314 COUNTY A1SD KEGIONAL GEOLOGY. 



principal beds of coal in the State lie within a series of strata 

 that belong entirely beneath all those to be fonnd exposed in 

 this county. Therefore, all the coal of any importance that 

 may yet be found within its limits, must be sought for by 

 sinking shafts to a considerable depth beneath the surface. 

 As all the strata lie in a comparatively horizontal position, 

 and do not conform to the inequalities of surface, it will 

 readily be seen that much useless labor will be saved by 

 commencing such enterprises in the valleys. Thus, for 

 example, if the people of Winterset should desire to commence 

 such a work they would save more than two hundred feet of 

 digging by commencing in the bottom of the valley of Middle 

 river, rather than upon the general surface upon which the 

 town is located. 



The most important practical question that presents itself 

 just here is, how deep must we go in this county to find a 

 good bed of coal ? This question cannot be answered with 

 certainty without actual trial, nor can it be said with certainty 

 that any profitable bed of coal will be found if such shafts 

 are sunk there. There are, however, excellent general 

 reasons for inferring that one or more profitable beds of coal 

 may thus be found, and none why they should not be, all 

 of which have been explained on previous pages. For 

 example, at Compton's mill, near Winterset, the upper strata 

 of the Middle coal-measures appear in the bottom of the 

 valley. This formation, Prof. St. John has shown in his 

 report to be about two hundred feet thick in the counties 

 northward, and also that it contains three or four thin beds 

 of coal, all of which are probably too thin for profitable 

 mining at any considerable depth. The Lower coal-measure 

 formation doubtless exists in this county beneath the Middle 

 and Upper, but its own upper strata are probably at least 

 two hundred feet beneath the bottom of the valley at Winter- 

 set. Since the Lower coal-measures contain all the thickest 

 and best beds of coal it may be expected that shafts sunk 

 in the bottom of Middle river valley would have to reach 

 a depth of at least two hundred feet before a bed of coal will 



