a 
232 H.R. Schoolcraft on a Coal Basin near Lake of the Woods. 
Arr. X XIIIl.— Discovery of a Coal Basin on the Western borders 
of the Lake of the Woods; by Henry R. Scnooucrart. 
Facrs observed during the several expeditions to ascertain 
the sources of the Mississippi river in 1820, and in 1832, under 
vite authority of the government, denote t this stream to originate 
the geological drift, or erratic block stratum, resting on silu- 
rian strata. This drift composes a wide crescent-shaped range 
of high lands, sweeping round from the Otter-tail lake to the 
sources of the St. Louis river of Lake nn nad which consti- 
tute the northern rim of the valley. It forms a well defined 
water-shed, which pours its drainage south tite the Gulf of Mex- 
ico north into the great Lake Winnipek ; and southeasterly into 
Lake Superior. The French denominate it Hauteur des Terres. 
From the principal lake, which occupies its summit, it has, 
since the era of the last ne a referred to, been called the 
Itascan summit or water-shed. Mr. Nicollet who ascended it, 
in 1836, cred its extreme altitude to be 1680 feet above the 
Gulf of Mexic 
The surface acetate of immense heaps and wave-like deposits 
of oceanic sand, and comminuted sandstones and schists, with 
boulders of both the sedimentary and igneous rocks. Although 
the silurian series are generally concealed by these deep an 
wide-spreading deposits of the drift era, yet, they appear in hori- 
zonta — o at the Naiwa rapids at the foot of the Itascan 
range ; on the Metoswa rapids, below Queen Anne’s Lake; ana, 
very sistintly at the Pakagama Falls, at the “oe be the great 
sphagnous plateau below the inlet of Leech Lake 
The whole column of formations is mnatitate: sofort’ y 
the igneous group of rocks, heavy boulders of which lie tumbled 
together in many of the sub-valleys, as if they could not have 
Fin transported far from their parent beds. Whether the silarian 
strata be, however, imposed directly on the igneons, or exist in 
juxtaposition with them, is not certain. This only can be stated, 
in regard to the general arrangement, that in descending the cnan- 
nel of the Mississippi from Itasca Lake, the sandstones, grits, 20 
quartzite are hear at the localities mentioned. At a point, 
where the river has worn its channel 550 feet into the geologics 
formations, (Dis. Sources Miss., p. 582,) the pyrogenous rocks are 
ound in place, in its bed and on its banks. Such are the ap- 
pearances near the influx of the river De Corbeau, in latitude Ab°, 
and below that point. Rocks of igneous character have crossed 
the track of the Mississippi below this point—covering @ belt of 
from the 
small river ee near the Crow Wing branch, to the inflax of 
e Sac o Mr. Norwood, in his geological visit in ~on 
i ont find rocks in place above the De Corbeau, and did not 
Vie IE 
