XX GEOLOGICAL FEATURES 



patches of mottled clay, often stained black and containing 

 flints in abundance, occur more frequently. 



Boulders of sandstone also occur imbedded in the clay 

 to the depth of 12 feet below the surface. At a depth of 

 about 20 feet, in some of the clay-pits, a bed of gravel, 

 formed of broken flints, has been reached. A similar gravel 

 comes to the surface in the valley further to the south near 

 Cadley, and again further to the east in the same valley 

 on the right of the road to Hungerford. 



Within a few yards of the top of the chalk slope at the 

 north-west corner of the Forest there is a trough-like hollow 

 in the Chalk, running from W.S.W. to E.N.E., 25 feet wide, 

 and 8 feet deep on one side and 6 on the other, the soil 

 above having been eroded. This hollow is filled up by 

 layers of red clay with large broken flints and chalk- rubble 

 with small pieces of flint, the layers being curved in the 

 same way as those illustrated in Jukes's Manual of Geology, 

 p. 194. These beds are thickly studded with two kinds of 

 fossil shells of the genus Helix, which very much resemble 

 H. occlusa, and a smaller species, H. d'Urbani, some of 

 which are beautifully marked. This hollow may have been 

 the course of a river during the time of the deposition of 

 some of the later Tertiary beds ; and a flood probably swept 

 into it the layers of broken fragments of chalk and clay, 

 together with the numerous land shells with which they 

 are studded. 



About 300 or 400 yards from this spot, towards the E.S.E., 

 in a narrow pit, there is, or more properly there was 

 (the greater part of the sand having now been dug out), a 

 deposit of light-yellow or buff-coloured sand, and also some 

 green and ash-coloured sand. The light-yellow sand is 

 coloured brown, in streaks, by water from the surface. On 

 one side is a brown sandy clay which contains some green- 

 coated flints and small well-rolled flint-pebbles. The pit is 

 about 18 feet deep ; and in the middle and on the south side 



