Late evolutionary stages of residual hills in tablelands (Elbsandsteingebirge, Germany)

It is commonly assumed that geomorphic evolution of tablelands, where durable caprock overlies weaker formations, proceeds via escarpment retreat which leaves residual tabular hills (mesas) in front of the receding scarps. These in turn are reduced in extent towards buttes and then pinnacles in the final stage. In this paper we use empirical evidence from Elbsandsteingebirge sandstone tableland in east Germany to show that different pathways of mesa decay exist and that various scenarios are possible. Depending on mesa morphology and the degree of its dissection, penultimate stages may include classic buttes, series of small isolated crags, or rock labyrinths (rock cities) subject to slow lateral outward displacement. These may evolve into pinnacles or boulder scatters, no longer rooted in bedrock. The latter are the last remnants of no longer existing tabular hills. These different trajectories are mainly controlled by lithology and structure, including the thickness of caprock, the proportion of caprock versus subcaprock slope, the pattern of jointing, and the presence of weaker intercalations within stronger lithological units. Literature review shows that some of these pathways were hypothesized long ago but little empirical evidence was offered and multiple trajectories were apparently not considered.