EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E
Our Earth: Its Climate, History, and Processes
David Schultz, University of Manchester
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C O U R S E L E C T U R E Measuring Geologic Time Notes taken on June 19, 2015 by Edward Tanguay |
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history of the Earth
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events in billions of years ago
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4.57 Earth's formation (Hadean Eon)
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3.8 first evidence of oceans (Archaen Eon)
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2.5 oxygen-rich atmosphere (Proterozoic Eon)
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0.542 explosion of fossils (Phanerozoic Eon)
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0.065 dinosaurs go extinct (Phanerozoic Eon - Cenozoic Era)
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0.0002 first hominids
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0.000022 maximum extent of last Ice Age
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classification scheme for geological time, from largest to smallest
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speak in these terms since these dates are rough estimates based on various ways of determining how long ego events occurred
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eons
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eras
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periods or systems
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epochs or series
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stages
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abbreviations
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Ma (mega annum)
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million years
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Ga (giga annum)
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billion years
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four eons
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PRECAMBRIAN supereon:
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[1] Hadean Eon - 4570 Ma
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named after Hades, or the under world
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formation of Earth and Moon
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molten earth surface
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formation of earliest crust
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[2] Archaen Eon - 3800 Ma
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[ar-KEE-an]
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oceans formed
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single-celled animals
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geologic record documents these single-celled fossils their structures they left behind called surmatelites
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process of plate tectonics was just beginning
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low oxygen concentration in air
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[3] Proterozoic Eon - 2500 Ma
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increasing oxygen concentration in the atmosphere
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periods of glaciations including a period in which the Earth may have been entirely covered in ice
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multicellular life began evolving
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Ediacaran Period (635-542 Ma)
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first multicellular life
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first appearance worldwide of somewhat complicated trace fossils
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[4] Phanerozoic Eon - 542 Ma
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increasing complexity of multicellular life
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the colonization of life from the ocean onto the land of plants and animals
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the eon in which complex life began to flourish
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but also with periodic extinction events that almost ended life on earth
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1. Paleozoic Era (542,000,000 - 251,000,000)
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Cambrian Period - 542 Ma
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rapid diversification of lifeforms known as the Cambrian explosion
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produced first representatives of all modern animal phyla
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high proportion of lagerstätte sedimentary deposits with exceptional preservation
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where "soft" parts of organisms are preserved as well as their more resistant shells
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therefore we understand Cambrian biology better than some later periods
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Ordovician Period - 485 Ma
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life continued to flourish
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end of period marked by a significant mass extinction
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invertebrates, namely molluscs and arthropods, dominated oceans
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fish, the world's first true vertebrates, continued to evolve, first jawed fish
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land life had yet to diversify
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Silurian Period - 444 Ma
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diversification of jawed and bony fish
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life also began to appear on land in the form of small, moss-like, vascular plants which grew beside lakes, streams, and coastlines
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small terrestrial arthropods (insects, spiders)
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but terrestrial life would not greatly diversify and affect the landscape until the Devonian
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Devonian Period - 419 Ma
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free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents
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fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish"
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Carboniferous Period - 358 Ma
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terrestrial life was well established
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amphibians were the dominant land vertebrates
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one branch would eventually evolve into reptiles
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Permian Period - 298 Ma
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the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs
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2. Mesozoic Era - 250 Ma
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Triassic Period - 250 Ma
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began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished
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it took into the middle of the period for life to recover its former diversity
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the first true mammals
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Jurassic Period - 200 Ma
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land dominated by dinosaurs
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supercontinent Pangaea had begun rifting into two landmasses
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created more coastlines and shifted the continental climate from dry to humid
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many of the arid deserts of the Triassic were replaced by lush rainforests
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first birds and earliest lizards
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Cretaceous Period - 145 Ma
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oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists
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dinosaurs continued to dominate on land
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new groups of mammals and birds, as well as flowering plants, appeared
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ended with a large mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs and large marine reptiles, died out
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3. Cenozoic Era (65,000,000 - today)
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Paleogene Period - 65 Ma
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Paleocene Epoch - 65 Ma
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brackets two major events in Earth's history: (1) the demise of non-avian dinosaurs, giant marine reptiles and much other fauna and flora, and (2) the Paleocene–Eocene Thermal Maximum, a geologically brief interval characterized by extreme changes in climate and carbon cycling
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Eocene - 56 Ma
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includes the warmest climate in the Cenozoic Era when little or no ice was present on the planet, but ends in an much colder climate
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ended in a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event
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Oligocene - 33 Ma
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an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene
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Neogene Period - 23 Ma
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Miocene - 23 Ma
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cooled in a series of ice ages
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apes arose and diversified becoming widespread in the Old World
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ancestors of humans split away from the ancestors of the chimpanzees
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Pliocene - 5.3 Ma
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cooled down from the Miocene temperatures
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Quaternary Period - 2.5 Ma
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Pleistocene - 2.5 Ma
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recent period of repeated glaciations
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Holocene (11,700 - 1800)
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current warm period
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(proposed) Anthropocene (1800 - present)
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epoch in which humans are affecting the climate
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mnemonic for eons and eras of geological time containing life forms on Earth
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Proterozoic Eon
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(E)VERY - Ediacran Period - 635 Ma - single-celled organisms
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Phanerozoic Eon
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Paleozoic Era - (FISH) - 542 Ma
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(C)AMEL - Cambrian Period - 542 Ma - multicelled diversity explosion
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(O)FTEN - Ordovician Period - 485 Ma - diversified ocean life
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(S)ITS - Silurian Period - 444 Ma - early jawed and boned fish
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(D)OWN - Devonian Period - 419 Ma - the age of fish
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(C)AREFULLY - Carboniferous Period - 358 Ma - dominant amphibians
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(P)ERHAPS - Permian Period - 298 Ma - mammal ancestral groups
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Mesozoic Era - (DINOSAURS) - 250 Ma
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(T)HEIR - Triassic Period - 250 Ma - extinction and recovery, therapsids and first mammals
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(J)OINTS - Jurassic Period - 200 Ma - age of reptiles, first birds
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(C)REAK - Cretaceous Period - 145 Ma - new mammals, ended with dinosaur extinction
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Cenozoic Era - (MAMMALS) - 65 Ma
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Paleogene Period - 65 Ma
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(P)ERHAPS - Paleocene Epoch - 65 Ma - dinosaurs gone, changes in climate
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(E)FFECTIVE - Eocene Epoch - 56 Ma - warmest, no ice on planet
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(O)ILING - Oligocene Epoch - 33 Ma - transition from tropical to modern ecosystems
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Neogene Period - 23 Ma
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(M)IGHT - Miocene Epoch - 23 Ma - humans and chimpanzees split
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(P)ROLONG - Pliocene Epoch - 5 Ma - climate cooled
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Quaternary Period
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(P)ERFECT - Pleistocene Epoch - 2 Ma - repeated glaciations, humans evolved into present form
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(H)EALTH - Holocene (11,700 - ca. 1800) - current warm period, major human civilizations
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(A)GAIN - (proposed) Anthropocene (ca. 1880) - humans altering the climate