GEOLOGICAL EXPLORATIONS AND LITEEATURE— 1876. 65 



XVI. Banded oclirey itorous qiiartz-si^hist. 



XV, Ijlackisb arnillaccous slate, with imiieifect cleavage, rarely micaceous, and 

 sometimes holding garnets. 



XIV. Grey arenaceous qitart~ite, often semi-scliistose and sometimes micaceous; 

 quartz conglomerate. 



XIII. Pure specular hematite and magnetite ores; ferruginous banded jaspery 

 scbist, with interstratified beds of ch 1 or it ic and hydromicaceous schists. "Trap dykes" 

 at Washington mine. 



XII. Ited arenaceous (iiiait; schist, banded with micacroiis iron; qunrtzose limotiitic 

 ores. 



XI. Dionjtf, hornblende-schist, chloritic schist, chloritic-looking mica schist; rarely 

 hornblende gneiss. 



X. Siliceous hematitiv and limonitic schistose ores, often manganiferous; siliceous 

 schists; garnetiferous antliophyllitic (eklogyte) schists; obscure compact chloritic (?) 

 magnetic schists, with conchoidal fracture. 



IX. Hornlilendic rock aud related diorite and diabase, often micaceous. 



VIII. Ferruginous quartzose flags ; clay-slate; quartsite ; rarely chloritic and 

 authophyllitic (?) schist. 



VII. Hornblendic rocks, with related greenstones. (?) 



VI. Ferruginous quartzose schist; clay and chloritic slates. 



V. Qnartzite graduating into protogine, with interstratified beds of dolomitic 

 marble; noracnlitc: rarely chloritic and micaceous schist, and dikes of chloritic schist. 



Syenite (quartzless), diorite, diabase, hornblende-schist, and obscure chloritic 

 slates, conglomeratic quartsite and various ([uartzose iron ores. Well-characterized 

 toZc-schist is found in this horizon oulj' at Mar(iuette. 



Xonconforuiiible with Laurentiau. 



Diabases are recognized as occuiTino' among the greenstones, contrary 

 to the earlier opinion of tlie author. These rocks, together with the diorites 

 and the rehited schists, are still reg'arded as "metaniorphic." 



Lithologically the division is into (1) fragmental rocks, exclnsive of 

 limestone: (2) me1amor])hic rock.s, not calcareous; (3) calcareous rocks; 

 and (4) igneous rocks. Among the fragmental rocks are noted quartz- 

 conglomerates in the middle horizon of the series. Tlie second division 

 includes granite, the gneisses, schists and slates, syenite, diorite, gabbro, 

 diabase, and the pyroxenic, the garnetiferous, the olivinitic, and the chloritic 

 and talcose rocks, besides quartzite, jasper, chert, and the iron ores. The 

 eruptive rocks are the granites, traps, and the hydrous magnesian schistose 



MON XXVIII ') 



