GREAT WESTERN AMERICAN COAL FIELDS. 



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vation is only a few feet, as ascertained by actual survey. The gen- 

 eral elevation of this plain, is above 800 feet above the sea. It is 

 crossed by the great rivers Missouri, Mississippi, Ohio, and their bran- 

 ches. As we go westerly up the Missouri and Arkansas to the sand 

 plains, we find nearly the same elevation. The great and numer- 

 ous rivers that cross this plain, instead of forming valleys, do but in- 

 dent narrow lines or grooves into its surface, hardly sufficient to re- 

 tain their floods. As the currents of these rivers roll on in their 

 courses, they sink deeper into the plain ; hence the large rivers Ohio, 

 Missouri, and others, seem bordered with hills of several hundred 

 feet elevation, towards their mouths ; but the tops of these hills are 

 the level of the great plain. 



" The base of this whole extent of plain appears to be transition or 

 mountain limestone, in neary horizontal beds : it has been perforated 

 to the depth of 400 and 600 feet. It contains trilobites, orthocera- 

 tites, the productus, and other fossils that characterise the transition 

 limestone. The uppermost stratum of limestone is not many feet 

 below the surface, and supports, nearly over its whole extent, strata 

 of bituminous coal and saline impregnations. The limestone ex- 

 tends under the Alleghany Mountains in the east, and the sand plains 

 on the west, and rest on the granite ridges of Canada on the north. 



" This coal field would cover half Europe, having an extent of 

 900,000 square miles; or 1500 miles in length, by 600 miles in 

 breadth. The coal is pure, and lies above the beds of the rivers, 

 and costs about twenty cents (the fifth part of a dollar) per ton to 

 quarry it. Iron ore abounds generally, but in Missouri there is a 

 mass of this ore 300 feet in height, and five miles in extent, which 

 yields 75 per cent, of fine malleable iron. The lead districts of 

 Missouri and Illinois cover 200 square miles." It is not mentioned 

 in the above account, but there can be no doubt, that the mines are 

 situate in the limestone, which identifies that formation still farther 

 with the mountain limestone of England. 



In the geological position and physical structure of this vast coal 

 field, we may, I think, trace, in a satisfactory manner, the mode of 

 its formation. Were the outlet of the waters that drain this large 

 surface to be only partially closed (as we may suppose the mouth of 

 the Mississippi to be) by an earthquake or upheaving of the surface, 

 then in the time of annual periodical inundations, the whole extent 

 of this level plain would be covered with fresh water, and form an 

 inland sea, which would gradually become dfy as the inundations sub- 

 sided. This plain would then become a vast swamp, suited for the 

 rapid development of vegetation. In this manner thick beds of de- 

 composed vegetable matter might every year be formed, and subse- 

 quently covered with strata of mud and earthy matter, deposited du- 

 ring the inundation. 



Now let us advert to what actually takes place in the lower valley, 

 or plain of the Mississippi, every year. When those mighty rivers, 



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