LOWER CHALK- -SOUTH WILTSHIRE. 
CHAPTEE XI. 
THE LOWEE CHALK IN SOUTH WILTSHIRE. 
General Description. 
Having in the preceding chapters described the Lower Chalk of 
Dorset and Devon, we now take up the formation again near Shaftes¬ 
bury, on the borders of Dorset and Wiltshire, and will follow its 
outcrop thence across England. 
From Charlton, near Shaftesbury, the Lower Chalk passes along 
the northern slope of the range of hills which forms the northern 
border of Cranborne Chase, and entering the Yale of Broad Chalk, 
extends as far as the west end of Ebbesborne Wake, where it passes 
beneath the Middle Chalk. This, however, is not its final disappear¬ 
ance, for, owing to a series of dome-shaped flexures which have 
bulged the beds upward, the Lower Chalk comes to the surface 
again in no less than four separate inliers to the eastward. The 
first of these is a small one south of Ebbesborne; the second is 
much larger, and surrounds the inlier of Selbornian Greensand at 
Bower Chalk; the third extends from Broad Chalk to Bishopstone, 
but mainly on the southern side of the river Ebble; the fourth and 
last is a small tract, almost entirely concealed by gravel and allu¬ 
vium, by Combe Bissett and Homington. 
The manner in which the Lower Chalk is thus brought up again 
and again is shown by the section Fig. 36, which has been drawn 
so as to traverse three of these inliers. It must be remembered 
that the flexures shown in this section are periclines, not axes, and 
that sections drawn at right angles to it would show the beds dipping 
both to the northward and to the southward. 
Northward, indeed, they plunge under the bold ridge of Chalk 
Downs which runs from White Sheet Hill to Salisbury Baceeourse. 
The main outcrop of the Lower Chalk passes round the west end of 
White Sheet Hill, and thence north-eastward along the southern 
side of the Vale of Wardour. Its outcrop terminates eastwards in 
the fine natural amphitheatre of Hoop Side, south of Bar ford. 
On the northern side of the Yale the outcrop is narrower than 
on the southern side, partly because of the higher dips and partly 
because it is in places traversed by the fault which runs through 
Baverstock, Chilmark, Hindon, and Mere. Between Baverstock 
and Hindon the northerly dips of from 15° to 25° cause the 
Upper Greensand to stand up as a ridge, wdiile the Lower Chalk, 
yielding more readily to detritive agencies, occupies a parallel longi¬ 
tudinal depression or trough (see Fig. 37). 
