CHAPTER III.--ON THE PLAINS AND VALLEYS OF CHILE:--SALIFEROUS SUPERFICIAL
DEPOSITS.

Basin-like plains of Chile; their drainage, their marine origin.--Marks of
sea-action on the eastern flanks of the Cordillera.--Sloping terrace-like
fringes of stratified shingle within the valleys of the Cordillera; their
marine origin.--Boulders in the valley of Cachapual.--Horizontal elevation
of the Cordillera.--Formation of valleys.--Boulders moved by earthquake-
waves.--Saline superficial deposits.--Bed of nitrate of soda at Iquique.--
Saline incrustations.--Salt-lakes of La Plata and Patagonia; purity of the
salt; its origin.


CHAPTER IV.--ON THE FORMATIONS OF THE PAMPAS.

Mineralogical constitution.--Microscopical structure.--Buenos Ayres, shells
embedded in tosca-rock.--Buenos Ayres to the Colorado.--S. Ventana.--Bahia
Blanca; M. Hermoso, bones and infusoria of; P. Alta, shells, bones, and
infusoria of; co-existence of the recent shells and extinct mammifers.--
Buenos Ayres to St. Fe.--Skeletons of Mastodon.--Infusoria.--Inferior
marine tertiary strata, their age.--Horse's tooth. BANDA ORIENTAL.--
Superficial Pampean formation.--Inferior tertiary strata, variation of,
connected with volcanic action; Macrauchenia Patachonica at S. Julian in
Patagonia, age of, subsequent to living mollusca and to the erratic block
period. SUMMARY.--Area of Pampean formation.--Theories of origin.--Source
of sediment.--Estuary origin.--Contemporaneous with existing mollusca.--
Relations to underlying tertiary strata. Ancient deposit of estuary
origin.--Elevation and successive deposition of the Pampean formation.--
Number and state of the remains of mammifers; their habitation, food,
extinction, and range.--Conclusion.--Supplement on the thickness of the