where,
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 boulder 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 Menominee
River, a field upon the northern slope of a mountain is densely covered
with boulders, so that a mile can be traversed without once touching
the ground. Again, huge nuggets of copper, torn from the immense
deposits of native copper at Keweenaw Point, Portage Lake, and the
Ontonagon district, on the southern shore of Lake Superior, are found
widely disseminated to the south of these localities in Michigan,
Wisconsin, Ohio, and Minnesota, a few of which have weighed 300, 800,
and one, 3,000 pounds. From the sides of the White Mountains fragments
of rock have been carried away, and not only conveyed southward, but,
as Agassiz first pointed out, distributed northward, though only at
comparatively slight distances.
Throughout
Ohio boulders are found which are composed of rock utterly foreign to
their present surroundings—indeed, of material not known within the
limits of the State. These are found perched over declivities, buried
in the soil with their exposed edges showing above the surface, or else
lying unencumbered in slight depressions of the ground. In Indiana,
Michigan, Illinois, Wisconsin, etc., they are omnipresent, and the
streets of Cincinnati are paved with the
