Abstract
The authors present a new type of DEM-processed map, named as “roughness map”, which might reflect the regional rock facies distribution or facies boundaries.
The roughness of a grid point of the DEM, reflecting the degree of point-wise unevenness of the surface excluding the topological undulation, is derived by calculating the difference between the actual elevation value and the value which is interpolated smoothly by using the lineup of adjacent 10 data points except the target point.
The roughness map covering entire Japan has been made, and comparisons of the characteristics of the map with the slope map and the geological map are presented for 3 areas. It is pointed out that: (1) the roughness map can enhance the rock facies difference between limestone and the peripheral sedimentary rocks in Akiyoshidai, Yamaguchi Pref., : (2) the facies difference of the east and west sides along the Mid Techtonic Line is distinguished correspondently by the roughness map in the neighborhood of Ina basin, Nagano Pref., : (3) a banded feature of facies existing in the central part of Shikoku becomes clearly observable by the roughness map.
