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Abstract: Application of the Texas Land Resources Map (1)
R. S. Kier, L. E. Garner, L. F. Brown, Jr. (2)
Texas is endowed with an enormous variety of natural land resources. Almost 270,000 square miles of plains, plateaus, mountains, hill country, beaches, river valleys, badlands, and many other land types comprise the natural land wealth of the State. Because of this great diversity, Texas exhibits a natural variability in energy and mineral resources, agricultural capacity, environmental sensitivity, and recreational potential that promotes industrial and cultural attraction. The desire to maintain the natural attractiveness of Texas has led to considerable interest in understanding the basic components of the States land resources. Production of oil and gas and development of lignite and uranium resources are prime examples of resource utilization that can exist in harmony with the natural characteristics of the land.
Essential to achieving balanced use of the environment is a comprehensive knowledge of physical, chemical, and biological characteristics limiting conditions and interrelationships of the varied land and water areas in Texas. Because no environment or group of environments is isolated, a regional perspective is necessary to ascertain the diversity of land and water resources, to assess their natural suitability, and to identify areas where more detailed studies are needed.
Land Resources of Texas, an inventory of Texas lands, has recently been published by the Bureau of Economic Geology. Seventy-one land resource units are depicted on a map at a scale of 1:500,000. The basis for mapping followed the concept of land and water resources, ". ... mappable entities, either natural or man-made, that are defined by the physical, chemical, and biological characteristics or processes which govern the type or degree of use that is consistent with both their natural quality and productive utilization" (St. Clair and others, 1975). Each land resource unit displays a limited and predictable range of relatively unique properties that determine its attributes for varied activities.
Names and classification of the land resource units are based on properties subjectively judged to be the most significant in their potential use. For example, "ceramic clay and lignite/coal" is a land resource unit recognized by its importance as a potential source of ceramic materials and energy. Some of the physical characteristics of the ceramic clays present limitations for construction purposes, but the resource potential of the land is deemed to be of greater importance, and the unit is categorized as a mineral land unit with other units of similar potential. Eight major categories of land resources are defined: geohydrologic units, mineral land units, physical properties units, geomorphic units and structural features, process units, biologic units, estuary/lagoon/open-gulf units, and man-made units or features.
Land resource units are recognized principally by unique combinations of substrate materials, soils, vegetation, topographic configurations, and active processes (Fig. 1). Field investigations provide the basis for discriminating and mapping land resource types and determining their interrelationships. Interpretation of aerial photographs and existing maps of soils and rock types greatly facilitates the mapping program. The Geologic Atlas of Texas provided much of the areal and descriptive data needed to prepare the Land Resources map. Land resource mapping of the Texas Coastal Zone was based on maps prepared for the Environmental Geologic Atlas of the Texas Coastal Zone. Predictable associations and relationships within and among geohydrologic systems, dynamic processes, biologic communities, and others also aided in determining factors that are important
FIGURE 1. Flow diagram illustrating the process of land resource analysis.
FOOTNOTE (1) Publication authorized by the Director, Bureau of Economic Geology, The University of Texas at Austin
in evaluating the natural capacity of a land area for specific activities.
The 71 land resource units are shown on the map with distinct colors or patterns and letter-number symbols. A brief explanation on the map describes the characteristics of each unit: substrate material, topography, vegetation types, active processes, and known or potential resources. A table on the map presents natural suitability and recommended use considerations. Additional tables in the text provide more specific information about physical properties, distribution, substrate composition, plants and animals, economic resources, and current land use of the resource units. There are 11 small auxiliary maps (Table 1) that summarize aspects of land resources in Texas that could not be shown on the large map.
The Land Resources of Texas map was designed to provide a regional perspective of Texas lands that should be useful to planning authorities, educators, individuals, residential and industrial developers, and government agencies. The map provides the means to appraise the kind and level of technology required to use Texas lands in a manner that is economically prudent and environmentally compatible with natural conditions (Fig. 2). Use of the Land Resources map to select potential sites for a particular activity provides an opportunity to consider economic trade-offs and to perform preliminary cost/benefit analyses prior to detailed site evaluation. Derivative or thematic maps can be prepared that focus on particular aspects of the State's natural resources (Table 2).
The Land Resources map is intended to serve as the basis for regional land analysis and as a basis for delineating areas suitable for more detailed site- and area-specific studies. By using the descriptive and interpretive tables and by compiling derivative maps, the user can evaluate the potential of a land area for a variety of activities on a regional or statewide basis. The approach emphasizes the positive aspects of natural capability as well as natural constraints on land and water use.
St. Clair, A.E., Proctor, C.V., Jr., Fisher, W.L., Kreitler, C.W., and Mc Gowen, J.H., 1975, Land and water resources--Houston-Galveston Area Council: Univ. Texas, Austin, Bur. Econ. Geology, 25 pp.
FIGURE 2. Flow diagram illustrating use of Land Resources of Texas map.
Table 1. Auxiliary maps to the Land Resources map.
Table 2. Types of derivative maps that can be constructed from the Land Rdsources of Texas map.
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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES
(2) Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas
Copyright © 1999 by The Gulf Coast Association of Geological Societies