THE CAMBRO-ORDOVICIAN LIMESTONES OF THE 

 APPALACHIAN VALLEY IN SOUTHERN 

 PENNSYLVANIA^ 



I 



GEORGE W. STOSE 

 Washington, D. C. 



The limestones of the Appalachian Valley, which in the South are 

 separated into many formations, have generally been treated as a unit 

 in the North under the name Shenandoah, or other local terms, such 

 as Valley, Lanqaster, Kittatinny, and York. These rocks include 

 all the strata between the Cambrian quartzites of Georgian age and 

 the Martinsburg ("Hudson") shale of Ordovician age. 



In a paper on the sedimentary rocks of South Mountain^ the author 

 briefly described the formations comprising the Shenandoah group 

 in southern Pennsylvania. Later studies of these rocks in the Cum- 

 berland Valley of Pennsylvania have furnished data for a more complete 

 description of the group, including the faunal content and correlation, 

 based on determinations by E. O. Ulrich. 



The formations comprising the Shenandoah group in southern 

 Pennsylvania are as follows: 



_E3 



in 



Martinsburg formation 



Chambersburg limestone 100-600 feet 



Stones River limestone 800-1000 feet 



Beekmantown limestone 2250-2300 feet 

 Conococheague limestone 1635 ± feet 

 Elbrook formation 3000 ± feet 



Waynesboro formation 1250 rt feet 

 Tomstown limestone 1000 d: feet 



Antietam sandstone 



Eden 

 Utica 



Upper Trenton 

 Lower Trenton 

 Black River 

 Lowville 

 Upper Chazy 

 Lower and 



middle Chazy 

 Beekmantown 

 Saratogan 



Acadian 



Ordovician 



[ Georgian 



Cambrian 



The general structure of the Cumberland Valley is a monocline, 

 the oldest rocks of the Shenandoah group resting against the Cam- 



iPublished with the permission of the Director of the U. S. Geological Survey. 

 2 Jour, oj Geol., Vol. XIV, 1906, pp. 201-20. 



698 



