LEFT-HAND AND BLACK RIVERS. 303 
Me-kud-d-sibi, or Black River, is a small stream, emptying into Left-hand River 
from the southeast. Its waters present a striking contrast to those of Left-hand 
River. They are entirely free from sediment, and so limpid, that in the shadows 
of the hills and trees they appear perfectly black. The stream is too much ob- 
structed by drift-wood near its mouth, and too shallow higher up, to be navigable 
for canoes. I therefore pitched my tent near its mouth, and proceeded to explore 
it on foot. About eight miles above the mouth, following the windings of the river, 
red sandstone shows itself, in place, at the water-level. It is in thin layers, from 
an inch and a half to eight inches thick, banded with red and grayish stripes, and 
dips northwest at an angle of 14°. (See Section from the Valley of St. Croix R. to 
Rainy Lake, Pl. 2, N., See. 2.) The intervening country is hilly; the general 
bearing of the ridges being northeast and southwest, with occasional spurs bearing 
easterly and westerly, and north and south. The deposits in this distance are :— 
1. Alluvion ; 
2. Red marl, with boulders ; 
3. Red clay ; 
overlying a deposit of red and drab-coloured sandstones. 
The upper beds of the sandstone are buff-coloured; made up of rounded grains of 
quartz, well cemented ; rather coarse-grained ; compact; and when exposed to the 
influence of the atmosphere for some time, acquire a reddish tint externally. The 
lower beds are of a beautiful maroon-colour, with irregular grayish bands and 
points; fine-grained, with an occasional coarse grain; tolerably coherent; and 
marked with fine parallel lines of deposition. 
The rock rapidly thickens to forty feet, overlaid by heavy clay and marl beds, 
and continues to increase in thickness up to the metamorphosed and trap rocks. As 
these last-named rocks are approached, the sandstone acquires a dark reddish-gray 
colour, is thicker bedded, harder, better cemented, weathers well, and would 
make an excellent building-stone. Beneath these beds it becomes thin and shaly, 
and contains small gravel, and is, finally, intercalated with beds of conglomerate. 
The sandstone is underlaid by a coarse conglomerate, which, at a distance from 
the trappous rocks, is loosely cemented, and weathers easily. It is made up of red 
sandstone, quartz, jasper, and clay-slate pebbles, most of them rounded, and many 
of the quartz pebbles polished. By far the greater portion of the pebbles, however, 
are derived from the red sand-rock. Those from the slate have assumed the pre- 
vailing red colour. Some of the quartz pebbles are from three to four inches in 
diameter. 3 
Where the sandstone and conglomerate approach the trappous rocks, they are 
altered both in texture and colour. The sand-rock acquires a dark brown colour, 
and is converted into a true quartzite, exceedingly hard and compact; while the 
siliceo-argillaceous cement of the conglomerate is similarly affected, but without be- 
coming more firmly united with the contained pebbles. Nos. 483 to 487, show the 
degrees of change produced by the intrusion of the trap dikes. 
Below the conglomerate, an altered argillaceous slate comes in, so completely 
