ON THE NORTHWEST SHORE OF LAKE SUPERIOR. 



413 



side of Watab Lake, are a number of perpendicular escarpments of No. 30, over- 

 lying argillaceous slate (No. 32). The slate is somewhat altered near the east end 

 of the lake, but to what depth it is impossible to say, as the junction is hidden by 

 a talus. The following section exhibits three of the principal escarpments on the 



a. Argillaceous ilate. Homblendic rock. 



American side of the lake. In general, the high mural walls here bear the greatest 

 resemblance to those seen on the shores of Lake Superior, near Hat Point, and 

 below Waswagoning, where the argillaceous and siliceous beds are overlaid by beds 

 of greenstone, as shown in the subjoined section of one of the points of Waswagoning 

 Bay. 



a. Argillaceous s.'ate. I>. Greenstone. 



Further west, on the shores of Watab Lake, some of the slate-beds immediately 

 under the trap are altered into a very compact rock, with a semi-crystalline struc- 

 ture, while other beds would make good roofing slates (No. 31). Near the west 

 end, the slates descend to the water-level, while the overlying beds form an escarp- 

 ment, over three hundred feet in height. Several small ponds, connected by a nar- 

 row stream, which is the commencement of Pigeon River, lead to the next portage. 



The eleventh portage is three thousand three hundred and fifteen paces long, and 

 terminates at Mud Lake, the source of Arrow River, or, more properly, the east 

 branch of Pigeon River. The portage passes over four low ridges, with swampy 

 dells between them. The path is rendered rough and somewhat difficult, by nume- 

 rous fragments of rock, which are scattered over it throughout its whole extent. 

 The rocks exposed on this portage are shown in the annexed section. Near the 



,■ n h 



a.a. Argillaceous slate, b. lIoii>li.Vtiui<- rro-k. c. Slaty greenstone. 



lower end is a sloping ridge of very thinly laminated argillaceous slate, which is 

 exposed in low knolls and ridges for nearly half a mile, where it is associated with 

 a bed of fine-grained hornblendic rock, and overlies or abuts against a coarsely 

 crystalline greenstone. Beyond this the slates continue, until, near the upper end 

 of the portage, they are underlaid by slaty greenstone, which passes into syenite. 

 The slate ridges have gentle slopes, and in the small valleys between them ponds 

 occur. Several springs, also, were noticed in these valleys, — a somewhat rare feature 

 in this region. 



