of JBosfo fi^a ml iis Vicin iiij. 



S23 



is bounded by the alluvion. Sienite and Greenstone sometimes 



appear in this 



ocks 



YQTY iutimately asso- 



ciated. Porphyry and Petrosilex arc so intimately combined in 

 many places, that it is difiS.cult to say, which ought to be repre- 

 sen ted. We have taken for the line of separation the brook 

 which runs through Maiden, and have Lcprcseated the Porphyry 



th-east, and the Petrosilex 



U must 



. be recollected, that accurate boundaries cannot easily he given to 

 mineral formations. 



^ 



