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Earth’s History Earth’s history began with the formation of solar system. It underwent evolutionary processes that can be described in geologic time. How do scientists determine the geologic time? Concept Map Analysis  Earth...

Earth’s History Earth’s history began with the formation of solar system. It underwent evolutionary processes that can be described in geologic time. How do scientists determine the geologic time? Concept Map Analysis  Earth Evolutionary process Relative dating Evidence/Information Geologic time scale Absolute dating Units Rocks Fossils eon era period epoch What are the four major units or divisions of geologic time scale? eon era period epoch What are the two evidences/information as bases for geologic time scale rocks fossils  WHAT WAS THE EARTH LIKE MILLION OF YEARS AGO? covered with thick blanket of ice lots of volcanoes and high mountains large organisms roamed the land the atmosphere did not have high oxygen content asteroids/ meteors frequently hit the surface the lands moved a lot or the continents were a little closer to each other volcanic eruptions a little bit warmer plants were bigger humans were not yet around.  WHAT IS THE AGE OF THE EARTH? 4.6 Billion Years Geologists reconstruct the sequence of events from the study of Petrology, Stratigraphy and Paleontology. Petrology is a branch of geology that deals with the origin, composition, structure, and classification of rocks. Stratigraphy is the study of rock layers (strata) and layering (stratifications). Paleontology studies the life that existed prior to, or sometimes at the start of, the Holocene epoch (the current geologic epoch). It includes the study of fossils to determine how they have evolved and interacted with the environment. Scientists measure geologic time using two methods: relative and absolute dating.  RELATIVE DATING & ABSOLUTE DATING RELATIVE DATING Relative dating places events or rocks in their chronological sequence or order of occurrence without knowing their actual age. – Principle of Original Horizontality – Principle of Superposition – Principle of Cross-cutting Relationships – Principle of Inclusions RELATIVE DATING ABSOLUTE DATING Absolute dating places actual ages of rocks and events. The method used in absolute dating technique is based on the decay rate of certain radioactive isotopes within the fossils, rocks, and artifacts.  Based on information gathered from the study of rocks’ composition and structure, rock layers, and fossils, geologists developed the geologic time scale. It represents the interval time occupied by the geologic history of earth. It provides a meaningful time frame within events of the geologic past are arranged. The history of earth is broken up into a hierarchical set of divisions for describing geologic time and these are eon, era, period, epoch. video Geologic Time Scale -Serves as the calendar for events in Earth’s History. - Standard timeline used to describe the age of rocks, fossils and the events that formed them. -divided into a series of time intervals according to significant events in the earth’s history such as mass extinction.  THE HISTORY OF LIFE AS DESCRIBED IN THE GEOLOGICAL TIME SCALE IS DIVIDED INTO: EONS ERA PERIODS EPOCH GEOLOGIC TIME SCALE Pre-Cambrian Supereon HADEAN EON ARCHEAN EON PROTEROZOIC EON HADEAN EON  SIGNIFICANT EVENTS IN THE HADEAN EON(4600mya): (beginning of the earth) earth’s surface was continually bombarded by meteorites and very hot mantle caused by severe volcanism. the solar system was forming within a cloud of dust and gas known as the solar nebula, which eventually spawned asteroids, comets, moons and planets. Astrogeophysicists theorize that about 4.52 billion years ago the proto-Earth collided with a Mars-size planetoid named Theia. ARCHEAN EON  SIGNIFICANT EVENTS IN THE ARCHEAN EON(3800mya): Earth had cooled enough Photosynthesizing cyanobacteria appear Active volcanism added gas and water vapor to the atmosphere Earth’s temperature continue to decrease. Appearance of Prokaryotes Cyanobacteria STROMATOLITES PROTEROZOIC EON  SIGNIFICANT EVENTS IN THE PROTEROZOIC EON(2500mya): Prokaryotes grew in abundance First soft-bodied animals appear Mass extinction of anaerobic organisms Formation of ozone layer Eukaryotes appeared Cyanobacteria absorbed significant quantities of CO2  PHANEROZOIC EON -(the visible life and current geologic eon) ,evidence of fossilized hard body parts of modern living things PALEOZOIC ERA MESOZOIC ERA CENOZOIC ERA PALEOZOIC ERA (the era of ancient life) Periods of Paleozoic Era Cambrian Period (570-505mya) -Marine-shelled invertebrates -First organism to be classed as true animals appeared (Ex. Trilobites, jelly fish, and the first fishes). -First fungi appear Ordovician Period(505-438mya) -Age of Invertebrates -Appearance of the first vertebrates. They came in the form of fish without jaws. Jawless Fish Silurian Period(438-408mya) -First land plants appear -Appearance of vascular plants. Devonian Period(408-360mya) -age of fishes -Rapid and diversification of fishes (jawless evolved into with jaws). -First insects appear -First amphibian appear -Late Devonian Extinction (70% of all species wiped out) Carboniferous Period(360-286mya) -(the age of amphibians, first seed plants appeared) -First reptiles appear -First large cartilaginous fishes appear - Vast forest ecosystem -Highest oxygenated state -Carboniferous Rainforest Collapse Permian Period(286-245mya) -Pangaea forms - (origin of conifers) - Permian-Triassic extinction event -Age of Land Vertebrates MESOZOIC ERA (age of dinosaurs, reptiles & gymnosperm) Periods of Mesozoic Era  PERIODS SIGNIFICANT EVENTS MESOZOIC ERA Triassic Period ⮚ Archosaurs (reptiles comprising the dinosaurs, pterosaurs and crocodilians) and Therapsids (mammal-like reptiles) began to repopulate. ⮚ Dinosaurs and pseudosuchian (crocodilian-like archosaurs) became dominant land animals. Jurassic Period ⮚ Pangaea separated into Laurasia and Gondwana ⮚ Sauropods (infraorder of large, four-legged, herbivorous dinosaurs) appeared. ⮚ Appearance of crocodiles, birds and mammals. ⮚ Birth of gymnosperms (cone bearing plants). Cretaceous ⮚ Continents continue to drift apart Period ⮚ Marine predators dominate the sea. ⮚ Angiosperms appeared (fruit or flower bearing plants). Triassic Period - First Dinosaurs - Pangaea cracks -First mammals appear -Reptiles are dominant Jurassic Period -(the age of dinosaurs and reptiles, dominance of gymnosperms) -First bird appear -Pangaea splits into Laurasia, Gondwanna -Dinosaurs are dominant Cretaceous Period (144-65.5mya) -Extinction of Dinosaurs - Earth looks closer to present-day - Flowering plants appear CENOZOIC ERA(age of mammals & angiosperm)  CENOZOIC ERA (65.5mya to present) TERTIARY PERIOD QUATERNARYPERIOD TERTIARY PERIOD (65.5-1.6mya) PALEOCENE EPOCH (65.5-57.8mya) – First large mammals appear – First Primates – Formation of present-day continents – Rise of angiosperms EOCENE EPOCH (57.8-36.6mya) – Primitive horse – Decreasing global temperature – Rise of grasslands – North and South American continents conjoined – Appearance of early humans  OLIGOCENE EPOCH (36.6-23.7mya) – Mammals are dominant – Apes and elephants MIOCENE EPOCH (23.7-5.3mya) – Grass becomes widespread/abundant. PILOCENE EPOCH (5.3-1.6mya) - Hominids (human ancestors appear) - Terrestrial mammals  QUATERNARY PERIOD Earth’s climate entered an ice age Fluctuations in climate conditions (quaternary extinction event) Interglacial period begins Homo sapiens evolved (rise of modern humans) PLEISTOCENE EPOCH (1.6-0.01mya) - Great ice age - Fauna animals - Earliest Humans appear HOLOCENE EPOCH (0.01mya-present) - Ice age ends - Humans are dominant - The age of Man -Current geological epoch Anthropocene Epoch The Anthropocene Epoch is an unofficial unit of geologic time, used to describe the most recent period in Earth’s history when human activity started to have a significant impact on the planet’s climate and ecosystems.