482 



Mr, Austen on the 



ously contorted. The greatest amount of disturbance is to be seen in Morte Bay, where the bedding also 

 is apparent, as well as the order of deposition of each stratum by means of lines of organic remains. 

 Fig. 20. exhibits the manner in which these planes pass through some arched strata near Ilfracombe. 



Most generally, the strike of the cleavage agrees with that of the beds, as in the older series just alluded 

 to ; but it will be found, that as soon as the carbonaceous deposits set on, as at Fremington, this strike 

 alters and makes a small angle with that of the bedding : so also with the fossiliferous strata of South 

 Devon ; where, though the two lines of strike often coincide, they will yet be also found at various 



Fig. 20. 



Section of cleavage planes passing through bent strata near Il&acombe. 



angles to one another, and instead of dipping with the beds, to have an opposite inclination ; in fact, the 

 superinduced structure is everywhere much more strongly pronounced than the original one of deposition ; 

 and it pervades districts over which all order of accumulation is wanting, or more probably was never 

 marked at all ; so that the greatest caution is constantly required. There can be no question, that through- 

 out large districts the cleavage lines have been given as those of stratification ; such indeed was the case, 

 only a very short time ago, with the whole of the Exraoor group : and calculations were made from 

 these observations, which gave a thickness to some of the deposits entirely at variance with the condi- 

 tions under which those strata were formed. 



The few foregoing observations tend to show, that this remarkable change in the 

 arrangement of the particles has not extended, in this part of England, to any beds 

 higher than those of the carbonaceous series ; and that it was superinduced subse- 

 quently to the disturbances which produced the contortions in all the older strata 

 of Devon ; and again, with reference to a given geological epoch, we know, from the 

 materials in the lower conglomerate beds, that the process, as just stated, had been 

 completed before the commencement of the new red sandstone formation ; but 

 there are also fragments in the Ugbrook strata which were derived from rocks pos- 

 sessed of a slaty structure ; and the limestone blocks in the lowest beds of carbo- 

 naceous deposits at Rydon show that the limestone generally at that early time had 

 its present crystalline, jointed structure. 



Faults, Fractures and Dislocations of the Strata. 

 These phaenomena are so familiar, that they require neither representation nor 



