U Bar U Retreat & Conference Center

U Bar U sits on rocks with more rocks underneath them.  The soil layer is thin.  The land is hilly and rocky, covered with live oaks and cedars with the cedars predominant.  There are two types of soil—Tarrant and Speck (Redland).  In many places one walks on large, flat rocks with vegetation seeming to grow right out of the rock.  This is Tarrant soil.  In other places, especially beneath large groves of cedar, is a reddish soil which one might dig into.  This is Speck.

While neither Tarrant nor Speck is particularly hospitable to diversification of vegetation, Speck offers more promise.  As one wanders over the surface, one must watch where the feet go.  Cactus is bountiful, and “Slide,” a large resident rattler, loves to lie in the sun.

Rocks come up out of the ground all around.  Native stone has been used for generations for buildings, fences, pathway definition, and just plain anything one wants to throw a rock at.

According to the Bureau of Economic Geology, the underlying geological structure is most apparent along the sides of Interstate Highway 10.  Notice the layering in the cut-throughs.  Many kinds of rock, ranging in date of origin from Precambrian to Cenozoic, are in Gillespie County, which is on the south flank of the Llano Uplift that brought to the surface rocks normally covered by several miles of younger rocks.

These rocks exposed by uplift are Precambrian, a billion years or so old, as well as rocks a half billion years old and younger.  The exposed rocks in the range of a billion years old are recrystallized as a result of high pressure and temperature during their deep burial beneath other rocks.  Local melting produced granite and various other types of igneous rock.

[from Virgil E. Barnes, 1954.  Geology of Gillespie County, Bureau of Economic Geology, The University of Texas at Austin.]