Probably from deep dark submarine hot water vents black smokers Thermophilic

Probably from deep dark submarine hot water vents

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- Probably from deep, dark submarine hot-water vents - “black smokers” - Thermophilic (heat-loving) bacteria or prokaryote archaea can exist in extreme conditions - Archean strata contain stromatolites: - The first large fossil structure - layered mounds of sediment - Still exist, growing today near Australia - Alternating layers of cyanobacteria and sediment settling from water - First appear 3.5 Ga The Proterozoic Eon - Proterozoic = early life - Around 2.5 Ga to 542 Ma - Several rounds of supercontinent assembly and rifting - 90% of continental crust formed by middle Proterozoic - Growth of continental crust - cratons: - Cold, stable, interior regions of continental crust - All of today’s cratons formed by 1 Ga - Consist of distinct orogens, blocks, and terrains - Parts of a craton - Shield - Platform - Basement - Atmospheric oxygen rose dramatically after the appearance of photosynthetic organisms 2.4 Ga - Great oxygenation event - 2.4-1.8 Ga: Banded Iron Formations (BIF)
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- Life forms evolved slowly - Eukaryotes (bacteria with nuclei) evolved 2.7-2.1 Ga - Multicellular life forms appeared by 750 Ma - Large life forms leaving obviously recognizable fossils evolved 620 Ma - Ediacaran fauna appeared in the late Proterozoic - Complex, soft-bodied forms - Resembled jellyfish, worms The Proterozoic Snowball Earth - Major climate shifts in late Proterozoic - Glaciers covered continents, ocean surface frozen - Many life forms probably became extinct as ocean chemistry and photochemistry changed due to ice cover - CO 2 from volcanoes warmed Earth, ended major ice age The Phanerozoic Eon - Phanerozoic = visible life - From 542 Ma to present - Defined by widespread, diverse life forms - Carbonate shells, skeletal material enhance preservation - Divided into three eras: - The Paleozoic Era: 542-252 Ma - The Mesozoic Era: 251-65 Ma - The Cenozoic Era: 65 Ma to present The early Paleozoic - Biological diversification of life shortly after 542 Ma - Cambrian explosion - rapid diversification of life forms - Did breakup of Pannotia into separate land masses open new ecological niches and stimulate evolution? - Paleozoic life forms included conodonts, trilobites, brachiopods, nautiloids, gastropods, graptolites, crinoids, echinoderms, jawless fishes - Mass-extinction event at the end of Ordovician - Driven by glaciation and sea-level lowering? The Middle Paleozoic - Silurian “greenhouse” - Sea levels rose, climate warmed, continents flooded - Vast reef complexes in shallow epicontinental seas - New marine species evolved in the early Silurian - Acadian orogeny uplifts early Appalachian Mountains The Middle Paleozoic: Life Arrive on Land - Around 420 Ma: life emerges from the sea, adapts to living and reproducing on land - First amphibians in Late Devonian: Tiktaalik fossil
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- Crustaceans, spiders, scorpions, insects evolved -
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  • Fall '09
  • Geological history of Earth

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