Lunar 100 – Object 33
The Serpentine Ridge is a long, winding ridge on the eastern side of Mare Serenitatis, marking part of the inner ring of the Serenitatis impact basin. Its curved, segmented structure follows the basin’s original topography, later exposed as mare lavas flooded the interior and left only the higher ring remnants visible. The Serpentine Ridge is included in the Lunar 100 because it is a clear example of a basin inner‑ring segment, illustrating how large impact basins leave behind arcuate ridges that trace their ancient multi‑ring structure.