BORDERING ON BIG FORK RIVER. 319 
tent to guide us to Fort Francis. Soon after leaving Wa-bush-kon-de-ga, he became 
bewildered, and acknowledged his inability to direct our course ; and we were there- 
fore left to our own resources, as on Vermilion Lake. We were detained two days 
on Rainy Lake ; one, in consequence of being unable to find the outlet, and the 
other on account of high winds. 
The rocks, which are well displayed on the numerous islands, consist of mica and 
talcose slates (Nos. 541 and 542), and occasional exposures of granite and gneissoid 
granite (No. 543). The talcose rocks were met with on the north shore, and the 
gneissoid granite near the west end of the lake. On an island where we encamped, 
the mica slate contains innumerable small garnets, and is traversed by granite veins 
(No. 540), a few inches wide. The tilted edges of the slate are also covered with 
a crust of coarse granite, of a character similar to that displayed in the numerous 
intrusions seen on the lower part of Vermilion River. It has every appearance of 
having been spread over the edges of the mica slate from the veins which traverse 
it. The slate is very hard and compact, and does not seem to weather with as 
much facility as the granite. 
From marks observed on Crane, Sand Points, Nemakan, and Rainy Lakes, their 
waters appear to rise at some seasons to about five feet above their present level. 
We reached Fort Francis on the 9th of September, and were received by Mr. 
Isbister, the Factor at this post. We remained at this place only long enough to 
make the portage around the falls, and then started for the mouth of Big Fork 
River. We were gratified while here by receiving a letter from Dr. Owen, and 
learning that all his party were well. 
While descending Rainy Lake River, a bed of blue clay was observed, similar to 
that seen and described on St. Louis and Embarras Rivers. It is full of gravel, and 
overlaid by a bed of yellow sand. 
7. Big Fork River—We began to ascend this stream on our way south on the 
10th of September. It is about sixty yards wide at its junction with Rainy Lake 
River, but soon grows narrower, and for several miles is not over thirty yards wide ; 
after which it is increased to forty and fifty yards, which width it maintains up to 
the mouth of Opimabonowin River. It is very crooked, and winds between banks 
of clay and sand, from six to twenty feet high for the first twenty-eight miles. The 
clay-beds are filled with small calcareous gravel and pebbles, as is also the bed of 
sand. The higher grounds are wooded with small aspen, poplar, birch, bass-wood, 
ash, spruce, fir, and occasionally a few small pines; and the river-bottoms with elm 
and soft maple. Where the woods are open, oak is common, and at one or two 
places hard maple was seen. 
The clay-beds resemble those already described on St. Louis River, the bluish- 
coloured bed being also associated here with a dark yellowish one. On the higher 
grounds the boulder-drift is seen, and associated with the crystalline boulders are a 
great many large water-worn fragments of drab-coloured limestone, some of them 
as much as two feet in diameter. Among these fragments Col. Whittlesey found a 
piece containing several small bivalve shells and remains of Crinoidea. 
About twenty-eight miles above the mouth, the first rock was seen 7 sit (No. 
