Natural Bridge Caverns – San Antonio, Texas

If you love to explore caves and are going to be visiting San Antonio, Texas, you’ll want to visit the Natural Bridge Caverns! It’s the perfect way to spend a hot summer day with your family in the cool cave!

It’s been quite a long time since we’ve visited any caverns. The last time was when we took our family to The Lost Sea in Sweetwater, Tennessee back in the 90’s.

So, imagine our excitement to go underground again to check out the magical wonders of what lurks beneath us, only twenty years later. This was also a cool refreshing adventure we picked to do on a 90some degree day.

Natural Bridge Caverns - Historic Sign

Visit Natural Bridge Caverns

The Natural Bridge Caverns are the largest known commercial caverns in the U.S. state of Texas. The name was derived from the sixty foot natural limestone slab bridge that spans the amphitheater setting of the cavern’s entrance. The span was left suspended when a sinkhole collapsed below it.
 
Natural Bridge Caverns - Texas

As mentioned above, Natural Bridge Caverns is located just north of San Antonio, Texas in the Hill Country Region next to the Natural Bridge Wildlife Ranch; a drive-through wildlife safari park.

Natural Bridge Caverns - Map

Natural Bridge Caverns features several unique speleothems and other geological cave formations. The temperature inside the cave is about 70° Fahrenheit year-round. The humidity rate is a constant 99%. The deepest part of the public tour is 180 feet below the surface. Although, undeveloped areas of the cavern reach depths of 230 feet.

The Caverns at Natural Bridge are still very active and considered living. Due to the porosity of the limestone, rainwater travels downwards through the layers of rock, where it dissolves out calcite, a weak mineral that makes up all of the speleothems in the cave.

After exiting the limestone, water enters the caverns where it flows and drips constantly throughout, causing the many different cave formations to retain a waxy luster that can be seen in few caverns.

Our Tour of Natural Bridge Caverns

Being with a small group allowed us to appreciate the quiet and true beauty of the cavern. Our guide, Bill, led us down into the Cavern after a little history lesson and to see the Natural Bridge that hovers over the entrance. But first, he had to unlock and open the gate at the Cavern entrance tunnel.

When we first entered, there were posted rules to remind those who may want to alter, remove or vandalize the grounds (or under it).


Then we began to learn everything about the formations in the cavern.

Speleothems

A speleothem, commonly known as a cave formation, is a secondary mineral deposit formed in a cave. Speleothems are typically formed in limestone or dolostone solutional caves.

Over time the accumulation of these precipitates forms stalagmites, stalactites, and flowstones, which compose the major categories of speleothems.

Speleothems take various forms, depending on whether the water drips, seeps, condenses, flows, or ponds. Many speleothems are named for their resemblance to man-made or natural objects.Types of speleothems include:
 
    • Dripstone is calcium carbonate in the form of stalactites or stalagmites.
    • Stalactites are pointed pendants hanging from the cave ceiling, from which they grow.
Natural Bridge Caverns - stalactites
Stalactites come from the ceiling
    • Soda straws are very thin but long stalactites having an elongated cylindrical shape rather than the usual more conical shape of stalactites.
    • Helictites are stalactites that have a central canal with twig-like or spiral projections that appear to defy gravity. Include forms known as ribbon helictites, saws, rods, butterflies, hands, curly-fries, and clumps of worms.
    • Chandeliers are complex clusters of ceiling decorations
This looks like a Jellyfish or  Man O’War, doesn’t it?
These are called Soda Straws and Broomstick Stalagmites
    • Stalagmites are the “ground-up” counterparts of stalactites, often blunt mounds

Natural Bridge Caverns - Stalagmites

    • Broomstick stalagmites are very tall and spindly. Totem pole stalagmites are also tall and shaped like their namesakes.
    • Fried egg stalagmites are small, typically wider than they are tall.
    • Columns result when stalactites and stalagmites meet or when stalactites reach the floor of the cave.
Natural Bridge Caverns - Columns
Columns of Sherwood Forest
    • Flowstone is sheet like and found on cave floors and walls.
    • Draperies or curtains are thin, wavy sheets of calcite hanging downward.

Natural Bridge Caverns - Cave Curtains

Cave Curtains
    • Bacon is a drapery with variously colored bands within the sheet.
    • Rimstone dams or gours, occur at stream ripples and form barriers that may contain water.
    • Stone waterfall formations simulate frozen cascades

Cave Crystals

Dogtooth spar are large calcite crystals often found near seasonal pools. Frostwork is needle-like growths of calcite or aragonite. Moonmilk is white and cheese-like. Anthodites are flower-like clusters of aragonite crystals. Cryogenic calcite crystals are loose grains of calcite found on the floors of caves, and are formed by segregation of solutes during the freezing of water.

Speleogens (technically distinct from speleothems) are formations within caves that are created by the removal of bedrock, rather than as secondary deposits. These include Pillars, Scallops, Boneyard, Boxwork.

Other Cool Cave Features at Natural Bridge Caverns

Natural Bridge Caverns - Creepy Formations
This one was actually creepy looking!
Natural Bridge Caverns - Discovery Crawlway
 

 

Natural Bridge Caverns - bat guano
The black section you see are reminents of a bat colony aka ‘bat crap’.
Natural Bridge Caverns Texas - Living Cave Fern
The only living plant in the cavern
Natural Bridge Caverns - Texas
This is a Column. It looks like the Leaning Tower of Pisa!
Natural Bridge Caverns - Chandelier
Cavern Water Feature
A small underground water pooling.  There’s actually tiny organisms in there!
Cave Chandelier
Look at this cool Chandelier.

Natural Bridge - Cavern Formations

Other things to do at Natural Bridge Caverns

There’s quite an array of other things to do at Natural Bridge Caverns to keep your family entertained.

There’s a wildlife park to take the young ones to. And, for the more adventurous daring types, they can experience the ziplines, tower climbing, rock mining, etc.

Welcome to Natural Bridge Caverns

Final notes on our visit to Natural Bridge Caverns

We totally enjoyed our 45-minute tour underground.  We learned so much and it gave us an idea of what may lurk under where we walked.

This is a great place to bring the family; especially RV road schoolers and homeschoolers! Something educational yet with a little fun and excitement.

Natural Bridge Caverns - San Antonio Texas

Looking for other cool things to do in San Antonio or Hill Country, Texas?

7 Friendliest Places to Visit in Texas Hill Country

Texas Hill Country: Bluebonnets on Willow City Loop

First Time Visitor’s Guide to Fredericksburg, Texas

The Great Camel Experiment: Camp Verde, Texas

 

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