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As the softer layers erode, a stair-step topography like balconies (hence Balcones Escarpment) is produced. From various points in Friedrich Wilderness Park and the surrounding Balcones Escarpment, you can

look over the autumn hillsides and see alternating layers of vegetation. These layers are easiest to see in the fall when deciduous tree leaves change color and in the spring when the same trees are growing new leaves which are light green compared to the darker greens of the junipers and live oaks.

The geologic foundation of Friedrich Wilderness Park is mostly Glen Rose limestone with a small cap of Edwards limestone on the top of the hills. The Glen Rose formation is characterized by alternating hard and soft layers, the softer layers being more susceptible to erosion. As the softer layers erode quickly and the harder layers, more slowly, a stair-step topography like balconies (hence Balcones Escarpment) is produced.

Over long periods of time as further erosion and soil formation continue, pockets of deeper soil tend to form on the steps of the balconies. In these deeper soils, hardwoods like Red Oak and Cherry can grow along the balcony steps, producing the alternating layers of hardwoods and live oak/juniper. Other environmental factors such as the exposure of the slopes and seepage from underground water affect the distribution of these bands also.

Peggy Spring is the Park Naturalist in charge of education and volunteerism for San Antonio Natural Area Parks.

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