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measuring up to about 9 

 feet in thickness. Near 

 the middle of the section 

 is a lliver-Drift channel 

 cutting through the Thanet 

 Sand, the relation of this 

 to the Trail being a little 

 obscure. Below the Thanet 

 Sand is the Bullhead flint- 

 bed resting upon a hori- 

 zontal but corroded surface 

 of the Chalk. 



Where the specimens de- 

 scribed in this paper were 

 collected there was nothing 

 in the nature of piping, 

 the corroded irregularities 

 of the Chalk surface be- 

 neath the Tertiaries being 

 on quite a small scale. 



The Bullhead flint-bed, 

 left from the solution of' 

 the Chalk, is about 9 inches, 

 thick, and there is a thin 

 layer of banded residual 

 material at the base. The 

 upper flints of this bed are 

 not only green-coated, but 

 deeply altered through 

 their substance, and much 

 corroded on their surfaces. 

 The lower flints are much 

 fresher in condition, while- 

 those next the Chalk have 

 not yet become green- 

 coated, and after removal 

 they could not be recog- 

 nized as Bullhead flints.. 

 Many of them still remain 

 partly embedded in the- 

 parent reck. The out- 

 standing feature at Hare- 

 field is that the sub- 

 Tertiary Chalk surface, 

 with its tubes of boring 

 organisms, still remains- 

 practically unaltered since 

 it formed the floor of the- 

 Eocene Sea. The out- 

 standing feature at Grays 

 is the extensive solution of" 



