264 DESCRIPTION OF THE MUSEUM. 



Then follow the numerous series of rocks 

 which compose the secondary formations, pro- 

 perly so called. It presents sediments and trans- 

 ported matter more easily recognized than those 

 of transition formation, although almost as per- 

 fectly consolidated and cemented. It is poor in 

 metals, but abounds in fossil remains without any 

 trace of mammiferous animals. It contains coal- 

 mines and the largest mines of sulphur and rock 

 salt. The volcanic productions of the middle age 

 of the globe are here seen dispersed under dif- 

 ferent forms. 



The rocks of tertiary formations immediately 

 fellow. The sediments and transported matter 

 which compose them are generally but imper- 

 fectly cemented, and of a very variable consis- 

 tence ; many are still loose ; with the exception 

 of iron ore, improperly called alluvial, we no 

 longer find amongst them metals which can be 

 worked. We meet with marls, clays, fuller's 

 earth and potter's clay, and common building 

 stones, materials easily worked because of their 

 softness ; but there are no more of those masses, 

 remarkable for the variety and brilliancy of the 

 polish which they are capable of receiving. The 

 only rocks, which are an exception, belong to 

 the volcanic productions of this period. 



The specimens of modern formations termi- 



