INTRODUCTION. XYll 



of an elephant (Evans, ArchcBologia, 1860). So many bones of tlie 

 elephant, rhinoceros, and hippopotamus have been found in the 

 gravel on which London stands, that there is no reason to doubt tlie 

 statement as handed down to us. Fossil remains of all these three 

 genera have been dug up on the site of VVaterloo Place, St. James's 

 Si][uare, Charing Cross, the London Docks, Limehouse, Bethnal 

 Green, and other places, within the memory of persons now living. 

 Li the gravel and sand of Shacklewell, in the north suburbs of London, 

 I have myself collected specimens of the Cyrena Jiumincdis in great 

 numbers, with the bones of deer and other mammalia.' (Lyell, Anti- 

 quity of Man, 18G3, pp. IGO, 161.) 



Alluvium. — Along the Thames there is comparatively little of this 

 modern deposit. Westminster is built upon alluvium, and was once 

 an island (Thorney Island). Alluvial tracts also occur in the Isle of 

 Dogs, and for about a mile above the mouth of the Lea. East of the 

 county there are broad alluvial flats. 



7. Deainage. — Middlesex is wholly included in the Thames 

 basin, the entire area of which is about 5,162 square miles, or 

 3,303,680 statute acres.* The greatest length of the Thames basin is, 

 according to the Rivers Commission Report, from Trewsbury Mead in 

 Gloucestershire to the estuary ; its greatest breadth from Priors Mar- 

 ston, in Warwickshire, to Fernhurst, in Sussex. Besides Middlesex, 

 which forms almost exactly one-nineteenth part of it, it includes the 

 whole or nearly the whole, of Bucks, Herts, Surrey, Berks, Oxon, 

 about one-fourth of Essex, one-sixth of Kent and Wiltshire, one-third 

 of Gloucestershire, and small portions of Warwickshire, Northampton, 

 Bedford, Sussex, and Hampshire. 



The Thames is usually stated to take its risef in the oolitic lime- 

 stone rocks of the Cotswold Hills, the escarpment of which is the 

 western boundary of its basin. It is not derived from any definable 

 spring at its head giving out all, or nearly all, its waters, but is fed 

 by many small rivers and brooks. | 



The following account is taken from the Penny CyclopcBclia : ' The 

 spring which has commonly been regarded as the head of the Thames is 

 about three miles S.W. of Cirencester, near a bridge over the Thames 



* Report of Rivers Commission, p. 8. 



t It is customary to regard a river as originating at the place where what is looked 

 upon as its main stream commences. A river is, however, after all, as ordinarily con- 

 ceived, a rather arbitrary notion. In nature the main stream is only part of a great 

 system of minutely ramifying streams. The edge of the basin in which these originate 

 is the real source rather than any one point upon the edge. A river sj'stem is no bettei' 

 represented by its main stream than a leaf by its mid-rib. 



t Bravender in Proceedings of Cotswold Club, 1887. 



