in Pennsylvania and Maryland. 



?relimi nary aMap 



of the 

 Volcanic 'Rocks 



of the 



South <tA\ountain 

 Tavvus$Yva<a\a ^MatojlwiA 



George H . Willia ms . 

 1892. 



Breccia. S*oidJtm Limes toil* 



(vdUanle) (Cambrian) 



