LAKE TEMAGAMI AND ITS FOUR EFFLUENTS. 301 



Lakes of Double Outlet. — The -widespread Archean area of Canada, having 

 nearly everywhere about the same general elevation, is naturally divided 

 into many hydrographic basins. The water-sheds separating them are not 

 well defined ridges but plateaus with such gentle slopes that it is often diffi- 

 cult to tell which side of the height of land one may be on, and there is an 

 interlocking of the upper waters of rivers which flow to opposite sides. The 

 country along these divides is so level and the streams are so sluggish that 

 all the brooks are navigable by canoes. Lakes of various sizes, some of 

 them being of the larger class, occupy these situations, and not infrequently 

 they have two outlets discharging their waters in opposite directions. This 

 condition could only happen in rock-basins where but little wear is possible; 

 for if the outlets were over soft materials one of them would soon become 

 deepened and the other would cease to flow. Among the more striking ex- 

 amples of this phenomenon which might be mentioned are the following : 

 Wollaston or Hatchet lake, which sends out two rivers of equal size and 

 each larger than the Mississippi at St. Paul, the one falling into Lake Atha- 

 basca and the other into Reindeer lake — that is to say, into the basins of 

 Mackenzie river and Hudson's bay respectively ; Summit lake, between Lake 

 Nipigon and Albany river, which discharges equal-sized rivers northward 

 by the Albany into Hudson's bay and southward by Lake Nipigon into the 

 St. Lawrence. These streams are navigable without interruption for small 

 boats for miles on either side of the lake, so that one may sail up one, through 

 Summit lake and down the other without getting out of his craft.* In 1887 

 I passed through no fewer than five lakes with double outlets connected with 

 different branches of the upper Ottawa between Lake Temiscaming and the 

 source of the river. 



The most remarkable instance of a lake with more than one outlet which 

 I have met with is that of Lake Temagami, between Lake Nipissing and 

 Montreal river. We have made a careful detailed survey of this beautiful 

 sheet of water. It measures about thirty miles from north to south and the 

 same from east to west, and has had until recently no fewer than four out- 

 lets, one towards each of the cardinal points. The east and west outlets 

 have dried up, either from the deepening of the other two or from a very 

 slight elevation on either side of the north and south axis of the lake. Some 

 time ago the northern outlet was evidently the larger of the two yet running ; 

 but it is now smaller than the southern, and appears to be still diminishing, 

 while the other is correspondingly increasing. This may be due to an ex- 

 tremely slight tilting in the surface of the country. A rise of a few feet in 

 the water of the lake would set all four outlets flowing again. 



Discordant Strice. — In regard to the courses followed by the glaciers of the 

 drift period, when the directions of the strise in all parts of the country are 



* Report of Progress, Geol. Survey of Canada for 1871-72, page 107. 



