Geological Observations On South America

Excerpt-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 causes of the absence of recent conchiferous deposits on the coasts of South America.--On the contemporaneous deposition and preservation of sedimentary formations.