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Geologic Time Scale Ch 18 Geologic Time Scale Law of superposition- youngest is on top oldest on bottom Law of superposition- youngest is on top oldest.

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Presentation on theme: "Geologic Time Scale Ch 18 Geologic Time Scale Law of superposition- youngest is on top oldest on bottom Law of superposition- youngest is on top oldest."— Presentation transcript:

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2 Geologic Time Scale Ch 18

3 Geologic Time Scale Law of superposition- youngest is on top oldest on bottom Law of superposition- youngest is on top oldest on bottom Geologic column- arrangement of rock layers Geologic column- arrangement of rock layers

4 Era- A very large unit of time Era- A very large unit of time Period-A division of an Era Period-A division of an Era Epoch-A division of a Period Epoch-A division of a Period

5 Section 18.1 review Scientists use events such as major changes in the earth’s surface and climate and the extinction of various species as the basis for dividing the geologic time scale into units. Scientists use events such as major changes in the earth’s surface and climate and the extinction of various species as the basis for dividing the geologic time scale into units. True

6 Section 18.1 review Using the law of superposition and the study of index fossils, nineteenth century scientists determined the relative ages of rock layers Using the law of superposition and the study of index fossils, nineteenth century scientists determined the relative ages of rock layers True False Eras are subdivisions of periods Eras are subdivisions of periods

7 Section 18.1 review False Scientists can use the geologic column to estimate the relative ages of rock layers only if the rock contains radioactive minerals Scientists can use the geologic column to estimate the relative ages of rock layers only if the rock contains radioactive minerals Fossils of mammals are common in Cenozoic rocks Fossils of mammals are common in Cenozoic rocks True

8 Complete the statement Rock layers in the geologic column can be distinguished from one another according to rock type and__________ Rock layers in the geologic column can be distinguished from one another according to rock type and__________ The geologic era that followed Precabrian time is called the _________ The geologic era that followed Precabrian time is called the _________ Fossil content Paleozoic Era

9 Complete the statement According to the geologic column in the diagram, the oldest rock layer is__________ According to the geologic column in the diagram, the oldest rock layer is__________ Based on late Precambrian fossils and other types of geological evidence, scientists theorize that life began _________ Based on late Precambrian fossils and other types of geological evidence, scientists theorize that life began _________ Layer 4 In the ocean

10 Last question in 18.1 The era that is divided into epochs is the ___________ The era that is divided into epochs is the ___________ Cenozoic Era

11 Theory of Evolution Organisms change over time. New kinds of organisms are derived from ancestors. Organisms change over time. New kinds of organisms are derived from ancestors.

12 Precambrian time Started 4.6billion years ago Started 4.6billion years ago Ended 540million years ago Ended 540million years ago Characteristics of this time: Characteristics of this time: Soft-bodies or single cell organisms, Stromatolites Soft-bodies or single cell organisms, Stromatolites Lots of volcanoes, mountain formation, sediment formation & metamorphism Lots of volcanoes, mountain formation, sediment formation & metamorphism

13 Paleozoic Era million years ago Periods: Periods: Cambrian Cambrian Ordovician Ordovician Silurian Silurian Devonian Devonian Carboniferous Carboniferous Permian Permian

14 Paleozoic Era million years ago Cambrian Cambrian Advanced forms of marine life and first invertebrates appear Advanced forms of marine life and first invertebrates appear Ordovician Ordovician Brachiopods increase: trilobites decline: graptolites flourish: First vertebrates (fishes appear) Brachiopods increase: trilobites decline: graptolites flourish: First vertebrates (fishes appear)

15 Paleozoic Era million years ago Silurian Silurian First land plants and animals appear First land plants and animals appear Devonian Devonian Age of fishes Age of fishes First amphibians First amphibians Ferns and cone bearing plants Ferns and cone bearing plants

16 Paleozoic Era million years ago Carboniferous Carboniferous Split into two epochs: Mississippian and Pennsylvanian Split into two epochs: Mississippian and Pennsylvanian Amphibians flourish Amphibians flourish Giant cockroaches Giant cockroaches Permian Permian Pangaea comes together mass extinctions Pangaea comes together mass extinctions

17 Mesozoic Era million years ago Periods Periods Triassic Triassic First Dinosaurs, tropical weather, First Dinosaurs, tropical weather, Jurassic Jurassic Large Dinosaurs, tropical weather, Large Dinosaurs, tropical weather, Cretaceous Cretaceous First flowering plants, mass extinction First flowering plants, mass extinction

18 Cenozoic Era 65 million years to today Periods Periods Tertiary Tertiary Paleocene Paleocene Oilgocene Oilgocene Miocene Miocene Pliocene Pliocene Quaternary Quaternary Pleistocene Pleistocene Holocene Holocene

19 Cenozoic Era 65 million years to today Periods Periods Tertiary Tertiary Age of mammals Age of mammals Pangaea separates Pangaea separates Quaternary Quaternary Ice age and human’s develop Ice age and human’s develop

20 18.2 review The presence of cross-bedded sandstone may indicate that the region where it is present was once: The presence of cross-bedded sandstone may indicate that the region where it is present was once: Shields are large areas of exposed rock of what era? Shields are large areas of exposed rock of what era? The fossil record indicates that which of the following thrived during the Paleozoic Era The fossil record indicates that which of the following thrived during the Paleozoic Era A desert Precambrian Advanced forms of marine life

21 18.2 review The Devonian period is also known as the Age of The Devonian period is also known as the Age of Dinosaurs first appeared during the Dinosaurs first appeared during the During which era did glaciers cover nearly one third of the earth’s land area? During which era did glaciers cover nearly one third of the earth’s land area? Fishes Triassic period Cenozic

22 18.2 review During which epoch did the first modern horses appear? During which epoch did the first modern horses appear? Which geologic period is missing from this diagram? Which geologic period is missing from this diagram? Pilocene Silurian The Paleozoic Era Cambrian  Ordovician  _________  Devonian  Time

23 18.2 review What are the most common Precambrian fossils called? What are the most common Precambrian fossils called? Which period of the Cenozoic Era includes the time before the last major ice age Which period of the Cenozoic Era includes the time before the last major ice age Stromatolites Tertiary


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