180 
SUB-AERIAL DENUDATION 
Brandon Hill forms a part, is composed of hard Millstone Grit, 
dipping to the S.E. at an angle of some 25°. That is followed 
by the softer Upper Limestone Shales, which form the southern 
slope of the Downs, and give rise to hollows or depressions, 
generally filled up with the rocks of the newer series. The 
whole ridge of the Downs, from Leigh Down, through Durdham 
Down, Westhury Down, Henbury Down, King's Weston Down, 
to Penpole Point, is formed of massive Mountain Limestone. 
How it comes that Clifton Down is separated from Durdham 
Down, we shall see presently. The depression to the N. of 
Leigh Down is occupied by softer Lower Limestone Shales. 
The Failands ridge, to the N. of this depression is composed 
of the upper and harder conglomeratic beds of the Old Bed 
Sandstone. And the discontinuous depression yet further N. 
is occupied by the lower and softer beds of the same group of 
Old Red rocks : the discontinuity being partly due to overlying 
newer beds. The same soft Old Red rocks also occupy the 
depression just W. of Stoke Bishop, on the Gloucester side of 
the Avon f see map ). 
On the inner side of what may be termed the Westhury 
horseshoe, the Lower Limestone Shales form a discontinuous band 
— the discontinuity being due to the presence of overlying strata 
of more recent age. Beneath these beds the Lower Limestone 
Shales are without doubt continuous. Inside this band, again, 
is the band of harder Old Red Sandstone, which, E. of Shire- 
hampton, N.E. of Cook’s Folly, and again at Coomb House, 
rises out of the mantle of newer rocks which elsewhere hides it 
from our view. The lower and softer beds of the Old Red 
Sandstone probably occupy the rest of the area within the 
horseshoe. But they are almost entirely covered up by the 
newer secondary rocks. 
The central axis of the horseshoe forms an anticlinal axis, 
from which the King’s Weston and Henbury beds dip down 
