CEETACEOUS AGE. 



396. The complete series of strata of the Cretaceous for- 

 mation, are found succeeding each other in their proper order in 

 the continuation of the section given in fig. 152. This conti- 

 nuation, 'extending from Sommevoire and Yassy to Yertus, is 

 given in fig. 170. The Cretaceous group terminates a little to the 

 west of Yertus, and the Tertiary or succeeding formation appears 

 from that point to Paris. We shall refer to this latter part of the 

 section when we come to notice the Tertiary age. 



CRETACEOUS FORMATION. 



1 1 



Fig. 170. Section from Vassy to Vertus, being part of the great section 

 from the Vosges to Paris. 



397. Proceeding upon observations and reasoning similar to 

 those explained in reference to the Jurassic formation (322), M. 

 D'Orbigny resolves the Cretaceous formation into seven stages, to 

 which names are given, derived from the localities severally where 

 the strata are most exposed at the surface, and where therefore 

 they have been most observed. To avoid encumbering the 

 memory of the reader with a nomenclature so complex, we shall 

 here, as in the former cases, designate the stages by their nume- 

 rical order, proceeding from the lowest upwards, and the periods 

 of their deposition into which the Cretaceous age is resolved, also 

 by their numerical order, proceeding from the earliest to the 

 latest. 



398. It will be convenient, however, as in the former case, to 

 indicate the names given to the stages and their approximate 

 mean thickness severally. 



95 



