The Hot Springs Artesian Basin is a geological formation and thermal water aquifer located in the

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

of the Rio Grande, in

Sierra County, New Mexico Sierra County is a county located in the U.S. state of New Mexico. As of the 2020 Census, the population was 11,576. Its county seat is Truth or Consequences. Geography According to the U.S. Census Bureau, the county has a total area of , of ...

. The rocks that make up the Hot Springs Artesian Basin and the surrounding the basin area include igneous, sedimentary, and metamorphic rocks. These range in age from the Pre-Cambrian (granite and shists) to the recent period. The major structural features mainly formed during early Tertiary igneous activity when andesite, latite and rhyolite was extruded to form the Black Range and the San Mateo Mountains in the Oligocene time. The thermal springs in the basin are located within the city of Truth or Consequences (formerly Hot Springs), New Mexico; temperatures of these hot springs range from 98°F to 114°F. The water table at Hot Springs Artesian Basin slopes downward 9 feet over a half mile, from 4,239 feet in elevation where the alluvium in the aquifer coincides with the piezometric surface at limestone hill, sloping downward to 4,230 feet at the granite bluff base where the alluvium extrudes. Some of the water flowing down the slope is intercepted by sumps and drains, however most of it discharges in the Rio Grande.

References

Geologic formations of New Mexico Geography of Sierra County, New Mexico Hot springs of New Mexico {{Geology-stub