Page:Popular Science Monthly Volume 68.djvu/203

 Rh but a precipitous escarpment on the southeast. The Gothics are like a steep wedge standing on its base, and tapering from all four sides of the base to the ridge. Whiteface is a long sharp ridge, steep if not actually precipitous on each side, and leading up to a peak at the southwestern end. Some buttresses run out from the ridge and make beautiful cirques on its flanks. Hurricane, when viewed from the east, resembles a sharp volcanic cone; from the west it is flat. There are several, of which Dix is the highest example, which, like Vesuvius, have a small conical summit set upon a large mountainous base. Nipple-top is a rather favorite name in the local nomenclature of the inhabitants. There are several smaller mountains which have the outlines of a steep haystack when viewed from certain directions, and their precipitous sides and doming tops fix the eye at once. Yet they may each be a ridge when seen from the opposite. One very exceptional peak, quite inappropriately called Sugarloaf, near Hulett's on Lake George, is a circular mesa, with a flat top several acres in area and dropping with steep sides to the lake slope below. It resembles a round fort or old-time castle, such as St. Angelo, across the Tiber from Rome, or Castle William on Governor's Island in New York Harbor. It is due to flat foliation in the gneisses combined with intersecting vertical joints. Not a few other mountains, although of very irregular shapes at the base, yet have flat tops of considerable area. Their level summits appear to be the surviving remnants of some old-time peneplain now faulted into relief, as will be later explained.

The plateau portion, which makes up practically the western half, is not absolutely flat, but is more or less diversified with low hills and intervening broad valleys. Occasional summits give views of moderate extent, but no elevations can properly be called mountains, and the general term plateau is most expressive. It may well be the remnant of an old peneplain, perhaps the important one widely developed in Cretaceous time in the east.

The Valleys.—The mountains can not all be described without parallel and complementary reference to the valleys, and in discussing the latter the causes which have led to the production of the former may best be mentioned.

At least two marked and contrasted types of valleys may be distinguished. There is an old series which in part probably dates back even to Precambrian time. In the eastern mountains the cause of their excavation is oftentimes obviously the presence of relatively soft and easily eroded limestone in the series of gneisses. In several notable cases the Potsdam and even later Paleozoic formations can be traced by the remaining outliers some miles into the old crystallines, and although subsequent faulting has exercised its modifying and disguising influence, yet it has appeared to several observers that the old