SpringerBriefs in Earth Sciences
2 total works
When in 1981 Louis and Walter Alvarez, the father and son team, unearthed a tell-tale Iridium-rich sedimentary horizon at the 65 million years-old Cretaceous-Tertiary boundary at Gubbio, Italy, their find heralded a paradigm shift in the study of terrestrial evolution. Since the 1980s the discovery and study of asteroid impact ejecta in the oldest well-preserved terrains of Western Australia and South Africa, by Don Lowe, Gary Byerly, Bruce Simonson, Scott Hassler, the author and others, and the documentation of new exposed and buried impact structures in several continents, have led to a resurgence of the idea of the catastrophism theory of Cuvier, previously largely supplanted by the uniformitarian theory of Hutton and Lyell. Several mass extinction of species events are known to have occurred in temporal proximity to large asteroid impacts, global volcanic eruptions and continental splitting. Likely links are observed between asteroid clusters and the 580 Ma acritarch radiation, end-Devonian extinction, end-Triassic extinction and end-Jurassic extinction. New discoveries of ~3.5 – 3.2 Ga-old impact fallout units in South Africa have led Don Lowe and Gary Byerly to propose a protracted prolongation of the Late Heavy Bombardment (~3.95-3.85 Ga) in the Earth-Moon system. Given the difficulty in identifying asteroid impact ejecta units and buried impact structures, it is likely new discoveries of impact signatures are in store, which would further profoundly alter models of terrestrial evolution.
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Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
by Andrew Y. Glikson
Unique among all creatures, further to the increase in its cranial volume from Australopithecus to Homo sapiens, the use of tools and cultural and scientific creativity, the genus Homo is distinguished by the mastery of fire, which since about two million years ago has become its blueprint. Through the Holocene and culminating in the Anthropocene, the burning of much of the terrestrial vegetation, excavation and combustion of fossil carbon from up to 420 million years-old biospheres, are leading to a global oxidation event on a geological scale, a rise in entropy in nature and the sixth mass extinction of species.