THE ANDES: A GEOLOGICAL OVERVIEW FROM A BIOLOGICAL PERSPECTIVE

Geological events of biological importance in the history of the Andes include their impact oil global eliminates through an influence oil atmospheric circulation, rainfall patterns, and the atmospheric concentration of CO2; habitat diversification from lowlands through paramo to glaciated peaks; and migratory pathways ranging front discontinuous (mesic elements), highly discontinuous (paramo elements), barriers (to cast-west migrations), to selective pathways (via the (In, Andean valleys). The timing of these effects is a function of the Uplift history of three (to nine) morphotectonic segments of the Andes resulting in (1) mostly lowalnd swamp and fluvial environment., in the, Cretaceous and Paleocene, (2) Moderate Uplands beginning in flit, Late Eocene (ca. 40 million years ago [Ma]), (3) appression of art offshore volcanic chain (the proto-Cordillera Occidental) in the Oligocene (ca, 30 Ma), (4) uplift of the proto-Cordillera Oriental and the Altiplano to about half their present altitude by the Middle Miocene (ca. 15 Ma). and (5) uplift of the remaining half within approximately the past 10 million years. The early appearance of a biological community recognizable as the Atacama Desert is estimated at ca. 15 Ma, and the beginnings of a paramo at ca. 3.5 Ma. Longer-term (Milankovitch) and shorter-term (Younger Dryas, Medieval warm/dry period, Little Ice Age, Heinrich, and Dansgaard-Oeschger [D-O]) climatic events, known initially front the high latitudes, are now widely recognized throughout Latin America, including the Andes. They document if dynamic physical environment from the Cretaceous through the Holocene and off till timescales.