{ _Pyrenees_ 8 to 18 12,000 { _Riphean_ 5 to 10 2,600 { _Haemus_ 10 to 20 6,300 { _Carpathian_ 15 to 19 6,000 { _Apennines_ 14 to 27 18,000 Northern { _Taurus_ 25 to 34 8,500 Hemisphere.

{ _Hercynian_ 17 to 29 3,400 { _Caucasus_ 33 to 40 17,000 { _Alps_ 42 to 30 10,000 Of these different chains, the most important is that of the _Apennines_, about 450 miles long, a length, however, far inferior to that of many of the great mountain ranges of our globe.

They skirt the western shores of the _Mare Imbrium_, over which they rise in immense cliffs, 18 or 20 thousand feet in height, steep as a wall and casting over the plain intensely black shadows at least 90 miles long.

Of Mt.
_Huyghens_, the highest in the group, the travellers were just barely able to distinguish the sharp angular summit in the far west.

To the east, however, the _Carpathians_, extending from the 18th to 30th degrees of east longitude, lay directly under their eyes and could be examined in all the peculiarities of their distribution.
Barbican proposed a hypothesis regarding the formation of those mountains, which his companions thought at least as good as any other.
Looking carefully over the _Carpathians_ and catching occasional glimpses of semi-circular formations and half domes, he concluded that the chain must have formerly been a succession of vast craters.