NORTHWEST OF LAKE SUPERIOR. 341 
SECTION II. 
LOCAL DETAILS OF THE SECTIONS MADE IN THE RANGES NORTH OF LAKE SUPERIOR. 
1, Mission Creek.—The sections already given of St. Louis and Black Rivers,* 
show the junction of the sandstone series with the underlying argillaceous and sili- 
ceous slates, upon which it rests unconformably. As these sections afford a key to 
much of the geology of the country, it is thought best to give another section, of 
the unaltered rocks near Fond du Lac, before proceeding to describe them in the 
more disturbed portions of the District, where they are associated with, and their 
relations obscured by, the numerous dikes and beds of GAR found between Fond 
du Lac and Pigeon River. 
Mission Creek is a small stream, which drains a cance of the country lying in 
the southern bend of St. Louis River, between the west end of Lake Superior and 
Grand Portage. It empties into the St. Louis at the village of Fond du Lac. _ The 
valley tirough which it runs before reaching the plain on which the village is 
situated, is deep and narrow, and bounded on the east side by the commencement 
of the high greenstone ridges which trend to the northeast, and on the west by 
deposits of drift, marl, and clay, such as overlie the sandstones, conglomerates, and 
slates of St. Louis River. 
About three-fourths of a mile above the mouth of the creek, sandstone shows 
itself in the east bank of the creek, on the flank of the greenstone ridge, overlaid 
by marl and clay-beds} (1), just as they occur on the St. Louis River. Between 
forty and fifty feet above the water-level, the marl contains beds of pebbles, from 
eighteen inches to two feet thick, and in the upper part and on the surface, nume- 
rous large boulders occur. 
The first exposure of sandstone (2) is about thirty feet in thickness, and 
southeast, at an angle of 10°. It is micaceous, and disposed to be shaly. Some of 
the beds are reddish gray, and others red, with marks of cross lamination. About 
two hundred yards further, red shale (5) comes up, eighteen feet thick, and con- 
taining bands of hard sand-rock, from four to eight inches in thickness. The bands 
are from eighteen inches to five feet apart. These shales are of a dark-red colour, 
but become bluish red on the planes of stratification, when exposed to the weather. 
In some places they look very much like indurated clay, but are gritty. The dip 
here is 20° southeast. Three hundred yards higher up the creek, the shale is 
underlaid by fifty-five feet of sandstone (4), in strata from six inches to four feet 
thick; and a short distance further on, the sandstone rests on twenty feet of thin, 
shaly rock (5). The upper part of the sandstone is reddish yellow, and resembles 
the thicker strata of St. Louis River. The lower part of the shales are bluish- 
coloured. They rest on a gray, pebbly, coarse grit (6), five or six feet thick, and 
* See section (Pl. 2 N, Sect. 2), from the valley of St. Croix River, near the mouth of Upper Pinnette 
River, northerly, to Rainy Lake. 
+ See section on Mission Creek. (Pl. 2 N, Sect. 1.) 
