226 Mr. G. J. Hinde’s Notes on the 
This high-level Southern Drift contrasts strongly with the 
valley gravels of the lower levels in the well-rolled condition of 
the larger flints, the large proportion of Tertiary flint-pebbles, 
the abundance of chert fragments from the Lower Greensand, and 
negatively in the absence of angular or subangular flints and the 
great rarity of pieces of iron sandstone. 
The slopes of the chalk valleys leading down from the water- 
shed plateau to Smitham Bottom are covered with angular and 
subangular flints and Tertiary pebbles, in part derived from the 
clay-with-flints of the plateau above, in part direct from the 
chalk, and these materials form beds of rough gravel 8 to 4 ft. 
in thickness in the valley of Hogden Bottom. Lower down the 
Chipstead Bottom they have been worked at Stagbury, and still 
more extensively from the cross-roads at Banstead Park, 317 ft. 
above O.D., to the junction with the Smitham Bottom at the 
Red Lion Green, Coulsdon, 255 ft. The flat bottom of this 
valley for a distance of one and three-quarter miles is covered 
by gravel to a depth of 4 or 5 ft. In the upper 2 ft. the stones 
are embedded in a brown loam, evidently washed from the chalk 
slopes on either side; in the lower portion the gravel consists 
of angular and subangular flints, green-coated flints, Tertiary 
pebbles, iron sandstone, and, very rarely, pieces of chert in a 
more sandy matrix. In some places between the gravel and the 
chalk beneath there is a thin bed of quartz sand, with rolled 
pebbles and grains of chalk, prisms of Inoceramus shell, and 
Foraminifera washed from the chalk. These Chipstead Bottom 
gravels are now largely worked for the roads, and in a few years 
they will be all removed. 
From the Red Lion Green, Coulsdon, 255 ft. above O.D., to 
the north end of Haling Park, South Croydon, 163 ft., a distance 
of nearly four miles, the main valley of Smitham Bottom and 
the Brighton Road has been covered by a fairly thick sheet of 
gravel of a similar character to that just mentioned in the 
Chipstead valley. In this distance, on the east side, the Cater- 
ham valley and some shorter valleys from Sanderstead and 
Selsdon join the main valley; and on the west side, only an 
inconspicuous valley at Foxley Hatch. 
In pits lately opened by the side of the Brighton Road, the 
gravel at the bottom of the valley is from 8 to 10 ft. in thickness. 
On the west side of this part of the main valley the chalk slopes 
are somewhat abrupt and they have no gravel over them, though 
traces of a former coating of gravel have been preserved in 
pockets or pipes in the chalk, one of which is at present exposed 
in the Avondale Road, at a level of 210 ft. On the east side of 
the valley, however, the chalk slopes are more gradual, and they 
are overlaid by gravel to heights of 40 or 50 ft. above the bottom 
of the valley. A good section of these higher valley gravels is 
