How Do Caves Form?

From Issue: Discovery 10/1/2019

A cave is a large, empty chamber underground, usually formed in a natural way (not man-made). Speleology (spee-lee-AW-low-jee) is the study of caves. While there are several different types of caves in the Earth, karst or solution caves are the most common. Geologists who believe in an old Earth believe that solution caves provide strong evidence of an old Earth and disprove the Bible’s description of a young Earth. Is that true?

It is tempting to believe that caves form from rushing water that slowly wears away a rock—“eroding” it until a hole appears. But that is not the action that forms most caves. Most caves are thought to be formed by rock being dissolved by an acid—a process called dissolution (DIS-uh-LOO-shun). After a chamber is dissolved in a rock, when the water level below the ground drops or the ground itself rises (yes, that happens in some places!), an empty cave is left.

Many old-Earth geologists believe that solution caves are formed when rain water picks up carbon dioxide in the air as it falls to the ground and begins soaking into the Earth. As it seeps through the Earth, it picks up more carbon dioxide from the decaying plants in the dirt, and the water turns into carbonic (kar-BON-ik) acid—the stuff that makes your soda fizz. When that acid sinks in the ground to a kind of stone that dissolves easily (like limestone), the acid slowly dissolves the rock, forming a hole. Old Earth geologists believe that over thousands of years, the hole gets bigger, eventually forming a cave. As you can imagine, that process is very slow. How, then, can the Bible be true?


Over the last several years, another kind of cave dissolution process has been studied and found to explain how many caves have formed. Instead of rocks being slowly dissolved by carbonic acid from above, they can be quickly dissolved by sulfuric acid that comes from below. This process is called hypogene (HIPE-oh-jean) speleogenesis (SPEEL-ee-oh-JEN-uh-sis). As water comes into contact with rocks that contain sulfur, dead plants and animals (which release sulfur as they decay), or hydrogen sulfide from volcanic gases, and then combine with oxygen, sulfuric acid forms. During the Flood, large amounts of hot water would have been trapped below the surface of the Earth while dirt was being piled up on continents. The water would have mixed with oxygen, as well as hydrogen sulfide from the volcanic activity in the Flood and sulfur from the dead plants and animals across the planet, making sulfuric acid. The sulfuric acid would have been trapped beneath the Earth’s surface where the pressure from the water and added dirt on the surface would have caused the sulfuric acid to move towards the surface, dissolving rock along the way. Bottom line: the Flood conditions would have been perfect for the rapid formation of solution caves.

Mineral Gypsum

To show that sulfuric acid dissolution explains most solution caves, I have studied 25 caves in eight states, looking for characteristics in solution caves that would support sulfuric acid dissolution: entry holes at the base of the cave (feeders), pathways leading from the feeders to the top of the cave (channels), dome structures on the ceilings of caves (cupolas), and the presence of the mineral gypsum (which forms quickly when sulfuric acid meets lime), for example.Without exception, every solution cave I have studied has characteristics that support sulfuric acid dissolution—exactly what we would expected if the Flood happened and formed caves only a few thousand years ago.


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