180 Sketch of the Geology of the Neighbourhood of Shaftesbury, 



band of greensand, which skirts the chalk all round and forms a 

 bold escarpment, overlooking the Vale of Blackmore to the west 

 and the Vale of Wardour to the north. As you come to Shaftesbury 

 from Semley, soon after leaving the station you have a good view of 

 this escarpment, three bold headlands like sea-cliffs stand out one 

 behind the other, very similar in shape, all alike clothed with pine 

 trees on their sides and summits ; and below this escarpment the 

 layer of gault forms a slope at its outcrop, and bears up the water 

 which soaks through the greensand above, and in this zone you 

 meet with oaks, contrasting with the pine trees above. Another 

 fine view is to be met with on Castle Hill, where to the east is seen 

 the greensand escarpment at King Settle, and a conical wooded 

 hill about two miles to the west, called Duncliffe, which is an outlier 

 of the greensand. And as we look at it and remember that all the 

 intervening space was once filled with similar rock, and that it has 

 been gradually removed by the action of rain and frost and snow, 

 we can form some idea of the vastness of geological time, and this 

 idea is intensified when we remember that not only has this green- 

 sand disappeared, but all the chalk which lay above it, uniting the 

 chalk downs above Melbury with those about Knoyle. 



Now we will examine the Vale of Wardour more carefully. 

 Turning to the map we notice that the gault lies uncomformably on 

 various wealden and oolitic strata. At the western end of the vale 

 on its south side it rests on Kimeridge clay, between Pyt House and 

 Wardour on Portland beds, then on the Purbeck beds ; then, as the 

 valley narrows, the gault crosses to the northern side and lies for a 

 short distance on Hastings sand ; then, as we follow it westward, 

 along the northern side we find it lying on Purbeck and Portland 

 beds, gradually thinning till between Fonthill and Knoyle it dis- 

 appears, and the greensand, which overlies the gault all round the 

 valley, rests directly on Kimeridge clay. 



Moreover, when we examine the dip of the strata, we find that 

 on the south they dip towards the south, on the north towards the 

 north, showing that the remaining rocks form parts of an anticlinal. 



We must now enquire how this state of things came about. In 

 the first place the fact that the gault rests unconformably on the 



