimated. Some such estimates have been compared with the results obtained in liquid‐limit tests on the same samples, from which it appears that the moisture‐content for flow at 10 bumps in the liquid‐limit test (i.e. about 11 ± 5 per cent. of the liquid limit) approximates to that at the lower thixotropic limit.The necessity for devising more precise experimental methods, and for agreement on definitions of liquid flow and plastic flow, is emphasized. The termrheotropyis suggested to include the phenomena of thixotropy s.s., false‐body, rheopexy, and age‐hardening (i.e. for the isothermal reversible gel/sol‐or‐more‐fluid‐gel transformation).Brief reference is made to certain natural occurrences of thixotropic or potentially thixotropic deposits and to the practical problems to which they give rise. Also, opportunity has been taken to include thixotropic values for a further se

ISSN:0072-1050    

DOI:10.1002/gj.3350010102

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe measures between the Soft Bed and the Middle Band Coal of Yorkshire and the equivalents of these seams in Lancashire, the Bassy and Lower Foot Mines, are remarkably uniform. The horizons of two thinLingulabands, first described by the author from Huddersfield, may be traced, usually as marine shale, northward to Bradford and Burnley, southward to near Sheffield, westward to St. Helens and south‐westward to Goyt's Moss, Derbyshire, where the lower band has yieldedGastriocerassp. The bands ofLinguladivide the measures into three small‐scale cyclic units of sedimentation which contain non‐marine lamellibranchs throughout much of their vertical extent.Studies of faunas from localities which yielded the types ofCarbonicola fallax, C. proteaandC. haberghamensisWright are described in some detail. At Feniscowles, near Darwen (type locality for the first two species) it is shown that with passage upward into slightly more coarse grained beds in the lower cyclic unit the small shells of theC. fallaxgroup show an upward increase in H/L ratio with some evidence of a split into two species.The non‐marine succession, of Honley, near Huddersfield, is regionally summarized. Attention is drawn to a maximum ofCarbonicola rectilinearisTrueman and Weir in the lower part of the lower cyclic unit and to the marker horizons ofCarbonicola discusEagar andC. haberghamensisWright in the upper part of the middle unit.Carbonicola pilleolum, the new species described, covers variants previously referred to, or compared with,C. sulcata

ISSN:0072-1050    

DOI:10.1002/gj.3350010103

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe south‐eastern part of the Lake District was glaciated almost entirely by local ice. The valleys show many typical features: cirques, cirque tarns, valley‐heads, U‐shaped troughs with over‐steepened sides, and change of slope above the maximum glacier‐ice level, hanging valleys, valley‐steps, rock barriers, paternoster lakes, rock‐basins, ice spillways, and a large variety of moraines, drumlins and roches moutonnés. The glaciers from Grasmere and Langdale converged on Windermere and there produced the northern rock‐basin. Ice spillways into the Kent and Winster valleys resulted in the shallow central part of the present lake. The addition of ice from the Esthwaite glacier produced the southern rock‐basin. The glacier moved southwards by Cartmel, but the present fluvial drainage follows Backbarrow Gorge to th

ISSN:0072-1050    

DOI:10.1002/gj.3350010104

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe type species of the genusProlecanitesis discussed. The generic nameParaprolecanitesKarpinsky 1889 is invalid, being founded on a hypothetical suture line. Forms showing this type of suture line have since been found and the genusEpicaniteswas erected by Schindewolf 1926 to include such forms. A possible development fromProlecanites to Epicanitesis suggested.

ISSN:0072-1050    

DOI:10.1002/gj.3350010105

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe correlation links which have been established within the Namurian (Plates VIII&IX) across the sedimentation facies of the Central Province and Northern Province are reviewed. It is possible to portray the palaeogeography during particular sub‐zones and to suggest limits for the various facies (Figs. 1–3). A total of seven facies is recognised—sedimentation facies, of fluvial‐grits, of grit‐shales, of coals, of limestones, of Yoredale‐limestones, of Yoredale‐grits and of marine‐shales.In E1atimes a marine‐shale facies lay in the Central Province between the Welsh‐Mercian ridge and an E‐W narrow ridge through the Isle of Man to the Settle district; in the Northern Province, northwards from this ridge to the Midland Valley of Scotland, there is a Yoredale‐limestone facies except in the extreme south‐west where lay a limestone facies.In E1c‐dtimes a fluvial‐grit facies invaded the Central Province from the east, whilst in the Northern Province a Yoredale‐grit facies occupied much area and passed northwards into a coal facies along the Scottish border.In E2btimes marine shales passed northwards into a grit‐shale facies in the Central Province whilst a Yoredale‐grit facies predominated in the Northern Province with land areas emerging in the Isle of Man—Lake District, on the Alston Block and along the Southern Uplands.During H times the Northern Province emerged and remained as land until the close of the Namurian. In the Central Province marine‐shales characterized the western part of the basin, the eastern part having a grit‐shale facies, except during upper R1times when a fluvial‐grit facie

ISSN:0072-1050    

DOI:10.1002/gj.3350010106

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractFollowing introductory notes on the historical aspect of the subject, this review of Irish Carboniferous Limestone and associated beds discusses the distribution of the principal lithological types in Ireland. The zonal stratigraphy is then reviewed throughout the island, opportunity being taken to incorporate certain unpublished results of recent work. Then follows a résumé of the history of the period from the palaeogeographical point of view. Detailed bibliographies (a) by counties, (b) of more general papers, are prefixed to the pape

ISSN:0072-1050    

DOI:10.1002/gj.3350010107

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY

ISSN:0072-1050    

DOI:10.1002/gj.3350010110

出版商:John Wiley&Sons Ltd    

年代:1951

数据来源: WILEY