TEE LAPSE OF TIME. 317 



glance how far the hard, rocky beds had once extended 



into the open ocean. The same story is told still more 



plainly by faults — those great cracks along which the strata 



have been upheaved on one side, or thrown down on the 



other, to the height or depth of thousands of feet; for since 



the crust cracked, and it makes no great difference whether 



the upheaval was sudden, or, as most geologists now believe, 



was slow and effected by many starts, the surface of the 



land has been so completely planed down that no trace of 



these vast dislocations is externally visible. The Craven 



fault, for instance, extends for upward of thirty miles, and 



along this line the vertical displacement of the strata varies 



from 600 to 3,0U0 feet. Professor Eamsay has published 



an account of a downthrow in Anglesea of 2,300 feet; and 



he informs me that he fully believes that there is one in 



Merionethshire of 12,000 feet; yet in these cases there is 



nothing on the surface of the land to show such prodigious 



movements; the pile of rocks on either side of the crack 



having been smoothly swept away. 



On the other hand, in all parts of the world the piles of 



sedimentary strata are of wonderful thickness. In the 



Cordillera, I estimated one mass of conglomerate at ten 



thousand feet; and although conglomerates have probably 



been accumulated at a quicker rate than finer sediments, 



yet from being formed of worn and rounded pebbles, each 



of which bears the stamp of time, they are good to show 



how slowly the mass must have been heaped together. 



Professor Eamsay has given me the maximum thickness, 



from actual measurement in most cases, of the successive 



formations in dirfferent parts of Great Britain; and this is 



the result: 



Feet. 



Palaeozoic strata (not including igneous beds) 57,154 



Secondary strata "^o'o m 



Tertiary strata w,L40 



—making altogether 72,584 feet; that is, very nearly thir- 

 teen and three-quarters British miles. Some of the for- 

 mations, which are represented in England by thm beds, 

 are thousands of feet in thickness on the Continent. More- 

 over, betv/een each successive formation we have, in tlie 

 opinion of most geologists, blank periods of enormous 

 length. So that the lofty pile of sedimentary rocks in 



