INTKODUCTION 



569 



across it at Piedmont, the southern extension of the basin being known 

 as the Upper Potomac basin and the northeastern as the Georges Creek 

 basin. The relations of these basins are shown in the accompanying map. 

 The investigation of the area under consideration presents many diffi- 

 culties. Its surface is mountainous and much of it is heavily forested. 

 The rocks have steep dips and are buried at many places under deep 

 overwash. Much of the region is little dissected. Trustworthy drill 

 records were entirely lacking in the chief coal-producing area, the 

 Georges Creek basin, when this investigation was undertaken. 



Figure 1. — Map of the Coal Basins of Maryland 



EARLIER INVESTIGATION 



The Coal Measures of Mar5dand have been studied in greater or less 

 detail by many able and talented geologists in the past, including 

 Tyson, I. C. White, Darton, Taft, Prosser, O'Harra, Clark, Martin. 

 Stose, and various members of the Maryland Geological Survey. The 

 coal beds have also been examined by mining engineers who have been 

 associated with the various coal companies of the State. The authors 

 feel that conclusions which differ from those obtained by such able 

 workers should be presented with great reserve. 



