GEORGETOWN, Texas (KXAN) — Drivers on Interstate 35 unknowingly pass over a system of caves lurking in the depths below.

Juxtaposing the noisy traffic, miles underneath the highway is Inner Space Caverns, home to fossils millions of years old. Holding secrets deep within, the caves have been hiding beneath Texas soil undiscovered for 10,000 years.

While constructing I-35, the Texas Highway Department made a historical discovery while they were drilling. In celebration of their 50th anniversary, organizers invited the original excavation team who first found the caves in 1963.

Memories and tears flooded the eyes of William Russel as he gazed longingly at a picture of him taken over 50 years ago. He was one of the original members of the excavation team that first descended into the caves.

A Tour into the Abyss

I got a chance to return to Inner Space Caverns for the first time in nearly 20 years. While the roadway above ground has changed, I was surprised to learn that some of the rock formations had too.

As the tour began, the first rocks I saw were pointed out by tour-guide Jay Banner. He noted the caves are continuously evolving, showing the group a newly-created rock that is only 40 years old alongside a larger rock that is 105-million-years-old.

Rounding a corner, the cave deposited me into a large room where the first crew descended. “That was the only opening we had,” said Jim Samson, the second excavator to enter the cave. The hole was used to move out excavation materials, including fossils and bones dating back to the Cretaceous period. A human tooth was even found in the trenches.

The original excavation team was greeted by a cloud upon entering the cave due to the cold air from above hitting the warm air of the cave for the first time. “The cave is constantly regulating itself,” said Samson.

As I went further and further into the caves I was hit by the stunning silence that blankets the rocks. The only sound is the slow drip of water from the Edward’s Aquifer leaving a layer of humidity in the air.

I caught up with the assistant manager of Inner Space Cavern, Tony Bowerman, who led the way armed only with a flashlight. Gesturing to pools of water, Bowerman said the excavators often drink the cave water while they are exploring because it is full of nutrients and tastes better than bottled water.

After the tour was over, Bowerman offered to take me on a secret passage tour with the current team of excavators. A group of six of us left the lit pathway and headed into the darkness.

One of the members of the team on the hidden tour, Ernest Lundelius said, “This cave has a long complex history,” as we passed by fossils still embedded in the rocks.

“Watch your head!” This is a sentiment constantly echoed throughout the cave.

A tour not meant for those with claustrophobia, we wedged our bodies through narrow passageways opening up to a large room. Bowerman drew our attention to a small opening under a rock and said before the stairs were created, he had to crawl on his stomach beneath the mammoth rocks to enter the chamber.

Despite the darkness, as flashlights scanned the room, calcium crystals winked at us glinting off each rock. According to Bowerman, the crystals reflect water casting a sparkling shimmer across the large cave.

Without natural light able to reach the cave, it is one of the darkest places you can venture. At one point Bowerman asked me if I had ever experienced complete darkness. Hesitant, I told him I had not. One by one we turned off our flashlights and plunged into the pitch black darkness. Unable to see my hand less than an inch from my nose, I was awe struck by the inky blackness. A wave of goosebumps swept over me as a chilling breeze blew through the room.

“You’re an honorary caver now,” said Bowerman as we turned on our flashlights and approached the first natural light seen at the end of the passageway.

After three hours exploring the caves, my eyes blinked away the darkness as I marched up the long hill that leads out of the cavern.