MARYLAND GEOLOGICAL SURVEY 93 



following generalized section for Maryland and southern Pennsylvania 

 lias been described by Ulrich in his Revision of the Paleozoic Systems : ' 



Generalized Section of Beekmantown Limestone in Southern Pennsylvania 



and Maryland 



Feet 

 Base of Stones River limestone with quartz pebble conglomerate and 



cauliflower chert 



Hard dense white chert and granular quartzose chert forming by 



secondary silicification, cauliflower chert 40 



Fine grained gray, finely laminated, interbedded pure and magneslan 

 unfossiliferous limestone with sandy chert and limestone and 



dolomite conglomerates at the top 400 



Turritoma zone. Thin bedded argillaceous and massive purer limestone 

 containing the Turritoma fauna. Many of the beds weather so 

 as to appear riddled with worm borings 200 



Alternating beds of pure dove, pure gray and magnesian gray unfos- 

 siliferous limestone often laminated, with occasional beds of fine 

 limestone conglomerate 300 



Massive pure dove gray and magnesian limestone terminated above 

 by sandy fossiliferous chert containing Syntrophia later alls, 



Maclurites sordida and species of Liospira 75 



Ceratopea zone. Blue and dove fossiliferous limestone cherty in the upper 

 half, containing Ceratopea and associated fossils. At the base is 



a blue limestone filled with rounded quartz grains 250 



Cryptozoon steeli zone. Fine grained nearly pure limestone with some 



magnesian beds and several layers of porous chert 275 



Dove, pink and bluish fine grained pure limestone and marble 300 



Oolitic, cherty blue and gray limestone holding the Cryptozoon steeli 



fauna and weathering into platy yellow chert 60 



Stonehenge limestone member. Massive dark blue to gray limestone with 

 contorted argillaceous and siliceous laminations weathering to 

 sandy shale, interbedded with edgewise beds and oolites 250 



Massive blue to gray pure limestone weathering white, with cepha- 



lopods and gastropods occurring in reef structures 250 



Top of Conococheague limestone with sandy laminae and beds of edgewise 



conglomerate 



2400 



From the stratigraphic standpoint the important divisions of the above 

 section are the Stonehenge member and the three zones marked respec- 

 tively the Cryptozoon steeli, Ceratopea, and Turritoma zones. The faunal 

 and other characteristics of these zones are discussed in succeeding 

 paragraphs. 



1 Bull. Geol. Soc. America, vol. xxii. No. 3, 1911, pp. 652-655. 



