CAEB0N1FER0US SYSTEM. 259 



of success, at moderate depth beneath the surface, or by 

 drifting into the sides of the valleys. Beyond the region 

 represented by that sheet, to the northward and eastward, 

 the search for coal will not only be extremely hazardous, but 

 there is in all that part of the State no hope of finding it at 

 all, except in probably insignificant quantities from small 

 outliers, or at no great distance from the unbroken border of 

 the coal-field, as represented in the map-model, and also 

 upon the geological map. To the southward and westward 

 of the area which the uncovered part of the sheet represents 

 in the map-model, however, the case is very different ; 

 because in those directions the coal-producing strata pass 

 entirely beneath the unproductive ones, and do not disap- 

 pear by thinning out as they do in the opposite directions. 



If the coal producing formations extend nearly two hundred 

 miles in a northwesterly and southeasterly direction, and more 

 than fifty miles in an easterly and westerly direction, as we 

 know they really do in the region where they occupy the 

 surface, it is reasonable to infer that they may extend at least 

 as far in a westerly and southwesterly direction beneath the 

 other formations with just as little change. In other words, 

 it is reasonable to infer, that beds of coal exist beneath the 

 surface of the southwestern part of the State, similar to those 

 now known and worked near the surface in the vicinity of the 

 valley of the Des Moines river. Of course this implies their 

 continuous extension beneath the surface of the whole area 

 comprised between the Des Moines and Missouri rivers, and 

 between the parallel of Fort Dodge and the southern boun- 

 dary of the State; and at a gradually increasing depth, at 

 least in a southwesterly direction. 



This view of the relative position of the strata being 

 accepted, the question of the greatest importance is, how far 

 beneath the surface, at any given point, do the beds of coal 

 probably lie, if they exist at all, and is the depth an imprac- 

 ticable one for mining operations ? The conclusions arrived 

 at from an examination of the subject thus far, may be 

 summed up as follows : It may be regarded as certain that 



