1 88 1 .] Glacial Phenomena in the Yellowstone Park . 
203 
(. From the American Naturalist, March, 1881.) 
GLACIAL PHENOMENA IN THE YELLOWSTONE 
PARK. 1 
BY WM. H. HOLMES. 
TN common with very many of the more elevated districts of 
^ the Rocky mountains, the Park district presents a variety of 
glacial phenomena. In exploring the deep valleys of the higher 
ranges, the geologist is never surprised^! ^encountering on all hands 
partially rounded masses of transparent rock. These are pretty 
sure to be found on most of the old flood plains of the streams 
and often high up the sides of the valleys. They are frequently 
the only remaining records of ancient glaciers which have filled 
the valleys at different stages of their erosion. The glacia- 
tion ol rocks in situ, in the narrow gorges, also bears testimony 
to the former existence of glaciers. Loose boulders are doubt- 
less, in many cases, carried from their original beds by the force 
torrents, and not infrequently reach places very far distant from 
their original station by a gradual creeping or sliding movement 
— the result of undermining or yielding of the soil beneath. It 
is, therefore, far from safe to conclude that wherever erratic rocks 
are found, glaciers have formerly existed, especially in cases where 
these rocks may have had their origin in surrounding highlands, 
or even quite distant mountains of very considerable elevation. 
In a region like this, however, there is every reason to suppose 
that glaciers once existed on a very extensive scale. The park, 
with the great continental water-shed that surrounds it, forms one 
of the grandest masses of highland in the United States. 
In early quaternary times, as now — if there have been no 
important changes of level in the meantime — the general level of 
the park district exceeded eight thousand feet, and the broad areas 
1 Extracted from the unpublished Report of the U. S. Geol. Survey of the Terri- 
tories. Exploration of 1878. 
