Horace B. Woodward — The Chalky Boulder-clay. 491 



find in the upper layers of the elibjacent strata were produced 

 prior to the deposition of the Boulder-clay, may be open to question, 

 but no doubt the majority were. S. V. Wood, jun., indeed, referred 

 certain disturbances in the strata to a time when "this antecedent 

 cushion of moraine " had been cut through by the ice.^ He gave 

 instances in the Oxford Clay near Huntingdon, in the Chalk near 

 Litcham, and in the Contorted Drift near Norwich — the last instance 

 being especially noteworthy when we bear in mind Wood's views 

 regarding the Contorted Drift of the Cromer coast, the disturbances 

 in which he attributed to grounding icebergs. The section Fig, 1, 

 which 1 noted in 187G, is probably the one referred to by Wood. 



Dealing now with the contorted underlying strata, we find evidence 

 of their being generally disturbed by glacial action prior to the accu- 

 mulation of the Boulder-clay. I have elsewhere figured disturbances 

 in the Upper Lias Clay beneath Chalky Boulder-clay at Gayton 

 Wharf, near Blisworth, in Northamptonshire ; ^ and a disturbed 

 surface of Great Oolite Clay and rubble beneath Boulder-clay at 

 Maidford, north-west of Towcester.^ In this latter case, as in 

 another instance near Eadstone, in Northamptonshire, it would seem 

 that locally the severed soil and rubble had not been moved far — 

 the stony base of the ice-sheet being perhaps arrested and over- 

 ridden. 



As before remarked, glaciated pavements in the Jurassic and 

 newer formations of the Midland or Eastern Counties have but 

 rarely been noted, nor could they often be produced in such easily 

 disturbed strata. The most interesting example is that observed 

 by Mr. W. J. Harrison in a cutting made in 1874-5 in widening 

 the Midland Railway between Leicester and Wigston. Referring to 

 the Boulder-clay, he remarks that " Its thickness here was between 

 20 and 30 feet. At the base the lower lias shales and limestones 

 were exposed to a depth of 3 or 4 feet for a distance of about 

 400 yards. The limestones were most beautifully striated in situ, 

 the slightness of the dip having prevented the ripping up of the 

 beds to any great extent, and the thick covering of clay having 

 preserved them from the percolation of water. Oblong slabs of 

 limestone, torn off, were to be seen lying in close proximity to 

 the outcrop of each stratum, and a little to the south of it. In 

 one spot the strata were bent up for a few yards into a sharp 

 anticlinal curve." * 



Where Boulder-clay rests on the New Red Sandstone in Icknield 

 Street, Birmingham, it was observed by Crosskey that in places 

 large fragments of sandstone had been disrupted and thrust into the 

 middle of the Drift; elsewhere a part of the sandstone had "been 

 lifted up almost like an arm," while the Drift had been accumulated 

 beneath it.^ 



1 See Quart. Journ. Geol. Soc, vol. xxxvi, pp. 482-90 ; and vol. xxxviii, p. 667. 



^ " Jurassic Rocks of Britain," vol. iii, p. 277. 



3 Ibid., vol. iv, p. 397 ; and Geol. Mag. 1897, p. 103. 



* " A Sketch of the Geology of Leicestershire and Rutland," 1877, p. 45. 



* Proc. Birmingham Phil. Soc, vol. iii, p. 213. 



