However, scientists now say the site about 60 miles southeast of Waco holds the remnants of a huge crater formed from an asteroid's impact about 58 million years ago.
University of Houston geoscience professor Arch Reid says shallow seawater or a marsh probably covered Marquez when it was struck by the asteroid, leaving a hole about a mile deep that was filled with rock over geologic time. The dome-like uplift gradually resulted from erosion.
"It's essentially a buried and exhumed crater with none of the crater left," Reid told the Waco Tribune-Herald in Monday's online edition.
Reid and three other scientists wrote one of the first research papers explaining why the Marquez Dome was a buried impact crater rather than a subterranean salt dome where petroleum can be trapped.
Discovered in 1989, the dome has also drawn a group of University of Tennessee students.
"The amount of energy released was around 10 million to 100 million megatons," said University of Tennessee geology professor Bill Deane, who visited the site in March with a group of students. "You're talking about 100 hydrogen bombs. It's estimated that 25 to 50 percent of the energy from (the impact) is turned into heat. The effects would be devastating."
The resulting crater was initially about 8 miles in diameter before erosion slowly started to cover it.
Discovery of the site came about 150 years after Maria de la Concepcion Marquez purchased from her native Mexican government the 48,000-acre land grant that became portions of Leon and Robertson counties.
Around the turn of the 20th century, the town of Marquez became a railroad stop. It's now a farming community of some 220 people.
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