Published online by Cambridge University Press: 01 May 2009
From remotely sensed images of rock surfaces at coasts it is possible to map some characteristics of different rock types. To do this a selection must be made of those parts of the image that correspond to the rock surfaces prior to interrogation of their geological information content. A comparative study of satellite-acquired multispectral Thematic Mapper data and aircraft-acquired multispectral scanner data at four test sites on the Pembrokeshire coast was made. The spatial resolution of the Thematic Mapper data (30 m) proved to be too coarse to provide any continuity of mapping over several kilometres of rock exposures, whereas the 10 m resolution of the aircraft data was adequate to do this. Using the aircraft scanner data, neighbouring Old Red Sandstone and Carboniferous (mainly carbonate) rocks could be discriminated in both three-band and principal components images. Furthermore, it proved possible to distinguish between limestone and dolomite lithologies in the Carboniferous succession and between some of the mudstones and sandstones in the Old Red Sandstone. Airborne multispectral scanning of rocky coasts is a new potential tool for geological mapping in exploration projects in which it would be best integrated with the acquisition of airborne geophysical and field geological data.