Surface Geology of the Yuko?i Territory. — Nordenskjold. 293 
3. A mud-like layer from the uppermost part of the silt, a few miles 
below the mouth of the Takheena river (about 50-75 feet above the level 
of the river) contains very rarely specimens of Pinnularia viridis 
(Nitzch.), and Staiironeis phcenicenteron, var. amphilepta Ehb. (fresh- 
water). 
4. Mud, probably younger than the silt formation, from the Yukon 
valley at the Tagish police station, contains the following freshwater 
forms; Cymbella ehrenbe)gii Kutz.; C. gastroides Ktitz; C. tiirgida 
Greg.; Cy m atop leu ra elliptica W. Sm.; Epithemia turgida Kutz.; 
Heiitzschia amphioxus Gmn.; Navicula ludlowiana A. Schu.; Neidiiitn 
affine (Ehb.); Pinnutaria jnajorKvAz.\ P. borealis ¥A\h.\ P. viridis v. 
distinguenii C\.; Pteurosig/na attenuatum (Kiitz.); Sfauroneis p/iani- 
centerojt v. amphilepta Ehb. 
The almost entire absence of organisms in the different 
layers of silt, with a few freshwater forms in the upper parts, 
and a richer flora in the youngest deposits seem to confirm 
the opinion of a deposition in glacial lakes rather than in 
fjords with salt or brackish water. 
3. TJie District of tJie Border Lakes. 
These lakes preserve their resemblance to fjords as far as 
up to the north end of lake Bennett. At about the same lati- 
tude the Windy bay of lake Tagish, the Atlin lake and several 
other large lakes not yet mapped out come to an end. The 
Taku Arm alone, after beingunited with the first two sheets of 
water mentioned by means of a considerable cross 
valley, continues as a lake for some miles further, then 
turning into the chief valley of the Lewes river. The 
topographical valley in which lake Bennett is situated 
continues northwards. In order to arrive at a knowl- 
edge of the mode of formation of these lakes a 
careful study of that depression through which the Watson 
river now rims would be of great importance. 
There are but few lakes of any size north of the latitude 
mentioned. The first of them is lake INIarsh, which, as stated 
above, is comparatively broad and shallow' and is immediately 
surrounded by wooded lowlands. It may from this circum- 
stance be said almost to form a group of itself. From that 
point the river pursues its course for 20 miles through a 
valley that for the most part is not particularly marked, and 
then another lake is reached, the last and at the same time the 
largest in this stretch. Its name is lake Lebarge. This is 
