The Texas Hill Country is a region of central Texas, USA, that features rolling, somewhat rugged, hills that consist primarily of limestone. The region is the eastern portion of the Edwards Plateau bounded by the Balcones Fault on the east and the Llano Uplift to the west and north. The terrain is punctuated by a large number of limestone rockss and boulders and a thin layer of topsoil whick makes the region prone to flash flooding.
Several cities, including Austin, Texas, San Marcos, Texas and New Braunfels, Texas were sited in the flat areas immediately to east of the Balcones Fault line where rivers flow across it, ostensibly because of their natural beauty and the natural wind break formed by the hills.
The area also features a large number of caves, such as Inner Space Caverns and Natural Bridge Caverns. The deeper caverns of the area form several aquifers which serve as a source of drinking water for the residents of the area.
