Logan's map op echo lake region. 115 



1857,-'^ and tliis is followed by a sketch of the " Character and distribution 

 of the rocks ; " the whole occupying six pages. The map represents the 

 lower portion of the lake as bordered on both sides by the upper slate con- 

 glomerate and the northern two-thirds of the lake as in the lower slate con- 

 glomerate. Between them is a limestone band which crosses the lake, 

 indenting conspicuously the east and west shores. The remainder of the 

 country recently visited is mapped as underlain by the quartzites holding 

 position at the top of the Huronian. Beyond the information contained in 

 the Report for 1857, nothing has come to our knowledge touching the region 

 here considered. 



The region to the east of the head of Great Lake George, for an observed 

 distance of eight or ten miles, is occupied by different members of the great 

 quartzite formation. This is mainly the white quartzite division. But the 

 red quartzite was occasionally seen. The pebbly character was very gener- 

 ally dispersed. The white quartzite is so massive that many observations 

 and expedients are requisite for ascertaining the dip and strike. The only 

 clews are the outcroppings of gigantic steps and the infrequent tendency of 

 the pebbles to distribution in courses. The general dip, as thus ascertained, 

 is about ten or fifteen degrees in a westerly direction. The quartzite is in- 

 tersected by many vertical joints and a few veins. Some of these are small, 

 recticulating, and filled with shining hematite, sometimes quite specular. 

 Others are broader, reaching a width of twelve to sixty feet, and filled with 

 a heavy, light gray, kaoliuic substance, in which were innumerable particles 

 of hematite not discernible by the naked eye. By an interesting change 

 these are seen to grow, in certain portions of the vein, until a general red 

 color is acquired and the vein is a " soft hematite," sometimes limonitic. In 

 a more advanced stage the hematite is hard and even brilliant. But it is 

 not known to be aggregated in workable quantity. The gray gangue is 

 found, on analysis, to be largely silicious, with much kaolin and iron. Its 

 specific gravity is 2.69. The quartzite is also intersected by vertical dikes 

 of diorite, and in some cases these are accompanied by small veins of spec- 

 ular hematite.f 



In approaching the foot of Echo lake by the deep and sluggish channel 

 of Echo river we pass from the higher members of the Huronian to the 

 lower. No outcrops, however, are seen along the immediate banks of the 

 stream, though from the foot of the lake its shores are occupied by an un- 

 broken series of outcrops. A section across the strata in this vicinity is 

 given by Murray as follows : 



* Geological Survey of Canada, Report of Progress for 1857. The reader may consult this map, 

 figure 1, ante, p. 88. 



t These veins have been more particularly described in the American Geologist, 1890, vol. IV, 

 pp. 360-370. 



