Geological Chronicle
Rimae Alphonsus is a lunar graben structure spanning 87 kilometers in length across the lunar basalt crust. Formed by structural faulting and crustal extension, the trench cuts through terrain within the Ptolemaeus quadrangle (LAC-77).
Officially cataloged by the International Astronomical Union at selenographic coordinates -13.4032° latitude and -1.9428° longitude, the rille designation notes: Within crater of same name.