Nebraska is not known for caves in fact most of the known (able to climb into) caves in the state can be counted on one hand. Nebraska is not a cave state, Missouri is, still there are caves forming and others that are deeper that have yet to be discovered. The world’s largest cave “Hang Son Doong” was just discovered in 1991 and as a solutional cave, it was formed in soluble limestone and is believed to be between 2 and 5 million years old. Caves have different stages of “life/stages” the basics are water seeps into the ground and starts dissolving the rock. This is followed by the formation of streams and rivers underground which the water that seeped through carved tunnels that now the water passes through. Over time the water erodes away the rock more and more and leaves behind caverns. We never get to see caves unless the stream/river punches through the rock in a hill side via a spring. As the spring water erodes the rock more and more it creates a bigger hole and soon humans can enter. Caves are deemed alive if there is water movement and likewise caves are deemed dead if there is no water in the cave. Water is key to cave formation without it, caves don’t happen. Cave tunnels and caverns are shaped and determined by the type of rocks the water encounters. The more soluble the rock the easier the water creates the tunnels and caverns. The path of least resistance wins. The cave here is still forming and the mineral spring here will someday be the entrance of the cave. This mineral spring was discovered long before the city of Omaha was formed. However, in 1917 the city of Omaha did a water test and found the spring had silica, magnesia, soda and some other minerals. This area was built up around this mineral spring, and this grotto provides enjoyment for all to enjoy. This natural spring produced cold and fresh water and people came from all over the area for the mineral water. The spring water was later piped through the seven different rocks to allow easier access to the water. The main source comes through the hillside. This means the formation of a cave is in the hillside area here. The rocks, in which this cave is forming, are Pennsylvanian period rocks. Pennsylvanian period was between 323.2 million years ago to 298.9 million years ago. There have been several different types of Pennsylvanian period limestone types found throughout the Omaha area. Winterset Limestone, Dennis Limestone, Drum Limestone, Chanute Shale, lola Limestone, Lane Shale, Wyandotte Limestone, Bonner Springs Shale, Merriam Limestone Plattsburg Limestone, South Bend Limestone, and Stanton Limestone have all been found around the Omaha area.
How caves form
Cave formation begins when rainwater absorbs carbon dioxide as it falls through the atmosphere. Rain water must have carbon dioxide to become acidic. It must be acidic to chemically react to the limestone bedrock. Rainwater is absorbed by the soil into the ground.
As rainwater comes through the soil it absorbs more carbon dioxide that is being produced by plants that are dead. This changes the ground water to a weaker form of carbonic acid (H2O + CO2 = H2CO3). As it travels down through the ground it comes to solid rock. When the rock is limestone or dolomite caves can form.
The water reacts chemically with limestone and slowly a larger and larger space will form. This happens because the rocks are made of calcium carbonate (CaCO3). This is what you call chemical erosion.
As the space becomes larger and larger the water can flow through. As it flows it erodes. Physical erosion washes away rock and sand. This is what makes a cave larger and forms an underground stream. Finally over hundreds of thousands of years or even millions of years the cave is formed.
**Logging requirements**
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Send the following answers to me.
- The text "GC8AXJG Life stages of a cave." on the first line
- How many spots does the mineral spring come out of?
- What minerals are known to be in this spring?
- What period of rock is this cave forming in?
- How long do you think it will take before you will be able to enter this cave?
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