Flashcards and Answers – Science Chapter 9
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Precambrian time
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the interval of time in the geologic time scale from Earth's formation to the beginning of the Paleozoic era, from 4.6 billion to 542 million years ago. It contains the first three eons of Earth's history.
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Mass extinction
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an episode during which large numbers of species become extinct.
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Geologic time scale
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outlines the development of Earth and of life on Earth.
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Mesozoic Era
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the geologic era that lasted from 251 million to 65.5 million years ago; also called the Age of Reptiles.
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Impact hypothesis
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the explanation for the extinction of the dinosaurs.
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Paleozoic Era
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the geologic era that followed Precambrian time and that lasted from 542 million to 251 million years ago.
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Evolution
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the process of change by which new species develop from preexisting species over time.
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Cenozoic Era
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the current geologic era, which began 65.5 million years ago; also called the Age of Mammals.
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Shield
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large areas of exposed Precambrian rocks.
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Geologic column
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an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom.
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1 million years
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What does the symbol Ma stand for?
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Four
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How many eons is the geologic time broken into?
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88% of Earth's history-formation of earth to about 546 million years ago-rocks that are severely deformed and have limited amount of fossils because life-forms lacked bones,shells,or other hard parts that commonly form fossils.
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What does Precambrian time consist of?
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During the Paleozoic era during the Permian period.
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When did Pangaea form?
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Bird-hipped and lizard-hipped
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What were the two main dinosaur groups during the Jurassic Period?
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Age of Mammals
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What is the Cenozoic Era known as?
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There are barely any fossils and the rock is usually deformed.
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What is Precambrian rock difficult to interpret?
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Devonian Period
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When did the first amphibians appear?
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At the bottom
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On a geologic column, where would you find the oldest rocks?
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Radioactive or carbon dating
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How do scientists most accurately determine the absolute ages of rock layers?
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the gradual development of new organisms forming from preexisting organisms.
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What is the concept of evolution?
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at the end of the Mesozoic era
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When did dinosaurs become extinct?
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during the Devonian Period
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During which period did land plants such as ferns begin to develop?
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that the rock formed in the same area and time
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What can scientist assume about a rock layer that matches a similar layer in a geologic column?
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deformed and barely any fossils. Could have some valuable minerals in it.
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How do you describe Precambrian rock?
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they came from swamps and forests that existed during the Carboniferous Period
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Where did the coal deposits found in Pennsylvania, Ohio, and West Virginia come from?
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during the Triassic period
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When did dinosaurs first appear?
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Earth's surface changed dramatically. Pangaea broke into smaller pieces and some mountain ranges formed. Shallow seas and marshes were everywhere and the climate was like it is in Louisiana (warm and humid). These conditions were awesome for the reptiles like lizards, turtles, crocodiles, snakes, and dinosaurs.
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***Describe the conditions on Earth during the Mesozoic Era and the effect these geologic conditions had on plant and animal life.
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There are two periods which are divided into Epochs. The first period is the Tertiary period, which is divided into the following Epochs: Paleocene, Eocene, Oligocene, Miocene, and Pliocene. The second period is the Quaternary period, which is divided into the Pleistocene and Holocene epochs.
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***Name the periods and epoch into which the Cenozoic Era is divided.
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The Paleozoic Era, The Mesozoic Era and the Cenozoic Era
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***List the eras of geologic time the followed Precambrian time.
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eon,era,period,epoch,age
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List the following units of geologic time in order of relative length, from longest to shortest: age, eon, period, era, epoch.
