COMMENT

Jones et al. (1998) applied a simplified analysis of the role of gravita-tional body forces to assess the cause of initial extension in the Basin and Range. With a set of “reasonable ” parameters and a few assumptions, they found that low elevations of the Great Basin until the Miocene are incon-sistent with a body-force origin for extensional tectonics in the early Tertiary. They concluded that an elevation probably>3 km is required for extension to be driven by internal buoyancy forces. We appreciate the simplicity of this modeling, but we have doubts about its robustness and that of the conclusions. In particular, what if Jones et al. (1998) had chosen another set of “reasonable ” parameters, and/or considered different, but still geologically realistic, assumptions? Here we show that it is possible to find different sets of “reasonable ” parameters and assumptions, for which buoyancy-driven extension is compatible with low elevation. In their modeling, Jones et al. (1998) assumed uniform thickening of the entire lithosphere. Figure 1A here represents the fc-fl plane (Sandiford an