The primary controls on the landslide geometry, quantified as the ratio of their thickness to length t/l, prove to be the residual friction angle of the slope material and the original slope angle. The t/l is observed to be unchanged for a given initial slope angle and independent of the slope material peak strength or the slope height. We suggest that the narrow range of observed natural t/l is a result of narrow ranges of mechanical properties and initial slope geometries involved in natural slope failure.