268 



the Tunnel — formed according to Cross sections, IN'os. 2 and 3 — 

 pierces tlie npper beds of tlie Inferior Oolite for a distance of 

 about 930 yards. Good sections of these beds are visible in 

 the Tunnel, their dip being here from south-east to north-west 

 four degrees is plainly seen and indicates the up-throw which 

 caused the hill. Rynchonella spinosa is found in the spoil heaps 

 at shaft No. 2, (from Sapperton face,) and Terebratula fimbria 

 at shafts Nos. 3 and 4. 



The various rockings at this part of the Tunnel are very 

 interesting, and quite worth a visit. It was here that the 

 fissures in the rock caused so much trouble originally — and 

 continue to do so — from the decay of the timber in the planking 

 and doors, before referred to, used as a casing over the fissures. 

 There seems to be a slight inacciiracy in the Ordnance Geo- 

 logical Map, which shows the Fullers Earth at a higher elevation 

 at Sapperton than it is proved by the Tunnel excavations to be 

 placed, and assigns to that formation the out-throw of the 

 spring, issuing just below Sapperton village, instead of to the 

 clays of the Forest Marble, to which its development is due. 

 In this view the isolated capping of Forest Marble, shown at 

 *'Ash Hill," should be extended further to the eastward, and 

 include Sapperton. 



The first fault which is intersected by the Tunnel (passing 

 towards the east) is in the exact position indicated on the 

 Ordnance Map; and near here the "Long Arching," shewn on 

 the longitudinal section, begins, and extends for a distance of 

 about 1190 yards. Nothing can be seen in this interval in the 

 Tunnel beyond the probable position of the fault, which I have 

 taken to be indicated by the point shewn on the section, where 

 the Cassey-well springs and others pour in considerable volume 

 into the Tunnel through the roof and northern side wall. The 

 large portion of the work, here entirely in arching, is without 

 doubt carried through the Fullers Earth, which has been 

 disclosed on different occasions din-ing frequent repairs ; and 

 this is also evident from an examination of the spoil heaps 

 at the various shafts. 



The second fault encountered is near but somewhat west of 



