NORTHWEST 



LAKE S U P E 11 1 0 E. 



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ing native copper, but was only able to discover the vein spoken of above. I can 

 only say, in reference to the metalliferous indications in the rocks of this river, that 

 I consider them sufficiently important to deserve the attention of the miner. 



The point at the mouth of Knife River is made by No. 609. The bay below 

 the mouth of the river is lined by an amygdaloid (No. 010), so full of cells that it 

 fractures with the greatest ease. It extends along the whole of the bay, and bears 

 north 30° east. It is more amygdaloidal at some points than others ; and, as the 

 first point is approached, the cells contain a great deal of thalite. At the point, the 

 rock is red, like No. 599, and is bedded, though much disturbed. Just around the 

 point is a heavy east and west dike (No. Gil), the junction of which with the 

 amygdaloid is well defined. After passing this dike, northerly, No. 610 again 

 shows itself, and continues the whole extent of the bay, in low exposures, mostly 

 covered with shingle. 



In the succeeding small pocket is a bed resembling No. 603 ; and beyond this 

 No. 610 is again seen, forming the small projecting points in the bottom of the bay. 

 At some points it presents the appearance of having been partially, and at others, 

 completely, fused, and injected with epiclote. Further on, it becomes cavernous, 

 and hollowed out into small pockets by the action of the Lake. The lower beds are 

 very soft, and disintegrate easily ; while the upper ones are hard and trappous. 

 The strata are much waved, as shown in the following figure, and the dip varies 



a. Shales. b a b b, b. Trap-beds. 



much, both in degree and direction, but is generally to the southeast, at a low 

 angle. 



These rocks continue up to the second small stream below Knife River, where 

 red clay banks make the shore nearly to the point below, when the rocks come in 

 again. Here they are thin-bedded and regularly stratified. Just before reaching 

 the point, they are separated by thin beds of trap, of which I noticed five at this 

 place. They appear rather to be injections from a north 30° east dike, which 

 subtends the arc of the bay, and shows itself just at the extreme point, bearing 

 north 5° east, and resembling exactly Nos. 592 and 601. In the upper side of 

 the deep bay below, there is an exposure of from forty-five to fifty feet of the rocks 

 just mentioned, resting on a bed of No. 603. The remainder of the bay has a 

 shingle beach. The long point which separates this from the next bay is composed 

 of the same rocks, except that, at the extreme point, they are traversed by a north 

 5° east dike. The escarpment here is from thirty to forty feet in height. The 

 next point, also, is made by No. 592, bearing north and south. Beyond this, the 

 lower rock is soft, and weathers into caverns. It is red, thinly laminated, and 

 some of the beds look very much like baked clay. Others show every evidence of 

 cross-lamination. These beds are overlaid by a trappous-looking bed, from four to 



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