132 Geology of the South East of Dorsetshire. 



13 



The four Pillars off Ballard Head, (Webster. 



1, Old Harry. 2, 



Wife. 3, Dr. Mitchell's tabular mass, 

 ed rock near No. 3. 



4, Point- 



existence of which is very clear at the junction of the beds 

 that dip to the west, with the horizontal beds immediately 

 under the flag-staff, as represented roughly in the following 



figure, {Jig. 14). 



14 



Buttress of chalk dipping to the west, under the signal staff, Ballard Head. 



At the point of junction, the crack is very evident all the 

 way down, and at the bottom there is an incipient arch, pier- 

 ced by the sea. This also explains the formation of those 

 arches and caves, existing at the foot of the cliffs, which are 

 not round, but rectilinear, and shaped by the removal of the 

 chalk blocks, according to the direction of the joints and bed- 

 ding. An arch of this kind, at the foot of another buttress, a 

 little distance from the flag-staff point, illustrates the lines of 

 fault, the joints, and bedding, most admirably. The follow- 

 ing is a rough outline, (Jig. 15), which shews the structure of 

 the pillar to be that of a coarse masonry. 



