136 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
The following brief account of the principal characteristics of the 
park from an ichthyological standpoint is from the report of Dr. Jor- 
dan :* 
The Yellowstone Park is a high plateau, having a general elevation of 7,000 to 
8,000 feet above the sea. Its entire surface, with the exception of the Gallatin 
Range of mountains in the northwest and some granitic summits in the northeast, 
is covered with lava, with its varieties of obsidian, rhyolite, ete. This mass of lava 
covers to a great depth what was previously a basin in the mountains. According 
to Mr. Hague, the date of the lava flow is probably Pliocene. Its existence was of 
course fatal to all fish life in this region. Since its surface has become cold, the 
streams flowing over it, most of them now wholly unaffected by the heat within, 
have become well stocked with vegetable, insect, and crustacean life, but are for the 
most part destitute of fishes. The cause of this absence of fishes is to be found in 
the fact that nearly all the streams of the park, on leaving the lava beds, do so by 
means of vertical falls situated in deep cafions. Except in the Yellowstone and its 
tributaries, in Gibbon River and in Lava Creek, no fishes have been found above 
these falls, and the presence of fishes in the Upper Yellowstone and Lava Creek is 
doubtless due to the imperfect character of the watersheds separating these streams 
from others. Outside of the park, the fallsin Clark Fork of the Yellowstone exclude 
fish from that river, and perhaps the Great Shoshone and American Falls in Snake 
River exclude from the upper part of the stream the fauna of the Lower Columbia. 
Another supposed obstacle to the spread of fish life in the Yellowstone Park is the 
presence of the innumerable hot springs, solfataras, and geysers, for which the 
region is famous. 
Dr. Jordan’s trip was made somewhat late in the season, and on that 
account was considerably hurried, but he was, nevertheless, enabled to 
study the leading points in the problem which had been suggested to 
him. Yellowstone River and Lake, including all their western tribu- 
taries, were examined at many places, and also all the principal streams 
and lakes of the Madison and Snake River basins. The total number 
of fishes discovered was 10, of which 2 belong to the Salmonide (the 
Rocky Mountain trout and the whitefish), 1 is the miller’s thumb or 
blob, 1 the grayling, 4 are minnows and chubs, and 2 suckers. No- 
where above the falls, except in the Yellowstone and its tributaries, in 
Gibbon River, and in Lava Creek, were any fishes found. The miller’s 
thumb or blob was very abundant above the falls in Gibbon River, and 
its presence there is unexplained; but the occurrence of trout in Lava 
Creek, where they are common, is supposed to be due to the imperfect 
character in some places of the watershed which surrounds it. The 
grayling is restricted to the extreme northwestern part of the park. 
Dr. Jordan describes with much care the peculiarities and distribution 
of the different species, and the characteristics of all the principal lakes, 
rivers, and creeks in the park, making his report invaluable as a guide 
in the stocking of those waters. His conclusions regarding the suita-~ 
bility of certain areas for that purpose are also NERY important. 
“A reconnaissance of the streams and lakes of tite Yéliouenaan National Park, 
Wyoming, in the interest of the U. 8. Fish Commission, 3y David Starr Jordan. 
Bull. U.S. Fish Com., 1x, for 1889, pp. 41-63, pls, VlI-xxu1, and one map. 
