# Valles Caldera

- **Country:** United States
- **Coordinates:** 35.900000, -106.533333
- **Type:** Complex Caldera
- **Range:** Jemez Mountains
- **Location:** Sandoval County, New Mexico, U.S.
- **Map Size:** 230
- **Elevation Ft:** 11253
- **Easiest Route:** New Mexico State Road 4
- **Last Eruption:** 68,900 ± 1,000 years BP
- **Volcanic Zone:** Jemez Lineament and Rio Grande Rift
- **Label Position:** bottom

From 1959 to 1983, approximately 40 exploratory geothermal wells were drilled into the Redondo Creek Graben as part of the Baca geothermal field, a joint operation by the United States Department of Energy and the Union Oil Company of California. 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.

![Photo of Valles Caldera](https://upload.wikimedia.org/wikipedia/commons/d/d6/Valle_Grande_dome.jpg)

**Source:** https://en.wikipedia.org/wiki/Valles_Caldera (Wikipedia, CC BY-SA)