Caves: Nature's Majestic, Mysterious Wonders
The world is full of natural beauty, but there’s nothing quite like the wonders of a cave. The natural voids are home to everything from mineral formations to ancient discoveries and have attracted the interest of adventurous explorers for centuries.
With seven different types of caves — plus various sub-styles — it's no wonder these mysterious and majestic enclosures continue to captivate the imagination. Time to go spelunking and check it out!
Caves Take Millennia to Form
Obviously, beautiful caves around the world don't just form overnight. It took more than 100,000 years for these natural holes and crevices to become what they are today. It takes that much time for hard substances like limestone, dolomite, gypsum and other types of sediment to erode to the point where the tunnels are large enough for humans to explore.
Caves are usually part of a system of underground tunnels that stretch underneath the Earth's surface. These types of formations are usually called karsts. Because of the way they form, caves can be similar but never exactly alike.
Water Erosion Plays a Role
Water erosion plays a huge part in most cave formations, especially those that are both underwater and against the shoreline. When water pushes and flows against the rock for a long enough time, it begins to wear it down until it slowly tears pieces away.
Over time, the erosion that is barely noticeable on a daily basis becomes the beginning of a cave. Eventually, an entire system of caves, grottos and underwater tunnels make their way across an area. The gradual breaking down of the rock wall is how water creates a cave.
Caves Wouldn't Exist Without Chemistry
It may sound strange, but chemistry has a hand in the birth of new caves around the world. The acid level of the water flowing through an area plays a part in grinding away at the rock. When the acidic water reacts with carbon dioxide gas that has been released from the top level of soil above, it forms carbonic acid.
This leads to a dissolve rate that is at least 25 times higher than the rate for water just eroding the surface of the limestone alone. When the limestone gets into the water, it causes a chemical reaction that contributes to the formation of a cave.
Volcanic Forces Help Caves Along
When it comes to creating new caves, volcanic forces such as flowing magma often lead to cave formations that have nothing to do with water erosion. When a volcano erupts, it sends a river of lava flowing that eventually makes its way into the crevices and canyons of the Earth.
As the top of the lava begins hardening, it creates the top of a future cave. Beneath the surface, as the lava begins to drain from the area, it begins to form lava stalactites. This creates a sort of trench that later becomes a cave.
It's All About the Pressure
It doesn’t matter if the cave is being carved out by water or wind. The most important part of erosion is the amount of pressure being applied by the force of the water or the wind. This pressure determines just how much erosion will take place.
The higher the pressure, the higher the chance of more significant erosion resulting in a larger cave. The level of pressure — whether it's high or low — is what makes the difference between a vast cave forming or a small channel snaking underneath the Earth's surface.
Plate Tectonics Create Magic
Another way caves are formed is through tectonic movement. When the rocks are moved by plate tectonics, fractures or joints in the Earth begin to pull apart. It's sort of like pulling apart a piece of bread. The sides have nearly identical patterns, and the narrow opening becomes a passageway of sorts.
These types of caves are also typically very strong because of how they were formed. The bedrock is usually sturdy, and gravity sliding is what makes it all happen when the rocks on the side of a mountain or ridge slowly dip away.
An Interesting Name Says It All
Geologists have long studied caves, and this study has its own special name. Speleology is defined as "the scientific study of caves and other karst features, as well as their make-up, structure, physical properties, history, life forms and the processes by which they form and change over time."
The name was derived from the Latin word spēlaion, meaning cave. It has also been used to describe exploring caves leisurely, but more often than not, those who explore caves for fun without any scientific purpose usually refer to it as caving or spelunking.
True Caves Appear All Over the World
A true cave is a cave that was created naturally and is large enough for humans to enter. That being said, there are so many caves across the world, that it would be impossible to officially confirm numbers. Suffice it to say, around 50,000 true caves have been found and are known to scientists.
That number doesn't include caves that have yet to be discovered, and many experts believe the number could be as high as 5 million unknown caves around the world. That's a whole lot of undiscovered territory that has yet to be explored by humans.
Not All Caves Are Alike
Due to the way caves are formed — erosion, lava, different pressures and materials — it would be impossible to find two caves in the world that are completely identical. They all have their own special markings that have been forged into their walls throughout creation, and those markings all vary from cave to cave.
Some may be the same type of cave and look very similar, but no two caves will ever be twins. Even if they were created with the same pressure, the same materials and the same level of erosion, they would be mostly unique in formation, size and markings.
The largest caves known to man are called solution caves. They are the most common and the most well-known cave type on the planet. Groundwater dissolves dolomite and limestone to form these caves and give them room to grow into monstrosities.
Solution caves rarely have natural entrances. The process that forms them starts in the deep bedrock, making it hard to believe these caves would be so common, but nature is a mysterious thing. Their openings can be man-made by accident or caused by a sinkhole or other natural process.
Lava caves are usually found near active volcanoes, and four different processes contribute to their formation. In the first scenario, lava tubes are created by the aforementioned volcanic process. The remaining three are created using pressure ridge caves, spatter cone chambers and blister caves.
Because of how heavy the flow of lava can be, it causes the crust below it to break or buckle under the pressure. When that happens, ridges are formed, and the lava flows into them. The direction of the flow is what separates the types of caves and the processes.
Glacier caves, otherwise known as ice caves, form between glacial ice and bedrock. This happens when water that has melted finds its way down through crevasses in the Earth and erodes the rock, eventually carving out a beautiful ice cave.
The floor of the cave is usually just rock, but depending on the level of water and temperatures in the area, it could be pooled with water. The melting of the glacier gives ice caves their intricate designs and sculptured walls, along with the branching of icicles throughout the tubular-shaped caves.
Sea caves owe their existence to the water erosion method of creation previously mentioned. The chemical reaction of the limestone and water helps break the caves down, and they are usually found either under the water or along the shoreline.
The waves from the ocean push the process along. When there's a weakness in the bedrock, the waves eat away at it over time, and the entrance of the cave changes with the tides. Some may also have an opening that allows for water to escape during storms and other rough waters.
Another unique type of cave is the fracture cave. These majestic beauties form in a different way than other caves. They are born when rocks around a particular area collapse due to a dissolving soluble layer, which is usually made of gypsum.
The end result of these fractures in the rocks is a unique, one-of-a-kind design, much like fingerprints. The fractured-like appearance of the cave is scattered across the walls of the newly formed cavern. These caves prove that sometimes the destruction of something can truly be beautiful.
Another impressive feat for Mother Nature's cave creations is the talus cave. These caves are on the small side, but that doesn't make them any less majestic. When boulders pile up on mountain slopes, the openings between them eventually form a talus cave.
These caves harbor a fun little secret. They form interconnected passages that humans can explore — kind of like secret passageways made by the Earth. The longest talus caves that have been mapped out are made of granite and found in New York and New England in the U.S.
The eolian caves found throughout the world are truly magical. They owe their creation to wind pressure and are usually found in desert areas. When strong winds continuously bombard sandstone cliffs, it eventually creates a cavity in the rock.
Once that cavity is formed, more wind can enter it, eroding the walls, ceiling and floor of what will ultimately become a cave. The chamber caves are usually bottle-shaped and are more extensive on the inside than the entrance appears to be. Although they aren't all that long — topping out at no more than 100 meters — they are still some of the most beautiful caves in existence.
When a sea cave made out of limestone or volcanic rock floods with seawater, it forms an anchialine cave. These caves are the underwater deep-sea caves that were seemingly lost to civilization prior to humans' ability to scuba dive at great depths.
Because these caves rarely get any sunlight, the sea creatures that dwell in their underwater passageways are usually blind because they don't need to see. The name "anchianline" comes from the Greek word "near the sea," which is well-suited to secret underwater homes for mysterious marine life.
In 2018, Russian scientists discovered a bizarre cave, but it wasn't how it was formed or even what it looked like that made it stand out. The crazy part was what they found inside the 5.5-million-year-old unexplored cave that really made an impression.
It turned out that the cave itself was poisonous. Movile Cave, as it's called, has such a high level of carbon dioxide and hydrogen sulfide in the air that it's barely breathable inside. What was even more wild about the find was that, despite the poisonous air, various undiscovered creatures still managed to survive inside it.
Perhaps one of the most beautiful things the Earth has to offer, blue holes are actually another type of cave. They formed during the Ice Age when sea levels were low, and typical erosion took place. The caverns open up at the surface of the ocean and reach down into the depths to carbonate bedrock.
It's believed that blue holes are connectors to other underwater passageways that have been submerged for centuries. The tide controls most of the water in blue holes. Interestingly, they're usually a mix of both freshwater and seawater.
The Hellfire Caves are a good example of a cave system not created by Mother Nature. These caves were carved out by humans in the 1700s for Baron Francis Dashwood. The cave system is made of chalk and flint and runs about 400 meters under Wycombe, England.
They were designed after Dashwood completed his Grand Tour of Italy, Greece, Turkey and Syria for the purpose of providing a secret place for meetings of the Hellfire Club, a club consisting of the most elite rakes — men prone to immoral conduct, particularly sexual exploitation of women — at the upper levels of society in Britain and Ireland. The caves are now a tourist attraction.
Some Caves Hide Ancient Secrets
Caves around the world have been long explored because of their connection to the past, and many amazing things have been found buried deep inside them. The remnants of what is considered to be the oldest ritual in the world were found in a cave in Botswana, for example.
The Lupercal in Rome is considered to be the "city's most sacred" spot after its discovery in 2007. Sacred sites and rituals, unknown animals and organisms, ancient artifacts, and evidence that Neanderthals weren't nearly as dimwitted as previously believed have all been found in caves around the world.
Others Have Yet to Be Touched
Most scientists believe there are millions of caves on the planet, and only a fraction of those caves have been explored. Due to the depths of the Earth and some of the caves, getting to the bottom of things isn’t easy. Even when experts try, some caves are simply impossible — or too dangerous — to explore.
As more caves are discovered over the years and geological technology increases, cave exploration could grow substantially. Still, it won’t be easy to uncover secrets that have been hidden by thousands of years of rock formations and rising sea levels.
They Harbor Hidden Ecosystems
Many creatures call caves home. Bats set up shop on the roofs of caves, because the damp, dark habitat suits their nocturnal ways. Deep-sea fish also find safe homes in underwater caves that can't be explored by humans.
Perhaps the most beautiful creatures to create their own little ecosystem in caves are glow worms. These shiny, star-like animals light up using bioluminescence. When they sense a threat, they light up to scare any predators away. When they get hungry, they also use their light to attract their next meal.
Man Has Used Caves for Centuries
Cave use goes all the way back to the earliest humans. Considering the times, they were perfect for providing sheltering from the elements and predators. The air in caves is usually cooler — no exposure to the sun — so in hotter climates, caves serve as great natural air conditioners.
In cooler climates, they provided protection from the wind and were the perfect place to set up homes where humans could safely start fires to ward off the harsh elements of winter. In some cases, caves also provided creatures that could be eaten, and some even had a good freshwater supply.
Grottos Are Wildly Popular
Grottos all over the world have grown in popularity because of their natural beauty. Instagram fanatics flock to famous grottos on their travels to capture that perfect selfie surrounded by the amazing wonder of one of Mother Nature's most beautiful creations.
A lot of grottos also double as swimming holes because of their proximity to the sea and crystal-clear waters that are cool and calm enough for taking a leisurely dip. They can also house hidden lakes, and what's cooler than swimming in a hidden lake in a cave?
They Are Shrouded in Mystery
Caves that have been discovered and explored have proven over and over just how much history they can hide within their depths. Some caves go so deep that no one has ever dared to spelunk their way to the bottom.
Deep-sea caves may never be fully explored because of technology's inability to get humans safely through all the passageways and crevasses. The bravest explorers frequent some of the most dangerous caves in the world. Their trips through the Earth require days of exploration, camping out in caves — and a lot of safety precautions.
Underwater Caves Make for Beautiful Exploration
Underwater caves are the least explored because of their inaccessibility. The ones that are within reach, however, feature some of the most beautiful finds nature has to offer. The deep-sea caves are so wild that animals have evolved over millions of years, just to be able to survive in them.
In some instances, fish have evolved to become blind. That sounds awful, but the blindness allows them to swim around in the dark crevasses with enhanced sensitivity to vibrations in the water. This gives them the ability to monitor the world around them without relying on vision, which is useless in pitch darkness.
Some Caves Form Natural Pillars
In some limestone caves, natural hanging pillars known as stalactites are formed as the caves are created. The formations hang from the ceilings of caves and can be made of lava, minerals, sand and other materials.
The pillars are formed when water and calcium salt deposits drip down slowly over time and solidify against the roof of the cave. The look of each stalactite is unique in nature and adds some beautiful visual appeal. You could almost say they are a cave’s natural version of crown molding.
The Depth of Some Caves Is Terrifying
Some caves are seemingly bottomless pits. No amount of exploration can help people get to the bottom of some of the most explored caves on the planet. A great example of one scary-deep cave is the Krubera Cave.
The cave has different campsites set up to help people try to make it to the bottom, but no one has ever reached it — so far. The farthest explored depth is 6,824 feet. The trek down isn't an easy one, and most people quickly find the excursion to be too difficult, even with the right materials and skillset.
Some Are Better Than Others
All caves are formed due to interesting — and time consuming — processes, but some feature results that are far superior to others. The most famous caves in the world are proof of that. The Glowworm Cave in New Zealand has become a huge draw for tourists over the years, thanks to its starry-night appearance.
The Kungur Ice Cave in Russia has more than a million visitors each year due to its glacial beauty. The Silver Cave in China is a huge attraction for travelers as well because of its silvery stalactites, three different caves to explore and a waterfall inside the cave.