Cave Facts

Caves are naturally occurring areas found under the surface of the Earth. The most common type, solutional caves form because of groundwater that contains acid. The acid erodes the rock. It forms caves when rocks fracture or break.
solutional cave in South Wales

Cave Facts for Kids:

  • There are approximately 17,000 caves in the US
  • Stalagmites rise from the ground up
  • Stalactites hang down from the ceiling
  • Caves can also be called a cavern
  • Spelunking is the term used for people who explore of caves
  • The longest cave system in the world is the Mammoth Cave in Kentucky.
  • The deepest cave in the world Krubera Cave in Abkhazia, Georgia
  • Caves that are made up of limestone are called “Cave of the Winds.”
  • A cave can only get up to 3,000 meters before it will collapse from the weight.
  • Acid rain that erodes rocks and makes caves is caused by rain that mixes with carbon dioxide.
  • It can take up to 100,000 years for a cave to be wide enough to hold a person.
  • Stalactites are made up of water that has lime or calcium bicarbonate.
  • Limestone is a type of sedimentary rock that is very soft.
  • Speleothems are rock formations that are found in caves.  These are also called stalactites or stalagmites, depending on which way they grow.
  • When calcite is on the walls or floors of a cave it is called flowstones.
  • Helictites are other formations in a cave that goes in different shapes and directions.
  • If there is a root growing in a cave, it usually looks like it is sparkling because of the water that collects on the root.

How are caves formed?

Most caves are made up of different types of rock such as limestone, marble, dolomite, and gypsum   When it rains, the water can take different paths, while much of the water will be used by plants and animals and flow into rivers, streams, and lakes.

Groundwater soaks into the surface of the Earth and has a  chemical reaction with carbon dioxide. This carbon dioxide gets in the soil from decaying plant and animal remains, a weak solution of carbonic acid is formed. This carbonic acid then eats away at the rock and dissolves it, forming a cave passage.

The water gets into the Earth through cracks or fractures, which geologists like to call joints or faults.

Types of Caves

Limestone cave

There are many types of caves such as:

  • Primary Caves-A primary cave is a cave that was formed the same time as the rocks that are surrounding the cave was formed.  Most of the primary caves are formed from lava or lava tubes.  When lava moves down the hill of a surface area, it will harden when it cools but underneath it, the lava is still flowing so it is very hot.  This causes there to be a hollow tube that is created.
  • Sea Cave-sea caves are caves that are found on the coast some are even underwater, close to an ocean.  These types of caves are created by the movement of the tides.  When the tides move on the shore continuously, they will cause the sea cliffs to erode and it will form a cave.
  • Corrosion Caves-Corrosional Caves are formed when water flows through rock.  When water flows through rock, it causes erosion.  Erosion can cause caves to form even in the hardest rocks.
  • Glacier Caves-A glacier cave is a cave that is formed when the ice melts, freezes, and melts again.  The water then moves through the glacier and creates a cave.
  • Fracture Cave-A fracture cave happens when softer rocks are found between harder rocks.  When the water flows through the softer rocks, it causes them to break and causes harder rocks to cave in.
  • Salt Cave – Also called Salt Mines these have so many uses. The salt for our food and salt for deicing roadways come from these caves.  The largest salt mine cave in the world is in Goderich, Ontario.
  • Limestone Caves -Limestone rock is much softer than other kinds of rocks. Limestone caves form when rainwater seeps through cracks and dissolves it. When it rains the

What Causes a Cave to Form?

Caves are formed when there is either erosion, a chemical action, volcanic eruptions, pressure, or plates move.  Something has to be done for a cave to be created.

Most of the time, caves are formed when there is an acid that is found in the water underground and the water causes the rocks to dissolve. When water runs over rocks, it causes them to get softer.  Most water has some acid in it and the acid dissolves some of the rocks.

When the rocks are dissolved, it makes a cave, but the cave can get bigger and bigger depending on how the water flows through it.

If the water changes path and stops flowing through a cave, the cave will not get bigger and will eventually dry out or stay the same.

Inside of a Cave

Lava tube in Hawaii Inside you can see interesting things.  Sometimes things grow on the ground and up and other times things grow from the ceiling of the cave down.

  • Stalactites-Stalactites grow from the ceiling down.  The way stalactites are formed is when water from the ceiling drips down and as the water keeps dripping it leaves mineral deposits.  The mineral deposits keep growing as the water keeps dripping.  The mineral deposits harden and keep hardening and growing.
  • Stalagmites-Stalagmites grow from the floor up.  Stalagmites are formed when water drops to the floor of the cave and they keep dripping.  The drippings will form mineral deposits and they will get hard.  As the water keeps dripping, the mineral deposits fall on top of each other and keep growing.

Stalagmites and stalactites can keep growing until they come together and form a mineral deposit that goes from the ceiling to the floor.  It takes 100 years for one to grow around an inch.

Exploring Caves

People sometimes make a profession of cave exploring, also called caving, potholing, or spelunking. They use equipment such as:

  • Helmet
  • Headlamp
  • Back-up Headlamp
  • Footwear (sturdy boots)
  • Caving Undersuit
  • Wet Suit
  • Knee Pads
  • Elbow Pads
  • Gloves
  • Harness
  • Chest Harness
  • Food and Drink

Caving is the act of exploring, and it’s not always physically demanding. It’s one of the oldest known actives of exploring tunnels underground.

It’s amazing to think that it might have taken a million years to create a cave. Safety is essential. If you’re inexperienced, you don’t go by yourself. Somebody should stay above ground at the cave entrance.

Studying Caves

Scientists and archaeologists help to study caves for many reasons. One of the reasons is the environment and what surrounds the caves.  Scientists study caves to see why they are formed and what causes them to develop.

  • A scientist who studies caves is called a Speleologist.
  • The study of caves is called Speleology.
  • The study of how a cave is formed is called Speleogenesis.

Underground in the bedrock, they can find Fossils, insects, and even waterfalls.

Animals in Caves:

There are many different types of animals that live in caves such as:

  • Bats
  • Fish
  • Insects
  • Spiders
  • Salamanders
  • Crickets
  • Ringtail Cats
  • Bears
  • Frogs
  • Birds
  • Owls
  • Troglobitic-The troglobite is the only animal that lives only in a cave.  These animals have no eyesight and most of them do not have color because they are always in the dark.

A bat is not considered a troglobite because a bat only uses the cave to sleep and to reproduce.  A bat leaves the cave to hunt for food and to fly around.

Plants in a Cave

Sometimes there are plants that will grow in the entrance of a cave.  As we know, plants need sunlight in order to have photosynthesis and grow and inside of a cave, there is little or no sunlight. At the entrance of the cave, however, there is some sunlight and since there is some sunlight some trees or plants might grow there.  Some of these include:

  • Trees
  • Grass
  • Moss
  • Ferns
  • Liverworts

The plants that grow in the entrance of the cave are able to have steady temperatures because the cave is warm and has a lot of humidity.

Plants are important for the ecology of the cave because they help to create carbon dioxide that creates carbonic acid, and this helps to dissolve the limestone that forms caves.

Caves that have plants sometimes have a root system.  Some of the roots will cause rooties to form in the cave and these happen when streams flow through the caves.

These rooties or root mats are important to the animals that live in the cave and they help to provide foods. Caves that do not have root mats have fewer animals living in them than caves that have root mats.

Another important thing about plants in caves is that when there are plants that grow at the entrance of caves, it helps to create more nutrients for the animals and will make the water better that comes into the caves.

What Makes Caves Important?

Prehistoric wall paintings of Magura Cave, Bulgaria

Caves are important because, in the past, they helped people that were hunters to be able to hide and to hunt.  People also used caves to bury their dead or for religious purposes.

Many artifacts have been found in caves. Now, caves are important because they help to give shelter to different animals.

Caves are also places that animals can go to hibernate. Some people even live in caves still and the cave can provide shelter for people that are in the wilderness or exploring nature.

What Did You Learn?

  • What is a cave?  A cave is a formation that is formed under the Earth’s surface.
  • How are caves formed?  Caves can be formed in many ways such as acid making a hole, water eroding the area, caves formed by hot lava, and tidal waters.  There are many different kinds of caves that can be formed.
  • What is in the water that helps to cause erosion?  Water is made up of some acid which helps to make things erode faster.
  • What is the formation called that hangs from the ceiling of a cave and is formed by rain and mineral deposits?  A Stalactite is a formation that grows from the ceiling of a cave and down.
  • What is the formation called that goes from the ground of the cave and up?  The formation that goes from the ground up is called a Stalagmite.  This formation is made from rain and mineral deposits that continuously stack on top of each other.