MARYLAND GEOLOGICAL SURVEY 151 



Section of Chambersburg Limestone on West Branch of Conococheague Creek, 

 2y 2 Miles Southeast of Mercersburg, Pennsylvania 



Martinsburg shale. Feet 



Fissile shale, overlying calcareous black shale and hard thin 

 black carbonaceous limestone, containing graptolites and 



Lingula 



Granocrystalline, very fossiliferous limestone (Sinuites bed) . . 2 

 Chambersburg limestone. 

 Nidulites bed. 



Cobbly dark subcrystalline limestone, both massive and thin 



bedded 73 



Tetradium cellulosum bed (Lowville). 



Coarse, massive granocrystalline limestone with massive beds 

 of pure fine-grained limestone containing Beatricea and 



Tetradium cellulosum 75 



Caryocystites bed. 



Platy granocrystalline limestone, very fossiliferous 25 



Dark subcrystalline limestone with wavy partings of shale; 



fossils rare 150 



Stones River limestone. 



Very thin bedded pure fine-grained drab limestone underlain by 

 more massive pure beds with magnesian layers and fine 

 laminations containing Leperditia 



323 



In the few bands of outcrops of this limestone in Maryland and West 

 Virginia its development is interesting for several reasons. First, the 

 Lowville limestone portion or Tetradium cellulosum bed, and also the 

 Caryocystites bed are both absent. Second, the Nidulites bed forms the 

 main mass of the formation, and, third, the Christiania bed is present 

 west of the shale belt, but in greatly diminished thickness. 



The following section at Pinesburg Station, Maryland, is typical for 

 the state. At this place the Echinospherites bed is well exposed, but the 

 best exposures of the Nidulites bed are farther north at Wilson, Maryland. 

 Nowhere are there good outcrops of the Christiania bed. 



Section of Chambersburg Limestone at Pinesburg Station, Maryland 



Martinsburg shale. Feet 



Black fissile shale 



Calcareous shale and argillaceous shaly limestone with grapto- 

 lites near base . . 



