Lunar mare

mare /ˈmɑːreɪ, -i/ MAR-ay, MAR-ee)[1] are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins.

[citation needed] They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to the naked eye.

The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus ('lake'), palus ('marsh'), and sinus ('bay').

The reason that the mare basalts are predominantly located on the near-side hemisphere of the Moon is still being debated by the scientific community.

Based on data obtained from the Lunar Prospector mission, it appears that a large proportion of the Moon's inventory of heat producing elements (in the form of KREEP) is located within the regions of Oceanus Procellarum and the Imbrium basin, a unique geochemical province now referred to as the Procellarum KREEP Terrane.

The near side of the Moon , with major maria and craters labeled
A global albedo map of the Moon obtained from the Clementine mission . The dark regions are the lunar maria, whereas the lighter regions are the highlands. The image is a cylindrical projection , with longitude increasing left to right from −180° E to 180° E and latitude decreasing from top to bottom from 90° N to 90° S. The center of the image corresponds to the mean sub-Earth point, 0° N and 0° E.
Irregular mare patch – evidence of young lunar volcanism (12 October 2014)