igo THE GEOLOGY OF THE LEA VALLEY. 



informed me some time since, that when the brothers Want were 

 the proprietors of the Broxbourne Fishery some forty years ago, 

 about 1850, there used to hang in the smoking-room of the inn 

 there a string of sahiion, trout, and pike heads. On their quitting 

 the place, however, the subsequent proprietor, Mr. Beningfield (who 

 was a gardener and cared httle for fishing), threw them away ! 

 Could they have been preserved to the present day, what in- 

 teresting relics they would be in the eyes of anglers and 

 naturalists. 



THE GEOLOGY OF THE LEA VALLEY. 



By T. V. HOLMES, F.G.S. {Vice-President). 

 [Read ai Meeting on the Rive7- Lea, J uly 14///, 1894 ] 



AT London we are in the midst of a broad synclinal fold or 

 basin, consisting of Tertiary and later rocks towards its 

 centre and of Chalk and other Secondary formations towards its 

 outer rim. The Tertiary area includes the greater part of Essex and 

 the south-eastern corner of Suffolk, while south of the Thames it 

 comprises a considerable portion of northern Kent and Surrey. 

 West of London it becomes gradually narrower and narrower, till 

 around Marlborough it is represented only by a few scattered out- 

 liers. Beyond this Tertiary district is one in which the underlying 

 Chalk is more or less exposed, as at Saffron Walden, Royston, 

 Hitchin, and Dunstable north of the Thames, and along the North 

 Downs from Folkestone to Guilford, south of it. As the Chalk dips 

 northward from its outcrop in Kent and Surrey, and southward in 

 the counties of Essex, Cambridge, Bedford, Hertford, and Buck- 

 ingham, it naturally follows that rain-water sinking into its surface, 

 or percolating through it from some overlying bed, tends to flow 

 southward from Essex or Cambridge, and northward from Surrey 

 and Kent. A few springs are occasionally found at the base of the 

 Chalk escarpment in certain localities, but in the main the water 

 flows through the Chalk ^ in the direction of its dip, and issues from 

 it in springs where the Chalk is so saturated that the saturation-level 

 is above the local level of the ground. South of the Thames, along 

 the North Downs, there is a much smaller breadth of bare Chalk " 

 than there is from the Chiltern Hills to Essex and Suffolk. 



1 See Whitaker, " Geology of London, " etc., \ol. !., pp. 61. 62. 



2 Chalk covered only by Glacial Drift is here included. 



