10 



than the River or Drift Gravels. Man is a tool-making animal, and 

 the earliest recognised specimens of his hand-work — the Eoliths — are 

 found in these high level gravels. 



The position and thickness of many of these gravel beds have been 

 revealed to us in the process of deep well boring. From papers com- 

 municated to the pages of The Rochester Naturalist, by Mr. W. 

 Whitaker, B.A., F.R.S., etc., etc., on "Well sections in the Rochester 

 District," supplemented by reference to his Water Supply of Ke7it, the 

 thickness of river drift at the following places has been obtained : 

 Sittingbourne (Lloyd's Paper Mill), loft.. Isle of Grain (Rose Court 

 Farm), 37ft. ; Allhallows, 31ft. ; Hoo Fort, 46ft. ; Rainham (Falcon 

 Cement Works), 40ft. ; Chatham (Electric VVorks), 14ft. ; Rochester 

 (Laundry Co.), 25ft. ; Strood (Electric Works). 24ft. ; Borstal (Booth 

 and Co.), SJft. ; Cuxton (London and Medway Cement Co.), 42ft. ; 

 Snodland (Crowhurst's), 27ift. ; Aylesford CForstal, close to Medway), 

 19ft. ; Maidstone, 7 to 8ft. 



Recent. 



Alluvium. — Mudd}' deposit along the bottom of the river vallej's 

 varying considerably in breadth and depth. Mud and peat are often 

 in alternate layers, as at Cliffe, where mud and peat layers succeed 

 each other thus, 15 m. i p. ; 8 m. 3 p. ; 7 m. 4 p.; total 3Sft. Similar 

 alternations of mud and peat were passed through in the excavations 

 for the Dockyard Extension Works on S. Mary's Island. Well borings 

 have revealed the following thickness of alluvium : — Allhallows, iift. ; 

 Isle of Grain, 24ft. ; Hoo Fort, 46ft. ; Chatham, iSft. ; Rochester, 22ft.; 

 Burham, 20ft. ; Greenhithe, 40ft.; Strood (Oil Mills). 42ft. 



