Along-rille morphological variation

Determine the origin of the along-rille morphological variation associated with the Marius Hills Pit, including whether it results from rille formation processes, pre-existing topography, or an uncollapsed lava tube beneath the central section.

Background

The Marius Hills Pit lies along a rille whose relief varies substantially along its length: it is deeply incised near the source, decreases to a few tens of meters at the pit, and increases again farther downstream. The paper identifies several possible explanations for this variation, including differences in rille formation processes, pre-existing topography, and the presence of an uncollapsed lava tube. Because subsurface data at rille scale are unavailable, the relative contributions of these mechanisms remain unresolved.