Delaware Basin.........much like Lurray C........near my alma mater.....JMU in Virginia......

Geology[edit]

For details on the region's geology, see Delaware Basin.

Capitan Reef[edit]

An estimated 250 million years ago, the area surrounding Carlsbad Caverns National Park served as the coastline for an inland sea. Present in the sea was a plethora of marine life, whose remains formed a reef.^[5] Unlike modern reef growths, the Permian reef contained bryozoans, sponges, and other microorganisms. After the Permian Period, most of the water evaporated and the reef was buried by evaporites and other sediments. Tectonic movement occurred during the late Cenozoic, uplifting the reef above ground. Susceptible to erosion, water sculpted the Guadalupe Mountain region into its present-day state.^[6]

Speleogenesis[edit]

Carlsbad Caverns National Park is situated in a bed of limestone above groundwater level. During cavern development, it was within the groundwater zone.^{[citation needed]} Deep below the limestones are petroleum reserves (part of the Mid-Continent Oil Field). At a time near the end of the Cenozoic, hydrogen sulfide (H₂S) began to seep upwards from the petroleum into the groundwater. The combination of hydrogen sulfide and oxygen from the water formed sulfuric acid: H₂S + 2O₂ → H₂SO₄. The sulfuric acid then continued upward, aggressively dissolving the limestone deposits to form caverns. The presence of gypsum within the cave is a confirmation of the occurrence of this process, as it is a byproduct of the reaction between sulfuric acid and limestone.^[5] Once the acidic groundwater drained from the caverns, speleothems began to be deposited within the cavern. Erosion above ground created the natural entrance to the Carlsbad Caverns within the last million years. Exposure to the surface has allowed for the influx of air into the cavern. Rainwater and snowmelt percolating downward into the ground pick up carbon dioxide; once this water reaches a cavern ceiling, it precipitates and evaporates, leaving behind a small calcium carbonate deposit. Growths from the roof downward formed through this process are known as stalactites. Additionally, water on the floor of the caverns can contain carbonic acid and generate mineral deposits by evaporation. Growths from the floor upward through this process are known as stalagmites. Different formations of speleothems include columns, soda straws, draperies, helictites, and popcorn. Changes in the ambient air temperature and rainfall affect the rate of growth of speleothems, as higher temperatures increase carbon dioxide production rates within the overlying soil. The color of the speleothems is determined by the trace constituents in the minerals of the formation.^{[citation needed]}