372 



HISTORICAL GEOLOGY 



FIG. 388. Trends of the folds produced during the late Paleozoic moun- 

 tain T building epoch in western Europe. 



are so old that they have been worn down to mere stubs, 

 such as the low mountains and hills of the Black Forest 

 and Cornwall. But in their prime they may well have been 

 lofty, snow-capped ranges, and for that reason they are styled 

 the Paleozoic Alps. 



LIFE OF THE MISSISSIPPIAN SEA 



On account of the wide extent of the clear Mississippian 

 sea, it is but natural that of all the life of the period we should 

 know the marine animals best. Very few animals and plants 

 of the dry land have escaped destruction, nor are those of 

 rivers and swamps well represented among the fossils of the 

 time. 



Abundance of the crinoids. In the limestones of earlier 

 periods we have noted the abundance of either corals or cri- 



