360 COUNTY AND KEGIONAL GEOLOGY. 



southwestern Iowa, if we except the lowest strata of Madison 

 and Decatur counties. It is regarded as equivalent with No. 

 1, of the section in the valley of the Tarkeo in Page county; 

 with No. 2 of the section at Winterset, in Madison county, and 

 with No. 2, of the section at Davis' mill, in Decatur county. It 

 will thus be seen that the lowest stratum exposed in Fremont 

 county, is regarded as equivalent with strata that further 

 eastward are known to be near the base of the Upper coal- 

 measures. It is of course inferred that that stratum is also 

 near the base of the same formation, unless those beneath 

 it have thickened very greatly in their westward extension. 



No doubt is entertained that the thin bed of impure coal 

 represented by No. 22, of the section at Wilson's, is identical 

 with the bed of coal that has been opened at various points 

 along the valley of the Nodaway, from the centre of Adams 

 county, to the southern boundary of the State. The horizon 

 of this coal is referred to near the base of the series of lime- 

 stone strata exposed near Winterset, in Madison county, and 

 above No. 3, of that section, as represented on a previous 

 page. If this reference is correct, it will be seen that there is 

 a greater aggregate thickness of limestone strata in Fremont 

 county, beneath the horizon named, than there is in Madison 

 county, which seems plainly to indicate a thickening of the 

 strata of the Upper coal-measures to the westward. 



Some borings and excavations have been made at Nebraska 

 City, on the west bank of the Missouri river, with the hope of 

 finding workable beds of coal among the strata beneath. The 

 boring is represented to have reached a depth of four hundred 

 feet without passing through a workable bed of coal, although 

 two or three thin coaly strata were pierced by the drill. It is 

 always difficult to obtain from a boring a perfectly clear idea 

 of the character of the strata passed through by the drill, but 

 judging from the report we obtained from the one in question, 

 all the strata seem to resemble closely in lithological charac- 

 ters, those of the Middle coal-measures. If this is really the 

 case, it gives evidence of a still greater thickening of the 

 strata of the Middle coal-measures than of the Upper. It can 



