8 PROCEEDINGS OF THE COLUMBUS MEETING 



The following paper was entitled: 



GEOLOGICAL RESULTS OF THE INDIANA COAL SURVEY 

 I'.Y GEORGE H. ASHLEY 



I 'ontents 



Page 



Introduction 7 



Distribution and character of the coal fields 7 



Stratigraphy 8 



The coal beds n 



Structure 9 



Introduction 



Under the supervision of Mr W. S. Blatchley, State Geologist of Indiana, the 

 coal survey of the state was started in August, 1896, and completed early in 1899. 

 Associated with the writer in the fieldwork were Messrs C. E. Siebenthal, E. M. 

 Kindle, J. A. Price, J. T. Scovell, and Thomas AVatson. 



Distribution and Oharactek of the Coal Fields 



Geographically the Coal Measures of Indiana are part of the eastern-central, or 

 Illinois, basin, and are found in the southwestern .part of the state. A line en- 

 closing the tield would include about 9,000 square miles; but actually the Coal 

 Measures cover only between 6,000 and 6,500 square miles, of which about one- 

 half is underlain by workable coal. 



The surface features of the coal field are largely of the flat type, common to the 

 glacial area of the northern central states. Exposures of the country rock are rare 

 over most of the area, and exploration is mainly by the drill. The southeastern 

 part of the field is outside of the glacial area and ranges from very rugged along 

 the eastern edge, where the heavy basal sandstone outcrops, to flat or rolling over 

 most of the area to the west where shale outcrops predominate. 



Stratigraphy 



The relations of the Coal Measures to the Lower or Eo-carboniferous are those 

 of nonconformability. An uplift seems to have taken place toward the close of 

 the Lower Carboniferous period, most noticeable to the north, which, through failure 

 of original deposition or by subsequent erosion, or both, resulted in the absence of 

 the uppermost beds of the Lower Carboniferous in that direction, and left an irreg- 

 ular surface, upon which the Coal Measures were laid down. 



The first appearance of coal-forming conditions resulted in the laying down of 

 one or two unimportant beds, which to the north are generally absent or, when 

 found, appear to be confined to the hollows in the Lower Carboniferous surface. 

 Then came the deposition of a massive sandstone along the entire eastern edge of 

 the present coal field. This sandstone, which is occasionally gritty, is the equiva- 

 lent of the Pottsville conglomerate series of Pennsylvania. It appears to have been 

 ashore deposit, not underlying the main body of the Coal Measures, or subse- 

 quently removed, from the fact that many drillings a short distance west of its 

 outcrop report only shale at its horizon. Between this basal sandstone and the 

 main body of the Coal Measures is another noticeable nonconformity, as before, 

 more marked to the north. In this case the non-coal-forming conditions persisted 



