But long before humans arrived and looked up to the sky, this rocky hill was under a shallow sea and something to be avoided. "It's the stump of a marine volcano, that erupted back during the late Cretaceous Period. The time frame I'd put on, it is 80 million years," said UT's Dr. Charles "Chock" Woodruff
Woodruff is known for his expertise in Central Texas geology.
"It was very active, and it was not the only one, its part of a whole series that runs northeast from Pilot Knob into Williamson County and probably beyond that, they are all buried," said Woodruff.
The volcano was large and looked something like the volcanos in the South Pacific. "Well it would have been like that, if you take the size of it as opposed to today, it’s something of the order of 5 square miles," said Woodruff.
The south Austin monster came back to life Monday night on 911 Lone Star. Thankfully the show writers didn't turn Austin into Pompeii.
The Monday night eruption is certainly the stuff of TV make-believe, but remnants of the real stuff can be found at McKinney Falls State Park. A lot of visitors have no idea
"No, I would've never believed you, if you'd told me that, without the facts," said a visitor who came to the park with a friend and two kids.
The evidence is in plain sight, according to park superintendent Tommy Cude. "You can see behind me. The gray-green rock behind me. That is Nontronite, which is, that volcanic ash from long ago," said Cude.
At the lower falls, under the limestone ledge, long lines of compressed ash can also be seen.
One big section even dips down into the water pool. "All of that was created because of water wearing down the Nontronite and creating the Falls and the caves under it," said Cude.
Dark green clumps of ancient volcanic ash can also be found on some of the park trails. "It’s very brittle. And that’s why it erodes much quicker than limestone," said Cude.
The chances of Pilot Knob coming alive again are slim.
"I would say, close to nil," said Woodruff.
Woodruff clarified, certainly not in our lifetime. In the world of geology, nothing is written in stone, and in the world of TV, Pilot Knob will erupt again; in re-runs.