There, within a space about 250 miles in length by 100 in width, is an exhibition of the most terrifying effects of volcanic energy that the eye of man can anywhere behold.

Three immense craters--Theophilus, 64 miles across and 3-1/2 miles deep; Cyrillus, 60 miles across and 15,000 feet deep; and Catharina, 70 miles across and from 8,000 to 16,000 feet deep--form an interlinked chain of mountain rings, ridges, precipices, chasms, and bottomless pits that take away one's breath.
But when the first impression of astonishment and dismay produced by this overwhelming spectacle has somewhat abated, the thoughtful observer will note that here the moon is telling him a part of her wonderful story, depicted in characters so plain that he needs no instruction in order to decipher their meaning.

He will observe that this ruin was not all wrought at once or simultaneously.

Theophilus, the crater-mountain at the northwestern end of the chain, whose bottom lies deepest of all, is the youngest of these giants, though the most imposing.

For a distance of forty miles the lofty wall of Theophilus has piled itself upon the ruins of the wall of Cyrillus, and the circumference of the circle of its tremendous crater has been forcibly thrust within the original rim of the more ancient crater, which was thus rudely compelled to make room for its more vigorous rival and successor.
The observer will also notice that Catharina, the huge pit at the southeastern end of the chain, bears evidence of yet greater age.