38 Prof. BucKLAND and Mr. De la Beche on the 



Portisharrij the fault again resumes its westerly direction, and at the same time 

 brings up the Kimmeridge clay into immediate contact with the base of the 

 escarpment of the chalk ; this contact continues for some distance towards 

 Abbotsbury. At Abbotsbury*, the Oxford oolite occupies the south side of 

 the fault ; and greensand, resting upon clay, the north side ; the two latter 

 are nearly horizontal, whilst the oolite rises to the north. 



The irregularities of structure occasioned by this fault on the west of 

 Abbotsbury are considerable, and not totally made out by us. A compound 

 disturbance, similar to that which has produced the trough-shaped disposition 

 of the Purbeck and Portland stone at Upway, has caused an analogous 

 derangement near Abbotsbury, along a tract of about a mile in length, from 

 east to west, and nearly a mile in breadth f. This tract occupies the slope 

 and under-terrace, between the summit of Abbotsbury Common and the sea, 

 and is composed chiefly of ferruginous Oxford oolite, dipping regularly to- 

 wards the north, on that side of Abbotsbury which is nearest to the sea, 

 until it terminates abruptly in a hill called Zoles (immediately above the 

 mansion of the Countess of Ilchester). In this hill it suddenly trends round, 

 changing its dip towards the east, and rising with an escarpment to the 

 west, for a short distance, until the dip again turns suddenly to the south, and 

 so continues along the line of fault, running east and west more than a mile 

 from Zoles to the town of Abbotsbury. By these three dips, tiie oolite is 

 thrown, at its termination, into the form of a spoon, rising outwards in three 

 directions from the lowest central line of depression, and terminated by high 

 escarpments on the south and west, and on the north partly by a false escarp- 

 ment |, and partly by abutting against the fault §. 



The existence of this false escarpment (fig. 7.) is due to the agency of the 

 upcast fault, which has elevated, not only these Oxford oolite beds, but even 

 the subjacent beds of Oxford clay and forest marble irregularly along the 

 under-terrace, between the false escarpment of oolite, and the true south 

 escarpment of the lofty ridge of greensand and chalk composing Abbotsbury 

 Common ; so that beneath and parallel to this true escarpment, at a distance 

 varying from one to two furlongs, the false escarpment forms a broken under- 

 terrace II facing the true escarpment, with opposite dip ; and between these 

 two escarpments a narrow band of forest marble is thrown up in great con- 

 fusion for about a mile, from the town of Abbotsbury west to Zoles. The 

 confusion is increased by land slips, which have brought down heaps of 

 rubbish from the greensand escarpment of Abbotsbury Common and Abbots- 



* Plate II. fig. 6. t See Plate II. fig. 6 & 7. + Plate II. fig. 7. 



§ Plate II. fig. 6. 11 See Plate II. fig. 7. 



