THE FORMATIONS 103 



above named. Every feature of the Tola field indicates a porous or res- 

 ervoir rock as the source of its gas. 



GEOLOGY OF THE REGION 



Sources of information. — The geology of southeastern Kansas is com- 

 paratively simple. In describing it I rely mainly on the published re- 

 ports of the geological survey conducted by the state university under 

 the direction of Professor Erasmus Haworth. 



The formations — Coal Measures and sub-Carboniferous limestone. — All 

 strata reaching the surface in this section of the state belong to the so- 

 called Coal Measures, with the single exception of the great sub-Carbon- 

 iferous limestone, which may be regarded as the floor of the eastern half 

 of Kansas. This stratum rises today only in the southeastern angle of the 

 state, and its outcrop does not exceed 45 square miles ; but though small 

 in area, it has extreme economic interest and importance, for it carries 

 zinc and lead ores in large quantities. As a source of the former, this 

 45 square miles is beyond question the most valuable tract known in 

 the United States. Perhaps no equal area in the world exceeds it in 

 this respect. This sub-Carboniferous stratum is coming to be known in 

 Kansas and the adjoining states as the Mississippian limestone. In 

 sinking deep wells it constitutes a particularly valuable landmark, be- 

 cause its flinty beds are certain to attract the driller's notice and are 

 universally regarded by him in his search for petroleum as the "fare- 

 well rock." When he strikes this floor he knows that his work is done. 



There are large areas of Kansas and adjoining states in which the 

 Coal Measures, so called, do not justify their name. In many long sec- 

 tions furnished by the drill they are found to consist altogether of lime- 

 stone, shale, and sandstone; but in other districts the series contain 

 imj)ortant beds of coal, the aggregate of which, as computed, runs into 

 large figures, and constitute an invaluable reliance of all these regions 

 for time to come. 



The western Coal Measures have been variously divided by the geol- 

 ogists who have studied them in the several states. It is a pleasure to 

 find that they are coming to a general agreement, which promises at no 

 distant day a harmonious account of this great chapter of our geological 

 history. 



Cherokee shales. — In southeastern Kansas, the lowermost division of 

 the Coal Measures, namely, that immediately overlying the Mis.sissip- 

 pian limestone, is known as the " Cherokee shales." It is counted the 

 equivalent of the " Des Moines shales " of Keyes in Iowa. The Cherokee 

 shales have a thickness of about 450 feet and contain, in certain districts, 

 by far the most valuable seams of coal found in Kansas. Though con- 



