History of the Earth

UNIT 2: Earth As A

System

The structure of Earth

After the planet formed about 4.6 billion years ago, several processes released heat that kept the surface a molten pool of metals.
1.

Bombardment: The young planet was bombarded by
material from space which collided with the planet causing
the planet to heat up. This kept the surface of planet earth
molten.

2.

Accretion: the process by which material from space is
added to the planet. This added mass to the planet. The
increase in the mass of earth causes an increase in the
gravitational force of earth.

The structure of Earth

3. Differentiation: describes how
molten material changed position in the planet based on density.
Molten metals like nickel and iron sank towards the center of the earth while the less dense
materials like aluminum and
silicon rose to the planet’s surface.

Chemical composition of Earth

Earth consists primarily of six elements:

● Iron (Fe)
● Oxygen (O)
● Silicon (Si)
● Magnesium (Mg)
● Nickel (Ni)
● Sulfur (S)

Chemical composition of Earth

Early earth is made primarily of
dense liquid metals.
The liquid iron and nickel were
more dense and sank to the center while the less dense materials like silicon and aluminum rose to the
surface.
Over time, the molten materials separated into 3 layers:

Multiple Select

Which of the processes contribute to the heating up of the young planet earth? Pick 3!

• Bombardment

• Accretion

• Creation

• Differentiation

Multiple Choice

____ is the process by which material from space is added to the planet.

• Bombardment

• Accretion

• Differentiation

Multiple Choice

____describes how molten material changed position in the planet based on density.

• Bombardment

• Accretion

• Differentiation

Multiple Select

Choose the elements that earth is made up of

• Iron

• Fluorine

• Magnesium

• Zinc

• Nickel

Multiple Select

The core is made from which 2 elements?

• iron

• aluminum

• silicon

• nickel

Multiple Select

The outer parts of earth are made from which 2 elements?

• iron

• aluminum

• silicon

• nickel

Layer

Divisions

Composition

Thickness

Temperature

Distance from
surface of
earth

More info

1.Core

Inner
core

Solid mixture
of iron and
nickel.

6,400 km

5,000 to
7,000 oC

5,150 to
6,370 km
below Earth

Has a density of
13.5 g/cm3

Outer
core

Liquid mixture
of iron and
nickel

5,100 km

4,400 to
6,100 oC

2,891 to
5,150 km
below Earth

Remains liquid
due to lower
pressure than
inner core

2. Mantle

Mantle

Aluminum,
iron,
magnesium
and silica

2,900 km

870 oC

Lies 2,891 to
40 km below
Earth’s
surface

Accounts for 70%
of the volume of
Earth

Asthenosphere: upper mantle which comes in direct contact with the lithosphere.

3. Crust

-

Rock

50 km

–

Relatively thin and adds very
little to the volume of the planet.

Earth’s Composition

Draw

Draw an arrow and point to the inner core and label it A.

Draw

Draw an arrow and point to the mantle and label it B.

Draw

Draw an arrow and point to the crust and label it .

Multiple Choice

Which layer makes up 70% of the earth's volume?

• core

• crust

• mantle

Multiple Choice

Which layer of earth is LIQUID?

• Outer core

• Inner core

• Crust

• mantle

Multiple Choice

Name the layer that has a temperature of 5,000 to 7,000 degrees Celcius.

• Inner core

• Outer core

• Mantle

• core

Multiple Choice

Name the layer that is thin and adds very little to the volume of the planet

• Inner core
• Mantle

• crust

• Outer core

Earth’s Early Atmosphere

The atmosphere is made up of gasses that
surround the surface of Earth.
The earliest atmosphere was made up of primarily two gasses: hydrogen and helium.
These gasses were too light and were swept away by solar wind to outer space.
Solar wind is made up of charged particles from the surface of the sun.

Earth’s Early Atmosphere

Gasses from early atmosphere came from volcanoes and consisted mostly of gasses such as hydrogen, water vapor, carbon dioxide and hydrogen sulfide.
Early atmosphere also contained small
amounts of nitrogen, carbon monoxide
and methane.

Earth’s Second Atmosphere

About 4 billion years later, earth began to cool.
Volcanic eruptions produced gasses
such as water vapor, carbon dioxide, hydrogen sulfide and trace amounts of nitrogen, carbon monoxide, methane and ammonia.
Many of these gasses reacted with
minerals on land or dissolved in the
ocean.

Earth’s Second Atmosphere

The gasses that did not react began to accumulate and form Earth’s second atmosphere.
The ammonia released from volcanoes was broken down by the
sun.
The breakdown of ammonia increased
the amount of nitrogen in the
atmosphere.

Earth’s Third Atmosphere

Around 2.5 billion years ago, oxygen in the atmosphere increased as a result of the byproducts of photosynthesis.

Formation of Earth’s Oceans

Early earth was inhospitable due to the high temperatures.
The surface of earth was a pool of molten materials.
When Earth’s surface cooled, a thin brittle layer called the crust was formed.
Over time, early crust was melted and
reformed many times.

The Lack of Oxygen

Oxygen in the atmosphere was
released by ancient blue green
bacteria.
These organisms conducted photosynthesis which is a reaction that changes carbon dioxide and water to glucose, a simple sugar.
A byproduct of photosynthesis is oxygen gas.

Multiple Choice

What is the process by which material from space is added to the planet?

• Differentiation
• Composition
• Bombardment
• Accretion

Multiple Choice

What process describes the separation of molten materials into Earth's core, mantle, and crust?

• Accretion
• Differentiation
• Bombardment
• Composition

Multiple Choice

Which of the following elements is a primary component of Earth's composition?

• Gold
• Sulfur
• Platinum
• Mercury

Multiple Choice

Solar wind is___.

• produced gasses such as water vapor, carbon dioxide, hydrogen sulfide
• is made up of charged particles from the surface of the sun.
• is the process by which material from space is added to the planet.
• is wind from the sun

Multiple Choice

Which of the following gasses was NOT a component of Earth's early atmosphere?

• Water Vapor
• Carbon Monoxide
• Hydrogen
• Nitrogen

Multiple Choice

Which layer accounts for 70% of Earth's volume??

• Core
• Crust
• Mantle
• None of these

Multiple Choice

What is the temperature of the mantle?

• 5,000 to 7,000 oC
• 4,400 to 6,100 oC
• 870 oC
• 25 oC

Multiple Choice

Which of the following gasses was NOT a component of Earth's second atmosphere?

• Nitrogen
• Hydrogen
• Water Vapor
• Carbon Dioxide

Multiple Choice

What caused the increase in the mass of Earth during its formation?

• Solar Wind
• Photosynthesis
• Accretion
• Volcanic Eruptions

Multiple Choice

What caused the young planet to heat up and remain molten?

• Accretion
• Photosynthesis
• Bombardment
• Differentiation

Multiple Choice

What is the primary role of solar wind in the evolution of Earth's atmosphere?

• Creating Volcanic Eruptions
• Sweeping Away Gasses
• Adding Oxygen
• Forming the Core

Multiple Choice

Which layer of earth is only 50 km thick?

• Inner core
• Outer core
• Mantle
• Crust

Multiple Choice

What were the two primary gasses in Earth's earliest atmosphere?

• Water Vapor and Ammonia
• Carbon Dioxide and Methane
• Hydrogen and Helium
• Oxygen and Nitrogen

Multiple Choice

Which layer of Earth is primarily composed of magnesium?

• Atmosphere
• Crust
• Mantle
• Core

Multiple Choice

What process describes the increase in the amount of oxygen in Earth's atmosphere around 2.5 billion years ago?

• Volcanic Eruptions
• Photosynthesis
• Solar Wind
• Accretion

Multiple Choice

Which layer of Earth is 6,400 km thick?

• Crust
• Mantle
• Core
• Atmosphere

Multiple Choice

Which layer of Earth consists primarily of liquid iron and nickel?

• Core
• Mantle
• Crust
• Atmosphere

Multiple Choice

Which of the following elements is NOT one of the six primary elements that make up Earth's composition?

• Fluorine
• Iron
• Nickel
• Oxygen

Multiple Choice

Which of the following elements is NOT a primary component of Earth's composition?

• Magnesium
• Oxygen
• Gold
• Silicon