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WorksheetsThe Geologic Time Scale
Total questions: 21
Worksheet time: 1hrs 21mins
The entire history of the Earth can be divided into the Precambrian (ancient) Eon and the Phanerozoic (current) Eon. Which of the following correctly represents the percent of Earth's history occupied by each?
88% Precambrian, 12% Phanerozoic
12% Precambrian, 88% Phanerozoic
81% Precambrian, 19% Phanerozoic
19% Precambrian, 81% Phanerozoic
Which of the following events occurred in the first 30 million years of the Earth life?
rapid separation of internal compositional layers of mantle and core
development of land animals
formation of an oxygen-nitrogen atmosphere
human accentuation of climate change
Which of the following best describes Earth’s very first atmosphere?
helium and hydrogen gases left over from the formation of the planet
carbon dioxide and water vapor from volcanic outgassing
a 78%-21% nitrogen and oxygen gas mixture
methane and ammonia gases from Earth's interior
All life on Earth is:
cellular.
bacterial.
aerobic.
photosynthetic.
Earth’s most primitive life forms are represented by:
prokaryotic cells.
plants.
fungi.
tube worms.
Earth's current atmosphere is composed mostly of nitrogen gas. Where did all of this nitrogen come from?
from the breakdown of the ammonia in the early atmosphere
from outer space via comets and asteroid
directly from the Earth's outer core
from the photosynthesis of early bacteria
What was the result of early bacterial life in the ocean starting to consume carbon dioxide and produce oxygen by photosynthesis?
None of this oxygen made it to the early atmosphere which was dominated by nitrogen and carbon dioxide.
This oxygen went on to build up to 21% in our current atmosphere.
This oxygen bonded with leftover hydrogen gas to produce Earth's first water.
This oxygen was lost into space because it is such a light gas.
Which of the following was the major importance of the dissolved iron in the ocean being used up?
As the iron was depleted, free oxygen become available to be added to the atmosphere.
As the iron was depleted, rocks on the land masses began to rust.
As the iron was depleted, the atmosphere began to fill up with carbon dioxide gas.
As the iron was depleted, the oceans transitioned from freshwater to saltwater.
What occurred to provide extensive evidence in the rock record around 700 million years ago?
a glaciation event (ice age)
a meteoroid impact
collision with a dwarf planet
global warming of the planet
Which of the following IS NOT one of the reasons for significant climatic contrasts between 700 million and 600 million years ago?
the last great ice age
changes to the output of the Sun
fluctuations in the carbon dioxide concentrations of the atmosphere
changes in ocean circulation
When did fossils become much more abundant in rocks, and what is the importance of this increase in fossils?
Fossils became much more abundant in the last 542 million years of geologic time. The presence of fossils allows geologists to further subdivide the eon into three shorter eras.
Fossils became much more abundant when the Earth was about 30 million years old. At this point the Earth was solidified into rocks that could contain the fossils.
Fossils became much more abundant during the breakup of Pangaea, which began about 200 million years ago. After this, Earth scientists could study fossils across oceans.
Fossils became much more abundant after the dinosaurs became extinct, because more animals lived to create fossils.
What is the leading cause of mass extinctions of life on Earth?
Mass extinctions are most commonly caused by a dramatic change in some part of the earth system that affects key populations of organisms.
Mass extinctions are most commonly by the shock wave from the collision of a comet or meteoroid with the Earth.
Mass extinctions are most commonly by radiation poisoning from the Sun's solar winds.
Mass extinctions are most commonly by floods that cover all of the land masses on the planet.
In our study of the Geologic Time Scale, how many Eons have we considered there to have been?
two
three
four
five
Anything that occurred here on Earth more than 542 million years ago occurred during which Eon?
the Precambrian
the Phanerozoic
the Proterozoic
the Jurassic
Which segment of time is the smallest?
Eon
Era
Period
Epoch
How many million years ago was the origin of the Earth and solar system?
1600
2600
3600
4600
Two geology student are working on a lab concerning the Geologic Time Scale. The are asked to draw a line on their tape to indicate an event that occurred 299 million ago. They are using a scale of 1mm = 4 million years. Which of the following best describes where on their tape this line will be drawn? Round your answer to the nearest mm.
75 mm back from the present day end of the tape
75 mm forward from the formation of Earth end of the tape
299 mm back from the present day end of the tape
299 mm forward from the formation of Earth end of the tape
