As rain falls through the air, it absorbs minute quantities of carbon dioxide. When carbon dioxide reacts with water, it forms a very weak solution: carbonic acid. After it rains, this same, now slightly acidic groundwater absorbs organic matter from the soil as it works its way down to bedrock.
This adds to its acidity. Bedrock in limestone country is anything but solid. Horizontal layers of limestone tend to develop cracks and joints — perfect avenues for this acidic water to reach deeper and deeper into the earth, dissolving away the limestone impure calcite as it goes. This creates the chambers, avenues, tunnels, and the like in the limestone. In many cases, the mineral-laden waters are drained away by underground streams.
But there can also be the development of cave formations, depending on conditions in the cave or even in a particular cave opening. If they are not carried away by flowing water, any opening encountered gives the water an opportunity to drop the mineral load, especially as the water evaporates.
Thus, acidic groundwaters dissolve away the limestone, creating an opening that later groundwater may use as a dumping ground, depositing thin layer upon layer of calcite. These are sometimes called travertine falls. If water drips from a crack in the ceiling, it leaves behind a minuscule amount of calcite. This builds and builds to form stalactites. The water that drips to the floor also deposits calcite as it evaporates, building stalagmites. If the two should grow enough to connect, a column is created.
Now, when Carlsbad was first studied, it was assumed that carbonic acid had been the key agent in the water that created this underground fairyland.
Initially, this was true, as the groundwaters created the cavernous interior. But something happened on the way to modern times. Gas and oil deposits deep below the Carlsbad area began releasing gases, mainly hydrogen sulfide. We call it battery acid! During this virtual field trip you will learn about how Brazilian Free-tailed Bats Tadarida brasiliensis use echolocation, explore the largest single cave chamber in North America, and gaze on some of the most beautiful geologic textures in the world.
Only limestone can be carved to make a cave. Large bodies of limestone are found only in particular places where extremely large coral reefs were once located. When this cave formed, the limestone bedrock was a part of the groundwater system that contains water within rock and soil.
When this water combined with hydrogen sulfide which has a rotten egg smell from hydrocarbon deposits below, the sulfuric acid that formed began rapidly dissolving the calcium carbonate of the limestone. The stalactite and stalagmite formations are amazing! From tiny pearls to massive ft tall columns, the beauty of these natural wonders is incredible. For over an hour you walk along a paved trail looking at stunning views of limestone gems.
The Hall of the Giants is breathtaking. Recently, one New Mexico national park has been made available so you can tour without even leaving your couch. Want to take another trip without leaving your home? During these uncertain times, please keep safety in mind and consider adding destinations to your bucket list to visit at a later date. While it is best visited in person, the park will still knock your socks off in photos and videos. The website has a number of activities, games, articles, and even virtual tours that allow you to learn all you want about art and culture around the world.
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