points, I found a layer of saline powder of exactly similar appearance,
and lying in the same relative position. I have no doubt that this
upper layer originally existed as a bed of shells, like that on the
eighty-five-feet ledge; but it does not now contain even a trace of
organic structure. The powder has been analyzed for me by Mr. T.
Reeks; it consists of sulphates and muriates both of lime and soda,
with very little carbonate of lime. It is known that common salt and
carbonate of lime left in a mass for some time together, partly
decompose each other; though this does not happen with small quantities
in solution. As the half-decomposed shells in the lower parts are
associated with much common salt, together with some of the saline
substances composing the upper saline layer, and as these shells are
corroded and decayed in a remarkable manner, I strongly suspect that
this double decomposition has here taken place. The resultant salts,
however, ought to be carbonate of soda and muriate of lime, the latter
is present, but not the carbonate of soda. Hence I am led to imagine
that by some unexplained means, the carbonate of soda becomes changed
into the sulphate. It is obvious that the saline layer could not have
been preserved in any country in which abundant rain occasionally fell:
on the other hand, this very circumstance, which at first sight appears
so highly favourable to the long preservation of exposed shells, has
probably been the indirect means, through the common salt not having
been washed away, of their decomposition and early decay.
I was much interested by finding on the terrace, at the height of
eighty-five feet, _embedded_ amidst the shells and much sea-drifted
rubbish, some bits of cotton thread, plaited rush, and the head of a
stalk of Indian corn: I compared these relics with similar ones taken
out of the Huacas, or old Peruvian tombs, and found them identical in
appearance. On the mainland in front of San Lorenzo, near Bellavista,
there is an extensive and level plain about a hundred feet high, of
which the lower part is formed of alternating layers of sand and impure
clay, together with some gravel, and the surface, to the depth of from
three to six feet, of a reddish loam, containing a few scattered
sea-shells and numerous small fragments of coarse red earthenware, more
abundant at certain spots than at others. At first I was inclined to
believe that this superficial bed, from its wide extent and smoothness,
must have been deposited beneath the sea; but I afterwards found in one
spot, that it lay on an artificial floor of round stones. It seems,
therefore, most probable that at a period when the land stood at a
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