RockHoundBlog

New Mexico’s Carlsbad Caverns National Park

Filed under: regular postings — Gary September 25, 2006 @ 4:39 pm

Thanks to scholtz at flickr for letting me use his pictures from Carlsbad Caverns! Checkout his whole series here http://flickr.com/photos/scholz/sets/72157594267632917/

I found the caverns an interesting read and now would love to check them out one day! Heres a little article about them from wikipedia.org, enjoy!

cavern

The story of the creation of Carlsbad Cavern begins 250 million years ago with the creation of a 400 mile (600 km) long reef in an inland sea that covered this region. This horseshoe shaped reef formed from the remains of sponges, algae and seashells and from calcite that precipitated directly from the water. Cracks developed in the reef as it grew seaward. Eventually the sea evaporated and the reef was buried under deposits of salts and gypsum.

Then, a few million years ago, uplift and erosion of the area began to uncover the buried rock reef. Rainwater, made slightly acidic from the air and soil, seeped down into the cracks in the reef, slowly dissolving the limestone and beginning the process that would form large underground chambers. At the same time, hydrogen sulfide gas was migrating upward from vast oil and gas deposits beneath the ancient reef. This gas dissolved in the percolating ground water to form sulfuric acid. The added power of this corrosive substance explains the size of the passageways. The exposed reef became part of the Guadalupe mountains and the underground chambers became the wonder of Carlsbad Cavern.

hit the read more button to continue:

The decoration of Carlsbad Cavern with stalactites, stalagmites and an incredible variety of other formations began more than 500,000 years ago after much of the cavern had been carved out. It happened slowly, drop by drop, at a time when a wetter, cooler climate prevailed. The creation of each formation depended on water that dripped or seeped down into the limestone bedrock and into the cave. As a raindrop fell to the ground and percolated downward, it absorbed carbon dioxide gas from the air and soil, and a weak acid was formed. As it continued to move downward the drop dissolved a little limestone, absorbing a bit of the basic ingredient needed to build most cave formations — the mineral calcite.

Once the drop finally emerged in the cave, the carbon dioxide escaped into the cave air. No longer able to hold the dissolved calcite, the drop deposited its tiny mineral load as a crystal of calcite. Billions and billions of drops later, thousands of cave formations had taken shape. Where water dripped slowly from the ceiling, soda straws and larger stalactites appeared. Water falling on the floor created stalagmites. Sometimes a stalactite and stalagmite joined, forming a column.

Draperies were hung where water ran down a slanted ceiling. Water flowing over the surface of a wall or floor deposited layers of calcite called flowstone. Cave pearls, lily pads and rimstone dams appeared where pools of water or streams occurred in the cave. Like oyster pearls, cave pearls were made as layer upon layer of calcite built up around a grain of sand or other tiny object. Lily pad-shapes formed on the surface of pools, while dams formed where water flowed slowly on the floor. Another type of cave formation that decorated cave walls and even other formations are popcorn-shapes, which may have formed when water evaporated and left behind calcite deposits.

Some of the more unusual formations to occur in Carlsbad Cavern are helictites, which grow seemingly without regard to gravity, their twisting shapes governed by crystal shapes, impurities and the force of water under pressure. Other rare formations are those composed not of calcite, but of aragonite, a mineral chemically identical to calcite but with a different crystal structure. These formations tend to be small, delicate and needle-like.


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