part of a great series of
physical events extending over the whole globe. Indeed, when the ice
period is fully understood, it will be seen that the absurdity lies in
supposing that climatic conditions so intense could be limited to a
small portion of the world's surface. If the geological winter existed
at all, it must have been cosmic; and it is quite as rational to look
for its traces in the Western as in the Eastern hemisphere, to the south
of the equator as to the north of it. Impressed by this wider view of
the subject, confirmed by a number of unpublished investigations which I
have made during the last three or four years in the United States, I
came to South America, expecting to find in the tropical regions new
evidences of a by-gone glacial period, though, of course, under
different aspects. Such a result seemed to me the logical sequence of
what I had already observed in Europe and in North America.

On my arrival in Rio de Janeiro,--the port at which I first landed in
Brazil,--my attention was immediately attracted by a very peculiar
formation, consisting of an ochraceous, highly ferruginous sandy clay.
During a stay of three months in Rio, whence I made many excursions into
the neighboring country, I had opportunities of studying this deposit,
both in the province of Rio de Janeiro and in the adjoining province of
Minas Geraes. I found that it rested everywhere upon the undulating
surfaces of the solid rocks in place, was almost entirely destitute of
stratification, and contained a variety of pebbles and boulders. The
pebbles were chiefly quartz, sometimes scattered indiscriminately
throughout the deposit, sometimes lying in a seam between it and the
rock below; while the boulders were either sunk in its mass or resting
loose on the surface. At Tijuca, a few miles out of the city of Rio,
among the picturesque hills lying to the southwest of it, these
phenomena may be seen in great perfection. Near Bennett's Hotel--a
favorite resort, not only with the citizens of Rio, but with all
sojourners there who care to leave the town occasionally for its
beautiful environs--may be seen a great number of erratic boulders,
having no connection whatever with the rock in place, and also a bluff
of this superficial deposit studded with boulders, resting above the
partially stratified metamorphic rock. Other excellent opportunities for
observing this formation, also within easy reach from the city, are
afforded along the w