BORDERING 



ON THE 



WISCONSIN RIVER. 



291 



rounded grains, many of which are limpid quartz, and cemented together with con- 

 siderable firmness. Some of the strata are banded with white and brownish-yellow 

 stripes. 



About six miles below Petenwell Peak, there is an exposure of fourteen or fifteen 

 feet of sandstone, in the east bank of the river. Seen from a distance, it reminded 

 me forcibly of the " Pillared Rocks" of Lake Superior. Some of the layers are soft 

 and friable, while others are hard, and weather with difficulty. The current of 

 the river, which continually washes the rock, has cut away the softer layers, leaving 

 the harder ones standing out in relief, in the shape of rude cornices, while the rills 

 produced by rains falling on the sandy slope above, and trickling down the rock at 

 intervals of from five to twenty feet, have divided the cornices into capitals, and 

 the rock below into pillars, so that it has, when seen from a distance, altogether 

 the appearance of a magnificent colonnade, nearly a quarter of a mile in length, 

 with the base of the columns resting in the water. There is a great difference in 

 one respect, however, between the Pillared Rocks of the Lake and those of the Wis- 

 consin. While the first, generally small in diameter and graceful in form, support 

 an entablature often forty or fifty feet in depth, and crowned with noble forest 

 trees, the latter, huge and massive in proportions, are capped by three or four feet 

 of sand, bearing a few stunted shrubs, as worthless as the soil from which they 

 spring. 



October 14. Nine miles below the last exposure of rock, thin shaly layers of 

 sandstone appear, just above the margin of the river, for the distance of half a mile ; 

 and four miles further, the rock rises to the height of twenty-five feet, in layers 

 from six inches to five feet in thickness, variegated with red and yellow bands, and 

 having very soft pulverulent nodules of oxide of iron, as large as walnuts, dissemi- 

 nated through some of the layers. The rock dips 4° to the southeast, is rather fine- 

 grained, and contains a considerable proportion of greenish-coloured grains, not, 

 however, in sufficient quantity to impart a greenish hue to any of the layers. 



Two miles below this place, Fortification Rock rises to the height of more than a 

 hundred feet above the general level. It stands on the west bank, about one hun- 

 dred yards from the main channel of the river. The northwest side, which is one 

 hundred and twenty feet long, is perpendicular, while it descends, on the southeast 

 side, by a succession of narrow terraces, to the general level. The top presents an 

 almost unbroken outline, while the front is singularly weathered, at a number of 

 points, into semblances of windows and loopholes. 



Below this place, the rocks are almost constantly exposed, on one or the other 

 side of the river, rising to the height of forty or fifty feet, sometimes pillared, gene- 

 rally mural, and with a constant dip to the southeast of from 3° to 4°. Some of 

 the strata have numerous cross-lines of deposition, are thinly laminated, and pre- 

 sent a very remarkable appearance ; the angle formed by the joints of the lamina? 

 and those of stratification, ranging from 1(J° to 23°. In some of the layers, the 

 lamina? are parallel with the plane of stratification ; in some they are waved, and 

 in others oblique ; in some the materials are fine, in others coarse : showing the 

 changeable direction and force of the currents by which they were deposited. I 



