SMITHSONIAN EXPLORATIONS, 1 939 



13 



Fig. 14.- 



-Great algal reef in nearly horizontal Upper Cambrian rocks on 

 San Saba River near Mason, Tex. 



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Fig. 15. — Northwest face of Beach Mountain showing Lower Ordovician 

 strata in middle ground and the massive Upper Ordovician limestone capping 

 the mountain. North of Van Horn, Tex. 



