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
Pampean formation.—Localities in Pampas at which mammiferous remains
have been found.