Gravels of Croydon and its Neighbourhood, 225 
Harpsoak Cottage to the Smitham Bottom at the Red Lion 
Green, Coulsdon, is three-and a quarter miles, and its fall in 
this distance is 184 ft. There is an extensive deposit of gravel 
in the open area where it connects with Smitham Bottom, but. 
most of this appears to have been brought down the Chipstead 
valley, referred to below. 
A well-marked dry valley coming down on the east side of 
Farthing Downs from the high plateau near Chaldon connects 
with the Hooley valley near the Coulsdon railway-station. At 
‘the foot of the valley, in the road immediately below the railway- 
crossing, a strong spring or bourne is now issuing, at a level of 
260 ft. above O.D., and the water runs down into the gravyel- 
pits below. 
More important than the Hooley valley in regard to the 
amount of gravel in its lower reaches is the Chipstead valley, 
the upper branches of which. take their rise in the high grounds 
of the watershed plateau near Banstead, Burgh Heath, Tadworth 
Court, Banstead Heath, and Walton Heath, at levels between 
500 and 600 ft., and, running in a north-easterly direction for a 
distance of about six miles, connect with Smitham Bottom at 
the Red Lion Green at the level of 255 ft. above O.D. 
On the watershed plateau at Burgh Heath, and near Walton- 
on-the-Hill, there are some outliers of Tertiary beds, and these 
are in places covered by a deposit of gravel at levels of 560-580 ft. 
above O.D., from which some of the constituents of the valley 
gravels may have been derived. Pits are at present opened in 
these gravels on the open heath between Walton-on-the-Hill and 
Dowding Castle, showing a section of 10 to 12 ft. in depth. The- 
gravel consists of large well-rolled flints, Tertiary flint-pebbles, 
and numerous blunted fragments of the yellow porous chert. 
from the Lower Greensand, from 1 in. in diameter to pieces 
measuring 7 x 8 x 3 in.; these stones are embedded in a matrix 
of reddish sandy loam without stratification, and in places there 
are layers of the loam free from stones. The gravels in one part 
of the pit rested on a greenish yellow sand, probably Tertiary. 
The character and position of these gravels on the watershed at 
so high a level show that, they belong to the deposits classed 
by the late Sir J. Prestwich * as ‘“‘Southern Drift,” and they 
occupy a higher level at this place than anywhere else in Surrey 
mentioned by Prestwich. So far as I am aware, no other 
deposit. of Southern Drift gravel is known within the Wandle 
drainage’ area, except that described by Sir J. Prestwich + on 
the summit of Westow Hill, Upper Norwood, at heights of 
360-380 ft. above O. D. 
* «Quart. Journ. Geol. Soc.,’ vol. xlvi., 1890, p. 155. 
+ Loe. cit. p. 159. 
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