264 GEOLOGY. 



less in extent in the latter than in the first part of the 

 age. The more the areas became divided, the more di- 

 versified and complicated were the deposits. 

 * 371. Tertiary Rocks. Most of the rocks of this age are 

 less firm than those of previous ages, but some of them 

 are very hard. They are, shell-rocks of various kinds, 

 shell-beds, or mixtures of shells and earth, sandstones, 

 marls, clays, beds of sand, compact limestones, conglom- 

 erates, buhrstones, etc. The lowest of the tertiary rocks 

 in Europe were made to a large extent from materials 

 derived from the denudation of the chalk formation. 

 For this purpose, the cretaceous strata were upheaved 

 from the sea in which they were formed, so that the de- 

 nuding water could act upon the chalk cliffs. A slow 

 process it was for the water to wear away sufficient 

 amounts of these emerged strata to form the lower ter- 

 tiary strata of Europe, and a long age was required to 

 do it. 



372. Nummulitic Formation. I have already noticed 

 in 239 those small shell-animals of the tribe Foramin- 

 ifera, the shells of which have formed such immense 

 quantities of rocky strata in Europe, and Asia, and Afri- 

 ca. In Fig. 159, at 1 and 2, are representations of num- 



Fig. 159. 



mulites as they are found in the rocks, and at 3 is a sec- 

 tion of one, showing its cells. The resemblance of these 

 fossils to pieces of money has given occasion to many su- 

 perstitious legends in regard to them among the Ger- 

 mans, and they are very commonly called the devil's 



