MOUNTAIN RANGES, ISOLATED MOUNTAINS, &c.—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 5000 to 8000 feet, are common. They extend in a south-west direction from Plato to the Caucasus, terminating somewhat abruptly, a little west of the central meridian, in about N. lat. 42 deg. 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 southwards, 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 3000 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 neighbouring promontory on the south-east of it is fully 14,000 feet, and another, close by, is still higher above the Mare. Mount Huygens, again, in N. lat. 20 deg., 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 towards the south-west, and includes some bright craters and mountain-rings. The Carpathians, forming in part the southern border of the Mare Imbrium, extend for a length of more than 180 miles eastward of E., long. 16 deg., and, embracing the ring-plain Gay- Lussac, terminate west of Mayer. They present a less definite front to the Mare than the Apennines, and are broken up and divided by irregular valleys and gaps; their loftiest peak, situated on a very projecting promontory north-west of Mayer, rising to a height of 7000 feet. Notwithstanding their comparatively low altitude, the region they occupy forms a fine telescopic picture at lunar sunrise. The Sinus Iridum highlands, bordering the beautiful bay on the north-east side of the Mare Imbrium, rank among the loftiest and most intricate systems on the moon, and, like the Apennines, present a steep face to the grey plain from which they rise, though differing from them in other respects. They include many high peaks, the loftiest, in the neighbourhood of the ring- plain Sharp, rising 15,000 feet. There are probably some still higher mountains in the vicinity, but the difficulties attending their measurement render it impossible to determine their altitude with any approach to accuracy.
The Taurus Mountains extend from the west side of the Mare Serenitatis, near Le Monnier and Littrow, in a north-westerly direction towards Geminus and Berselius, bordering the west side of the Lacus Somniorum. They are a far less remarkable system than any of the preceding, and consist rather of a wild irregular mountain region than a range. In the neighbourhood of Berselius are some peaks which, according to Neison, cannot be less than 10,000 feet in height.
On the north side of the Mare Imbrium, east of Plato, there is a beautiful narrow range of bright outlying heights, called the Teneriffe Mountains, which include many isolated objects of considerable altitude, one of the loftiest rising about 8000 feet. Farther towards the east lies another group of a very similar character, called the Straight Range, from its linear regularity. It extends from west to east for a distance of about 60 miles, being a few miles shorter than the last, and includes a peak of 6000 feet.
The Harbinger Mountains.—A remarkable group, north-west of Aristarchus, including some peaks as high as 7000 feet, and other details noticed in the catalogue.
The above comprise all the mountain ranges in the northern hemisphere of any prominence, or which have received distinctive names, except the Hercynian Mountains, on the north-east limb, east of the walled plain Otto Struve. These are too near the edge to be well observed, but, from what can be seen of them, they appear to abound in lofty peaks, and to bear more resemblance to a terrestrial chain than any which have yet been referred to.
The mountain systems of the southern hemisphere, except the ranges visible on the limb, are far less imposing and remarkable than those just described. The Pyrenees, on the western side of the Mare Nectaris, extend in a meridional direction for nearly 190 miles, and include a peak east of Guttemberg of nearly 12,000 feet, and are traversed in many places by fine valleys.
The Altai Mountains form a magnificent chain, 275 miles in length, commencing on the outer eastern slope of Piccolomini, and following a tolerably direct north-east course, with a few minor bendings, to the west side of Fermat, where they turn more towards the north, ultimately terminating about midway between Tacitus and Catherina. The region situated on the south-east is a great table-land, without any prominent features, rising gently towards the mountains, which shelve steeply down to an equally barren expanse on the north-west, to which they present a lofty face, having an average altitude of about 6000 feet. The loftiest peak, over 13,000 feet, rises west of Fermat.
The Riphaean Mountains, a remarkably bright group, occupying an isolated position in the Mare Procellarum south of Landsberg, and extending for more than 100 miles in a meridional direction. They are most closely aggregated at a point nearly due west of Euclides, from which they throw off long-branching arms to the north and south, those on the north bifurcating and gradually sinking to the level of the plain. The loftiest peaks are near the extremity of this section, one of them rising to 3000 feet. Two bright craters are associated with these mountains, one nearly central, and the other south of it.
The Percy Mountains.—This name is given to the bright highlands extending east of Gassendi towards Mersenius, forming the north-eastern border of the Mare Humorum. They abound in minute detail—bright little mountains and ridges—and include some clefts pertaining to the Mersenius rill-system; but their most noteworthy feature is the long bright mountain-arm, branching out from the eastern wall of Gassendi, and extending for more than 50 miles towards the south-east.
The principal ranges on the limb are the Leibnitz Mountains, extending from S. lat. 70 deg. on the west to S. lat. 80 deg. on the east limb. They include some giant peaks and plateaus, noteworthy objects in profile, some of which, according to Schroter and Madler, rise to 26,000 feet. The Dorfel Mountains, between S. lat. 80 deg. and 57 deg. on the eastern limb, include, if Schroter's estimate is correct, three peaks which exceed 26,000 feet. On the eastern limb, between S. lat. 35 deg. and 18 deg., extend the Rook Mountains, which have peaks, according to Schroter, as high as 25,000 feet. Next in order come the Cordilleras, which extend to S. lat. 8 deg., and the D'Alembert Mountains, lying east of Rocca and Grimaldi, closely associated with them, and probably part of the same system. Some of the peaks approach 20,000 feet. In addition to these mountain ranges there are others less prominent on the limb in the northern hemisphere, which have not been named.