horizontal beds. From what I have myself seen in dredging, I believe this
to be improbable in the highest degree, if not impossible; and I think
everyone who has read Professor E. Forbes's excellent researches on the
subject, will without hesitation agree in this conclusion.): to me it
appears far more probable that the movement was gradual, with small starts
as during the earthquakes of 1822 and 1835, by which whole beds of shells
attached to the rocks were lifted above the subsequent reach of the waves.
M. d'Orbigny also found rolled pebbles extending up the mountain to a
height of at least six hundred feet. At Iquique (latitude 20 degrees 12'
S.), in a great accumulation of sand, at a height estimated between one
hundred and fifty and two hundred feet, I observed many large sea-shells
which I thought could not have been blown up by the wind to that height.
Mr. J.H. Blake has lately described these shells: he states that "inland
toward the mountains they form a compact uniform bed, scarcely a trace of
the original shells being discernible; but as we approach the shore, the
forms become gradually more distinct till we meet with the living shells on
the coast." ("Silliman's American Journal of Science" volume 44 page 2.)
This interesting observation, showing by the gradual decay of the shells
how slowly and gradually the coast must have been uplifted, we shall
presently see fully confirmed at Lima. At Arica (latitude 18 degrees 28'),
M. d'Orbigny found a great range of sand-dunes, fourteen leagues in length,
stretching towards Tacna, including recent shells and bones of Cetacea, and
reaching up to a height of 300 feet above the sea. ("Voyage" etc. page
101.) Lieutenant Freyer has given some more precise facts: he states (In a
letter to Mr. Lyell "Geological Proceedings" volume 2 page 179.) that the
Morro of Arica is about four hundred feet high; it is worn into obscure
terraces, on the bare rock of which he found Balini and Milleporae
adhering. At the height of between twenty and thirty feet the shells and
corals were in a quite fresh state, but at fifty feet they were much
abraded; there were, however, traces of organic remains at greater heights.