"lOO GEOLOGY OF TUB WEST. 



And in passing the Niagara and Trenton groups we were in the horizon of 

 the blue shales, cap-rock, ujiper and lower galena and blue limestone of the 

 npper Mississippi lead field. On reaching the bottom of our shaft we find a 

 coarse, brown, ferruginous sandstone ; and we might in the imagination fol- 

 low this floor to where it rises to-day around the Iron Mountains, 100 miles 

 south of the city, and where it dips under the great coal basins of Central 

 Illinois and Kansas, and comes to-day on the shores of Lake Pepin, Lake 

 Superior, and covering large areas in Northern Wisconsin, being the stratum 

 that bears the great pine flora of that State, and to where it extends out from 

 the "great basin," in a long finger through central New York. 



We have now a general idea of the underground system under this city, 

 and if we go back in the imagination to the time when the strata of the up- 

 per, middle and lower coal series had been laid down, and the inauguration 

 of the river systems commenced, we shall find that the coal vein of St. Louis 

 County coal basin and the Illinois coal basin in that era lay in solid strata 

 where the Mississippi Eiver now-fiows— that the strata were elevated along 

 the lines now followed by the river, and 300 feet of coal measures and St. 

 Louis limestone has been abraded, and a coal vein for ten miles wide has 

 been cut away to form the valley through Avhich the river now flows oppo- 

 site the city. 



The science of geology is based on the idea that like produces like ; that 

 the great is in the little, and vice versa, and that all the phenomena of the 

 earth's surface, and its strata, and vein system have been produced by the 

 constancy of action of natural economic laws, and that these causes are now 

 m action. And where are we to look for the causes now in action that laid 

 down upon the floor of an ocean the sedimentary matter to form all the strata, 

 from the sandstone in the bottom of this artesian well to the upper coal 

 series, say 6,000 feet vertical of strata ? We shall see. 



The Mississippi Eiver carries out millions of tons of sedimentary matter 

 daily from the washings of the banks of the hundred tributaries of the Gulf 

 of Mexico ; this sediment is there taken up by the Gulf Stream, and carried 

 North and spread over the floor of the Atlantic, when it settles in compara- 

 tively still water under what is known as the Saragossa Sea; and if we fol- 

 low up the genealogical thread or heraldry of this river system, we shall see 

 that this process of spreading detrital matter over the ocean's floor has been 

 going on since the river system in the "great basin "•Tvas inaugurated, and 

 the wearing down of the valleys of the Ohio, Tennessee, Eock Eiver, the 

 Missouri, Arkansas, and a hundred other branches, were carried forward. 



At Dubuque, Iowa, 600 feet-vertical strata have been cut away ; at Pitts- 

 burg, 400 ; at Cincinnati, 100 ; from the head of the Ohio to its mouth from 

 100 to 500 feet. The same of the Missouri, Arkansas, St. Peters, Cumber- 

 land, White, and hundreds of other branches. Enough sedimentary- matter 

 has gone out of the mouth of the Mississippi Eiver from the washing down 

 of the valleys of these streams and forming of the topographj^ of the great 

 basin of the Mississippi Eiver to have filled up the Gulf of Mexico and 



