Abstract
Theories of landform evolution have been in existence for over 100 years, and yet they are still controversial. Considering the denudation of a highland mass, two general schools of thought have emerged: (1) the Davisian school which favours summit lowering, and (2) the Penckian school which emphasises slope retreat. The controversy is unresolved mainly because uniformitarianism does not seem to provide a solution: 'The critical testing of these rival hypotheses has been thwarted by a lack of quantitative evidence. Short-term observations throw little light on the issue, for determining how landscapes have evolved over enormous periods of time [uniformitarianism] requires reliable chronological markers that are absent from many landscapes.' So the hope is that if quantitative data can be garnered then geologists can better understand how a particular landscape has developed over time. By applying radiometric dating to lava flows, this hope is now being realised, but major surprises have resulted.