Trend-Surface Mapping in Geographical Research

ALTHOUGH GEOGRAPHERS are traditionally concerned with the description, analysis and explanation of areal distributions of phenomena, much of the most vigorous development of new techniques in this field has come from outside geography. The harnessing of the vast potential of computer systems to mapping problems has been pressed forward both in subjects like meteorology where mechanical graph-plotters, line printers, and cathode-ray tube displays are being used to map directly the output of digital computers (Sawyer, 1960; Wippermann, 1959), and in botany where field information on the occurrence of vascular plants are being rapidly processed and printed out (for example, the 1,623 maps of the Atlas of the British Flora (Perring and Walters, 1962)). The most striking adaptations of computer technology to traditional mapping problems are being employed in the earth sciences, however: for example, in geophysical prospecting, structural mapping and sedimentary petrology (Krumbein, 1958). Here the most fundamental developments in mapping techniques lie less in the automation of traditional techniques (a field reviewed for geographers by Tobler (1959)) but in the evolution of new ways of extracting more information from map data. This paper reviews developments in one of the most promising of these techniques, trend-surface mapping, and attempts to assess its significance for, and applications in, the wider field of geographical research.