THE SAGANAGA AND BASSWOOD AREAS. 363 



ters of half an inch to three-quarters. In composition the rock varies con- 

 siderably. The prevailing dark element is hornblende, but this is locally 

 replaced by muscovite in moderate sized folia, but in places, near the 

 borders of the area, in very small scales. In one place, a mile within the 

 southern boundary, extensive generations of quartz occur, imbedded in a 

 feldspathic groundmass. The quartz, in places, is sericitic, and actually 

 passes into cuneately brecciated patches of sericitic material, only less 

 schistic than the sericitic beds of the Kewatin, to be described subsequently. 

 In this region the dark element is wanting. In other places this gneissoid 

 mass assumes the constitution and structure of a mica schist. In certain 

 regions the hornblende has degenerated to a chloritic state. This condition, 

 when present, is always found near the borders, and consequently, as we 

 shall see, in the higher portion of the crystalline mass. At one point, in 

 the southern part of the body of Saganaga lake, the formation seems to 

 consist of a chlorito-augitic groundmass, with a small quantity of light 

 feldspar and a greenish mineral disseminated. 



This Area includes also Granite, West-Seagull, and Seagull lakes, and 

 the general character of the formation is everywhere preserved. The so- 

 called Giant's Range stretches a little north of east, and, passing Granite 

 lake, enters Canada. The Minnesota Survey has located its southern border 

 at sundry points, as far east as the middle of North lake. Beyond this I 

 have no personal knowledge of it, though incomplete information from the 

 Canadian Reports indicates its extension so as to include Dog lake, north of 

 Thunder bay, Lake Superior. 



A remarkable feature of this gneissic mass, as far as examined by myself, 

 is the wide distribution of rounded pebbles, and their occasional aggregation 

 into truly conglomeratic formations. The significance of this will have to 

 be considered in another connection. 



Throughout the whole extent of the Saganaga Area the rocky beds stand 

 nearly vertical and trend east-northeast, becoming more easterly in the 

 eastern prolongation.* 



The Bassivood Area lies upon the national boundary, through ranges nine 

 to thirteen, or from Sucker lake to Iron lake — a sinuous line about forty 

 miles in length. From this boundary it extends northeastwardly into Canada 

 an unknown but rather limited distance. On the Minnesota side it has not 

 been completely explored, but has been traced southwestward well toward 

 Vermilion lake, while its western limit is still undetermined. It is known, 

 however, not to extend over fifty miles from the boundary. The beds of this 

 mass of gneissoid rock stand everywhere in a vertical position, so far as I 



* The Saganaga Area has been more particularly described by me in the Sixteenth Annual Report 

 of the Minn. Surv., 1887, pp. 211-233, 292-209, 331-334. 



