TTLOR QUATERNARY GRAVELS. 81 



There is a bed of marl on the 6 feet of solid chalk, shown in fig. 13, 

 Fig. 13. — Section of the Cliff East of the Ga^, Rottingdean, Sussex, 



W. E. 



and also continuous bands of flints. We can thus accurately ob- 

 serve the marks of the movement which has taken place in the upper 

 surface of the denuded chalk. The bed of tabular flints, about 1 inch 

 thick, touching the upper part of the artificial opening marked cave, 

 is fractured and contorted, while the traces of a still higher band of 

 large detached flints are visible in the gravel above the top of the cave, 

 where it ends. Then comes a coarse ochreous flint-gravel 7 feet 

 thick, with veins of sands and some chalk fragments. This is eaten 

 into by the covering dark bed of sand with flints. The middle por- 

 tion of this section is chalky, and must have been more altered 

 by chemical than by mechanical action, as the flint-veins have been 

 so Kttle disturbed. At p. 113 of the last volume of this journal I 

 gave some illustrations of the destruction of chalk in situ by some 

 kind of chemical action, which was probably contemporaneous, if not 

 identical, with that which has eroded the surface of the chalk, and 

 formed pipes over such large areas. 



Fig. 14, representing the highly-inclined chalk with flint veins 200 

 yards east of Freshwater Gate, Isle of Wight, is given for com- 

 parison. The covering bed is nearly horizontal, as usual. The cha- 

 racter of the chalk and the disposition of the gravel closely re- 

 semble those at Rottingdean ; and the latter is about the same height, 

 from 25 to 30 feet. Mammalian remains have been found in this bed 

 close by Freshwater Gate. 



Fig. 15, Sangatte Cliff, near Calais, is given for comparison with 

 these Brighton sections. The escarpment of the chalk, near the upper 

 part is 43°, then it reaches 55°, and descends to 43°. The Sangatte 

 raised beach is just above the level of high water at this point, and 

 is composed of large flints and pieces of chalk, as at Brighton. 



VOL. XXV. PART I. G 



