When studied further, the invertebrates will also doubtless yield many
forms new to science.
Sedimentary, igneous, and metamorphic rocks are all present in the
State in great variety. Marine sediments, such as sandstones, lime-
stones, and shales, and the terrestrial or continental deposits of rivers,
lakes, glaciers, and the wind, have already been mentioned. Intrusive
igneous rocks occur as batholiths, stocks, dikes, sills, and laccoliths;
extrusive igneous rocks in the form of volcanic cones, lava flows, and
ash deposits cover large portions of the State. Volcanism continued
until fairly recent times, and some basaltic lavas are possibly less than
1,000 years old. Metamorphic rocks are abundant in the pre-Cambrian
basement complex and occur also in the aureoles surrounding the
younger intrusive bodies. What is generally conceded to be the finest
display of volcanic necks in the world exists in the Mount Taylor-Rio
An investigation, still in progress, reveals that more than 275 species
of minerals have been recorded in the State. Many fine specimens can
still be found, especially on the dumps of hundreds of abandoned mines.
A number of minerals, for example some of the potash salts, either do
not occur elsewhere in North America or are very rare. Both metallic
and non-metallic minerals have yielded richly.
Much of the State's striking scenery is in large part the result of
deformations of the earth's crust. Folds and faults of many varied
types abound. A standard classification of mountains recognizes: (1)
residual mountains, or mountains of erosion; (2) volcanic mountains;
(3) tectonic mountains, a group of mountains formed by displacements
of the earth's crust, including fault rock (broken and displaced blocks),
dome, and fold (folded rock strata) ; and (4) complex mountains, or
those in which combinations of several of the above types occur. Good
examples of all except the pure fold type are found in New Mexico.
The fault block type is particularly well developed and marvelously
displayed. Practically all of the deformation and its accompanying
igneous activity have occurred within the past 60 million years, since
the end of the Mesozoic era.
SCENIC GEOLOGIC FEATURES
Underground Waters: Carlsbad Cavern National Park; Bottom-
less Lakes State Park; several groups of hot springs and their deposits,
notably the Soda Dam near Jemez Springs; Rosewell Artesian Basin;
sinkholes of the Pecos Valley.
Volcanic Features: Capulin Mountain National Monument, Ban-
delier National Monument, the great Valle Grande Caldera, the vol-
canic necks of the Mount Taylor-Rio Puerco field, Shiprock and asso-