598 



been named. The great inconvenience of the 

 antient classifications is that of obliging the 

 geologist to establish fixed demarkations, while 

 he remains in doubt, if not respecting the spot 

 or the immediate superposition, at least on the 

 number of the formations which are not deve- 

 loped. How can we pronounce in many cir- 

 cumstances, on the analogy which a limestone 

 with but few petrifications may present with 

 intermediary limestone, and zechstein, or a 

 sandstone superposed on a primitive rock, with 

 variegated sandstone and quadersandstone, or 

 finally, muriatiferous clay, with the red marl of 

 England, and the gem-salt of the tertiary soils 

 of Italy ? When we reflect on the immense 

 progress made within twenty-five years, in the 

 knowledge of the superposition of rocks, it will 

 not appear surprizing that my present opinion 

 on the relative age of the formations of Equi- 

 noxical America, is not identically the same 

 with what I advanced in 1800. To boast of a 

 stability of opinion in geognosy is to boast of 

 an extreme indolence of mind ; it is to remain 

 stationary amidst those who go forward. What 

 we observe in any one part of the earth on the 

 composition of rocks, the subordinate beds 

 they contain, and the order of their position^ 

 are facts immutably true, and independent of 

 the progress of positive geognosy in other 

 countries, while the systematic names imposed 



