[3] The canyons facing Austin are deeply etched into the limestone of the Edwards Plateau by tributaries of the Colorado River.

Beneath the surface of the Edwards Plateau lies an underground labyrinth of caves, sinkholes, and springs.

The aquifer is also the source of many springs that feed Hill Country rivers, which eventually flow into the marshes, estuaries, and bays along the Texas Gulf Coast.

[3] The vegetation found in the Hill Country includes various oaks, elms, and Ashe juniper trees (often referred to as "cedars" in Texas).

[4] This article incorporates public domain material from websites or documents of the United States Fish and Wildlife Service.