Serpentine Ridge

The eastern side of the mare surface is crossed by a series of low mare wrinkle ridges. Unofficially these are known as the Serpentine Ridge. The wrinkle ridges consist of two main segments, which are officially known as Dorsa Lister and Dorsa Smirnov. Both are about 10 km wide and extend, more-or-less following the trend of the edge of the mare, over considerable distances: Dorsa Lister for around 300 km and Dorsa Smirnov for about 130 km.

South of Dorsa Lister lies the crater Plinius with a diameter of 43 km. In between, oriented east—west is the Rimae Plinius rille system, with a length of 124 km. The small crater Very, with a diameter of just 5 km lies almost in the centre, directly on top of the ridge of Dorsa Smirnov.

Posidonius Gamma is the designation, no longer used, for a small peak on the Dorsa Smirnov wrinkle ridge. The mountain has a summit crater, which is surrounded by a small halo of bright ejecta. The rilles (Rimae Littrow, Rimae Chacornac) on the eastern edge of Mare Serenitatis are fracture zones, created by a subsidence of the Serenitatis Basin's central lava area.

In the western portion there are Dorsum Buckland, Dorsum Azara and a few others. All these mare wrinkle ridges in Mare Serenitatis branch and partially intersect one another. They are, in general, no more than about 200 m high, and are therefore only visible at very low solar elevations, when near the terminator.