Those unknown structures?

Using sonar, Ran mapped 54 square miles of ice underside beneath Dotson Ice Shelf. The maps revealed flat plateaus, terraced steps, and teardrop-shaped pits, all carved by basal melt, melting that attacks the ice from below.

In the east and center, Ran saw icy terraces stacked like steps, while the west looked smoother, with channels and scooped depressions.

None of these terraces or teardrop pits show up on satellite images, so they had remained completely hidden until Ran’s mission.