Page:Popular Science Monthly Volume 12.djvu/337

Rh, but they are also discovered capping the cliffs of mountain chains, hanging by the side of depths, over which they must have been carried, and into which, by the Nemesis of destiny, they are now doomed to fall. The Jura Mountains, north of the great valley of Switzerland, and opposite the western or Bernese Alps, along the frontier of France, are thus studded with these bowlders, some of them containing 50,000 to 60,000 cubic feet of stone. These have come from the Alps; they are crystalline rocks, gneiss, and granite, and they lie upon ridges of limestone. They are virtually nothing less than dislocated fragments of those abraded and decreasing hills perched upon the Jura cliffs. Prof. Guyot has placed, beyond all doubt, their home upon the summits and sides of the Swiss Alps, and shown that they have attained their present eminence by a positive carriage from these original localities. This position has indeed been made impregnable by a protracted and laborious survey of innumerable "wanderers" found upon the Juras, whose lithological character identified them with the Alpine formation, while it served to trace the probable path of their transmission. These blocks have been found at elevations ranging from 2,000 to 3,500 feet above the sea, and in Carinthia similar erratics have been described at great elevations, proceeding from an opposite quarter of the Alps.

In North America, and especially throughout the Northern States, the bowlders are numerous, often of great size, and indicating transits of many miles. Over the Eastern, Middle, and Northwestern States, bowlders, that have emigrated from distant points to the northward, occur in such abundance that they may almost anywhere be found if the inquirer will only examine the country he passes over. Upon Mount Katahdin, in the Moosehead region of Maine, stones can be seen, lying over 4,000 feet above the sea, fossiliferous in their nature and coming from northern sites; while toward Mount Desert, masses, some forty to fifty feet in height, are sprinkled everywhere, and, as in the case of the Dedham granite distributed to the south, invariably show northern origin. In Berkshire County, Massachusetts, these traveled rocks lie in long alignments, passing over the Lenox Hills, and extending in a generally southeasterly direction for fifteen or twenty miles, and have been filched from the Canaan and Richmond Hills across the line in New York, being of chloritic slate, with angular specimens of limestone intermixed. Some granites from Vermont, on the west of the Green Mountains, have been lifted over these barriers and transferred to the southern margins of Massachusetts; while in Vermont a bowlder weighing over 3,400 tons, and known as the Green Mountain Giant, has been drifted from the Green Mountains easterly across the valley of the Deerfield River, and planted 500 feet above that stream. In Michigan, near the Menomonee River, a field upon the northern slope of a mountain is densely covered with bowlders, so that a mile can be traversed without once touching the