162 GEOLOGY. 



growing and extending southward from its Archseon nucleus. The 

 next age, called often the age of fishes, and also known as the De- 

 vonian, followed, but neither in this or in the preceding Silurian 

 was any dry land in Nebraska. By the close of this age, however, 

 the continent in its southern extension had reached the south line 

 of what is now New York, and maiTy islands also existed still 

 farther south, and in some places w r est. The Appalachian region 

 seemed to have been rich in low islands, covered with a colossal 

 vegetation. The sub-carboniferoos period, which had such a re- 

 markable development in some sections of Illinois, Kentucky, Iowa 

 and Missouri, and which was the stage preparatory to the carbon- 

 iferous period proper, is not represented by any known deposits in 

 Nebraska.* Even the millstone grit so common in the East, under 

 the coal, has not here been found. Whether it exists at all in this 

 region can only be ascertained when borings or shafts reach its 

 geological equivalent. We come now to 



The Carboniferous Age Ptoper. — This is a geological age of the 

 most absorbing interest, because of the general character of the 

 time, and because during its progress the first dry land a£)peared in 

 Nebraska. The carboniferous age was one of the most wonderful 

 in all the history of the globe, for during its progress the thickest, 

 most extensive and most valuable of all the coal beds were formed. 

 It has excited the most profound interest alike of the political econ- 

 omist, the statesman, the chemist and the geologist. 



To understand the probable history of geological events in Ne- 

 braska during this period, let us look at the oldest coal beds that 

 are nearest to us. These are the beds along the Des Moines River 

 and some of its tributaries extending westward within from seventy- 

 five to one hundred miles of the Missouri. The coal here, which 

 Dr. White regards as of Lower Carboniferous age, is from one to 

 seven feet in thickness. Worthen first, and then Dr. White to a 

 much greater extent, investigated these beds. Meek also carefully 

 re-examined them. Subsequently I passed over the same region, 

 attempting as Meek and White had done before me, to estimate the 

 thickness of the rocks that lapped over the coal bearing strata as 

 far west as the farther or Nebraska shore of the Missouri. Meek's 

 objective point was Nebraska City, and mine was Plattsmouth. I 

 shall therefore use Meek's observations to supplement my own. 



*The opinion of Marcou and Geinitz (Bulleton Geological Society of France, XXI., etc., 

 New Series), that some of our Nebraska rocks are sub-carboniferous, was shown long ago, by 

 Meek, to be a mistake. 



