SEDIMENTARY ROCKS OF SOUTH MOUNTAIN 



207 



Table of Geologic Formations for South Mountain, Pa., and Adjoining 

 Portions of the Cumberland Valley 



almost the whole interval of the formation, indicating a gradual 

 change from a fine mud deposit in the south to coarser siliceous sedi- 

 ments in the north. Similar conditions may have continued into 

 Antietam time, and have affected the deposition of the Antietam sand- 

 stone. The patchy occurrence of the Antietam in the Maryland 

 area, as mapped and described by Keith, may be due to its irregular 



