The White Rock Escarpment, a dominant physiographic feature of central Texas, can be traced for over 350 miles from south of San Antonio, Texas to north of Dallas, Texas. The escarpment is capped by the Cretaceous Austin Chalk Formation and underlain by the highly overconsolidated smectite clays of the Eagle Ford Shale.

Development pressure along the escarpment in southwest Dallas prompted a detailed study of this landform by the Planning Department of the City of Dallas. Guidelines and subsequent ordinances for development along the escarpment were based on combined data from geology, soils, physiography, vegetation, and engineering analysis. A “no-build corridor” was adopted by the City Council eight years after initiation of the original study. This corridor parallels the chalk/shale contact and establishes set-backs from the crest and toe of the slope. Building within this zone necessitates a permit which requires detailed geotechnical evaluation, soil erosion control plans, grading plans, and vegetation clearance plans.

Effective use of geologic information in the planning process involves education of the planning staff, developers, and city officials as to the relative tolerances of the natural system to the potential impacts of urbanization. As in the case of this study, examples of such impacts can be taken from other municipalities which have more extensive histories of development on the same toposequence; areas of similar geology, soils, and slope.

The escarpment ordinance and accompanying research have been shown to produce cost savings to both the city and developers, as well as subsequent homeowners.

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