POSITION OF STRATIFIED ROCKS. 55 



fore assumed a position more highly inclined to the 

 horizon than those of a subsequent formation." 



83. " Are earthquakes just the shifting of strata 

 while accommodating themselves to a globe which is 

 constantly diminishing in magnitude ? " 



84. " Was the substance of a vein originally dif- 

 fused throughout the strata which include the vein, 

 and which has been expressed from the strata after 

 the formation of the fissure which now contains it ? " 



ON THE FORMATION OF LIMESTONE 

 BEDS. 



85. What is the origin of those beds of limestone 

 which are found associated with the members of 

 the various geological formations ? As beds of lime- 

 stone are not the result of a mechanical deposit, but 

 of a chemical precipitate, must not the formation of 

 those beds be accounted for, not upon mechanical, 

 but chemical principles ? 



86. It is a fact well known to chemists, that two 

 equivalents of carbonic acid gas, when subjected to 

 a given pressure, will combine with one equivalent 

 of lime, when held in solution, and form the bi-car- 

 bonate of lime a salt that is soluble in water ; and 

 should the pressure be afterwards removed, one of 



