Recent investigations have revealed several sets of linear ridges and grooves located in the seafloor of the submarine Dover Strait. The formation of these features is associated with the occurrence of megaflood flows during Middle–Late Pleistocene glacial stages. These megaflood events are also linked to the formation of a prominent inner channel within the Lobourg Channel and the incision of streamlined islands and longitudinal scours into its bed. However, the erosional origin of the linear ridges and grooves and their possible relationship to megaflood erosion have never been demonstrated.In the present study, high-resolution geophysical data were combined with geological data and direct observations to better understand the mechanisms that caused the formation of linear ridges and grooves in the Dover Strait. The combined interpretation of these datasets corroborates that those features are carved into a hard substratum. However, the linear ridges and grooves are truncated by scours, the formation of which is associated with the last episodes of megaflood erosion that imprinted the seafloor of the Dover Strait. Therefore, the linear ridges and grooves were carved by erosional/weathering processes that took place before the incision of those scours. Based on their morphology and regional palaeogeographic reconstructions, it is proposed that the incision of the linear ridges and grooves was caused by fluvial and high-magnitude (not necessarily mega) flood erosion. The linearity of these features and their location in carbonate rocks might also indicate some control of the erosion by permafrost processes, chemical weathering and/or the rock's fabric. |
