fringes on several parts of the coast, both northward of Valparaiso and
near Coquimbo; but at this latter place, from the change in form which the
coast has undergone since the old escarpments were worn, it may be doubted
whether the sea, acting for any length of time at its present level, would
eat into the land; for it now rather tends to throw up great masses of
sand. It is from facts such as these that I have generally used the term
COMPARATIVE rest, as applied to the elevation of the land; the rest or
cessation in the movement being comparative both with what has preceded it
and followed it, and with the sea's power of corrosion at each spot and at
each level. Near Lima, the cliff-formed shores of San Lorenzo, and on the
mainland south of Callao, show that the sea is gaining on the land; and as
we have here some evidence that its surface has lately subsided or is still
sinking, the periods of comparative rest in the elevation and of contingent
denudation, may probably in many cases include periods of subsidence. It is
only, as was shown in detail when discussing the terraces of Coquimbo, when
the sea with difficulty and after a long lapse of time has either corroded
a narrow ledge into solid rock, or has heaped up on a steep surface a
NARROW mound of detritus, that we can confidently assert that the land at
that level and at that period long remained absolutely stationary. In the
case of terraces formed of gravel or sand, although the elevation may have
been strictly horizontal, it may well happen that no one level beach-line
may be traceable, and that neither the terraces themselves nor the summit
nor basal edges of their escarpments may be horizontal.

Finally, comparing the extent of the elevated area, as deduced from the
upraised recent organic remains, on the two sides of the continent, we have
seen that on the Atlantic, shells have been found at intervals from Eastern
Tierra del Fuego for 1,180 miles northward, and on the Pacific for a space
of 2,075 miles. For a length of 775 miles, they occur in the same latitudes
on both sides of the continent. Without taking this circumstance into