The engineering significance of the scale-independence of some Franciscan melanges in California, USA

Block size distributions were determined for several Franciscan melanges contained within regions with measured areas (A) ranging between cm2 and km2. The data were plotted as log-histograms and were found to be individually fractal and, when normalized, collectively scale-independent. Hence, blocks will be encountered in melanges at all scales. A block/matrix threshold size for a Franciscan melange rock mass of any scale is defined as 0.05√a. A tentative generic fractal dimension of 1.3 for Franciscan melanges allows rough estimates to be made of the block size distributions of Franciscan melange rock masses, given A and the volumetric proportion of blocks.