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. 
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A, A, A. Alluvial bottoms. Me mr os 
B, B, B. Ancient bed of St. Peter’s, about fifty-five feet deep. As Aye Tin\Y 
C. Isolated prairie table-land, seventy feet above the present level of = \\ AN \ \ = 
the St. Peter’s River, bounded by perpendicular eli ss \ \\ Psu \ Ws Vs 
sian Limestone, resting on Lower Sandstone. ‘ : \\\\ ‘S @ \\ «) \ _— é 
D, D. Prairie table-land, seventy feet above present level of the St. \\ Ng SS ES Wy \ : 
Peter’s. a i \\y y NY \\ 2 
E, E. Prairie table-land, about 150 feet above the St. Peter’s. \\\\\\ES 9 4 Mf \ 
P. St. Peter’s River. \\\ = uy \\ 
g- Granite boulder, thirty-six feet in circumference. WS I @ a = 
Weve . 
M\ Se ZN 
O 5 AN \ N\) % Zs : 3 
AS \\\ \\ Ae '\\ y 
| : \ * \ \\ ‘" \\ ay VW WAN \ “\\ \ 
3 \\\ WW \\ i \\ Ma \\ WY 
E AAA A 
ANNAN VAN ! 
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 further 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: 
