EXPLANATION OF PLATE. 



From •tieoloy\ of tn« Bomoii Basin " by W. i >. <;ru*l»y, in Bos. <"C. Nat. Hist., 

 Occasional Papers, vol.4, part ]. 



Fig. 1. Natural section of the inclined double dike (34) on the western 



end of Rocky Neck. 

 Fig. -'• Dike 157 cutting a ledge of srrauile. near White Head, on 



Hominy point, Cohasset. 

 Tig. 3. A highly brecciated portion of the thin bed of indurated tnff 



on Long Beach rock. 



