The Balcones Fault is a geologic fault in Texas that runs approximately from the southwest part of the state to the north central region. It forms the eastern boundary of the Texas Hill Country and was a site of volcanism during prehistoric times.
The city of Austin, Texas is sited where the Colorado River of Texas flows from the Texas Hill Country across the fault. Shifts in the fault were responsible for the emergence of Barton Springs during the Cretaceous period, and much more recently for significant damage to the Lyndon B. Johnson Presidential Library on the University of Texas campus.
