Vol. 56.] ANNIVEESAEY ADDEESS OF THE PEESIDENT. lxxix 



on the south to Ware on the north and to Crossness on the east, 

 there is none, the Gault resting directly on some much older forma- 

 tion. One is led, however, to infer the presence of this division at 

 Lough ton, where the Gault is underlain by sand. 



Never again on the north of the Thames do we get evidence of 

 the underground occurrence of Lower Greensand in places far 

 removed from the outcrop, until reaching Culford, in Suffolk, where 

 a thickness of about 32 feet of beds has been classed with this 

 formation, and on the far north at Holkham, where there are either 

 50 or 70 feet of it, accounts varying, and where the base may or 

 may not have been reached. Eastward, however, from Culford the 

 borings at Weeley, at Stutton, and at Harwich show that the Lower 

 Greensand has thinned out. 



South of the Thames, in Kent, though evidence of considerable 

 thinning northward from the fairly broad outcrop is available, there 

 is as yet no proof of the underground thinning out of the Lower 

 Greensand eastward of the Darent : all the borings that have gone deep 

 enough having demonstrated the presence of this formation. West- 

 ward of the Darent its thinning out is known, from the Crossness 

 boring. 



Along the valley of the Medway several borings have struck a good 

 supply of water from the Lower Greensand, but in one alone, at 

 Chatham, has it been pierced to its base, and proved to be only 

 41 feet thick. It certainly reaches some way farther north, to 

 beyond Chattenden. 



Farther eastward there is no evidence, except close to the out- 

 crop, until reaching the valley of the Little Stour, at the higher 

 point of which a boring at Ottinge, in the parish of Elham, starting 

 in the Lower Chalk, has proved that the Lower Greensand is more 

 than 200 feet thick, while at Eopersole, some 5 miles north-east and 

 at a greater depth, the thickness is only 72 feet. 



Again, at the workings for coal south-west of Dover, 124 feet 

 of beds have been assigned to this formation, less than the thickness 

 at the outcrop at Folkestone ; whereas at the Convict Prison north- 

 east of the former town the thickness has fallen to 31 feet. 

 Unexpectedly, however, a boring at Margate, many miles farther 

 north, has passed through more than 70 feet of what is apparently 

 Lower Greensand, without reaching the base. 



In the foregoing notes no attempt has been made to deal with the 

 various divisions of the Lower Greensand ; it seems better to leave 

 that branch of the subject until detailed descriptions of the Kentish 



