Response to the discussion by Van Vliet-Lanoë et al. of the paper ‘Features caused by ground ice growth and decay in Late Pleistocene fluvial deposits, Paris Basin, France’ (Bertran et al., 2018, Geomorphology 310, 84–101)
Abstract
The response by Van Vliet-Lanoë et al. to our paper on potential thermokarst features in Pleistocene alluvial deposits from the Paris Basin (France) presents inconsistencies that we consider here successively. These are (1) the map of the maximum extent of Pleistocene permafrost in France, (2) the genesis of liquefaction and fluidization structures in periglacial environments, (3) the origin of thermokarst lakes and recumbent folds, (4) the depositional context of sandy units, and (5) the age of the studied deposits. All structures result from the interplay between (1) the growth and degradation of ice wedges, which are responsible for the development of a mound-like topography (badland thermokarst reliefs) on the edge of the alluvial terrace and from the initiation of ponding elsewhere on the terrace, (2) the degradation of lithalsa that developed later in the lacustrine deposits. The sequence was dated confidently to the Late Weichselian.