THE MOON’S FACE. 
279 
craters are those of the later series, as the older have been 
filled and buried. Craters of the older series have lost in 
accentuation not only through the paring of their rims but 
also through the partial filling of their valleys, and their 
rims no longer exhibit the fine details of inner terracing and 
outer furrowing. Compare in these respects Hipparchus, 
Albategnius, and Alphonsus of the old regime with Alpe- 
tragius, Horrox, Theophilus, and Copernicus of the new. 
Adjoining this district on the south and extending thence 
to the south pole is a broad area, known as the honeycomb 
district, to which the flood did not extend and with which 
the characters of the flooded district may be compared. In 
the honeycomb district distinctions of age may, indeed, be 
recognized, but there is gradation instead of sharp demar¬ 
cation between old and new. Those parts of the surface 
which have been longest exempt from the downfall of large 
bodies are profusely pitted with minor craters, and it is these 
which dim the outlines of larger formations of ancient date. 
Thus, by the outrush from the Mare Imbrium were intro¬ 
duced the elements necessary to a broad classification of the 
lunar surface. A part was buried by liquid matter whose 
congelation produced smooth plains. Another part was 
overrun by a flood of solid and pasty matter w r hich sculp¬ 
tured and disguised its former details. The remainder was 
untouched, and probably represents the general condition 
of the surface previous to the Imbrian event. 
Furrows .—In strong contrast with all other features of the 
moon’s surface are a series of gigantic furrows. In general 
direction they are remarkably straight, but their sides and 
bottoms, with a single exception, are jagged, abounding in 
acute salients and reentrants. If one thinks only of their 
apparent size instead of their real magnitude as he examines 
them through the telescope, he is reminded of the rude 
grooves sometimes seen on glaciated surfaces where the 
corner of a hard boulder, dragged forward by the ice, has 
plowed its way through a brittle rock. Despite the enormous 
disparity in size—a disparity no less than that of a mountain 
