AIRBORNE LIDAR AS A PRACTICAL TOOL FOR HIGH RESOLUTION GEOLOGIC MAPPING— A DECADE OF LESSONS LEARNED AND POTENTIAL REVEALED

During the past decade, airborne lidar has evolved from a curiosity to a useful and increasingly available tool for practicing geologists interested in mapping landforms or, in areas where soil cover is thin to absent, bedrock structures. In the simplest applications, lidar-based shaded relief images and contours are used to support geologic mapping in a qualitative manner similar to which aerial photographs and topographic maps have been used for decades, albeit with the ability to discern more detail than before in heavily forested areas. Given the spatial density and inherently digital nature of lidar data, however, using lidar products as little more than high-resolution versions of their predecessors largely ignores the potential of high-resolution digital topographic data to fundamentally change the way that we map and interpret landforms and structures. As illustrated using examples from several consulting projects, the value of lidar data can be leveraged by using ground strike patterns to assess spatial variations in the visual resolvability of landforms and creating optimally gridded digital elevation models (DEMs), creating geomorphic derivative maps that accentuate spatial rates of change of the topographic surface (e.g., aspect, slope, curvature, and roughness) on different scales, developing methods to understand the geologic significance of reflection intensity values or waveforms, integrating high-resolution qualitative maps with the results of physics-based numerical models of processes such as landsliding, and performing multi-layered virtual mapping within a geo-referenced graphics environment. Utilizing airborne lidar to its full potential for high-resolution geologic mapping will require significant changes in traditional geologic thinking and education. First and foremost, real numeracy— not just speadsheet fluency— must be added to the skill set of working geologists. Second, geology curricula will need to include quantitative geometric and numerical thinking as core principles even if it means the loss of some potential students who shy away from numbers. Third, practitioners need to break down the walls that separate geologists from GIS specialists in many consulting firms and government agencies, taking geologically oriented GIS work into their own hands.