GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA
GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA
Although in some respects more technical in their subjects and style than
Darwin's "Journal" the books here reprinted will never lose their value
and interest for the originality of the observations they contain. Many
parts of them are admirably adapted for giving an insight into problems
regarding the structure and changes of the earth's surface and in fact
they form a charming introduction to physical geology and physiography in
their application to special domains. The books themselves cannot be
obtained for many times the price of the present volume and both the
general reader who desires to know more of Darwin's work and the student
of geology who naturally wishes to know how a master mind reasoned on most
important geological subjects will be glad of the opportunity of
possessing them in a convenient and cheap form.
The three introductions which my friend Professor Judd has kindly
furnished give critical and historical information which makes this
edition of special value.
PLATE I. GEOLOGICAL SECTIONS THROUGH THE CORDILLERAS.
SECTION 1/1. SECTION OF THE PEUQUENES OR PORTILLO PASS OF THE CORDILLERA.
SECTION 1/2. SECTION OF THE CUMBRE OR USPALLATA PASS.
SECTION 1/3. SECTION OF THE VALLEY OF COPIAPO TO THE BASE OF THE MAIN
PLATE II. MAP OF SOUTHERN PORTION OF SOUTH AMERICA.
TABLE OF CONTENTS.
CHAPTER I.--ON THE ELEVATION OF THE EASTERN COAST OF SOUTH AMERICA.
Upraised shells of La Plata.--Bahia Blanca Sand-dunes and Pumice-pebbles.-
-Step-formed plains of Patagonia with upraised shells.--Terrace-bounded
valley of Santa Cruz formerly a sea-strait.--Upraised shells of Tierra del
Fuego.--Length and breadth of the elevated area.--Equability of the
movements as shown by the similar heights of the plains.--Slowness of the
elevatory process.--Mode of formation of the step-formed plains.--Summary.-
-Great shingle formation of Patagonia; its extent origin and
distribution.--Formation of sea-cliffs.
CHAPTER II.--ON THE ELEVATION OF THE WESTERN COAST OF SOUTH AMERICA.
Chonos Archipelago.--Chiloe recent and gradual elevation of traditions of
the inhabitants on this subject.--Concepcion earthquake and elevation of.-
-VALPARAISO great elevation of upraised shells earth or marine origin
gradual rise of the land within the historical period.--COQUIMBO elevation
of in recent times; terraces of marine origin their inclination their
escarpments not horizontal.--Guasco gravel terraces of.--Copiapo.--PERU.--
Upraised shells of Cobija Iquique and Arica.--Lima shell-beds and sea-
beach on San Lorenzo.--Human remains fossil earthenware earthquake
debacle recent subsidence.--On the decay of upraised shells.--General
CHAPTER III.--ON THE PLAINS AND VALLEYS OF CHILE:--SALIFEROUS SUPERFICIAL
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
Pampean formation.--Localities in Pampas at which mammiferous remains have
CHAPTER V.--ON THE OLDER TERTIARY FORMATIONS OF PATAGONIA AND CHILE.
Rio Negro.--S. Josef.--Port Desire white pumiceous mudstone with
infusoria.--Port S. Julian.--Santa Cruz basaltic lava of.--P. Gallegos.--
Eastern Tierra del Fuego; leaves of extinct beech-trees.--Summary on the
Patagonian tertiary formations.--Tertiary formations of the Western Coast.-
-Chonos and Chiloe groups volcanic rocks of.--Concepcion.--Navidad.--
Coquimbo.--Summary.--Age of the tertiary formations.--Lines of elevation.--
Silicified wood.--Comparative ranges of the extinct and living mollusca on
the West Coast of S. America.--Climate of the tertiary period.--On the