Earth's Formation

How old is the Earth?

• 4.5 billion years

• 1 billion years
• 2 billion years
• 3 billion years

Match the following

• Planet

• C

• Protoplanet

• A

• planetesimal

• B

Match the following

• Constant bombardment causes Earth to become molten

• Gravity causes the solar nebula to collapse

• The protosun forms at the center of the nebular disk

• Planetesimals form through accretion

• Protoplanets form

Match the following

• The Earth cools

• Chemical differentiation occurs

• Planetesimals form through accretion

• Protoplanets form

• Constant bombardment causes Earth to become molten

How did the Earth get its water?

• much of it was trapped inside the Earth as it formed and released as the Earth cooled

• much of it was delivered to Earth through the impact of comets and other icy bodies

• much of it was pulled from the moon's surface when the moon was much closer

• early cyanobacteria produced it as a by product of photosynthesis

• much of it was trapped in the form of glaciers and was released as the Earth warmed

Which 2 gases made up the majority of Earth's atmosphere when it first formed?

• carbon dioxide

• oxygen

• ozone

• water vapor

• ammonia

The waste gas released by plants as they synthesize food sugars (photosynthesis) from carbon dioxide and water is ________.

• oxygen

• methane

• nitrogen

• carbon dioxide

The graph below represents the change of two atmospheric gases over Earth's history.  Which gas does the red line represent?

• carbon dioxide

• oxygen

• nitrogen

• argon

• Ammonia

The graph below represents the change of two atmospheric gases over Earth's history.  Which gas does the blue line represent?

• carbon dioxide

• oxygen

• nitrogen

• argon

• Ammonia

In the early history of Earth, the solid surface of the earth weathered more rapidly than now because ________.

• the early rain was very acidic

• the rocks at the surface were weak because there was little oxygen available

• the atmosphere contained large amounts of corrosive methane

• there was little topography so shallow water washed across the surface often

• there were numerous earthquakes and volcanoes breaking up the surface