雨海
Fra Mauro is thought to have been formed from ejecta, or debris, from the impact which formed Mare Imbrium. During Apollo 14, the crew members sampled ejecta from Cone crater, a feature close in proximity to the immediate landing site of the mission, which provided insight into the composition of material deep inside the formation. Data from the mission has helped to determine the approximate age of Mare Imbrium, suggesting that it is no more than about 4.25 billion years old.