Full Title: Pre-Mesozoic Ice Ages: Their Bearing on Understanding the Climate System
Authors: John C. Crowell
Ancient ice ages are revealed primarily by distinctive stratal facies that tell usmuch about times of collness and how the climate system works. Several strong ice ages were recorded in late Paleozoic time and during transitions from the Devonian into the Carboniferous and from the Ordovician into the Silurian. In Precambrian time, several are documented for both the Late and Early Proterozoic, but none in the Middle Proterozoic. The oldest occurred in mid-Archean time, nearly 3 b.y. ago. Coolness episodes correspond to tectonic plate arrangements that influenced bathymetry and land elevations, to sea-level fluctuations, to changes in fluxes of greenhouse gases, and to biogeochemical changes resulting from evolution of life forms. Orbital variations and extraterrestrial events modulate climate, and bolide impacts drastically affect it temporarily. Climate is primarily the result of rectonobiogeochemical activities rooted in the changing complex earth-air-ocean system, as described in this volume.
Published: 3/01/1999
ISBN Number: 0813711924
Pages: 112
Product Category: EBooks