Reports & Proceedings — Geological Society of London. 283 



the water derived from them was either ferruginous or saline, and tht^ 

 supply was not continuous. 



The present boring passed through 178 feet of alluvial deposits, 

 resting on a considerable thickness of dune sand, which yields highly 

 ferruginoiis water. Below 280 feet the beds are estuarine and marine 

 in character, and these continue until granitic rocks, presumed to bo 

 Archaean, are reached at 579 feet. These formations supply evidence 

 of a depression of the granitic rocks to a depth of not less than 

 280 feet. Tlie dune sands mark an elevation or cessation of movement, 

 and indicate a long period of rest followed hj a further depression, 

 during which the upper alluvial deposits were formed. 



Water was found at nine levels, but the only good drinking-water 

 was yielded by two beds of sand immediately above the granitic rocks. 

 This water is derived from the thick lateritic and lithomargic deposits 

 which rest on a floor of igneous rocks in the high lands of the colony. 

 The water from the lowest level contains only 5"3 grains of solid in 

 solution per gallon and has a temperature of 904° F. The mean 

 daily flow from August 25 to November 27 was 198,000 gallons. 

 Analyses are given of the water obtained from nine different levels in 

 the borinff. 



I?.E:^^0I?,TS .A.1<TJD :F'K,OCE!E!I3I]SrGrS. 



Gkological Society of London. 



1. Aprils, 1914.— Dr. A. Smith Woodward, F.R.S., President, 

 in the Chair. 



The following communications were read : — 



1. " The Evolution of the Essex River System, and its Relation to 

 that of the Midlands." Ry John Walter Gregory, D.Sc, F.R.S., 

 F.G.S., Professor of Geology in the University of Glasgow. 



The post-Eocene geology of Essex must be learnt from its gravels 

 and their non-local constituents. In the absence of any rock whicli 

 affords a certain proof of its route, the effort was made to determine 

 the direction of transport by tracing the variations in the proportions 

 and size of the non-local constituents. Tliis test shows that tlie 

 quartzites and felsites came from the north-west and the Lower 

 Greensand cherts from the south and south-east. 



A. The gravels may be classified as follows : — 



(1) The oldest series. The Brentwood group, which consists of 

 redeposited Bagshot Beds and of local materials only. 



(2) The Danbury Gravel, which was deposited before the arrival 

 of the felsites, and at the beginning of the arrival of the Lower 

 Greensand cherts. 



(3) The Brainti'ee Gravel, which is largely composed of quartzitio 

 drift, with abundant Lower Greensand cherts and some felsites tliat 

 were probably derived from the Lower Greensand conglomerates 

 north-west of Essex. 



(4) and (5) Glacial and post-Glacial gravels. 



