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Art. XIV . — On Fossil Organic Remains as a means of dis^ 
tinguisMng Rock-formations. * 
The relative position of rocks can alone furnish the essential 
characters for recognising and distinguishing the different for- 
mations of mineral masses which constitute the solid crust of the 
globe, and afford us data for judging of their identity and relative 
age. Their structure, the minerals of which they are composed, 
and the organic bodies which several of them contain, should only 
be considered by the geologist as accessory, and in a manner 
subordinate, characters, however important the aids which they 
afford him in his inquiries. 
The observations of M. de Buch and M. Hausmann, with re- 
gard to the syenite of Norway ; those which have been made up- 
on a similar deposit by M. Brongniart in the Cotentin ; those 
which M. Brochant has made upon the transition formation of 
the Tarentaire; and those of M. de Bonnard upon the same for- 
mation in the Hartz, sufficiently prove, that neither the struc- 
ture nor the composition of rocks, taken by themselves, can af- 
ford certain indications with respect to the relative age and iden- 
tity of the different formations. The Pyrenees present similar 
facts, as will be presently seen. 
The presence of organised bodies is, it is true, the most essen- 
tial character according to which we may pronounce that a rock 
belongs to the class of secondary, or to that of transition, for- 
mations. But, as each of these classes contains several sorts of 
deposits, it is necessary to determine the one to which the rock 
in question is to be referred ; and, for this purpose, we must pre- 
viously have distinguished these particular deposits from each 
other with accuracy, fixed their number, which is perhaps great- 
er than has hitherto been supposed, and determined their rela- 
tive age, as well as found means to recognise their identity in the 
different countries in which they are observed. Now, it is for 
this important inquiry, which, in some measure, constitutes one of 
the chief objects of geognosy, that the knowledge of the organi- 
sed bodies which these deposits contain, does not appear to me 
to be sufficient. 
From Charpentier’s Essay on the Pyrenees, 
