688 



THE WONDERS OF GEOLOGY. Lect. VII. 



field, when treating of the trappean ridges of that part of 

 England. 



The faults and dislocations of the strata are so numerous 

 in many coal-fields, that they have been very aptly com- 

 pared by Dr. Buckland to a fractured sheet of ice: — "If 

 we suppose a thick sheet of ice to be broken into frag- 

 ments of irregular area, and these fragments again united 

 after receiving a slight degree of inclination to the 

 plane of the original sheet, the reunited fragments of ice 

 will represent the appearance of the broken masses or sheets 

 of coal strata. The intervening portions of more recent 

 ice, by which they are held together, will represent the clay 

 and rubbish that fill the faults, and form the partition 

 walls that insulate these adjacent portions of strata, which 

 were originally formed, like the sheet of ice, in one con- 

 tinuous plane."* 



There is a circumstance connected with the upheaving 

 and disruption of the carboniferous strata, and which is 

 also observable in other loosely aggregated deposits, that 

 demands attention. However great the uprise or downcast 

 of the rocks on one side of a fault, it is seldom that there 

 are any external indications of the displacement visible ; 

 as for example in the fault of Barrow above sketched 

 {Licjn. 153). J The removal of the upraised masses has 

 doubtless, in many instances, been occasioned by debacles 

 or floods of water that have swept over the surface of the 

 country ; but in those cases in which the elevated strata 

 were of great extent, and the displacement involved large 

 areas, it is probable that the removal was effected by the 

 action of the sea, when the rocks were first dislocated and 



* Bridgewater Essay. 



f Mr. Bakcwcll has treated this subject with great ability: see 

 chap. ix. " On the general removal and disappearance of the coal 

 strata, raised by faults above the surface of the ground." — Introduction 

 to Geology, 5th edit. p. 200. 



