TO YELLOWSTONE NATIONAL PARK. 135 
characteristic of the formation. Upper layers are very yellow and ferruginous, and lower beds 
white and gray. The local changes are very great. At the Judith Mountains, the thickness of the 
sandstone, at a point where some estimate of its relation to the underlying clays could be made, was 
thought to be about 300 feet. North of the Missouri, at the Little Rocky Mountains, sandstones 
similar to those of No. 5 were seen overlying concretions, and selenite-bearing shales, presumably 
No. 4; and hence their existence here may be considered probable. If now Cretaceous No. 5 is 
found at two points, on cvither side of the river, at a minimum distance of twenty-five miles, while 
between is No. 4, and no trace of No. 5, what has become of the latter? One fact observed may be 
mentioned in this connection: the dark clays are carried from Carroll one hundred miles and more 
down the river; and, at some of the lower points, these clays, which appear alone in the immediate 
river-bank, have a capping at a little distauce of white and yellow sandstone. This observation, 
made from the deck of the steamboat, is of little value; but it suggests that the No. 5 may be here, 
where it belongs, directly overlying No. 4, while farther west, in the neighborhood of Carroll, it has 
been removed by the glacial flood, to be mentioned later. 
A more thorough study of the Cretaceous beds at the mouth of the Judith would no doubt have 
assisted us materially in deciding the point in doubt had we been able to give the requisite time to 
their examination. As it was, the relations of the beds were, as has been said, somewhat compli- 
cated; and we were able to do no more than to identify by fossils the several members of the group 
exposed at that point. We found here the Fort Pierre clays in close apposition with rocks 
containing No. 5 fossils. 
No. 6. Fort Union Group.—Beds of white sandstone, containing occasional layers of a clayey 
brown sand-rock, were found at the mouth of the Judith River, evidently overlying the beds of No. 
5, before referred to. From these deposits of sand, we obtained the vertebra and long bones of 
Dinosaurs, identified by Professor Marsh as belonging very near the genus Hadrosaurus of Leidy. 
With these remains were found Unios, and, in some layers, a little lignite; the general association 
seeming to refer the deposits to the Fort Union beds. Their thickness was estimated at 400 feet, 
though no sufficient data were collected to warrant any great confidence in this estimate. 
Tertiavy.—Distinct tertiary strata were observed in the neighborhood of Camp Baker, and their 
relations have been so fully described that a repetition is unnecessary. It may be mentioned, how- 
ever, that the occurrence of a Miocene lake at this point, with beds 250 feet thick, is a matter of 
no little interest, and opens many interesting questions as to the relations of this with the other 
well-known Miocene lakes, as also to the Pliocene beds of the Upper Missouri and the Yellowstone 
Valley. The red and yellow slates, which seem to accompany the Miocene beds of Camp Baker, 
may possibly be Lower Tertiary, although, as has been remarked, they are not conformable with 
the overlying beds. In the absence of any decisive facts, however, we must leave this point 
undecided. 
Quaternary.—More or less distinct evidence of Quaternary action was obtained at several 
points. True traveled drift was observed in the Missouri Valley alone. In Upper Yellowstone 
region, the amount of material transported has been immense; but the action is, comparatively 
speaking, local. Tine strive, presumably glacial, were seen in the cation above the mouth of Work 
Creek, and also in the granitic rocks near the bridge. At the latter point, the amount of trans- 
ported blocks was very large. It may be of interest to note that the blocks apparently from this 
spot were traced south ; and some few scattered bowlders were seen within 1,500 feet of the top of 
Mount Washburne, as if the action had been in that direction. This matter has been discussed 
for this locality by others, and we refrain from carrying it further. 
The drift at the foot of the Bridger Mountains, the Elk Range, Little Belt Mountains, Snow 
Mountains, and Judith Mountains, in many cases exceedingly abundant, is in all cases purely local ; 
almost exclusively Carboniferous limestone or trachyte. The masses and pebbles were distributed 
in the time of glacial flood, when the flow of water from these hills was very great. The action of 
this flow of water, in washing out deep valleys, has already been noticed. The special interest 
attaching to Quaternary phenomena is connected with the facts observed in the Missouri Valley, 
which have been alluded to, though not described in detail. North and south of the river from 
Carroll, the prairie is more or less covered with drift-pebbles and masses, whose source is not to be 
found in the neighboring ranges of hills. On the contrary, the southern limit of this drift is reached 
