| Sheeting joints (shallow, surface-parallel, opening-mode rock fractures) are widespread and have been studied for centuries. They are commonly attributed to removal of overburden by erosion, but erosion alone cannot open a sheeting joint. I test an alternative hypothesis that sheeting joints open in response to surface-parallel compression along a convex topographic surface using field observations, a large-scale fracture map, and analyses of stresses, slopes, and surface-curvatures (derived from aerial laser altimetry data) for a dome along Tenaya Creek in Yosemite National Park. Approximately 90% of the surface of detailed study is convex in at least one direction. Existing stresses and topography there can account for the nature and distribution of sheeting joints on the doubly-convex surfaces. Sheeting joints parallel and constitute the surface where the surface is doubly convex. Elsewhere, sheeting joints daylight, implying the surface has been eroded since the sheeting joints formed. My findings support the hypothesis. |
