ON T H E 



NORTHWEST S H O R E 0 F LAKE SUPERIO R. 381 



On the lake-shore, below the mouth of Kawimbash River, an earthy, decomposing 

 amygdaloid is found, overlaid by a bed of basaltic rock, such as was found on the 

 southern flank of Carlton's Peak. The cells of the amygdaloid are numerous, and 

 filled with zeolites and thalite. The basaltic bed appears to have been deposited 

 over an exceedingly irregular surface, previously worn on the now underlying- 

 amygdaloid, as shown by Section 2, PL 3, N. 



The dip in this neighbourhood is very irregular. Further down the Lake, in the 

 distance of half a mile, there are five alternations of trap and shale-beds to be seen. 

 In one of these beds, a great many large wrinkles occur, the corrugations extending 

 through the whole body of the rock, and looking more like layers of cables than 

 anything else. The escarpment here is thirty feet in height, but as the Lake is 

 descended, decreases to twenty and finally to ten feet, with a dip to the southeast 

 of 9°. The bottom rock here is a brick-red shale, weathering into small caverns 

 and arches, and overlaid by brecciated, amygdaloid, and metamorphosed beds of 

 gritstone, from an inch to three feet in thickness. For the next three-fourths of a 

 mile, the metamorphosed shales, with intercalated beds of trap, form the shore. 

 The dip is about 11° to the southeast, except where a low upheaval of greenstone 

 reverses it for a short distance, as shown in the following section. 



a. Greenstone. 



b, b. Metamorphosed 



shales. 



a l> c h 



The dip of the bedded rocks is persistent for a long distance, because the ridge to 

 which it is due, runs parallel to the lake-shore for many miles, and at about the 

 same relative distance from it. The dip, however, is often exaggerated at the 

 shore, in consequence of the washing away of the lower soft beds, and the conse- 

 quent subsidence of the upper strata in the direction of the Lake. 



A mural precipice in this vicinity exhibits, in descending order, 



1. A bed of coarse-grained trap, consisting of felspar and hornblende, with some tolerably large frag- 

 ments of other rocks embedded in it. 



2. Amygdaloidal shales, decomposing with facility, and causing the upper rock to form overhanging 

 precipices. 



3. Amygdaloid, shelving into the Lake, and containing numerous veins of calcite, laumonite, and 

 quartz. 



c. Trap lied. 



A. Shaly amygdaloid. 



« Amygdaloid. 



The dip is apparently affected by the nature of the surface on which the trap-bed 

 has been deposited, which appears at many points to have been undulating. This 

 gives to the strata the appearance of having been subject to slight elevatory move- 

 ments, as shown in the section on p. 182. At some places, the shaly amygdaloid 



