102 
GEOLOGY. 
the Nah-un-kah-rea, blocks of a dark trachytic porphyry lie over the sandstone and shale, extend¬ 
ing some miles along our road. Boulders of this trachytic rock are occasionally met with quite 
up to the Wahsatch mountains In the valley of the Blue river, a coal measure, supported 
by sandstone, crops out at several places; hut the coal does not seem to be of a good quality. 
Not far from where the latter river empties into Grand river, a hard conglomerate of pebbles 
baked together, a hard, bluish limestone, and a dark, silicious shaly rock, with agate, are met 
with, but do not seem to have a great extension. 
That the disintegrations of such rocks cannot yield a good soil is evident, and not much 
organic life can be expected in such a country. But there does not even seem to have been any 
organic life in the ancient seas, in which the sedimentary rocks of this country have been 
deposited. I could not detect any rock including organic remains of any kind whatever. It 
is true, in the neighborhood of Grand river, near camp 72, there are fragments of a dark 
gray limestone, with numerous casts of shells—mostly fragments of amonites—strewed over 
the ground on the top of a sand-hill, together with quite a number of loose shells, “Gryphsea 
pitcherii,” showing the rock to have originated in the cretaceous period ; but within a circuit 
of several miles, it could not be found in situ. The want of petrifactions in the rocks of these 
desolate regions, renders a determination of their relative ages somewhat hazardous. 
It is a remarkable feature in the character of the country between the Rocky mountains and 
the Sierra Nevada, that whole formations disappear, as it were, before our eyes. The wearing 
and washing away of mountains takes place here on an immense scale, and is the more easily 
observed, as no vegetation of any account covers the country, hiding the destruction from the eye. 
Nature here seems only to demolish, without showing any compensating creative activity. Days 
before we found the above-mentioned towery conglomerate on Grand river, we saw mostly small 
pieces of rocks on the road which did not belong to the surrounding mountains, and which 
afterwards could be identified with the rocks contained in that conglomerate. As these rocks 
could not have been drifted there from a place about a thousand feet lower, we must conclude 
that large masses of this conglomerate have been carried away, leaving a number of these rocks 
behind. All along our road in the Grand and Green river country, on the slopes of high 
mountains, and in the level country, the soil is overstrewed with pieces of agate, cornelian, 
calcedony, and other quartzose minerals, which I could not refer to any rock. In the neigh¬ 
borhood of the Wahsatch mountains, these minerals again make their appearance; but here 
they are traceable to a rock which still constitutes a great part of the mountains of this range. 
The devastation may here be followed step by step. A similar process has been going on in the 
country of Blue and Green rivers with other strata. The black, soft shale, with gypsum and 
the strata below it, have disappeared from an immense tract of land. For days before we 
struck Green river, we travelled over a black, clayish, absolutely sterile soil, produced by the 
decaying mountains, and in different places, chiefly at a short distance from where we crossed 
Green river, we found remnants of those strata in buttes of sometimes considerable height, some 
of them assuming the shape of huge chimneys. 
On the foot of the Wahsatch mountains, close to Akanaquint creek, and about a mile from 
camp 88, a coal measure of an excellent bituminous coal crops out. It rests on sandstone, a thin 
layer of a brown, soft clay intervening between them, and is about three feet thick on the out¬ 
cropping. 
As soon as we are over the first ridge of thp Wahsatch mountains, porphyritic rocks again 
make their appearance, and their disintegration again gives rise to a better soil and more 
luxuriant vegetation. These porphyries, from red to dark gray, belong undoubtedly to dif¬ 
ferent periods. One of them erupted, when an oolitic limestone covered the country. At a 
short distance from our road over the second high ridge, numerous pieces of this limestone 
may be seen. That the presence of the latter rock in these localities is not merely accidental, 
is proved by the fact that by contact with the porphyry it has been altered, .and has baked 
together with it. White sandstone, a white, very pure, compact limestone, a greenish and a 
