The origin of closed depressions in Northeastern France: A new assessment

Pollen records of mardel deposits: The effects of climatic oscillations and land management on soil erosion in Gutland, Luxembourg

“…Natural mardels (in sinkholes and subsidence basins) may develop during the whole Holocene (Barth, 1996;Thoen and Hérault, 2006), and anthropogenic mardels (in abandoned quarries) are the result of clay extraction in Roman Time (Etienne et al, 2011) or later (Schmidt, 1995).…”

“…She reported possibilities for natural and anthropogenic genesis of the mardels, but this research focused on water quality and wetland species in these unique biotopes. Etienne et al (2011) considered anthropogenic factors as an explanation for CDs in the Lorraine landscape. The sediments in the majority of the CDs could be palynologically dated as Post-Roman and consequently the majority of the depressions are Roman excavations.…”

Features caused by ground ice growth and decay in Late Pleistocene fluvial deposits, Paris Basin, France

“…Alternative hypotheses (karst, anthropogenic activity) remain problematic to eliminate in the majority of cases. Detailed analysis and dating of the filling of depressions from NE France (Etienne et al, 2011) has, for example, led to an anthropogenic origin (marl extraction to amend fields during the Medieval period).…”

Natural versus anthropogenic genesis of mardels (closed depressions) on the Gutland plateau (Luxembourg); archaeometrical and palynological evidence of Roman clay excavation from mardels

“…15 Etienne et al (2011) considered anthropogenic factors as principal explanation for CD's in the Lorraine landscape. The sediments in the majority of these CD's could palynological be dated as Post Roman and consequently the majority of the depressions raised as Roman excavations with a Post Roman colluvial filling.…”

“…The first results of the research of the Gutland mardels have been published by him in his PhD the-5 sis (Slotboom, 1963). 50 years later, triggered by the contrasting results of researchers as Etienne et al (2011), we decided to return to the Gutland to find new data to contribute to the controversial issue natural/anthropogenic mardel genesis. Some preliminary results concerning the mardels on the Strassen marls have been published (Slotboom and van Mourik, 2015) short before Ruud passed away in February 2015.…”