Around Ripon, North Yorkshire, catastrophic subsidence locally occurs because of natural underground dissolution in the Permian gypsum. This airborne study assesses the merits of multispectral scanning (MSS) as a method of detecting incipient subsidence areas and as an aid to geological mapping. The multispectral method indicates subsidence areas by vegetation, soil colour and temperature variations. Computer enhancement of the multispectral images allow some subsidence details not seen by conventional photography to be delineated. The MSS images are two-dimensional and even the most detailed ones have a fairly coarse resolution (1.5–2.0m). Because of this, conventional 3D interpretation of stereo air photographs better indicates the morphology of the subsidence hollows and the geology.