Valles Caldera (or
Jemez Caldera), is a 12-mile-wide collapsed
volcanic caldera in the Jemez
Mountains of northern New Mexico
. Within its
caldera,
Valle Grande is the largest
valle
(
grass valley) and the only one with a
paved road.
History
Until recently, the Valles Caldera was part of the
Baca Ranch. The Dunigan family sold the entire
surface estate of 95,000
acres
(380 km
2) and seven-eighths of the
geothermal mineral estate to the
federal
government.
Valles Caldera National Preserve
On July 25, 2000, the
Valles Caldera Preservation
Act, 16 U.S.C. Sections 698v-698v-10, created the
Valles Caldera National Preserve. The careful
husbandry of the Baca Ranch by its private
owners, including selective
logging, limited
grazing and
hunting,
and the use of
prescribed fire, had
preserved a mix of healthy range and
timber
land with significant
biodiversity,
including New Mexico's largest herd of
elk, and
served as a model for self-sustaining land development and use.
Funds for the purchase came from the
Land and Water Conservation
Fund derived from royalties the US government receives from
offshore
petroleum and
natural gas drilling.
Under the terms of the Act, the Preserve will have to produce
sustaining income;
environmentalists had lobbied for the more
inclusive protections of
National Park
status instead.
The preserve is located in northeastern
Sandoval
County
and southern Rio Arriba
County
, just west of Los Alamos
. It has a land area of 89,716
acres (140.18 sq mi, or 363.07 km
2).
It is
administered from United
States Forest Service offices in Jemez
Springs
.
Geology and science
Valles Caldera is one of the smaller volcanoes in the
supervolcano class. The circular
topographic rim of the caldera measures 19
kilometers (12 miles) in
diameter.
The
caldera and surrounding volcanic structures are the most thoroughly
studied caldera complex in the United States
. Research studies have concerned the
fundamental processes of
magmatism,
hydrothermal systems, and
ore deposition. Nearly 40 deep cores have been examined,
resulting in extensive subsurface data.
The Valles Caldera is the younger of two calderas known at this
location, having collapsed over and buried the
Toledo
Caldera, which in turn may have collapsed over yet older
calderas. The associated
Cerros del Rio volcanic field, which forms the
eastern Pajarito Plateau and the
Caja del
Rio, is older than the Toledo Caldera. These two large calderas
formed during
eruptions 1.47 million and
1.15 million
years ago. The Caldera and
surrounding area continue to be shaped by ongoing volcanic
activity. The El Cajete Pumice, Battleship Rock
Ignimbrite, Banco Bonito
Rhyolite, and the VC-1 Rhyolite were emplaced
during the youngest eruption of Valles caldera, about 50,000–60,000
years ago. Seismic investigations show that a low-velocity zone
lies beneath the caldera, and an active geothermal system with
hot springs and
fumaroles exists today.
The volcanic properties of the Valles Caldera make it a likely
source for renewable and nonpolluting
geothermal energy. However, some people
oppose development of the geothermal energy, considering it
destructive to scenic beauty and recreational and grazing
use.
The lower
Bandelier
tuff which can be seen along
canyon walls west of the Valles Caldera,
including San Diego Canyon, is
related to the eruption and collapse of the Toledo Caldera.
The upper Bandelier tuff is believed to have been
deposited during eruption and collapse
of the Valles Caldera. The now eroded and exposed orange-tan,
light-colored Bandelier tuff from these events creates the stunning
mesas of the
Pajarito Plateau.
Mule resting in Valle Jaramillo during
an endurance race; trees in the background lack lower branches due
to browsing
These calderas and associated volcanic structures lie within the
Jemez Volcanic Field.
This
volcanic field lies above the intersection of the Rio Grande Rift, which runs north-south through New Mexico,
and the Jemez Lineament, which
extends from southeastern Arizona
northeast to western Oklahoma
. The
volcanic activity here is related to the tectonic movements of this
intersection.
Recreation
A number of recreational and/or historical uses take place in the
Valles Caldera. Many of these uses involve trails. Valles Caldera
has many miles of ranch roads and livestock and game trails. These
include a network of trails currently designated for horse riding.
Historically, Valles Caldera was a location for
equestrian endurance race. After
establishment of VCNP the first race in the caldera was held in
2009. The largest grass valley, Valle Grande, is a venue for
ski orienteering.
Wildlife and livestock
Throughout the caldera the grass valleys appear groomed: there are
few saplings and mature trees lack lower branches. This is due to
heavy
browsing by
elk and
cattle. Although the
grass appears abundant, it is a limited resource. Its growing
season is short, it feeds thousands of cattle in the summer and
more thousands of elk all year, and during most of the year its
nutritional value is low.
Films shot in Valles Caldera
Exterior "town" set in Valle
Grande
Valles Caldera has provided several
filming locations, most for films in the
Western genre. Some of these
locations include exterior sets, such as the weathered "ranch
house" that can be seen from the highway in Valle Grande, and a
small "town".
See also
Notes
- In local English, "Valle Grande" is . Some people
use pronunciations closer to Spanish.
- 16 U.S.C. Section 698v(a)(5).
- CNN.com "New Mexico's Baca Ranch soon to be public
land".
- Table 6 - NFS Acreage by State, Congressional
District and County - United States Forest Service -
October 10, 2007
- [1]
- Martin, Craig (2003) Valle Grande: A History of the Baca
Location No. 1, All Season Publishing.
- Hephner, Tracy (2006) See Us on the Silver Screen
(Again!), La Ventana en los Valles, volume 1, number 2, page
3.
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