Geography
The Balcones Escarpment divides Hays County into two very different landscapes
A geological fault line called the Balcones Escarpment runs through Hays County, separating rocky Hill Country in the west from flatter farmland in the east.
The Balcones Escarpment is a series of faults that created a sharp edge between the Texas Hill Country and the coastal plains. In Hays County, it splits the terrain roughly along the IH-35 corridor. The western part of the county has hilly, tree-covered ranch land with elevation rising over 1,400 feet. The eastern part is lower and flatter.
This geological divide also matters for water. The rocky limestone on the west side allows rainwater to seep into the Edwards and Trinity aquifers. That recharge zone is why water policy is so important in western Hays County. If you are buying land in the county, the east-west difference affects soil types, flood risk, water availability, and land use.
Source to confirm: Handbook of Texas — Hays County