THE PROBLEM OF HUMAN-MODIFIED LANDSCAPES IN MAPPING URBAN GEOLOGY

by
G.A. Ludvigson, E.A. Bettis III, J. Giglierano, M.R. Howes, R.R. Anderson, J.C. Prior, C.K. Contant

The Geological Society of America
29th Annual North-Central Section and South-Central Section Meeting
University of Nebraska-Lincoln, Lincoln, Nebraska, April 27-28, 1995
1995 Abstracts with Programs, v. 27, no. 3, p. 69-70

ABSTRACT


Hooke (1994, GSA Today, v.4, no.9, p.217-225) has argued that human earthmoving activity is the most volumetrically significant process currently shaping the surface of the earth. These activities are intensively focused in expanding metropolitan areas of the United States. Detailed surficial geologic mapping at the 7.5 minute quadrangle scale in urban areas forces geologists to grapple with the issue of mapping extensive areas of human-modified surficial deposits. Examples include borrowed and scraped areas, and landfilled deposits. This critically important aspect of urban geology should not be ignored, and we argue that the temptation to depict interpretations of natural landscapes prior to urban development must be resisted. Earth scientists are traditionally trained to interpret natural landscapes, relegating the analysis of human impacts on the landscape to other disciplines. By following this practice in urban areas, however, geologic mappers neglect an important responsibility to map users to delineate existing deposits that should be considered in future local decision making on the suitability of different land tracts for new uses. Geologists should utilize all available tools and actively seek interdisciplinary collaboration in their efforts to analyze the extent of human landscape modification. In order to improve such an analysis in the Cedar Rapids, Iowa metropolitan area, the Iowa GSB is developing a partnership with the University of Iowa Graduate Program in Urban and Regional Planning. In this proposed collaboration, the Planning Program would synthesize a map chronology of landscape disturbance from sequential analysis of aerial photo archives, multiple generations of maps, and records of construction plans. Resulting disturbed-land map units and linked databases, including information on the amounts of fill or removed material, type of fill materials, timing of construction, and past landuses, can be constructed as Geographic Information Systems (GIS) coverages, and be included as final geologic map elements. This proposed interdisciplinary collaboration would be beneficial because geoscientists do not have extensive experience with the types of data collection and analysis that are required, and because of their involvement in map construction, the Planning Program would be in a better position to assist local agencies in experimentation with GIS analysis of planning functions, an area also outside of geological expertise.