PART SECOND— GEOLOGY. 



CHAPTER I. 



CARBONIFEROUS AGE IN NEBRASKA. 



Preceding Conditions. — Carboniferous Age Proper. — Age of the Nebraska 

 Rocks. — A Different Opinion. — Section at Nebraska City. — Coal Features of 

 the Carboniferous Age in Nebraska. — Vegetation of the Coal Age. — Animal 

 Life of the Coal Age. — Climate of the Coal Age. — Permian Age. — Its Tran- 

 sition Character. — Character of the Permian Rocks. 



Preceding Conditions. 



IT does not enter into the plan of this work to treat of the 

 early condition of the globe, or even to discuss the earlier 

 periods of Palaeozoic times. Suffice it to say that our globe 

 was once companion star to the sun, and that after it had cooled 

 down sufficiently, the oceans were at first probably universal. 

 Then came a nameless period when lofty uplands were formed 

 towards the far north that supplied the materials for the old sea 

 bottoms that were afterwards uplifted and became known as the 

 Archaeon highlands of Canada and the United States. The two- 

 well marked divisions of these old deposits are known as Lau- 

 rentian and Huronian rocks. As the rocks of these ages still left 

 in Canada are forty thousand feet thick, and at least as extensive in 

 the Rocky Mountains and the Sierras, and still greater in Bohemia 

 and Bavaria, after being subjected to numberless ages of erosion, 

 the time represented by their deposition was greater, probably, than 

 the whole of geological history since their close. So far as we now 

 know, during all this immense age there was no dry land in Ne- 

 braska. 



Then followed what the geologists call Palaeozoic times, because 



of the antique or old life form of all the animals and plants in the 



old world. The earlier portions are known as the Silurian ages, 



during which invertebrate life was dominant, and the continent was 



ii 



