Much of the park's limestone bedrock is exposed on elevated terrain, which has a shallow, discontinuous cover of dark gray stony clay (Eckrant series). Most valley bottoms have deep, dark brown silty clay (Krum series) or clay loam (Pratley series). Deposits of gravel, sand, and loam (Orif-Boerne association) lie within a few hundred feet of the Sabinal River. All of these soils have free calcium carbonate throughout their profiles and are moderately alkaline. Despite a high clay content in most cases, poorly drained soils are too inextensive to be mapped. When conditions are right, the Maple trees put out dazzling show of fall colors. Unfortunately this year the conditions were not optimal. Late September and October were too warm. We did not get a good frost until November. Too late to force out the intense colors.
Among the trees are American Sycamore (Platanus occidentalis), Bald Cypress (Taxodium distichum), Black Walnut (Juglans nigra), Pecan (Carya illinoinensis), Green Ash (Fraxinus pennsylvanica), Black Willow (Salix nigra), Chinkapin Oak (Quercus muehlenbergii), Lacey Oak
population that flourished during the cooler and wetter climate of the last glacial period. Today, soils and microclimate control their present distribution.
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