Gilpin observer., 1905-11-16
Routt County Coal Fields.

In remote geologic age thick
sheets of lava were intruded into
coal-bearing formation in Routt
county, Colorado The result was that
beds of coal within fifty or seventy-five
feet of such sheets became anthracite
of semi-anthracite in character Just
how great is the area over which this
change occurred is not yet known, but
the biologists of the United States
Geological Survey who studied this
coal field during the past summer will
doubtless have many interesting
things to tell about 1t in the report
that they will bring out early in 1906.
who studied the coal field in the basin
The members of this survey party
OF the Yampa river, Colorado, were
Messrs. n. Nj. Fenneman and Hoyt S.
Gale, geologists, and Mrs. X. G. Allen,
topographer, who was engaged in the
preparation of a topographic map OF
the region. The area covered by this
reconnaissance extends from the Elk
river on the east to Lay on the west,
distance of i!fty miles, and from Cali
fornia park on the north to Williams
Fork on the south, distance of thirty
miles. From 1000 to 1,200 square miles
were examined and will be repre-
sented on the maps which will accom-
pany the report.
1t was determined that the creta-
ceous Goals examined were of Pierre
Fox Hills age. These are distributed
through "A vertical thickness of from
LOO 10 1000 feet of strata, chiefly
sandstones a nd sandy shales. The
Goals fall naturally into three groups.
which will be distinguished on the
map as Lower, Middle and Upper.
One the west and north sides of the
field the cretaceous is overlain by
a thick formation which Hayden
mapped as tertiary. This also con
tains much coal, but only small areas
of it are included in the field eX-
amined.
1t is in the northeastern part of the
field that thick sheets of lava have
been intruded into the coal-bearing
formation. The extent of the area
over which such change has occurred
is not known. because much of the so
called Anthracite range" is densely
wooded and outcrops of rock and coal
are few. There is. however, one lava
sheet which lies near an important
| coal horizon and forms ledge or
''rim-rock" for several miles. This
continuous exposure gives rise to the
hope that the sheet may underlie a
sheets may be extensive also. An
thracite coal occurs. at least in
patches, over an area of perhaps fifty
square miles. but the size of the sew
eral patches has not yet been deter
mined. They are not sharply
bounded. for between the anthracite
and the unaltered bituminous all
transitional phases are found.
Owing to the nature of the work. It
was not possible for the survey party
TO determine by extensive excavation
! the number and thickness OF the coal
beds Since, in large areas, the Goals
are not worked and have not even
been extensively prospected. II is quite
impossible to give fair estimate of
| the amount of coal within the area.
A single bed of coal ten feet thick eX-
tending over 500 square miles, or one
| half the area studied, would contain
about one cubic mile of coal. or nearly
six thousand millions of tons. Prob
ably more than 500 square miles af-
fording more than ten feet OF. workable
coal could be selected from the area
examined. In places the thickness of
the coal is more than five times as
! great.
The coal resources of this region
have thus far been little developed
Few tunnels have been driven more
than 100 feet. The coal has been re
| quired for domestic use only, and as
the population of the county is small.
! that demand has easily been met
With the coming of the hoped-for
Denver & Northwestern railroad
the Importance of the Goals of Routt
county Will at once be recognized