Earth's History and dating of the Earth
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
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1. The geologic species scale has units based on changes in rocks and fossils. _____________
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2. If all Earth’s history took place in one year starting on January 1, humans would have appeared in March.
_____________
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3. If a very large asteroid impacts Earth, the dust and debris thrown into the atmosphere will act like a blanket
and trap the heat from the Sun, causing global warming. _____________
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. Geologic time is divided into units based upon types of _____.
a. sedimentary rocks
c. organisms
b. climatic changes
d. igneous rocks
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2. The longest subdivision in geologic time is a(n) _____.
a. epoch
c. century
b. period
d. eon
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3. A life-form in the Precambrian time was _____.
a. cyanobacteria
c. reptiles
b. humans
d. dinosaurs
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4. A life-form that evolved during the _____ Era was the dinosaur.
a. Cenozoic
c. Precambrian
b. Mesozoic
d. none of the above
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5. Little is known about much of Earth’s early history because _____.
a. Precambrian rocks have been deeply buried
b. Precambrian rocks have been changed by heat and pressure
c. Precambrian soft-bodied life-forms weren’t often preserved as fossils
d. all of the above
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6. The division of Earth’s history into smaller units makes up the _____.
a. eras
c. periods
b. geologic time scale
d. sequence of events
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7. Humans first appeared during the _____ Era.
a. Precambrian
b. Paleozoic
c. Mesozoic
d. Cenozoic
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8. Geologists organized the geologic time scale based on _____.
a. superposition
c. fossils in the rock layers
b. evenly spaced time segments
d. both a and c
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9. The divisions on the geologic time scale are most like which of the following?
a.
b.
c.
d.
a calendar with evenly divided weeks
sand pouring steadily through an hourglass
marking your life by the major events
marking your life by years
____ 10. Imagine all of Earth’s history taking place within 1 year, starting January 1. When did humans appear?
a. January 1
c. November 20
b. February 10
d. December 31
Completion
Complete each statement.
1. Radioactive elements decay at a _______________ rate.
2. As you move from left to right on the chart, each circle shows _______________ as many parent atoms as the
circle preceding it.
3. The geologic time scale is always drawn vertically with the _______________ rocks at the bottom.