492 MR. F. W. HAKMEE ON THE [Nov. I907, 



from this area, I submit, that the Cretaceous detritus of the Trent 

 Valley and the district to the south of it was derived, while that of 

 East Anglia and the Ouse basin came principally from the "Wolds 

 south of Market Rasen. 



From the chalky Drift of Korthorpe and Blyton, Boulder-Clay 

 with Cretaceous debris may be traced along the low ground west of 

 the Jurassic ridge to Lincoln. Between Lincoln and Grantham it 

 is unknown, as before stated ; but it comes on again south of the 

 latter place in great force. ISTear Grantham, the ice-stream of the 

 Trent seems to have split — one part continuing to travel up the 

 Trent Valley towards Stanton and Chellaston, and thence via 

 Leicester to Rugby and Stockton (see map, PI. XXXIV), the re- 

 sulting Boulder-Clay containing abundance of hard chalk and grey 

 tabular flint ; another part appears to have overridden the Marlstone 

 escarpment near Grantham, spreading a sheet of typical Chalky 

 Boulder-Clay, often of considerable thickness, over the high ground 

 south and south-west of that place. The map (PI. XXXIII) shows 

 that, whereas the Liassic escarpment is continuous and undisturbed 

 for some miles to the north and south of Lincoln, save by the gaps 

 already referred to, it is abruptly broken up in the neighbourhood 

 of Grantham. 



Prof. J. W. Judd & Mr. A. J. Jukes-Browne have described, in 

 the region south of the latter place, a number of enormous masses 

 of Marlstone-rock comparable in size to the great boulders of Chalk 

 or marl in the Cromer cliffs. 1 When plotted on the map, these 

 Marl stone-erratics form a trail 12 miles long, the alignment of 

 which is from north to south. Broken off, I suggest, from the edge 

 of the escarpment by the ice overriding it from the Trent Valley, 

 these masses have been carried to the south of their parent-rock, 

 indicating an ice-drift in that direction. The position which they 

 occupy, shown on the map by crosses ( + ), lends no support to the 

 hypothesis of ice moving across the region from the east or the 

 north-east, that is, from the Wash. 



Mr. H. B. Woodward's observations during the construction of 

 the railway from Bourn to Saxby, at which time some fine sections 

 of Chalky Boulder-Clay were opened up, seem equally opposed to 

 that view. He says (Geol. Mag. 1897, p. 486) :— 



' The country was trenched in an east-and-west direction from the Oxford 

 Clay of Bourn to the Lower Lias of Melton Mowbray. Amongst the Jurassic 

 materials in the Boulder-Clay there was a noteworthy preponderance of 

 Oxfordian fossils in the eastern, of Great Oolite fossils in the central, and of 

 Lias fossils in the western portion of the area.' 



The strike of the Jurassic strata named, north of the railway, is 

 from north to south ; the facts noted by Mr. Woodward appear 

 therefore to point to a similar movement of the ice. 



The piling-up of the Chalky-Jurassic Drift on the highlands of 



1 ' The Geology of the S.W. part of Lincolnshire, &c.' Mem. Geol. Surv. 

 1885, p. 79. 



