Texas Almanac, 1939-1940 Page: 41

PHYSIOGRAPHY OF TEXAS.

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-Courtesy of 111th Photo Section, Texas National Guard.
Airplane view of Santa Helena Canyon. The sheer walls of the gorge at this point where
the Rio Grande cuts its way through the Mesa de Anguila are about 1,600 feet high. To the
right is Mexico, to the left is Brewster County, Texas, U.S.A. Compare this bit of Texas
boundary line with that shown on page 35.

the principal concentration and ship-
ping points for wool, mohair, cattle, pe-
cans and other products of the area. The
trade of tourists and sportsmen greatly
supplements the agricultural income of
the people of this area. The density of
population is relatively low. It is pre-
dominantly native white stock, though
there is a considerable Mexican popula-
tion in the southern and southwestern
sections. In Mason and Gillespie Coun-
ties are found many descendants of the
German migration of 1840-1850.
Except for the great petroleum devel-
opment in the northern and Pecos Valley
sections, the Edwards Plateau has no ap-
preciable mineral production. A great
variety of minerals is found, however,
especially on the eastern edge including
lead, gold, clays including kaolin, and a
variety of building stone including
granite, marble and limestone.
Lying on the northeastern edge of the
Edwards Plateau is the interesting
Burnet-Llano region described on a pre-
ceding page as a part of the North Cen-
tral Province. Some physiographers,
however, include it under the same ma-
jor area as the Edwards Plateau.

TRANS-PECOS TEXAS.
That part of Texas lying west of the
Pecos, except the extension of the Ed-
wards Plateau into Pecos, Terrell and
Brewster Counties as mentioned above,
belongs properly to the great Rocky
Mountain Province of the United States.
It is a high plateau ranging in elevation
from 3,000 to 5,000 feet, traversed by
mountain ranges running usually from
northwest to southeast. Geologically it
is a conglomerate with many older strata
revealed. The principal mountain
ranges are the Guadalupe, rising to a
peak of maximum height of 8,751 feet
in Guadalupe Peak, highest point in
Texas; the Davis Mountains with a
maximum height of 8,382 feet in Mount
Livermore, and the Chisos Mountains
with a maximum elevation of 7,835 in
Mount Emory.
Drainage is into the Pecos on the east
and the Rio Grande on the south, excent-
ing the Diablo Bolson consisting of about
8,284 square miles in Texas and drain-
ing into the salt flats at the base of the
Guadalupe Mountains. This great in-
land territory with no outlet to the sea
is one of the unique physiographic fea-

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