ually quiet, containing identical materials
throughout, and that these materials must have been deposited over the
whole bottom in the same way. It is usually separated from the
superincumbent beds by a glazed crust of hard, compact sandstone, almost
resembling a ferruginous quartzite.

Upon this follow beds of sand and sandstone, varying in the regularity
of their strata, reddish in color, often highly ferruginous, and more or
less nodulous or porous. They present frequent traces of
cross-stratification, alternating with regularly stratified horizontal
beds, with here and there an intervening layer of clay. It would seem as
if the character of the water basin had now changed, and as if the
waters under which this second formation was deposited had vibrated
between storm and calm,--had sometimes flowed more gently, and again had
been tossed to and fro,--giving to some of the beds the aspect of true
torrential deposits. Indeed, these sandstone formations present a great
variety of aspects. Sometimes they are very regularly laminated, or
assume even the appearance of the hardest quartzite. This is usually the
case with the uppermost beds. In other localities, and more especially
in the lowermost beds, the whole mass is honeycombed, as if drilled by
worms or boring shells, the hard parts enclosing softer sands or clays.
Occasionally the ferruginous materials prevail to such an extent, that
some of these beds might be mistaken for bog ore, while others contain a
large amount of clay, more regularly stratified, and alternating with
strata of sandstone, thus recalling the most characteristic forms of the
Old Red or Triassic formations. This resemblance has, no doubt, led to
the identification of the Amazonian deposits with the more ancient
formations of Europe. At Monte Alegre, of which I shall presently speak
more in detail, such a clay bed divides the lower from the upper
sandstone. The thickness of these sandstones is extremely variable. In
the basin of the Amazons proper, they hardly rise anywhere above the
level of high water during the rainy season, while at low water, in the
summer months, they maybe seen everywhere along the river-banks. It will
be seen, however, that the limit between high and low water gives no
true measure of the original thickness of the whole series.

In the neighborhood of Almeirim, at a short distance from the northern
bank of the river, and nearly parallel with its course, there rises a
line