374 The American Geologist. June, 1904. 
uous Mt. Deception, strow the land in marvelous profusion.* • 
Boulders of wasting rock formations are most plentiful on 
the slopes and tops of mountains and hills . Where such areas 
were enveloped by the ice-sheet during any prolonged stage of 
glaciation, the loose rock masses were swept ofif into the drift 
for a long distance on the lee side. That Mt. Washington, 
the culminating peak of the White mountains, still bears ex- 
ceedingly abundant frost-riven masses of its underlying schist 
and gneiss, although it has also very rare and comparatively 
small glacially transported boulders found by Prof. C. H. 
Hitchcock near to the summit, implies that this high mountain 
top was enveloped only a short time by the ice-sheet when it 
attained its greatest thickness. Excepting the rare glacial 
boulders, this peak resembles, in its great numbers of residual 
rock fragments, the upper parts of Mt. Katahdin in Maine 
and of the Three Buttes or Sweet Grass hills in northern Mon- 
tana, which rose as nunataks above the ice-sheet at its time of 
maximum accumulation . t 
Besides the many residual boulders provided in preglacial 
times on areas' of crystalline rocks for incorporation with the 
glacial drift, the ice-sheet also gathered many masses and 
fragments of the sedimentary rocks wherever it overspread 
their weathering cliffs along the river courses, or their tur- 
reted and pinnacled remnants of prolonged erosion, such as 
are common in v?rious parts of the Driftless Area of Wis- 
consin, and on hilly tracts south of the glacial boundary. One of 
the most remarkable deposits of small and large blocks of rock, 
up to 25 feet in dimension, thus removed by ice currents only 
a very short distance from their original positions, is seen in 
the upper half of the left bluff of the Mississippi river in St. 
Paul, Minnesota, along an extent of about 1,000 feet at the 
northern end of the Smith Avenue bridge (commonly called 
the High bridge) . The blocks are from the adjacent Tren- 
ton limestone, which forms a wide terrace on that side of the 
river and about 100 feet above it, extending for the distance 
of six miles from Fort Snelling to the center of the city. 
Without attempting any very close estimate or computa- 
tion, I ani led to think, from the foregoing and other related 
• Ambr. Geol., vol. xxxiii, pp. 13, 14, Jan,' 1904-. 
fGlaciation of Mountains in New England and New York," Appalachia, 
vol. T, 1889, pp. 291-312. 
