Trend surfaces can be produced by a number of mathematical techniques and have been used widely to depict the regional variation of various geological parameters. In this paper, it is demonstrated that trend surfaces can be constructed by a simple graphical method and may be applied successfully to palaeoenvironmental reconstructions using elevation contours of tilted or folded contacts. Two case studies are discussed to illustrate different aspects of the technique. In the first example, the upper contact of a shallow marine sandstone outcropping over an area of roughly 4000 km 2 in the southwestern part of the Sydney Basin (Australia), is restored by means of a first order trend surface. This reveals the palaeotopography as a sinuous shoal trending towards the northnortheast. The second example, from the Beaufort Group of the Karoo Basin (South Africa), restores the basal contact of a fluvial sandstone by means of a second order (quadratic) trend surface. The restored surface portrays the individual thalwegs and islands of a braided stream system over an area of about 4 km 2 .