518 LOCAL SECTIONS 
excepting the upper beds, which weather and split into prismatic blocks, from one 
inch to one foot in thickness, and stand out in the form of turrets. 
From the summit an immense plain can be traced, apparently about thirty miles 
in extent, its uniformity broken at intervals of a few miles by these curious, isolated 
peaks of sandstone, most of which seem to have about the same elevation. 
The plain is elevated about seven feet above the water. 
About five miles above the Dalles, thirty-five feet of sandstone appears on the 
left bank of the river, and continues for a few hundred yards. Not far from this 
place there rises one of those isolated peaks, two hundred feet above the plain, like 
some time-worn castle, with turrets, towers, and battlements. 
Two and a half to three miles further, the sandstones of F. 1 are again exposed ; 
at first on the right bank, twenty-nine feet high; then on both sides, from fifteen 
to fifty feet high. The upper layers are thinly laminated; the lower are thicker, 
but soft and easily worn by the current, so that the superior strata often project, 
even as much as ten feet beyond the base. Here the soil is sterile and sandy, 
bearing a growth of small pine and scrubby oak. 
The strata rise to the northwest, so that half a mile beyond this last exposure 
the sandstone is ninety-five feet high, presenting a mural face to the river. At 
several points the beds are intersected by vertical fissures, that traverse the rocks 
from top to bottom, and divide the strata into large square blocks. About eight 
feet above the river, a band of sandstone, of brick-red colour, contrasts strongly 
with white sandstone beneath. 
Between two and three miles higher up stream, the rocks show themselves to the 
height of one hundred feet ; here the dip begins to be reversed, and the rocks gradually 
decline to thirty feet, about one mile below Fortification Rock. This remarkable 
peak is situated on the right bank of the river, with an elevation of one hundred 
and fifty-five feet. On the northwest face is a perpendicular escarpment; on the 
southeast, there are a series of offsets and abrupt descents to the level of the plain. 
On the top, its length is about one hundred yards; its width, fifteen to twenty feet. 
The inferior beds, composing Fortification Rock, are thick-bedded white and 
brown sandstones. At forty feet, the sandstone is red and ferruginous for twenty 
feet, passing upwards into a variegated rock, with brown, red, and white streaks, 
ten feet thick ; over this, white and brown sandstones are again repeated. The red 
beds are hard and massive, without lines of stratification. a 
A little over a mile above Fortification Rock, sandstone is again seen, sixteen 
feet high. At the base it is soft, and of a deep red hue, with a few thin layers 
of more compact, chocolate-brown sand-rock, passing upwards into variegated sand- 
stones, like those on Snake River. 
Three miles further is Eagle Rock, which is a perpendicular wall of sandstone, of 
thirty feet; the lower layers yellow, surmounted by the red bands of the preceding 
section, then yellow and brown layers, containing ferruginous concretions, with 
fine-grained yellow sandstone on the top, some layers of which are ripple-marked. 
_ The current has here also worn away the inferior strata, leaving the upper layers 
jutting out ten feet, like an entablature, supported at intervals by heavy columns, 
