NORTHWEST OF LAKE SUPERIOR. 355 
tant point, but too far removed from the focus of volcanic action to have been 
affected by the causes which produced so great a change in the slate-beds in near 
proximity to the trap-dikes, and where they alternate with basaltic beds. 
Some of the beds of No. 348, as before stated, are amygdaloidal. They contain 
large nodules, from one to three inches in diameter, formed by concentric layers of 
a siliceous material, and are filled with beautiful crystals of laumonite and calcareous 
spar. ‘These nodules resemble, in all respects, except size, many of those occurring 
in the altered clay slates of Encampment Island River. The rock containing them 
on this stream, however, has been so changed by igneous action as to bear no resem- 
blance, in general appearance, to that of Encampment Island River. 
Below the mouth of Kinewabik River, the section along the lake-shore exhibits 
beds of shale, like those already described, with overlying trap-beds, until the first 
point is reached, where there is a heavy dike of greenstone (No. 613), which cuts 
through all the sedimentary beds, and near the contact alters the schistose rocks to 
No. 614. 
The overlying and sedimentary rocks then continue along shore, and around the 
point to the next bay. At the point, however, a north-30°-east dike shows itself, 
and assumes a somewhat columnar form as the turn is made into Encampment 
Island Bay. In this bay, the overlying trap (No. 333) is about one hundred and 
twenty feet in thickness, and rests upon thirty-five feet of metamorphosed shales, 
with beds of a very compact rock intervening, as shown in the annexed section. 
a. Trap. 
™ 
aa 
LTTE 
tay 
ACT 
= i i 
The bottom of this bay presents a shingle beach, with a heavy deposit of red clay 
and marl on the lower side, as far as the point opposite the island. For the last 
three miles of the shore, the dip of the bedded rocks is very irregular, varying from 
northwest to southeast. : 
7. Encampment Island River—This river was explored to the distance of four 
miles, in a direct line from the Lake. At its mouth there is a deposit of drift 
and red marl, which continues for about a quarter of a mile up stream, when 
amygdaloid appears in the river-bed, dipping southwest 7°. This rock continues 
about two hundred yards, when a very hard, compact, fine-grained, siliceo-argilla- 
