A Little-Known Region in Northwestern Montana . 
199 
contact; (2) that the diabase structure is restricted to portions of the 
mass which consolidated quite near the the contact; (3) that nearness 
to the contact measures the tendency of the magnetite to appear in 
skeleton forms; (4) that the hornblende and augite show more tendency 
to crystallize in parallel growths nearer the contact. 
In his study of the diabase dykes of the Rainy Lake region,* Dr. Law- 
son has shown that in some cases a porphyritic structure, a diabase 
structure, and an allotriomorphic-granular or granitic structure in turn 
characterize the rock of a single dyke in passing from the contact toward 
the center of the dyke. The conditions of consolidation of the rocks 
here studied have not been such as to give rise to the formation of a 
porphyrite, but with that exception the observations are quite similar. 
EXISTING GLACIERS. 
At the close of his interesting paper on this subject, Mr. I. C. Russell| 
writes as follows: “Existing glaciers were discovered by Prof. Pumpelly 
during the progress of the Transcontinental Survey, at the head of the 
Flathead River in northern Montana. No scientific account of these ob¬ 
servations has yet been published; but I am informed by Prof. Pumpelly 
that two glaciers were seen in the mountains in which the East Fork 
of the Flathead rises at an elevation of about 7,000 feet. It was observed 
that the glaciers broke off suddenly at the summit of precipices 2,000 feet 
high and that the waters flowing from beneath the ice had the milky 
color characteristic of glacial streams. The mountains in which these 
glaciers were discovered extended northward into British America, and 
are supposed to reach their greatest elevation north of the boundary. It 
seems safe to predict that when this little known region is more fully 
explored additional glaciers will be found about the peaks known as the 
Crows and Mountain Head.” I am unable to determine from this ac¬ 
count just where the glaciers seen by Prof. Pumpelly are. Two glaciers 
answering almost perfectly to the description here given are plainly visible 
from the crest of the Milk River ridge, and from very many points on and 
near the International Boundary. These glaciers, however, are on the 
head-waters of the Belly River, a fact which could not escape Prof. Pum- 
pelly’s notice had he come near enough to see the milky color of the water. 
He would also have seen that there were four instead of two glaciers; hence 
I conclude that these are not the ones referred to by him.J Small gla¬ 
ciers are numerous in all the higher mountains within twenty or thirty 
* Petrographical Differentiation of certain Dykes of the Rainy Lake region: Am. Geol., 
March, 1891. 
t Existing Glaciers of the United States: 5th Ann. Report U. S. Geological Survey, p. 347. 
t Since the above was written I have seen Prof. Pompelly and find that the region referred 
to is northwest of the Cut Bank Pass, between MacDonald’s Creek and the main divide of 
the Rocky Mountains. It seems entirely probable that this glacier is in the same mountain 
mass as those described in the present paper. 
