Penck, Walther (1888–1923)

Walther Penck was the son of the famous German Quaternary scientist and geomorphologist Albrecht Penck. Albrecht had both a professional and a personal relationship with William Morris Davis that eventually became acrimonious. Walther Penck's claim to fame as a geomorpholo-gist rests on the posthumous publication by his father, in 1924, of his book Die morphologische Analyse (Morphological Analysis). Written in highly convoluted German, it received very little attention in Germany but became a central and contentious topic within the English-speaking world of geomorphology due to what some perceived as a self-serving interpretation by Davis. This article remained the authoritative English source of Penck's ideas until Hella Czech and Katharine Cumming Boswell published an English translation of the work 40 years later.

The idea in Penck's work that received so much attention in the English-speaking geomorphologic world was that of the parallel retreat of slopes. Such a pathway would produce an entirely different history of both slope and landscape development from that proposed by Davis, whose convexo-concave slope profiles decline in angle with time and whose landscapes become peneplains. This alternate view of slope development became most significant in Lester King's description of landscape development that produces pediplains, not peneplains. While King and others assigned the concept of parallel slope retreat to Walther Penck, this is a misconception that was first found in Davis's interpretation. Penck initially launched his ideas cautiously, apparently trying to avoid direct conflict with Davis, but later he became more openly critical of Davisian ideas.

The reality is that Penck produced a very logical and internally consistent model of slope development that argued not for the parallel retreat of slopes but for slope replacement extending upslope from the base. However, the slope model was not Penck's primary objective; his real objective was to investigate tectonic, or crustal, movements, which he attempted to do by relating surficial form to subsurface activity. He tied his ideas on slope form closely to local tectonic history and synthesized his views on individual slopes to produce regional assemblages such as Piedmontreppen (stepped erosional benches) and Primarrumpf (primary peneplains). Complicated German and an early death left many of Penck's ideas undetermined in detail within the English-speaking world, making him a major figure in English language geomorphology and a minor one in his native Germany.