GLACIAL BEDS. 489 



of Cheshire and Lancashire : but most of the rocks have come from the Lake 

 District, the south of Scotland, and the Pennine hills. Faint indications of strati- 

 fication may be occasionally observed in the Boulder Clays, but, as a rule, the 

 pebbles and boulders are embedded pell-mell and at all angles in the mass. 

 Ripple-marks have been observed in places in the Drift. ^ A peat-bed has been 

 noticed in the Boulder Clay at Oldham, and similar beds have been observed in 

 the Drifts at Lindal, Crossgates, Walney Island, Drigg, St. Bees, and Maryport.^ 

 Curious weathered boulders have been obtained by Dr. C. Ricketts from the 

 Boulder Clay, and these, in his opinion, may indicate variations in the severity of 

 the seasons during the Glacial period.'' Portions of consolidated sand and shingle 

 belonging to the Middle Drift stand out between tide-marks off the Norbreck 

 coast, near Bispham, north of Blackpool.^ 



The divisions of the Drifts are well exposed in the Valley of the Ribble at Red 

 Scar, east of Preston, in the railway-cuttings between Chorley and Blackburn, in 

 the cliffs from Blackpool to Norbreck, etc., on the banks of the Mersey at Egre- 

 mont, near Eastham in Wirral, on the banks of the Dee near Parkgate, and at 

 Colwyn Bay. 



The value of the tripartite classification of the Drifts in the north-west of 

 England has been questioned by several observers, for seldom can the three 

 divisions be clearly seen in sequence. The case is similar to that in the Eastern 

 counties, where the triple division is locally maintained, but in many places the 

 Upper and Lower Boulder Clays come together, and it is difficult to distinguish 

 between them. This must always be the case where a newer rests directly on 

 an older Boulder Clay. 



Mr. De Ranee has observed that in the Furness district Upper Boulder Clay 

 rests on sands and gravels at Ulverston, and a Lower Boulder Clay can be seen 

 resting on the rock, but in following any of the streams reaching the sea in this 

 district into the deep valleys of the Lake District from which they flow, the 

 sequence is lost, and the character of the Drift becomes more and more confused 

 as the mountains are approached. Well-preserved moraine mounds occur in 

 numerous valleys, far above the level of glaciated rocks lower down in the valleys, 

 and there is clear evidence of an early excessive glaciation, during which era those 

 lakes which lie in the rock-basins probably came into existence, and of later 

 glaciers, which shrunk gradually as the period of glacial cold passed away.^ 



Mr. Mellard Reade observes that the section at Blackpool has long been con- 

 sidered a typical one by those who divide the Drift into three important beds. 

 His section (Fig. 83) shows the lower part of tiie Boulder Clay generally harder, and 

 with a larger number of striated boulders than the higher Boulder Clay, from which 

 it is separated by sands and gravels. Northwards, however, these sands and 

 gravels taper away into the upper Clay. And if we could see a section further 

 inland, Mr. Reade thinks it highly probable that these two clays would coalesce 

 and shade into each other, as indeed, was shown to be the case in a section 

 drawn by Mr. E. W. Binney in 1852.'' The main mass of the higher Boulder 

 Clay, which usually occupies the lower grounds (Low-level Boulder Clay), 

 is, in Mr. Reade's opinion, a marine deposit ; and the period of greatest cold 

 preceded the deposition of this Boulder Clay. He, however, notes evidence of 

 land-glaciation of the Keuper Beds beneath it, at the Moor Hey brickyard, Great 

 Crosby. Mr. Strahan has also noticed terminal curvature in the Keuper Marls of 

 Cheshire : there the Upper Boulder Clay occupies a large area, and is thickest 

 on the lower grounds. 



In addition to waterworn fragments of Mollusca, many specimens of Forami- 

 nifera and Ostracoda have been obtained from the Boulder Clay by Mr. W. Shone. ^ 



' T. M. Reade, Q. J. xl. 267 ; see also Q. J. xxxi. 34. 



^ J. D. Kendall, Q. J. x.xxvii. 29 ; G. H. Hollingworth, Ibid. 713. 



' Q.J. xli. 598 ; Proc. Liverpool Geol. Soc. 1879, 1881. 



* C. E. De Ranee, Superficial Geol. S. W. Lancashire (Geol. Suurv. ), p. 52; 

 Q. J. xxvi. 641, 648, G. Mag. 1869, p. 489, 1871, p. 107. 



* P. Geol. Assoc, iv. 223 ; G. Mag. 1883. p. 505. 



* Reade, Q. J. xxxix. 106, no, xli. 102, 456. See also G. Mag. 1877, p. 39. 

 ' A. Strahan, Geol. Chester, p. 26. 



