A HISTORY OF SURREY 



district, although it is true that now and again we have found the forces 

 of destruction and reconstruction going hand in hand even within this 

 limited field of observation. But henceforward we shall have to deal 

 only with the shaping of the land as the strata which we have been con- 

 sidering were uplifted above the waters and broken down piecemeal by 

 rain, frost, heat and wind, to be carried away by brooks into rivers and 

 by rivers into seas, to take their part in the construction of a newer land. 



In the passage, seaward, however, the detritus of the land makes many 

 halts. It forms gravel-banks and flats in the streams, of which portions 

 are sometimes left stranded for a while as terraces on the slopes when 

 the valley is deepened ; it is blown by the wind from dry channels and 

 spread over tracts where it may find temporary rest ; or it is carried as 

 mud by river-floods and deposited on low ground beyond reach of im- 

 mediate re-transport. In these and other similar ways, the remnants from 

 the waste of the land, termed by geologists the ' superficial ' deposits, are 

 formed ; and as we shall presently see, we may glean from their examina- 

 tion some knowledge of conditions which though geologically ' recent ' 

 are still long since past. 



It is not indeed certain that because no newer ' solid ' strata than 

 the Bagshot Beds now exist in our county none were ever deposited ; in 

 Hampshire there are newer (Oligocene) beds several hundred feet in 

 thickness ; but if such were ever laid down in Surrey they have since 

 been entirely removed. Of a still later period the Pliocene it is be- 

 lieved that there are actually some faint traces in the form of small 

 masses of ferruginous sand and loam which are preserved in ' pipes ' or 

 hollows of the chalk in a few places on the summit of the Downs. 

 No conclusive evidence has yet been found in Surrey to indicate the age 

 of this material, though it has recently yielded a few ill-preserved traces 

 of shells at Netley Heath, while in hardened sand similarly situated at 

 Lenham and Harrietsham in Kent the casts of marine shells of Early 

 Pliocene age have been discovered. 1 



DEEP-SEATED ROCKS 



Before following the later development of the geological history of 

 our county, however, let us turn back for a moment to investigate its very 

 foundations. We started our examination with the oldest rocks which 

 are exposed at the surface ; but as previously mentioned there have been 

 two deep borings in the north of the county which have proved the 

 existence of a sequence of much older rocks at considerable depths below 

 the surface. These borings were made at Richmond and at Streatham, 

 and their results are arranged and classified in the following summary. 

 In both records the lower portions printed in italics represent strata 

 older than those exposed at the surface in Surrey, or indeed in any part 

 of the south-east of England. 



1 See C. Reid, Mem. Geol. Survey, ' Pliocene Deposits of Great Britain ' (1890) p. 48 ; 

 and W. P. D. Stebbing < Excursion to Netley Heath and Newlands Corner,' Proc. Geol. Assoc., 

 vol. xvi. (1900) pp. 524-526. 



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