Schematic illustrating basal melt rising from collection area at depth toward the surface of SP. Panel (A): map view showing detail in one representative, stylized polygonal cell, domed in the center (contours are dashed). Once on the surface, melt flows down gradient toward the cell margins, in a manner akin to flank eruptions on shield volcanoes. Whereas the channel guiding the flow is too narrow to be imaged in New Horizon imagery, the collection of such N₂ lavas at the cell edges serve to darken the cell perimeters. Panel (B): schematic, cross-sectional view of a single convective cell. A conduit collects melt from the surrounding, and guides it toward the surface, here envisioned as flow in a dike. Once emerging on the surface, the melt cools as it flows down channel and ultimately pools and solidifies in the creased junctions between cells.