'Baron Humboldt on Hock Formations* 
live rocks, and placed below those in which the vestiges of or- 
ganic life begin to appear, are newer than the secondary rocks 
of another country. I confess, that, in the part of the globe which 
I have had an opportunity of examining, I have not seen any 
thing that might tend to coniirm this opinion. Granular syeni- 
tic rocks repeated twice, perhaps even three times, in primitive, 
intermediary (and secondary) deposits, are analogous phenome- 
na with which we have become acquainted within these fifteen 
years. The disagreement in regal'd to age of great homonymous 
formations, does not by any means seem to me to be proved as 
yet by direct observations, made upon the contact of superim- 
posed formations. The chalk or Jura limestone may, on one 
hand, immediately cover primitive granite, and, on the other, be 
separated from it by numerous secondary and transition rocks : 
these very common facts demonstrate only the abstraction, the 
absence, or non-development of several intermediary members 
of the geognostical series. The greywacke may, on one hand, 
dip beneath a felspar rock, or rock of which felspar forms a 
principal constituent ; for example, beneath transition granite or 
'zircon syenite ; and, on the other hand, be superimposed upon 
the black limestone containing madrepores ; but this position 
shows only the intercalation of a bed of grey wacke between fel- 
spar rocks. Since the minute investigation of fossil organic bo- 
dies has, through the important labours of Messrs Cuvier and 
Brongniart, diffused a new life as it were in the study of the 
tertiary formations, the discovery of the same fossils in analogous 
beds of very distant countries, has rendered the isochronism of 
very generally extended formations still more probable. 
It is4his isochronism alone, this admirable order of succession, 
which seems given to man to investigate with some degree of 
certainty. The attempts which theological geologists have made 
to subject the periods to absolute measurements of time, and to 
connect the chronology of ancient cosmogonic narrations with 
the observations of nature, could not possibly have been produc- 
tive of satisfactory results. “ It has been more than once,"” says 
M. Ramond, in a discourse replete with philosophical views, 
‘‘ thought that a supplement to our short annals might be found 
in the monuments of Nature. There is, however, enough of his- 
torical ages, to let us see that the succession of physical and mo-^ 
