OF MARLBOROUGH. XIX 



the soil above, shows horizontal layers of flints, and is 

 flanked by layers of red clay running parallel to its surface, 

 as in the case of the pinnacle of chalk described and illus- 

 trated by Sir C. Lyell in his * Elementary Geology' (p. 135) ; 

 only in this case the dome of chalk is fixed, and the sur- 

 rounding portion has been eroded and its place supplied by 

 a red clay. The upper surface of this dome, which is about 

 10 feet across, is hollowed out: some of the hollows are 

 more than a foot deep, and are filled up with clay. On the 

 north side of the same pit there is another similar mass of 

 chalk, the intermediate space having been occupied by clay. 



To the south-west of Ivy's Farm, on both sides of the 

 road from Marlborough to Pewsey, a clay of a bright-red 

 colour, but not so hard as the mottled clays, is exposed to 

 the depth of from 12 to 16 feet, in brick-pits. 



The general mass of the clay is quite free from flints, 

 and is much used for making bricks ; but frequent patches 

 of flint-nodules occur in it, and also smoothed boulders of 

 sandstone to the depth of 8 or 1 feet. 



In one of these pits there is a large, but comparatively 

 thin, smooth boulder, lying obliquely on its side, with one 

 end exposed, which has been split longitudinally, and with 

 the corresponding edges of the fissure, nearly parallel to 

 one another, about 8 inches apart. This boulder must 

 have been broken into two parts at the time it was depo- 

 sited in the clay, otherwise the two parts would not have 

 been so near together. The upper half rests against a patch 

 of flints, which may have prevented it from sinking so much 

 as the lower half. The same kind of clay extends very 

 nearly, if not quite up to Martinsell Hill ; but as there are 

 few sections further in this direction, its extent has not 

 been accurately determined. 



The north-west corner of Savernake Forest is occupied 

 by a bright-red clay of the same character as the last, which 

 is, like that, very much used for making bricks, although 



