What?

The west Austin Hill Country, also known as the Balcones Canyonlands, is composed of rugged topography, with flat-topped hills separated by steep canyons. The Austin Hill Country starts just west of the Balcones Escarpment.

Why?

Faulting occurred in Central Texas millions of years ago, when the coastal plains to the east bent downward while the more stable central Texas interior of the Llano Uplift remained relatively stable. The Balcones Escarpment and the west Austin Hill Country are the result of this fault episode.

The east side of Austin moved downward by as much as 700 feet. After millions of years of erosion, the soft sediments in the Hill Country area were eroded away, exposing the hard, Lower Cretaceous limestones and dolostones. This erosion created hills and steep canyons in the west Austin Hill Country.

Links and other neat stuff:

• Austin lidar VRML (see right sidebar) and flyover (see below)
• The Texas Hill Country Through Time
  Local geological history (Texas A&M)
• Geologic time scale (PDF)
• The Balcones Escarpment
  (Geological Society of America)
• Collins, E. W., and Laubach, S. E., 1990, Faults and fractures in the Balcones Fault Zone, Austin Region, Central Texas: Austin Geological Society Guidebook 13, 34 p.
• Trippet, A. R., and Garner, L. E., 1976, Guide to points of geologic interest in Austin: The University of Texas at Austin, Bureau of Economic Geology, Guidebook 16, 38 p.

View a flyover of Austin from the Coastal Plain, to the Balcones Fault Zone, and the West Austin Hill Country. Requires player (such as Windows Media Player or RealPlayer) for .wmv format movie.