Mare Fecuditatis is 909 miles in diameter, and sits in the
Fecunditatis basin. The basin is of the Pre-Nectarian epoch,
while the basin material surrounding the mare is of the
Nectarian epoch. The mare matierial is of the Upper Imbrian
epoch,and is relatively thin, as compared to Mare Crisium
or Mare Tranquillitatis. This basin is overlapped with the
Nectaris, Tranquillitatis, and Crisium basins.
Along the western edge of Fecuditatis is where it meets
the Nectaris basin. The area along this zone is faulted by
arcuated grabens. You can make out Mare Tranquillitatis
in the upper left corner of the picture below, while the patch
of grey in the lower-left is Mare Nectaris. On the eastern
edge of Fecunditatis is the crater Langrenus, seen as the
lighter grey area on the right-center of the photo.