310 



Mr. A. J. Jukes-Browne on the 



breaks away along joint-planes, which are often discoloured, 

 and still further obscured in summer time by the mud washed 

 down from above. Sir Charles Lyell writes as follows* : — 

 " A layer of chalk flints in situ shows that the stratification 

 of the chalk is vertical, although the beds seen in a large cave 



Fig. 2. 



Northern Bluff, Trimminghani, 1839. 

 «. Chalk ; b. Sand ; c. Boulder-clay. 



facing the sea show a slight curvature only." Others have 

 considered the beds to be nearly horizontal ; and certainly the 

 flint layers in the upper portion of the mass appeared to be so 

 in 1875. 



Mr. Clement Reid, in his recent paper on the Glacial de- 

 posits of Cromer, has completely explained these conflicting 

 appearances f. He had opportunities of visiting the spot 

 after winter storms had cleared the section ; and he discovered 

 that the beds are bent into a sharp curve or loop, and are so 

 contorted as to be horizontal in one place and nearly vertical 

 in another. The diagram (fig. 3) is an enlargement of part 

 of the cross section given by Mr. Eeid. 



Fig. 3. 



Northern Bluff, side view. 

 «. Chalk ; b. Boulder-clay ; c. Sand ; d. Contorted Drift. 



* Phil. Mag. 1840, vol. xvi. p. 356. 

 t Geol. Mag. dec. 2, vol. vii. p. 55. 



