Detrital Theory of Geology. 327 



formation, being derived from previous strata or rock, is so 

 plain and under such simple physical conditions, that the 

 resuk is entirely impossible. 



No one has more simply and lucidly described these con- 

 ditions than Mrs. Somerville (" Physical Geography," 4th 

 edition, 1858) : " Aqueous rocks are all stratified, being 

 sedimentary deposits from water. They originate in the 

 wear of the land by rain, streams, or the waves of the ocean. 

 The debris carried by running water are deposited at the 

 bottom of the seas and lakes, where they are consolidated, 

 and then raised up by subterranean forces, again to undergo 

 the same process of destruction, after a lapse of time. By 

 the washing away of the land, the rocks are laid bare ; and 

 as the materials are deposited in different places according 

 to weight, the strata are exceedingly varied, but consist 

 chiefly of arenaceous or sandstone rock, composed of sand, 

 clay, and carbonate of lime." 



Taking the above as a correct statement of the detrital 

 theory, the inevitable conclusion arrived at must be that of 

 a contradiction, providing it is maintained that every stratum 

 has its own peculiar organic remains, and every stratum 

 derived from such previous order of stratification is, as to 

 entire identity of individual species, perfectly free. Or, in 

 other words, the derived must be, in all points of organism, 

 self- created and independent of the source from whence it 

 proceeds. And the organic remains being to each stratum 

 peculiar, upon a derived or detrital theory, is self-destruc- 

 tive. 



Many other difficulties, upon a detrital theory, might be 

 urged such as the tertiary basins ascending above and de- 

 scending below the sea level in the midst of secondary rocks, 

 and obtaining successive land and marine remains ; whilst 

 the granite itself, which underlies all rocks, must fracture 

 around the limits of the basin several successive times, in such 



