CHAPTER IV. 



OBSERVATIONS ON SNAKE, KETTLE, AND RUSH RIVERS. 



Snake River. — Near the mouth of this stream, the hills, which are about fifty feet 

 high, are composed, as far as can be seen, of loose sand. 



The first rock exposure occurs about half a mile above its confluence with the 

 St. Croix. The base of the section is a coarse-grained quartzose sandstone, of a 

 light brown colour, the grains of which are loosely cemented by a siliceous paste. 

 On this reposes a coarse, pebbly sandstone ; the pebbles, which are of quartz, vary 

 in size from a pea to an almond, and are cemented with coarse sand. This latter 

 bed is two and a half feet thick, and supports nine feet of ash-coloured sandstone, 

 with brown spots disseminated, and traversed occasionally by ferruginous bands. 

 The stratification at this place is horizontal. Over the rocks is about twenty feet 

 of loose sand, of a light red colour, with boulders of trap towards the summit. 



Half a mile further, sandstone again appears, fifteen feet thick, similar in appear- 

 ance and colour to the beds on the St. Croix, below the mouth of Wood River, and 

 softer than the rocks at the previous section. At neither localities was I able to 

 detect any fossils. 



Two miles further, the same rock shows itself, but only in a low wall, just above 

 the water's edge. 



A succession of rapids commence at the mouth of the river, and continue, with 

 little or no interruption, for six miles ; and the shores and beds of the stream are 

 generally lined with boulders of dark porphyritic trap, containing crystals of epidote, 

 fine and coarse-grained granite, syenite, micaceous slate, and red sandstone. The 

 soil is for the most part light and sandy, but the alluvial lands bear a dense 

 growth of hard and soft maple, ash, elm, basswood, and large pines, with a thick 

 undergrowth of hazel and prickly ash. 



At the head of these rapids there is slack water for about half a mile ; the rapids 

 then set in again, and continue to Lac Travers. 



The first exposure of trap in place is three miles below the lake ; it rises, how- 

 ever, only a few feet above the water. A mile further, a gray compact trap is 

 elevated eight feet out of water, which is followed, a mile still higher, by eighteen 



