The more massive and extended mountain ranges of the moon are found in the Northern Hemisphere, and (what is significant) in that portion of it which exhibits few indications of other superficial disturbances. The most prominently developed systems, the Alps, the Caucasus, and the Apennines, forming a mighty western rampart to the Mare Imbrium and giving it all the appearance of a vast walled-plain, present few points of resemblance to any terrestrial chain. The former include many hundred peaks, among which Mont Blanc rises to a height of 12,000 feet, and a second, some distance west of Plato, to nearly as great an altitude; while others ranging from 5,000 to 8,000 feet are common. They extend in a southwest direction from Plato to the Caucasus, terminating somewhat abruptly, a little west of the central meridian in about N. lat. 42°. One of the most interesting features associated with this range is the so-called great Alpine valley, which cuts through it west of Plato. The Caucasus consist of a massive wedge-shaped mountain land, projecting southward, and partially dividing the Mare Imbrium from the Mare Serenitatis, both of which they flank. Though without peaks so lofty as those pertaining to the Alps, there is one, immediately east of the ring-plain Calippus, which, towering to 19,000 feet, surpasses any of which the latter system can boast. The Apennines, however, are by far the most magnificent range on the visible surface, including as they do some 3,000 peaks, and extending in an almost continuous curve of more than 400 miles in length from Mount Hadley, on the north, to the fine ring-plain Eratosthenes, which forms a fitting termination, on the south. The great headland Mount Hadley rises more than 15,000 feet, while a neighboring promontory on the southeast of it is fully 14,000 feet, and another, close by, is still higher above the Mare. Mount Huyghens, again in N. lat. 20°, and the square-shaped mass Mount Wolf, near the southern end of the chain, include peaks standing 18,000 and 12,000 feet respectively above the plain to which their flanks descend with a steep declivity. The counterscarp of the Apennines, in places 160 miles in width from east to west, runs down to the Mare Vaporum, with a comparatively gentle inclination. It is everywhere traversed by winding valleys of a very intricate type, all trending toward the southwest, and includes some very bright craters and mountain-rings.