GEOLOGICAL EXCURSION O 



GEOLOGICAL EXCURSION IN THE PITTSBURG REGION 

 BY II. S. GRANT 



Contents 



Page 



Intiodnctiou 3 



Stratigraphic and economic geology 3 



Physiographic and glacial geology 4 



Personnel of the excursion 4 



iNTRODUCTfON 



Previous to the Pittsburg meeting of the Geological Society of America and the 

 American Association for the Advancement of Science, an excursion, lasting from 

 June 23 to June 30, 1902, was arranged for members of these two societies by our 

 Treasurer, Dr I. C. White, of Morgantown, West Virginia. 



Pittsburg is the center of one of the most important manufacturing districts in 

 the world, and owes its high commercial standing to the richness of the surround- 

 ing district in coal, and latterly in oil and gas. With this city as a center, daily 

 trips were taken in various directions within a radius of 50 miles, and the excur- 

 sion ended with a trip to Morgantown, 102 miles from Pittsburg. Throughout the 

 excursion there was abundant opportunity to study each day two different sets of 

 phenomena, which may be conveniently grouped under the heads of (1) strati- 

 graphic and economic geology, and (2) physiographic and glacial geology. 



Stratigraphic and Economic Geology 



In the region adjacent to Pittsburg are numerous and complete exposures of the 

 rocks from the base of the Lower Carboniferous to the top of the Coal Measures. 

 The formations present are as follows : 



f Dunkard formation (Upper Barren Measures). 

 Monongahela formation (Upper Productive Measures). 

 Upper Carboniferous or Pennsylvanian...^ Conemaugh formation (Lower Barren Measures). 



Alleghany formation (Lower Productive Measures). 

 [Pottsville formation (Millstone grit), 

 f Mauch Chunk formation. 



Lower Carboniferous or Mississippian \ Greenbrier formation (Mountain limestone). 



[ Pocono formation. 



Pittsburg is located on the Conemaugh formation, and the great Pittsburg coal 

 seam (at the base of the Monongahela) caps the hilltops. Within the Conemaugh 

 are several members, one of the most important of which is the Green Cri- 

 noidal limestone, which is used as a horizon marker, being recognizable in western 

 Pennsylvania, western Maryland, West Virginia, and Ohio. In the last named 

 state it is known as the Ames limestone. 



During the excursion an examination was made of several detailed sections, 

 especially of the Pottsville, Alleghany, Conemaugh, and Monongahela formations, 

 and there was an opportunity to compare sections of these same formations at 

 widely separated localities. In this comparison those who participated in the ex- 

 cursion were impressed with the great extent of some of the thin members of the 

 Coal Measures and with the fact that these thin beds retained their characteristic 



