Geologic History of the Big Bend

Big Bend was formed over millions years by a combination of an ocean that covered the area 300 to 500 billion years ago; sand, gravel, and clay layers that were squeezed to form mountains; shallow seas that receded leaving limestone and fossil layers; erupting volcanoes; and fractures in the earth's crust.

Size

Big Bend National Park covers over 800,000 acres in southwest Texas.

Origin

The Rio Grande River, separating the United States from Mexico, forms the southern border of the park, which gets its name from the "big bend" in the river itself.

Fun Fact

When the shallow sea that covered Big Bend retreated about 100 million years ago, it became the Gulf of Mexico.

Time Frame

Scientists believe that the oldest rocks found in Big Bend are about 500 million years old.

Giant Crocs

Fossil remains of giant crocodiles have been found in Big Bend; at 40 to 50 feet long, they are the largest ever found.

References

• National Park Service - Big Bend
• Texas A&M University Department of Geology
• University of Texas Libraries

Resources

• National Park Service - Geology of Big Bend National Park