LITHOLOGIC OHAKACTEES OF THE STEATA. 
209 
and upper Permian shales, with their gorgeous belts of richest colors and 
beautiful ripple-marks, and with their silicified forests, have hardly varied a 
baud or a tint from the brink of the Sheavwits to the pagoda-buttes of 
western Colorado. Still there are exceptions. The great Jurassic white 
sandstone fades out from northwest to southeast, and wd are in doubt, at 
present, whether it failed of deposition or is blended with the Trias. Other 
members might be mentioned which undergo slow changes from place to 
place. But such changes are always very gradual. Nowhere have we 
found thus far what may be called local deposits, or such as are restricted to 
a narrow belt or contracted area. 
All of these strata seem to have been deposited horizontally. Even 
the base of the Carboniferous has a contact with unconformable rocks 
beneath, which was but slightly roughened by hills and ridges. In the 
Kaibab division of the Grand Canon, while the great body of Carbonifer- 
ous strata was horizontal, we may observe near the brink of the inner gorge 
a few bosses of Silurian strata rising higher than the hard quartzitic sand- 
stone which forms the base of the Carboniferous. These are Paleozoic 
hills, which were buried by the growing mass of sediment But they are of 
insignificant mass, rarely exceeding two or three hundred feet in height, and 
do not appear to have ruffled the parallelism of the sandstones and lime- 
stones of the massive Red Wall group above them. 
(2.) Another consideration is as follows: as we pass vertically from 
one formation to another in the geological series, we observe the same 
diversity of lithological characters as is found in other regions. The lime- 
stones occur chiefly in the lower Carboniferous, and in very great 
force. At the summit of the Carboniferous also are 70.) to 800 feet of cal- 
careous strata. But in the Mesozoic system limestones are rare, and con- 
stitute but a very small portion of the volume. By far the greater part of 
the entire stratigraphic column is sandstone, and the various members of 
this class show great diversity of texture and composition. Some are 
excessively hard adamantine quartzites, very many are common sandstones 
in massy beds. By small gradations these pass into sandy shales, contain- 
ing more or less argillite, and such shales form a large proportion of the 
bulk of the Permian and Trias. These shales in turn pass into marly beds, 
II G c 
