E. Petitot on the Athabasca District. 45 



precipitated with violence into the forests, opens fresh channels, 

 whilst the old ones, obstructed by the mire and sand brought 

 down, are filled up and transformed into a marshy savanna. The 

 Duck Portage was formed in this way. Entering it from the 

 north (the direction facing the current), the idea is suggested 

 that it is a channel of the river or one of its affluents; but the 

 traveller soon finds himself in an immense dried-up marsh, quite 

 level, and entirely composed of black viscous mud, cracked by 

 desiccation and covered with timber formerly deposited by 

 the waters. Its Chipewyan name, " Tedh dedh-heli t'ue" " (Float- 

 wood Lake) points to its origin. There is however, no trace of 

 any lake; but a chain of wooded and elevated isles shows that 

 this is the ancient bed of the Slave River, which, after filling in 

 with muddy deposits, has been obstructed in its course by imbed- 

 ded timber and forced to break a passage to the right by an 

 abrupt eastern elbow. I think this alteration of course has been 

 effected recently. It may perhaps be the outlet which I saw in 

 course of formation in 1862, though I had then no opportunity of 

 accurately fixing its position. 



During extraordinary floods the surplus waters of the Slave 

 River spread over this great marsh and scour the Duck Portage ; 

 but at an epoch before the formation of the present bed, when the 

 Duck Portage was the ordinary channel, the overflow passed to 

 the left by another natural channel, now dry. This shows a 

 gradual tendency of the Slave River towards the east in this dis- 

 trict. The conditions above referred to as existing at the mouth 

 of the Athabasca, are also shown at the mouth of this river, for 

 the current has so clogged its bed and filled up its estuary as to 

 be compelled to divide and make its way across the sedimen- 

 tary deposits of its delta, which it cuts up into a great number of 

 mud islands. 



The first and oldest of its branches contained large and lofty 

 islands, identical as to soil with the mainland, and wooded, like it, 

 with white pines, Populus balsamifera, aspens, and birches, whose 

 venerable trunks show an existence of at least six or eight centu- 

 ries. If a line be drawn on the right from this point to the mouth 

 of the Des Seins River, and on the left to that of the Oxen River, 

 a triangle or delta will be described wholly occupied by the 

 ancient and recent mouths of the river. The latter, after divid- 



