200 Geological Survey of the Territories in 1872. 
rendezvous, from Bozeman, about five hours earlier, a strangely 
close connection for trips.of a month, without communication. 
e geysers of the Fire-hole have been so fully represented 
in this Journal, that it seems best to pass them with but brief 
mention, and that rather upon generalities than upon par- 
ticulars. 
The bedding of the volcanic sandstone which forms the 
mountain boundaries of the basin indicates this as probably the 
site of an old crater of huge dimensions, whose eruptions long 
since ceased, but whose fires still heat the rocks at depths acces- 
sible to the waters which readily permeate these porous strata, 
and which escape in springs of various temperatures up to 200° 
or a fraction above the normal boiling point at this elevation. 
At several points, masses of this voleanic sandstone are found 
perforated by irregular holes, evidently formed by solution of 
the siliceous ingredients in the escaping hot waters. By this 
process, degradation of the hills and enlargement of the basin 
are in progress. On the other hand, the deposition of various 
clumsy branching forms resembling sponges, sometimes in long 
waving fibers, ‘The former kinds are generally either green oF 
