514 W. Whitaker — Coal-search in 8.E. of England. 



V. — Suggestions on Sites fok Coal-search in the South East 



of England. 1 



By W. Whitaker, B.A., F.R.S., F.G.S. 



THE general question of the rise of older rocks beneath the 

 Cretaceous beds of south-eastern England is now so familiar to 

 geologists that there is no need to discuss it here : it is enough to 

 note that the Secondary beds (beneath the Gault) thin northward, 

 for many miles, from the axis of the Weald. The practical applica- 

 tion of our knowledge of the subject is however in its infancy, and 

 our knowledge stops short at the Wealden axis; for we do not know 

 what happens south of it. 



Having regard to the great expense of making the deep trial- 

 borings that would be needed in the search for coal in this district, 

 it is clearly well, as far as possible, to select sites where a good 

 amount of the work has been already done. The object of this note 

 is to point out that there are such sites, and that they are favourably 

 placed for the search. 



These sites will be noticed beginning at the south-east, near the 

 only place where coal has yet been proved in the large tract in 

 question, and working thence westward and northward. 



1. Saint Margarets. About 4^ miles north-eastward of the boring 

 that has shown the presence of coal underground near Dover, is a 

 trial-boring, made by the former Channel Tunnel Co., which reaches 

 the Gault at the depth of 548 feet. Presuming that the beds beneath 

 are the same as at Dover, a further depth of say about 900 feet (in 

 the absence of precise information) would be needed to show whether 

 coal is present or not; but as, on the southern side of the London 

 Basin, the thinning of the beds between the Gault and the older 

 rocks is in a northerly direction, we should expect that there would 

 be less of these beds at St. Margarets than at Dover. 



It is remarkable that whilst at the Dover trial-boring no Wealden 

 beds were found, another boring, at the Convict Prison, a little to 

 the north-east, seems to have reached beds of that age, at the depth 

 of 849 feet. A continuation of this boring would of course be of 

 interest, though the site is near that of the successful trial. 



2. Chartham. Some three miles south-westward of Canterbury 

 another boring has reached the same horizon, having touched the 

 Gault at the depth of 735 feet, and here probably the beds between 

 the Gault and the older rocks would be much thinner than at 

 Dover. 



3. Chatham. A boring at the Dockyard has given us much more 

 information than either of the above, for it has reached the bottom 

 of the Cretaceous Series at the depth of 943 feet, and has been carried 

 22 feet in Oxford Clay. Seeing that at Dover all the three divisions 

 of the Jurassic Series are represented, and that at Chatham the whole 

 of the Upper Jurassics and part of the Middle Jurassics are absent, 



1 A paper read to the Brit. Assoc, at Leeds, and printed in the Yorkshire Fost (and 

 other newspapers), and in the Brighton Magazine (October, 1890). Some slight 

 additions and corrections are now made. 



