walled plain

American  

noun

1. a circular or almost circular area on the moon, sometimes with a floor that is depressed, usually partially enclosed by walls that rise to varying heights and that are usually lower than those of a crater.

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walled plain British  

noun

1. any of the largest of the lunar craters, having diameters between 50 and 300 kilometres

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Example Sentences

Thus the terse remark of Mädler, “The full Moon knows no Maginus,” has become a proverb amongst selenographers; yet Maginus is a fine walled plain some eighty miles in diameter, and its rampart attains a height in parts of 14,000 feet.

From Project Gutenberg

We begin with the range of vast inclosures running southward near the central meridian, and starting with Ptolem�us, a walled plain one hundred and fifteen miles in its greatest diameter and covering an area considerably exceeding that of the State of Massachusetts.

From Project Gutenberg

In the neighborhood of the south pole lies the large walled plain of Newton, whose interior is the deepest known depression on the moon.

From Project Gutenberg

The latter hypothesis seems the more probable: and its probability is strengthened by much evidence of actual obscuration or variation of tint in other parts of the lunar surface, more especially on the floor of the great "walled plain" named "Plato."

From Project Gutenberg

Usually the floor of a walled plain becomes brighter as the sun rises higher and higher in the sky, but Plato actually becomes darker under a high sun.

From Project Gutenberg