Vol. 62.] CHALK AND BOULDER-CLAY NEAR ROYSTON. 495 



have been subsequently enlarged ; such is the explanation of the 

 relations of Boulder-Clay and Chalk in the cliffs of Moen, as we 

 maintained in 1899. * That there are such cavities 2 is distinctly 

 proved in the Island of Kiigen. We described some in pits at the 

 back of Sassnitz, on the hill-slope above the town. 3 But the chalk- 

 cliff rising from the shore to the north of the bathing-place affords 

 an even closer parallel. 4 The appended diagram (tig. 2), although 



Pig. 2. — Section in the cliff north of the bathing -place, 

 Sassnitz (Riigen). 



A = Chalk-with-fiints. B=Boulder-01ay, as described in the text, (a) Piece of 

 chalk, marked ' ? if in situ.' Probably it was, for a very rough sketch made 

 the following year (1899) shows the outline of the cavity to be still more 

 like a foot cut off just above the ankle, (b) A streak and a lump of chalk ; 

 (c) more sandy and stratified hereabouts. The length of the part sketched 

 measures about a dozen yards. 



not pretending to be very accurate, for it had to be drawn from the 

 adjoining beach, may save a long description. We examined the 

 section again in 1899, when the shape a little more resembled that 

 of afoot in a stocking, and the small hollow at the bottom was more 

 conspicuous and pointed forward instead of backward. The cavity 

 was a little over 12 yards long, was filled with a Boulder-Clay 

 generally resembling, but not quite identical with, the ordinary grey 

 Boulder-Clay of the district, which contained one fair-sized block 

 and some smaller streaks of Chalk, more especially in the lower 

 part, and became a little more sandy in the upper. 6 The neigh- 

 bouring Chalk, as shown by the flint- bands, not only dips at a 

 rather high angle, but is locally much contorted. It is impossible, 

 as a study of the diagram will prove, to explain this enclosure of 

 Boulder-Clay, by either faulting or thrusting during Glacial 



1 Quart. Journ. Geol. Soc. vol. lv, p. 305, &c. 



2 They are of course very similar to those which supply w r ater in several 

 parts of England, and are commonly called ' fissures,' but I avoid this term as 

 slightly misleading. 



3 Op. cit. pp. 313, 314. 



1 Ibid. p. 313; & vol. lvii (1901) p. 9. 



5 Flints are common, but there are also some ' Scandinavian ' stones. 



The cliff was about 7 yards high, and the ground, if I remember rightly, 

 rose at the back. Both Boulder-Clay and stratified Sand occur in the 

 vicinity. 



2l2 



