486 



DESCRIPTION OF THE COUNTRY BORDERING 



sixty feet wide ; its length nearly two miles ; both extremities converging towards 

 the present channel. Its sides consist of perpendicular ledges of sandstone, sur- 

 mounted by magnesian limestone, sixty feet high on the east, and forty-five feet on 

 the west. The bottom is perfectly level, and supports a rank growth of tall grass, 

 presenting the appearance of a luxuriant meadow. Near the centre are two lakes, 

 of nearly an elliptical form, connected by a short and narrow stream. The height 

 of the ancient channel above the present bed of the Minnesota, was ascertained to 

 be twenty feet. The following wood-cut exhibits the topography of this curious 

 region. 



To explain how the channel, B, became forsaken, we conjecture that the St. 

 Peter's once divided its waters around the isolated table-land, C, which was then 

 an island ; that the portion of the river flowing in the present bed was the first to 

 wear through the limestone down to the underlying soft sandstone, which, from 

 its softness, was worn away faster, and soon drained all the waters from the chan- 

 nel, B. 



At the upper end of the gorge, B, a strip of woods crosses its entrance, about one 

 hundred yards wide, while at the lower end the timber extends some distance into 

 the old channel. The trees are mostly large, many of them measuring four feet in 

 diameter. 



A mile and a half farther up the river, the sandstone and magnesian limestone 

 again protrude, with the same lithological appearance. The height of the sand- 

 stone above the water-level is thirty feet ; the magnesian limestone eight feet. 



Three miles and a half above this place is the highest exposure of these rocks 

 observed on the Minnesota. An unbroken perpendicular escarpment rises to 

 the height of one hundred and fifteen feet above the bed of the river. The diffe- 

 rent beds occur in the ascending order as follows : 



