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Desert thresholds are narrow zones of spatial instability between semi-arid and arid regions. Identifying and mapping such thresholds is difficult because of the high diversity of vegetation, soil and bare rock patterns in these regions. Here, we suggest incorporating pattern information from remote sensing imagery in the assessment of eco-geomorphic transitions. A new methodology was developed for this purpose based on the analysis of potential inverse trends of erosion and recovery embedded in these patterns. The methodology applies spectral mixing analysis to map surface conditions and uses mathematical morphology algorithms of dilation and erosion to identify potential erodibility and recovery trends. Boundary lines are then delineated by classifying combinations of these inverse trends and assessed with reference to their separability. This approach is implemented along the climatic gradient between the Judean Mountains and the Dead Sea in central Israel using mid-resolution Landsat TM data. The identified threshold lines fit well with lithological, soil and phytogeographical boundaries as delineated in low-scale maps, yet add significant explicitness to their spatial definition. Such explicitness is instrumental for assessing future desert shifts because of global warming and extended overgrazing. Copyright (c) 2012 John Wiley & Sons, Ltd.