486 Mr. Austen on the 



amount uncertain. Nearer Teignmouth the same fault may be traced through some 

 conglomerate beds ; and westward it ranges along the foot of the cliff of greenstone 

 opposite Hackney claycellars, by Newton ; and from Bradley to Holbeam Mill it 

 traverses a great mass of limestone, in a zigzag course, owing to the rock having 

 yielded alternately along its two sets of joints ; beyond this it cuts a line of hill, 

 consisting of slate with trap dykes : the direction of the hill is diagonal to the 

 direction of the fault, which passes through at a right angle, but immediately 

 resumes its course along the valley of the Lemon ; still further it breaks the band 

 of hmestone below Bickington, then enters the carbonaceous deposits, and may 

 perhaps be connected with some of the east and west faults, which, as at Owle- 

 combe, become metalliferous as they approach the granite beneath Rippon Tor, 



At Bickington and along its whole course (see map), the displacement of strata, 

 both vertically and horizontally, is very remarkable, the beds on the north side of 

 the fault being apparently shifted to the east. 



The faults exhibited in the cliffs of Dawhsh (PI. XLII. fig. 5.) range westward in 

 their inland course, and the lower beds of greensand on the Haldons are put at dif- 

 ferent levels, by faults having a like direction, and which traverse the superficial beds. 



It appears therefore, that the more recent disturbances had a general east and 

 west direction. In the description of the granitic region of Dartmoor it has been 

 stated that very many of the lines of hill and valley, instead of conforming to the 

 range of the several masses of Cornwall and Devon, have courses from north to 

 south ; and many of these lines of elevation extend from the granite into the area of 

 the carbonaceous deposits on the north. The Haldon hills are on a line due north 

 and south, and the proofs of elevation observable along the western slope have 

 already been noticed ; it was this disturbance which also opened the north and 

 south joints of the limestone ; and, parallel with the Haldons, is the greensand 

 escarpment of the Blackdowns. 



The course of the Exe, as low down as the head of the estuary, where it falls 

 into another line of disturbance, is along a most extraordinary north and south 

 dislocation, which, like the east and west fault already described, has severed beds 

 once continuous, and to a much greater extent: numerous faults with the same 

 direction range through the Blackdown hills*. 



The character >''Mch principally distinguishes this system of faults, apart from 

 direction, is the very great amount of vertical movement which the beds to the east 

 experienced ; thus we have seen that the greensand of Haldon acquired an elevation 

 of 800 feet above that of the Bovey valley ; and the displacement along the course 



* This system of faults, which affects in a remarkable manner the Blackdown range and adjacent di- 

 stricts, was traced out and first described by Mr. De la Beche, in his ' Researches in Theoretical Geology,' 

 and subsequently in his valuable ' Report on the Geology of Cornwall and Devon.' 



