Transcript Geologic Time Scale

Geologic Time Scale
Ch 18
Geologic Time Scale
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Law of superposition- youngest
is on top oldest on bottom
Geologic column- arrangement
of rock layers
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Era- A very large unit of time
Period-A division of an Era
Epoch-A division of a Period
Section 18.1 review
True
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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.
Section 18.1 review
True
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Using the law of superposition
and the study of index fossils,
nineteenth century scientists
determined the relative ages of
rock layers
False
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Eras are subdivisions of periods
Section 18.1 review
False
True
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Scientists can use the geologic
column to estimate the relative
ages of rock layers only if the
rock contains radioactive
minerals
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Fossils of mammals are
common in Cenozoic rocks
Complete the statement
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Rock layers in the geologic
column can be distinguished
from one another according to
rock type and__________
Fossil content
The geologic era that followed
Precabrian time is called the
_________
Paleozoic Era
Complete the statement
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According to the geologic
column in the diagram, the
Layer 4
oldest rock layer is__________
Based on late Precambrian
fossils and other types of
geological evidence, scientists
theorize that life began
_________
In the ocean
Last question in 18.1
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The era that is divided into
epochs is the ___________
Cenozoic Era
Theory of Evolution
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Organisms change over time.
New kinds of organisms are
derived from ancestors.
Precambrian time
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Started 4.6billion years ago
Ended 540million years ago
Characteristics of this time:
Soft-bodies or single cell
organisms, Stromatolites
 Lots of volcanoes, mountain
formation, sediment formation &
metamorphism
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Paleozoic Era
540-248 million years ago
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Periods:
Cambrian
 Ordovician
 Silurian
 Devonian
 Carboniferous
 Permian
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Paleozoic Era
540-248 million years ago
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Cambrian
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Advanced forms of marine life and
first invertebrates appear
Ordovician
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Brachiopods increase: trilobites
decline: graptolites flourish: First
vertebrates (fishes appear)
Paleozoic Era
540-248 million years ago
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Silurian
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First land plants and animals
appear
Devonian
Age of fishes
 First amphibians
 Ferns and cone bearing plants
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Paleozoic Era
540-248 million years ago
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Carboniferous
Split into two epochs:
Mississippian and Pennsylvanian
 Amphibians flourish
 Giant cockroaches
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Permian
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Pangaea comes together mass
extinctions
Mesozoic Era
248-65 million years ago
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Periods
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Triassic
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Jurassic
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First Dinosaurs, tropical weather,
Large Dinosaurs, tropical weather,
Cretaceous
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First flowering plants, mass extinction
Cenozoic Era
65 million years to today
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Periods
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Tertiary
Paleocene
 Oilgocene
 Miocene
 Pliocene
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Quaternary
Pleistocene
 Holocene
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Cenozoic Era
65 million years to today
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Periods
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Tertiary
Age of mammals
 Pangaea separates
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Quaternary
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Ice age and human’s develop
18.2 review
A desert The presence of cross-bedded
sandstone may indicate that the
region where it is present was once:
Shields are large areas of exposed
Precambrian
rock of what era?
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Advanced The fossil record indicates that which
of the following thrived during the
forms of
marine life Paleozoic Era
18.2 review
Fishes
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Triassic period
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The Devonian period is also
known as the Age of
Dinosaurs first appeared during
the
Cenozic During which era did glaciers
cover nearly one third of the
earth’s land area?
18.2 review
Pilocene During which epoch did the first
modern horses appear?
Silurian Which geologic period is
missing from this diagram?
The Paleozoic Era
Cambrian Ordovician_________Devonian
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Time
18.2 review
Stromatolites What are the most common
Precambrian fossils called?
Tertiary Which period of the Cenozoic
Era includes the time before the
last major ice age