NOVA....."The Mysterious Life of Caves" ...simply an amazing program on the "extremophiles microbes" and the formation of the underground caverns. Life forms that can exist without sunlight and tolerate temps approaching 185 degrees, and feed off of chemicals giving off gasses later turning into strong acids etching away the interiors of limestone mountains , that were once coral reefs of a great inland ocean of the greater southwest .
pbs.org
Also that was a great perspective changing & elegant hypothesis they came up with for the formation of the gypsum crystals which could not have formed by the usual carbonic acid eating away the limestone ...but an extremophile feeding on the oil deposits 1000's of feet below releasing gasses that seep upwards to form sulphuric acid which would be the only catalyst to leave the rarer gypsum crytaline deposits behind .
beautiful science ...beautiful "jewels of discovery" this stuff is :
Gypsum Crystals here ...just BEAUTIFUL !:-)
pbs.org
Whatever process created Carlsbad and Lechuguilla is largely dormant now. So the team visits a more active and dangerous cavern: Cueva de Villa Luz in Mexico, which emits the toxic, rotten-egg smell of hydrogen sulfide from its entrance. Inside, explorers must wear respirators and carry poison-gas monitors to protect themselves from the hydrogen sulfide that reacts with water in the cave to form caustic sulfuric acid. Deep within, they discover "snottites," mucous-like stalactites of sulfur-eating bacteria that also drip sulfuric acid. Oddly enough, the noxious environment teems with microbes, spiders, insects, crabs, and fish -- all thriving in complete darkness.
As strange as it may seem, sulfuric acid produced by microbial life is the cause of about five percent of all limestone caves, including Cueva de Villa Luz, Carlsbad, and Lechuguilla. Sulfuric acid not only dissolves limestone, it leaves a distinctive chemical residue: gypsum. This process, which is ongoing now in Cueva de Villa Luz, was completed millions of years ago in Carlsbad and Lechuguilla, where microbial activity continues today at a very slow pace.
Sulfuric acid is produced not just by snottites but also deep underground in oil deposits. Microbes consume oil and release hydrogen sulfide gas, which rises through rock fissures and combines with groundwater to produce sulfuric acid.
To scientists, the biggest surprise is that this Earth-transforming process is connected to life -- especially life where no one expected to find it, since caves were long considered virtually sterile environments. Dubbed "extremophiles," these newfound organisms, living beyond the margin of what was considered possible, are turning up in more and more environments, from hot springs at Yellowstone National Park to volcanic vents at the ocean bottom.
Some scientists believe these bacteria descend directly from the earliest life forms that emerged on Earth some 3.5 billion years ago. They may even be our best guess of what life is like on other planets -- buried beneath the surface of Mars, floating in the oceans of Jupiter's moon Europa, and otherwise thriving in extreme conditions throughout the cosmos.
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