DE]Sr^T:R & RIO GRANDE WESTER]^ ROUTE. 



193 



The sandstone which rises above water level just below Ruby 

 siding is massive — that is, it is almost without bedding planes or 

 lines of separation — and consequently it makes a canyon which has 

 smooth, nearly vertical walls (PI. LXXIX). The color, except in 

 the uppermost layer, about 100 feet thick, is decidedly red, so that 

 in general the canyon walls are a bright red, and the name Euby is 

 quite appropriate. A close look at the sandstone will show that it 

 is not evenly banded like many of the sandstones in the region to 

 the east, but that the marks along the edges of the beds — which indi- 

 cate the form of the layers in which the sand was laid down — dip 

 at all angles, or rather are generally curved, showing that the sand 

 was carried into the place where it was deposited by strong currents 

 of air or water, which cut away much of the sand that had been 

 formerly laid down and in its place deposited layer after layer in 

 a cur\-ed position. This process is termed cross-bedding, and an 

 extreme example of it is shown in Plate LXXYI, C (p. 179). 

 These beds were all laid down on the land, or at least no marine 

 fossils have been found in them. 



The graceful swing of the river from bend to bend and the corre- 

 sponding curves in the smooth massive walls of the canyon are well 

 shown in Plate LXXIX. 



The rocks rise gently downstream, and near milepost 477 the 

 canyon walls have a height of about 300 feet. Just a little below 

 this point dark granite ®° appears in the bed of the river, and there- 

 fore 300 feet is about the full thickness of the sedimentary beds in 

 this canyon. The granite is exposed on the crest of a small anticline 

 or uplift, and in a few hundred yards it disappears. The upper sur- 

 face of the granite is smooth and doubtless once formed the land 

 surface upon which the sand was laid down.''^ 



^The crystalline rock that c®nsti- 

 tutes the foundation upon which west- 

 ern Colorado and eastern Utah have 

 been built presents different phases 

 from place to place; in one place it 

 may be a true granite, in another a 

 gneiss, and in another a schist. As 

 these phases grade into one another 

 the exact character of the rock in all 

 places can not easily be specified, and 

 so it is here called granite because this 

 term is in general sufficiently exact, 

 and an attempt to differentiate the 

 various kinds of crystalline rocks 

 might be complicated. 



° In the canyon of Colorado River 

 just above Glenwood Springs the same 



granite or gneiss is exposed, and the 

 stream has cut its channel in this rock 

 to a depth of 1,000 feet. The quartz- 

 ites, limestone (Ouray), and variegated 

 Carboniferous rocks above the lime- 

 stone, extending fron the canyon just 

 mentioned almost as far as Wolcott, 

 are not found in Ruby Canyon. As 

 many of these formations are of ma- 

 rine origin it seems probable that they 

 were originally deposited over all this 

 region but that later the sea bottom 

 was uplifted so as to form land and 

 then the streams and the weather 

 slowly cut the rocks away until in 

 places the formations mentioned were 

 removed before the red sands were laid 



