some instances since European occupation, violent earthquake shocks
have resulted in considerable elevations of certain parts of the
coast. After the great earthquake of 1835 Captain Robert FitzRoy
(1805-1865) of H.M.S. "Beagle" found putrid mussel-shells still
adhering to the rocks 10 ft. above high water on the island of Santa
Maria, 30 m. from Concepcion, and Charles Darwin declares, in
describing that disaster, that "there can be no doubt that the land
round the bay of Concepcion was upraised two or three feet." These
upheavals, however, are not always permanent, the upraised land
sometimes settling back to its former position. This happened on the
island of Santa Maria after 1835. The existence of sea-shells at
elevations of 350 to 1300 ft. in other parts of the republic shows
that these forces, supplemented by a gradual uplifting of the coast,
have been in operation through long periods of time and that the
greater part of central and southern Chile has been raised from the
sea in this way. These earthquake shocks have two distinct
characteristics, a slight vibration, sometimes almost imperceptible,
called a _temblor_, generally occurring at frequent intervals, and a
violent horizontal or rotary vibration, or motion, also repeated at
frequent intervals, called a _terremoto_, which is caused by a
fracture or displacement of the earth's strata at some particular
point, and often results in considerable damage. When the earthquake
occurs on the coast, or beneath the sea in its vicinity, tidal waves
are sometimes formed, which cause even greater damage than the
earthquake itself. Arica has been three times destroyed by tidal
waves, and other small towns of the north Chilean coast have suffered
similar disasters. Coquimbo was swept by a tidal wave in 1849, and
Concepcion and Talcahuano were similarly destroyed in 1835. The great
earthquake which partially destroyed Valparaiso in 1906, however, was
not followed by a tidal wave. These violent shocks are usually limited
to comparatively small districts, though the vibrations may be felt at
long distances from the centre of disturbance. In this respect Chile
may be divided into at least four great earthquake areas, two in the
desert region, the third enclosing Valparaiso, and the fourth
extending from Concepcion to Chiloe. A study of Chilean earthquake
phenomena, however, would probably lead to a division