392 DESCRIPTION OF THE\COUNTRY BORDERING 
lake. On the northwest side of the ridge, this rock (No. 92), presents beautiful 
clusters of columns, as shown in the subjoined sketch by Major Owen. They are 
CLUSTERS OF INCLINED COLUMNAR BASALT, LAKE SUPERIOR. 
mostly pentangular, and from ten to eighteen inches in diameter. The sedimentary 
rocks near the trap dip 30° to the northwest, and the columns make about the same 
angle with the horizon, favouring the idea that the basaltic rock is not a dike, but 
a bed. At another point, the columns stand without order or regularity in reference 
to the bedded rocks, and are separated from them by four feet of breccia, as shown 
in the annexed cut, and such as is found to underlie the basaltic beds of other 
a. Basaltic rock. 6. Breccia. c. Metamorphosed slates. d. Quart 
localities. The slate within ten feet of the trap is very much altered, and resembles 
the rock making the Great Palisades; farther off, it becomes less and less changed, 
softer and more amygdaloidal. The ridge which begins at this point crosses Mani- 
tobimitagico River, about a mile above its mouth. 
a. Shale. b. Amygdaloid. c. Shaly beds. d,d, d. Volcanic grits. e. Basaltic rock. J. Breccia. g. Bed of trap. 
Half a mile farther up the Lake, the bedded rocks are very much disturbed, as 
shown in the preceding section, and their relations obscured by a fault. 
