[4] In general, the plateau's highest elevation rests in its northwest corner, closest to its hinge between Noctis Labyrinthus and the Claritas Fossae at the approach of Syria Planum to Pavonis Mons.
[4] Some authors have suggested that the Thaumasia Plateau was once a large, ancient drainage basin pre-dating the extensive volcanic formation of the Tharsis Rise.
[5] The burial of this putative drainage basin has been proposed as a source of the catastrophic floodwaters that are hypothesized to have formed the circum-Chryse outflow channels, and the northwestern slope valleys (NSVs) to the northwest of the Tharsis Rise.
Despite their location and morphology, they have been stratigraphically found to cross-cut younger terrains (ranging from Noachian to early Hesperian age) and thus are probably not the remnant massifs of a putative Tharsis impact basin.
[4] A proposed mechanism for the formation of the Thaumasia Plateau invokes mantle convection eroding the crustal root underlying the province, rapidly inducing a regional-scale uplift.
The shock of impact cratering events in water-saturated target rock is thought to cause either the catastrophic release of groundwater or the induction of a subsurface hydrothermal system.