It is a widespread hilly geological area covering large portions of the lunar surface around Mare Imbrium, and is thought to be composed of ejecta from the impact which formed the mare. The area is characterized by ridges a few hundred feet high which radiate from the Imbrium basin separated by undulating valleys. The ejecta blanket is now buried by younger rubble and lunar soil churned up by more recent meteoroid impacts and possible moonquakes. Fra Mauro debris may have come from as deep as 100 miles (161 km) below the original lunar crust, and returned samples provide evidence of when the Imbrium basin was formed and help to establish the age and physical/chemical nature of pre-impact material from deep in the crust.
The southern edge of Mare Insularum extends between the craters Lansberg and Fra Mauro. The lower half of the section is occupied by Mare Cognitum. Although this area is seemingly uninteresting, it contains a number of geologically important locations and therefore is one of the most studied regions of the Moon. This is the area where the probe Ranger 7 crashed landed and where two Apollo expeditions landed: Apollo 12 close to Surveyor 3, and Apollo 14 in the hills at the edge of the crater Fra Mauro.
The Fra Mauro formation became more interesting to scientists when the Apollo 12 seismometer at Surveyor crater 110 miles (177 km) to the west relayed to Earth signals of monthly moonquakes believed to have originated in the Fra Mauro crater as the Moon passed through its perigee.
A recent impact near the landing point of Apollo 14 formed Cone crater, nearly 1,000 feet (305 m) across and 250 feet (76 m) deep, with large blocks of original Imbrium material around the crater rim. Shepard and Mitchell climbed Cone crater's gently sloping outer wall to photograph the crater's interior and chip samples from the boulders around the edge.
The Fra Mauro crater and surrounding formation take their names from a 15th century Italian monk and mapmaker, who in 1457 mapped the then-known Mediterranean world with suprising accuracy.