Mare Marginis
The origin of Reiner Gammalike other lunar swirlsis not completely understood. It is associated with a localized magnetic field, but not with any particular irregularities in the surface. Similar features have been discovered in Mare Ingenii and Mare Marginis by orbiting spacecraft. The feature on Mare Ingenii is located at the lunar opposite point from the center of Mare Imbrium. Likewise the feature on Mare Marginis is opposite the midpoint of Mare Orientale. Thus one hypothesis is that the feature resulted from seismic energies generated by the impacts that created these maria. However, no such lunar mare formation is on the opposite side of the Moon from Reiner Gamma.