Are you confused about the various cave types? Below are descriptions and photographs of the various cave types found in the United States. Decide for yourself which are most interesting to you.
The most common type of caves and caverns open to the public and also the longest and deepest caves in the world are limestone caves. These are my personal favorites.
They are formed over thousands of years by water. What happens is that rain mixes with carbon dioxide in the air and forms a weak solution of carbonic acid. This “acid rain” dissolves limestone and forms caves over time.
Some limestone caves like Carlsbad Caverns are formed by rainwater mixing with hydrogen sulfide in the earth. This creates a weak solution of sulfuric acid which also dissolves limestone.
In either case, other minerals are dissolved by the acidic water which then drips inside the cave. Over many years this dripping deposits the minerals in the form of stalactites and stalagmites and other beautiful formations that are commonly found in limestone caves.
Limestone caves can be found all over the USA. A couple of the most famous ones are Mammoth Caves in Kentucky and Carlsbad Caverns in New Mexico.
Lava caves or lava tubes as they are formally called are formed by volcanic flows. What happens is that during a volcanic eruption, the outer layer of lava will harden first but the lava inside remains molten and will sometimes flow out leaving a hollow tube.
These caves usually lack the beautiful formations found in limestone caves but sometimes contain stalactites, stalagmites and other formations created by dripping and splashing lava. They are normally dry and easy to explore.
These caves are of course located in areas of active or extinct volcanoes. The Lava Beds National Monument and Hawaii Volcanoes National Park are examples of lava tubes.
Sea caves are also known as Littoral caves. They are formed by the action of waves pounding against the land and removing material over time. Sea caves are relatively small, with only a few over 300 meters in length.
Because this type of cave is generally found facing the open sea, just getting to them can be an adventure in itself! Many of these caves can only be approached and explored by kayak or small boat. Others drain out at low tide and can be explored on foot.
Sea caves are obviously located in coastal areas. Examples are the sea caves of Santa Cruz Island in California and the Na Pali Coast on the island of Kauai, Hawaii.
This is my least favorite cave type. Although they are very beautiful, I highly dislike cold weather. You may not have any problem with it.
Ice caves come in two forms. A cave formed entirely of ice is actually called a glacier cave and as the name implies, forms in glaciers. Water runs through or under the glacier and forms a cave.
Glacier caves are very dangerous to enter and explore because of shifting and melting ice. They are a little too adventurous for the novice.
The other type of ice cave can be any cave type (limestone, lava tube, etc.) that has ice in it year round. These caves trap cold air. Water entering the cave freezes and stays frozen year round.
Ice caves can be explored like any other cave with the added cautions of wearing warm clothing and taking care with slippery surfaces. These caves often contain very beautiful formations.
Glacier caves can be found in the Pacific Northwest and ice caves are found in many locations where temperatures drop below freezing. Once cold air enters the cave, it generally stays there.
I once found a small cave containing a large block of ice in the Lava Beds National Monument. This was the middle of Summer and it was 80 degrees outside!
Sandstone caves are relatively rare. They are formed over time by water and wind action loosening the grains of sand and carrying them away. Not surprisingly, this cave type is often found near the ocean and formed by wave action and therefore can also be considered sea caves. These caves are usually not very long.
Aside from sea caves, sandstone caves can form inland anywhere there is sandstone. An example would be Castle Rock State Park in California.
Mud caves are even rarer. Some are located in an area of Southern California’s Anza Borrego State Park called Arroyo Tapiado. These caves were formed by floodwaters digging out channels that were later filled in by landslides. Subsequent floods move out lower level debris leaving behind a hollow tube or cave.
Sinkholes or Cenotes as they are called in Mexico are formed when the roof of a cave collapses, leaving a vertical entrance.
Sinkholes are also caused by man when a water or sewer pipe breaks underground and the soil is carried away, leaving a void that cannot support the surface. These are the kind of sinkholes that make the news but we are more interested in the natural kind.
Some sinkholes are dry and can be entered with ropes or by way of another cave entrance. Others are filled with water and require scuba equipment and special training for exploration.
Sinkholes can occur in many areas but are most common in Florida.
Talus caves are also called boulder caves. They are open spaces under large boulder piles. These caves are often formed at the base of a slope after a large rock-slide. They also form when there is a stream running underneath the boulders that washes away dirt and smaller stones, leaving opens spaces.
I hope that gives you a better understanding of the different cave types available for your exploration. Chances are, there is at least one type near you. Take a look at the other information on this site as you prepare for your next adventure.