Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1911-12-09
NEW MAP OF NORTH AMERICA
Forty-two Colors Shown on Map Of
the Continent Issued by q. 8.
Geological Survey.

the year is the large geologic map o.
North America just issued by the United
States Geological Survey. 1t represent.
an exceptional type of engraving and
photographic color work and is printed
in four sheets which fitted together and
mounted make q map feet inches
high by 5 feet wide, the largest piece oil
worr ever issued by the Survey. The
scale is to 100000, or 80 miles to the
inch, and the plan Of projection is in
harmony with the universal world map
on scale Of l to 1000, 900, in that il
shows the units of publication of the
world map, each of which embraces
four degrees of latitude and six degrees
Of longitude.
The color scheme of the map is q
striking one. In oil there are AZ color
distinctions, varying from brilliant red
to pale tints approaching white. These
were produced by IA separate printings
from lithographic stones, requiring in
many places two or three combinations
of color to produce the desired effects.
II the weight of paper and heavy stones
lifted back and forth in the printing Of
this job were to be computed it would
run into the hundreds Of tons. The
accuracy of the register, or fitting to-
getber of the color blocks in small areas
throughout the map, is remarkable.
The work was done in the Surveys own
engraving and printing plant, and it is
believed that there are few il any other
establishments in the United States
capable of turning out such production.
The AZ color distinctions represent as
divisions of rock strata. Thus the rocks
of seven divisions Of the Paleozoic era
are each represented by color, besides
three separate colors for undi ffersntiated
rocks, and there are other colors for the
divisions of the Mesozoic, the Tertiary,
and the Qusrtenary.
The coloring OF the map is both effect
i've and pleasing. The scheme is sys-
tematic In that the colors range in pris.
matte order from yellow in the upper
portion in the geologic column through
green's, blues, and puppies to pinks and
browns at the base. The colors for the
igneous rocks, both plutonic and vol
canic, are mostly bright red. Viewed
as wall map, the map of North America
shows only the larger geologic units, as
the smaller divisions are represented by
different shades and tints of the same or
closely allied colors which are indistin.
guishsble at a moderate distance.
VALUABLE FOR DETAILED STUDY.
Viewed close at hand these minor
distinctions can be read and the map
can be used for detailed study limited
only by the scale. When it is used as
wall map the regions illustrating differ
ent types Of geology stand out boldly.
The great Canadian shield of pre-Cam-
brain rocks is represented by a subdusd
color in pattern Stimulating crystalline
texture. Parallel bands of darker colors
from New Brunswick to Alabama mark
the trend of the Appalachians, while
the broad area of blue and gray colors
to the west represent the coal fields of
the interior, and a fringe of yellow colors
to the east and south represents the
Coastal Plain sediments. A vermilion
covering over much of the western part
of the continent from Alaska to Central
America strikiugly portrays the volcanic
activity in this region during the Ter
tiary period, and the broad area of green
and yellow in the Middle West marks
the last stages of deposition of sedi-
ments in the interior sea which covered
that part of North America in Creta-
ceous time and in the continental de-
pressions in Tertiary time, including
many of the coal deposits of the public
domain.
The map smbodies all the available
published data and unpublished manu-
script maps in the Offices of the Survey
and corrections from gsologists in all
parts of the country, based on former
geologic map of North America, pub
lished by the Survey in 1906, in cooper
alton with the Canadian and Mexican
geological surveys, for the international
Geologic Congress which assembled In
the city of Mexico in that year. As an
example of the interest taken in the
publication Of the present map, it may
be stated that important corrections to
the map of 1906 were received by
the Survey from leading geologist of
France.
SOLD AT COST OF PAPER AND PRINTING.
Not only will the geologic map Of
North America be indispensable as
wall map in colleges and schools where
geology is taught, but each student will
desire copy for the study of broader
problems in areal and regional geology
and will wish to carry folded copy on
railroad trips across the continent.
This map is now on sale by the United
States Geological Survey at the nominal
price of rs cents each. 1t is safe to as
sumo that any private map-publishing
house would charge SIS to $40 copy for
such q map.
A member of the supreme court In ex-