A Maria.
Maria
The lunar highlands are older than the maria.
The lunar highlands are older than the maria because they have accumulated more impact craters over time. This suggests that the highlands are composed of older, more geologically stable rock compared to the volcanic plains of the maria.
A maria looks like a dark, flat region
The Lunar Highland rocks reflective and anothositic in composition, while the Lunar Maria are less reflective and basaltic in composition.
The "lunar maria".
Maria
lunar
maria.
The lunar maria are large, dark, basaltic plains, formed by ancient volcanic eruptions
Our Moon's maria are currently believed to have been formed by ancient volcanic eruptions.