Жемез тауларындағы жанартау кальдерасының тарихы

Volcanic caldera in the Jemez Mountains of northern New Mexico, United States

Valles Caldera (or Jemez Caldera) is a 13.7 mile (22 km) wide volcanic caldera in the Jemez Mountains of northern New Mexico.

Use of Valles Caldera dates back to the prehistoric times: spear points dating to 11,000 years ago have been discovered. Several Native American tribes frequented the caldera, often seasonally, for hunting and for obsidian, used for spear and arrow points. Obsidian from the caldera was traded by tribes across much of the Southwest. Eventually, Spanish and later Mexican settlers as well as the Navajo and other tribes came to the caldera seasonally for grazing with periodic clashes and raids. Later, as the United States acquired New Mexico as part of the Treaty of Guadalupe Hidalgo in 1848, the caldera became the backdrop for the Indian wars with the U. S. Army. Around the same time, the caldera and its forest began to be used commercially for ranching and logging.

The caldera became part of the Baca Ranch in 1876. The Bacas were a wealthy family given the land as compensation for the termination of a grant given to their family near Las Vegas, in northeastern New Mexico. The family was given several other parcels by the US Government as well, including one in Arizona. This area, , was called Baca Location number one. Since then, the land has been through a string of exchanges between private owners and business enterprises. Most notably, it was owned by Frank Bond in the 1930s. Bond, a businessman based in nearby Española, ran up to 30,000 sheep in the calderas, significantly overgrazing the land and causing damage from which the watersheds of the property are still recovering. The land was purchased by the Dunigan family from Abilene, Texas in 1963. Pat Dunigan did not obtain the timber rights, however, and the New Mexico Lumber Company logged the property very heavily, leaving the land scarred with roads and removing significant amounts of old growth douglas fir and ponderosa pine. Dunigan bought out the timber rights in the 1970s and slowed the logging. He negotiated unsuccessfully with the National Park Service and the US Forest Service for possible sale of the property in the 1980s. The legislation provided for the federal purchase of this historical ranch nestled inside a volcanic caldera, with funds coming from the Land and Water Conservation Fund derived from royalties the US government receives from offshore petroleum and natural gas drilling. The Dunigan family sold the entire surface estate of and seven eighths of the geothermal mineral estate to the federal government for $101 million. As some sites of the Baca Ranch are sacred and of cultural significance to the Native Americans, of the purchase were obtained by the Santa Clara Pueblo, which borders the property to the northeast. These include the headwaters of Santa Clara Creek, which is sacred to the pueblo. The Valles Caldera Preservation Act of 2000 also created the Valles Caldera Trust, an experimental management organization consisting of nine board members, including seven appointed by the President of the United States. The Trust combined private sector practices with federal land management protocol. Under the terms of the Valles Caldera Preservation Act, the preserve was to become financially self sustaining by 2015. The experiment was controversial. In 2010, the Trust admitted that it would be unable to achieve financial self sustainability, having raised only about $850,000 of the $3 million needed to manage the property each year. Environmentalists had lobbied for the more inclusive protections of national park status instead of the Trust model, but then Senator Pete Domenici (R) insisted on the experimental approach as a condition for his support for public purchase. Beginning in 2010, US Senator Jeff Bingaman (D) introduced legislation that would transfer the property to the National Park Service as a national preserve. The 2011 bill was supported by the VCNP trustees and a majority of New Mexico's Congressional delegation. On December 19, 2014, President Barack Obama signed the 2015 National Defense Authorization Act, which transferred administrative jurisdiction of the preserve from the Valles Caldera Trust to the National Park Service. After a brief transition period, the National Park Service assumed day to day management on October 1, 2015. On October 10, the preserve held an official dedication with dignitaries including U. S. Secretary of the Interior Sally Jewell, U. S. Senator Tom Udall, U. S. Senator Martin Heinrich, former U. S. Senator Jeff Bingaman, National Park Service Intermountain Region Director Sue Masica, and the first National Park Service Superintendent of Valles Caldera National Preserve, Jorge Silva Bañuelos.

In July 2011, the Las Conchas Fire, started by a power line on nearby private land, burned of the Valles Caldera National Preserve. The wildfire burned a total of in the Jemez Mountains, including most of neighboring Bandelier National Monument.

The circular topographic rim of the caldera measures 13.7 mile (22 km) in diameter. The caldera forming Toledo eruption emplaced the Otowi member of the Bandelier Tuff 1.61 million years ago, which can be seen along canyon walls west of Valles Caldera, including San Diego Canyon. The younger Tshirege Member of the Bandelier Tuff was formed during the Valles Caldera eruption 1.23 million years ago. The now eroded and exposed orange tan, light colored Bandelier Tuff from these events creates the stunning mesas of the Pajarito Plateau. Valles Caldera is the type locality for a resurgent dome caldera, the formation of which was first developed by C. S. Ross, R. L. Smith, and R. A. Bailey during field work at Valles in the 1960s. After the initial caldera forming eruption at Valles, the Redondo Peak resurgent dome was uplifted beginning around 1.2 million years ago. The El Cajete Pumice and Battleship Rock Ignimbrite were emplaced in a single eruptive event 74,200 ± 1,100 years ago, followed by the eruption of the Banco Bonito obsidian flow during the youngest eruption of Valles Caldera, at 68,900 ± 1,000 years ago. An active geothermal system with hot springs and fumaroles exists today. NASA used the caldera in October to November 1964 and again in September 1966 to geologically train the Apollo Astronauts in recognizing volcanic features, such as ash flow tuffs, pumice air falls, and rhyolite domes. Notable geologist instructors included Roy Bailey.

According to the Köppen climate classification, Valles Caldera has a subarctic climate (Dfc), with cold winters and mild summers. The caldera is subject to strong temperature inversions, causing very cold nights year round and high diurnal temperature variation.

The volcanic properties of Valles Caldera make it a likely source for renewable and nonpolluting geothermal energy. However, some people oppose the development of geothermal energy, considering it destructive to its scenic beauty, recreational and grazing use. Its impact on the hot springs and supplying aquifers is unknown as experiences from other past geothermal projects proved that production of reservoir fluids had dramatic impacts to the surface thermal features. Valles caldera was home to the first experiments into development of an Enhanced geothermal system (EGS) or Hot dry rock (HDR) geothermal system, beginning in 1974 by the Los Alamos National Laboratory at the Fenton Hill reservoir, approximately 3 km west of Valles caldera. Originally, the Fenton Hill site was chosen as an EGS laboratory in hopes that the proximity to Valles caldera would increase the temperature of the bedrock, thus requiring shallower drill depths. However, the abundance of hydrothermal fluids discharged from the nearby caldera resulted in hydrothermal alteration of the rocks at depth, weakening the sealed nature of the reservoir. The Fenton Hill HDR experiment was finally abandoned in 1998. The experiments demonstrated that a potential EGS reservoir must be characterized by low permeability, crystalline basement rock with no active faults or joints. Despite measuring a maximum temperature of 342 °C and having a likely production capacity of 20 MWe, the geothermal field was too small to be economic. Three scientific cores were drilled in Valles Caldera during the mid 1980s as part of the United States Continental Scientific Drilling Program in order to analyze the chemistry of geothermal fluids and the presence of a vapor dominated cap in the Sulphur Springs region. The maximum bottom hole temperature measured during drilling was 295 °C. Overall, the geothermal reservoir at Valles Caldera is liquid dominated rather than vapor dominated and has a neutral chloride fluid chemistry with a maximum temperature below 300 °C. Historically, Valles Caldera was a location for equestrian endurance races. 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. Activities are open to the public, though some require reservations. Customer service and concierge services are provided by the Public Lands Interpretive Association. The valley floor is above 2438.40 m altitude.

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 and because of frequent grass fires of human and natural origin which kill the lower branches on the Engelmann spruce, Douglas fir and Ponderosa pine that populate the uplands around the grasslands dominating the bottoms of the calderas. Extreme cold in winter prevents tree growth in the bottoms of the calderas. The grasslands were native perennial bunch grass maintained by frequent fire before sheep and cattle grazing. Although the grass appears abundant, it is a limited resource. Its growing season is short. Through the VCNP's limited grazing program, it feeds hundreds of cattle in the summer and thousands more of elk in the warm seasons and in drought winters, and during most of the year. Its nutritional value is low.