Bismarck daily tribune. [volume] (Bismarck, Dakota [N.D.]) 1881-1916, 1911-12-14

Thus the rocks of seven divisions of
the Paleozoic era are each represented
by "a color, besides three separate COL
ors for undRfferentiated rocks, and
there are other colors for the divisions
of the Mesozdic, the Tertiary and the
Quaternary.
The colorimg of the map is both
| effective and pleasing. The scheme is
systematic in THAT the colors range in
prdsmatic order from yellow in the
| upper portion of the geologic column
through greens, blues and puppies to
pinks and browns at the base The
colors for the igneous rocks, both plu-
tonic and volcanic, 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 ints of the same or close
ly allied colors which are indistin-
guishable at moderate distance.
Valuable far Detailed Study.
Viewed close at hand these minor
distinctions can be read and the map
can be used for detailed sturdy limited
only by the SCALE When it is used as
wall map the regions illustrating
different types of geology stand out
boldly The great Canadian shield of
pref ambrian rocks is represented by
a smbdued color in a pattern simulat-
ing crystalline texture. Parallel bands
of darker colors from New Brunswick
to Alabama mark the trend of the
AppaFachans, while the broad area of
blue and gray cOlors TO the west rep
resent the coal fields of the interior,
and fringe of yellow colors to the
east and south represents tine C5astal
Plain sediments. A brilliant vernlil-
lion ooloring over much of the west
ern part of the continent from Alaska
ito Central America striking,y por-
trays the volcanic activity in this re-
gion during the Tertiary period, and
the broad area of green and yellow in
the middle west marks the last stages
of deposition OF sediments in the in
terror sea which covered that part of
North America i'm Cretaceous time
and in the continental depressions in
Tertiary thine, including many of the
great coal deposits of the public do
main.
The map embodies all the available
published data and unpublished man.
uscrlpt maps in the Offices Of the sur
vey and corrections from biologists in
all parts of the country, based ON
former geologic map of North Amer
lea, published by the survey i'm 1906.
in cooperation 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 a leading |
geolbgist of France
Sold at Cost Iof Paper and Printing.
Not olly will the geologic map of
North America be Indispensable as a
wall map in colleges and schools |
where geology is taught, but each stu
dent will desire copy for the study |
Of broader problems in areal and re-
gional geology and villa wish to carry
a 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 Is cents each It is
safe to assume that any private map
house would charge IS to
SO copy for such a map.