Chapter 13 Geologic Time – Flashcards
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The division of Earth's history into smaller units makes up the _______ _____ _______.
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Geologic time scale
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Geologic time is divided into subdivision:
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eras, periods, and epoch.
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major subdivisions of the geologic time scale based on differences in life-forms.
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Eras
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1- Paleozoic = ancient life 2- Cenozoic = recent life 3- Mesozoic = End is marked when the dinosaurs pass away.
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3 Major Eras:
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subdivisions of eras.
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Periods
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smaller units of periods.
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Epochs
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1. Help describe Earth's past environments 2. To interpret how dead organisms lived 3. To document changes in organisms through time.
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Why do Geologists study fossils?
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organism that lived hundreds of millions of years ago.
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Trilobites
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is a process that causes changes in environments on Earth.
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Plate tectonics
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the longest geologic time unit of Earth's history.
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Precambrian time
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are buried deep inside Earth and are changed by heat and pressure.
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Precambrian rocks
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the earliest forms of life on Earth, contained chlorophyll and as they photosynthesized they gave off oxygen.
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Cyanobacteria
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1. When Cyanobacteria photosynthesized, they produced oxygen. 2. Oxygen became a major gas in Earth's atmosphere. 3. The ozone layer began to develop, shielding Earth from ultraviolent rays. 4. These major changes in the air allowed species of single-celled organisms to evolve into more complex organisms.
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Why are Cyanobacteria important to Earth's Evolution?
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is marked by the presence of the first organism with hard parts and easily preserved.
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Paleozoic Area
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Warm shallow seas covered much of Earth's surface during only Paleozoic time and most of the life-forms were ____.
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marine
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The _____________ marks the appearance of marine animals with hard parts or skeletons.
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Cambrian period
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The first vertebrates developed during the ____________.
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Ordovician period
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live on land and breathe air but must return to water to reproduce.
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Amphibians
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do not return to water to reproduce.
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Reptiles
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Reptiles have skin ______________________________________.
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with hard scales that prevent loss of body fluids.
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The _______ came about during the Mesozoic era.
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dinosaurs
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began about 245,000,000 years ago and all the continents were joined together.
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Mesozoic era
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single large land mass made up of all the continents.
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Pangaea
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Dinosaurs were reptiles, however, __________________________.
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recent findings suggest they were much faster than most reptiles.
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Due to their bone structure, dinosaurs were believe to be ____________________.
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warm-blooded
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Scientists have concluded that _____ evolved from dinosaurs.
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birds
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a dinosaur with wings and feathers like a bird.
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Archaeopteryx
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stones swallowed to aide in suggestions.
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Gastoliths
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flowering plants that produce seeds inside a fruit.
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Angiosperms
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Common angiosperms are ____.
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magnolias and willows
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began 65,000,000 years ago when dinosaurs passed away.
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Cenozoic era
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During the Cenozoic era, the climate became cooler and...
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ice ages occurred.
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The Alps formed when _____.
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the African plate collided with the Eurasian plate.
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The Himalayas started to form when _______.
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the Indo-Australian plate collided with the Eurasian plate.
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Fossil evidence shows that ancestors of the present-day whales and dolphins...
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once lived on land.
