MOXROE COUNTY. 



269 



from 8 to 12 degs. This axis forms a synclinal trough or valley on its 

 western sHe, extending; from the river bluffs north-west of Columbia to 

 the vicinity of Waterloo, with a varying width of from one to three 

 miles, in which an outlier of coal has been deposited, hereafter to be 

 described. The following weed cut will give a general idea of the rela- 

 tive position of the beds in this part of the county and the relation of 

 the Coal Measures to the underlaying limestones. The section repre- 

 sented by the cut crosses the beds from north to south, and extends 

 from the Coal Measures in the edge of St. Clair county east of Colum- 

 bia westwardly to the river bluffs, a distance of about three mil- 



a. Coal Measures; 6, St. Louis Limestone ; c, Chester Group ; d, Keokuk Group. 



From an examination of this section it will be seen. that, at its 

 northern extremity, the Coal Measures rest directly upon the St. Louis 

 limestone, while in the synclinal basin the coal holds its normal position, 

 overlaying, though unconformably. the Chester group. From these 

 facts we may infer that the disturbance in the underlaying limestones 

 took place anterior to the coal epoch, and that the beds on the northern 

 slope of the axis were subjected to erosive agencies, by which the whole 

 of the Chester group, including a thickness of at least one hundred and 

 fifty or two hundred feet of strata, were entirely removed, so that the 

 subsequently deposited Coal Measures rest directly upon the St. Louis 

 limestone. Evidences of the powerful action of erosive agencies im- 

 mediately antecedent to the coal epoch, have been observed in other 

 portions of the State, but no locality has been noticed where so great a 

 thickness of strata has been removed by such agencies as in this vicinity. 



The other axis to which we have referred, crosses the Mississippi in 

 the vicinity of Platin rock, in Missouri, where, according to the section 

 of Dr. SHUMARD, given in Vol. I of the Missouri report, page 14o, the 

 St. Peter's sandstone (or Saccharoidal sandstone of that report,) is ele- 

 vated above the river level, and there forms the nucleus of an anti-cliual 

 axis, and although the dip and strike of the beds at that point are not 

 given in the report above referred to. yet it seems quite probable that 

 the elevation of the Trenton limestone alx>ve the surface at Salt-lick 

 Point, in this county, is but a continuation of the same axis, which 

 brings up the underlaying sandstone on the Missouri shore. This axis 

 does not appear to extend very far to the eastward of the river bluffs 

 in this county, and the Trenton limestone only appears along the base 

 of the bluffs for a mile and a-half or two miles, when it sinks rapidly 

 below the surface, and is replaced by the overlaying shales and liine- 



