A vocabulary of landscape — a landscape of words
1469 entries
mare
A mare is one of the large dark plains on the near side of the Moon, which early observers with poor instruments took for seas. They are floods of basalt that welled up into enormous impact basins and cooled flat, and they are darker than the surrounding highlands because the rock is different. They cover about a third of the near side and almost none of the far side. The plural is maria.
Etymology
The word is Latin for sea, and it survives on the moon because the seventeenth-century astronomers who drew the first detailed maps kept the interpretation in the naming even after it was doubted. The naming scheme they used has stuck entirely: the Sea of Tranquility, the Ocean of Storms, the Bay of Rainbows, the Marsh of Sleep, and the Lake of Dreams are all still the official names.
Notes
The same Latin word is behind English marine, maritime, and mere, and behind the German maar. Apollo 11 landed in Mare Tranquillitatis. The mare basalts are younger than the highlands and carry far fewer craters, which is how their relative age was worked out long before anyone brought a sample home.