AZOIC AGE. 183 



contracted, and this contraction crumpled it into folds, 

 regular and irregular, and thus made channels and cavi- 

 ties for the water to run and dash in. Water then be- 

 gan that great work of denudation, which, as you have 

 seen in previous parts of this book, it has been carrying 

 on ever since. From that denudation in this first age 

 of the world was supplied material for the strata of the 

 grand azoic floor, which covers up the fiery deeps with- 

 in, and upon and against which the rocks of after ages 

 were laid. So great have been the changes in the azoic 

 rocks, that it is impossible to distinguish among them 

 any that can with certainty be made out to be portions 

 of the original crust that is, portions of the first solidi- 

 fication. 



266. Some of the present Land formed in the Azoic 

 Age. In some quarters of the earth the azoic rocks ap- 

 pear upon the surface of the earth's crust. These, as 

 Professor Dana states, are "either, 1. Those which have 

 always remained uncovered ; 2. Those which have been 

 covered by later strata, but from which these superim- 

 posed beds have been simply washed away without much 

 disturbance ; 3. Those once covered, like the last, but 

 which, in the course of the upturnings of mountain-mak- 

 ing, have been thrust upward among the displaced stra- 

 ta, and in this way have been brought out to light." The 

 areas in which the rocks appeared above the surface of 

 the water during the Azoic age were scanty compared 

 with the whole area occupied by the land at the present 

 time. These areas were the beginnings of the conti- 

 nents, and it was by successive additions to them during 

 the succeeding ages that the continents grew to be what 

 they now are. 



267. America and Europe in the Azoic Age. The azoic 

 rocks that come to the surface in North America occupy, 

 for the most part, a very long and comparatively narrow 

 strip of land extending from Nova Scotia west to the 

 base of the Rocky Mountains. This monstrous island 



