An area in the Negev desert in Israel was chosen to demonstrate the capability of the SIR-C sensor system to differentiate lithological units. In addition DAIS hyperspectral data were investigated. The area around Timna mountain is characterized by Cambrian sandstones, carbonates and alluvial fans of Pleistocene and Holocene age. The mountain itself consists of diverse magmatic rock assemblage. The whole area is mapped using conventional methods. The remote sensing data are sensitive for the mapping parameters and allow the extraction of their spectral and radar signatures. Specific areas have been classified on their lithology, mineralogy, stratigraphy, grain size distribution, surface roughness and weathering state. In addition, field measurements of the roughness of the alluvial fan's terraces and of the Cambrian rocks surrounding Mount Timna were investigated. The stereoscopic images taken were used as a basis for the height models of the different targets and the standard deviation (RMS) of the height was calculated. This was used as the parameter for the surface roughness and can be correlated with the radar backscatter. The SIR-C system offers the unique possibility of multi-frequency and multi-polarized data. The sensitivity for the surface roughness for the different wavelengths of X-, C- and L-band in accordance to their incidence angle ranges between 0,13 and 27 cm absolute RMS. The RMS measured for example in the alluvial fan ranges between 0,25 and 7, this corresponds to a smooth surface with pebble size of a few mm and a coarse terrace up to 50 cm block diameter. It can be shown that the age of the terraces corresponds to the backscatter. The more ancient the terrace the lower is the backscatter, the smoother the surface, the younger and rougher the terrace, the higher is the backscatter.