20 Mr. Fairholme on the Falls of Niagara 



miles, and from the northern lakes to the mouth of the Ohio, 

 a width of nearly 600 miles. They have been so well de- 

 scribed in the second Number of the Illinois Monthly Maga- 

 zine, as quoted by Mr. Stuart in his late able work, that I 

 cannot resist inserting an outline of the statement. These 

 plains embrace the States of Ohio, Indiana, Illinois, Missouri, 

 Kentucky, and parts of Pennsylvania, Virginia, Tennessee, 

 Arkansas, and Michigan, as well as a wild region of about 

 500 miles wide, lying to the west of these States. No part of 

 the globe, perhaps, presents so uniform an extent of fertility. 

 There are no sterile districts, no"rocky or precipitous ridges, 

 and but few swamps to deform so fair a surface. This unin- 

 terrupted fertility is stated to arise from the decomposition of 

 the great limestone pan on which they repose, and which 

 pan, we have seen, is in part intersected by the action of the 

 waters of Niagara. This whole level region, though traversed 

 by numerous rivers, is not a valley, or a system of valleys, 

 but a real steppe, or plain, over the whole of which there is 

 but a very slight difference of elevation. The N.E. corner of 

 the plain near Pittsburgh, in Pennsylvania, is about 800 feet 

 above the level of the sea ; the plain of Kentucky and Ten- 

 nessee is about the same height ; that of the Ohio is but little 

 different; and to the westward of the Missouri and Arkansas 

 to the sand plains, the same conclusions force themselves 

 upon us. 



The great and numerous rivers which cross these plains, 

 instead of forming distinct valleys, do but indent narrow 

 scratches or grooves into the surface, barely sufficient to con- 

 tain their waters. These river channels have formed a decli- 

 vity for themselves, and towards their terminations they sink 

 deeper into the plain : hence the larger rivers appear to be 

 bordered by abrupt hills of several hundred feet of elevation ; 

 but this is, in fact, only in appearance ; the tops of these 

 heights are but the general level of the great plains. 



The following short outline of the general geology of these 

 countries is given in the Magazine above mentioned. " The 

 formation of these plains is decidedly secondary, reposing on 

 a horizontal limestone rock, the thick strata of which have 

 never yet been penetrated, although the auger has pierced in 

 many different places from 400 to 600 feet in search of salt 

 water. This limestone is hard and stratified, imbedding in- 

 numerable sea shells of the Terebratula, Encrinites, Ortho- 

 ceratites, Trilobites, Products, &c. This limestone pan is ge- 

 nerally but a few feet below the surface, and supports strata 

 of bituminous coal and saline impregnations through almost 

 its whole extent. The decomposition of its parts has fertilized 



