The riverbed here is full of pink and gray boulders that belong to no other part of Texas. This is a broad structural dome about 65 miles across where erosion has stripped away the flat-lying limestone of the Hill Country and exposed the Precambrian basement beneath it — granite, gneiss and schist between about 1.0 and 1.4 billion years old, the oldest rock at the surface in the state. The uplift is also the state's mineral district: llanite, topaz, iron and the granite quarried at Marble Falls all come out of it.
Getting there
30.7530, -98.6750
Locations are approximate and may be inaccurate, on private land, or otherwise inaccessible. Check before you travel.
Hear it from the road
Whistlestop tells you this story automatically when you drive past. No searching, no tapping, nothing to ask.
