POSITION OF STRATIFIED ROCKS. 51 



could not have been greater than was commensurate 

 with the width of the fissure through which the 

 molten matter was discharged. Now in geological 

 sections, the fissures through which the igneous 

 matter is discharged, are represented as not of 

 great width, and quite inadequate to have induced 

 by a lateral pressure those undulations which often 

 extend over a whole district of country. 



79. What is true in respect to the primitive and 

 transition strata holds true in respect to the secondary 

 and tertiary classes of rocks, inasmuch as the hori- 

 zontal base which subtended those strata when they 

 were deposited was greater than the horizontal base 

 which now subtends them, while this difference in 

 respect to the horizontal base of the tertiary strata 

 is less than that of the secondary rocks ; and, as a 

 general law, the difference is always the greater, 

 according to the seniority of strata in respect to the 

 period of their deposition. How is this ? May it 

 not be explained, as before, upon the supposition, 

 that, during the formation of the crust of the earth, 

 the nucleus of the globe has ceased not to undergo 

 a constant increase of density, and therefore a con- 

 stant diminution of magnitude ? 



80. What has been the cause of that want of 

 conformability which is found so often to occur 



E 2 



