PLATE LXXXVII. 



THE CARI.TOS PLATE, 1899. X. H. WISCHKLL. 



The valley of Otter creek is wide and terraced, at least as far west as aec. 17. T. 

 48-17, indicating that it was not formed by the present stream. Above that point 

 the stream runs on the drift surface without marked terraces. The old terraced 

 valley continues sonthwestward and south, and blends into the valley of the Black- 

 hoof river, which runs south to the Xemadji, there being thus a continuous wide 

 terraced valley running from the St. Louis river at Carlton into the Blackhoof and 

 Nemadji valleys. This was during the waning of the Glacial epoch, but when the 

 Lake Superior ice-lobe still remained and thrust its western margin upon Carlton 

 connty, thus forcing the St. Louis river into the glacial lake Xemadji. At a previous 

 date this ice-lobe had been extended slightly further west and the St. Louis river was 

 then driven from the Lake Superior basin altogether. Its waters, at first forming a 

 small lake at a higher level than lake Xemadji. were carried across the divide in 

 Carlton county to the Moose river and reached the Mississippi river through the - 1 

 Croix valley. The early, smaller, glacial lake has been named lake St. Louis. 



When finally the ice-lobe had retired far enough to uncover the lower outlets 

 of lake Superior further east, the St Louis river, below Carlton. took its present 

 route to the sea, flowing at first over the clay that had been deposited by lake 

 Xemadji. Its excavation through this clay and into the underlying till, down to 

 the rocks which now form the rapids, has been done since, while above Carlton the 

 river was gnawing into the rocks over which it flows during that earlier period while 

 it fed the glacial lakes St. Lonis and Xemadji. The difference, however, in the 

 amount of erosion of the rocks, above and below Carlton. is hardly observable, except 

 when the river comes into contact with some older bluffs, as at and above Fortress 

 island, where the river runs in a shallow, rock-cut gorge in thin slates. 



The rocks of this plate are supposed to belong to the Animikie. and to the 

 Eeweenawan, the latter being of Potsdam age. The former are abundantly uncov- 

 ered along the St. Lonis valley, and about Carlton and Thomson they form numerous 

 short monoclinals whose strata dip toward the south. These strata have not only 

 been tilted but they have been pressed and sheared with a crushing force which has 

 greatly deformed them. These features are specially observable at Cloquet. These 

 strata are also penetrated by numerous Keweeuawan dikes, most of them running 

 nearly north and south. One of the largest of these is visible at the railroad where 

 it crosses the St. Lonis just north of Fortress island, on the west side. Others appear 

 at Carlton and at Thomson, and below Thomson, where they cross the river. These 

 and the diabasic gabbro rock which appears in the St. Louis valley a little to the 

 east of this area are referred to the Cabotiau of the Keweenawan. s. H. w. 



