absolutely covered with shells. Close to Conchalee, a gravel-plain is
fronted by a lower and similar plain about sixty feet in height, and this
again is separated from the beach by a wide tract of low land: the surfaces
of all three plains or terraces were strewed with vast numbers of the
Concholepas, Mesodesma, an existing Venus, and other still existing
littoral shells. The two upper terraces closely resemble in miniature the
plains of Patagonia; and like them are furrowed by dry, flat-bottomed,
winding valleys. Northward of this place I turned inward; and therefore
found no more shells: but the valleys of Chuapa, Illapel, and Limari, are
bounded by gravel-capped plains, often including a lower terrace within.
These plains send bay-like arms between and into the surrounding hills; and
they are continuously united with other extensive gravel-capped plains,
separating the coast mountain-ranges from the Cordillera.

COQUIMBO.

A narrow fringe-like plain, gently inclined towards the sea, here extends
for eleven miles along the coast, with arms stretching up between the
coast-mountains, and likewise up the valley of Coquimbo: at its southern
extremity it is directly connected with the plain of Limari, out of which
hills abruptly rise like islets, and other hills project like headlands on
a coast. The surface of the fringe-like plain appears level, but differs
insensibly in height, and greatly in composition, in different parts.

At the mouth of the valley of Coquimbo, the surface consists wholly of
gravel, and stands from 300 to 350 feet above the level of the sea, being
about one hundred feet higher than in other parts. In these other and lower
parts the superficial beds consist of calcareous matter, and rest on
ancient tertiary deposits hereafter to be described. The uppermost
calcareous layer is cream-coloured, compact, smooth-fractured, sub-