Greater Austin - Geography

Geography

Greater Austin is located in Central Texas along the Balcones Fault and Interstate 35, northeast of San Antonio. As a result of its straddling the Balcones Fault the eastern part of the city is flat, whereas the western part and western suburbs consist of rolling hills on the edge of the Texas Hill Country.

The region is crossed by the Colorado River with several man-made lakes, known as the Highland Lakes, along its length. Because the hills to the west are primarily limestone rock with a thin covering of topsoil, the western portions of the area are frequently subjected to flash floods from the runoff caused by thunderstorms. To help control this runoff and to generate hydroelectric power, the Lower Colorado River Authority operates a series of dams that form the lakes.

The Austin area is located at the intersection of four major ecological regions and is consequently a temperate-to-hot green oasis with a highly variable climate having some characteristics of the desert, the tropics, and a wetter climate. The area is very diverse ecologically and biologically, and is home to a variety of animals and plants.

The soils of Central Texas range from shallow, gravelly clay loams over limestone in the western outskirts to deep, fine sandy loams, silty clay loams, silty clays or clays in the city's eastern part. Some of the clays have pronounced shrink-swell properties and are difficult to work under most moisture conditions. Many of Austin's soils, especially the clay-rich types, are slightly to moderately alkaline and have free calcium carbonate.