Earth History
Lesson 1: What’s Inside the Earth
Key Vocabulary:
Inner Core:
The innermost layer of the earth, an extremely hot, solid sphere of
mostly iron and nickel. The inner core is 3,200 to 3,960 miles (5,150 to
6,378 km) below the surface and about 750 miles (1,200 km) thick.
Outer Core:
This layer of the earth lies between the mantle and the solid inner core.
It is the only liquid layer, a sea of mostly iron and nickel about 1,400 miles
(2,300 km) thick.
Mantle:
This dense layer of the earth is made of hot, semisolid rock and is located
directly below the crust. It is about 1,800 miles (2,900 km) thick.
Crust:
Hard and rigid, the earth's outermost and thinnest layer. It is only a few
miles (5 km) thick under the oceans and averages 20 miles (30 km) thick
under the continents.
Lithosphere:
Made up of the crust and a tiny bit of the upper mantle, this zone is divided into several
constantly (very slowly) moving plates of solid rock that hold the continents and oceans.
Asthenosphere:
A hot, malleable semiliquid zone in the upper mantle, directly underneath the lithosphere,
on which the plates of the lithosphere move (or float).
Tectonic Plates:
Several large slabs of the lithosphere that hold the continents and oceans and are slowly
but constantly moving around the earth.
Oceanic Crust:
The type of crust lying under the oceans of the world. It is only 4 to 6 miles (7 to 10 km)
thick and usually younger than continental crust.
Boundary:
The border between two tectonic plates.
Continental crust:
A layer of the earth's crust that lies under the seven continents. It is about 20 to 40 miles
(35 to 70 km) thick and very old
Convergent boundary:
The boundary that occurs where two plates are pushing toward each other.
Divergent boundary:
The boundary that occurs where two plates are moving apart from each other.
Transform boundary:
The boundary that occurs where two plates slide past each other.
Introduction What’s Inside Earth
Task:
• Click on the above image to open interactive website.
• Read the Introduction
• Use the glossary and the chapters to define each vocabulary word.
• Go to next slide
What’s Inside The Earth?
Task:
• Inside your science note, illustrate the different layers of the Earth . Be sure
your notes are detailed. Use the link below for additional information.
• Link: Earth’s Interior
• When complete, go to next slide.
Who was Alfred Wegener?
A German scientist from the early 1900’s
What was Alfred Wegener’s view of the continents?
Alfred Wegener noticed that the coastlines of Africa and South
America looked like they might fit together. He also discovered
evidence that the same plant and animal fossils were found
along the coasts of these continents, although they were now
separated by vast oceans. In addition, he noticed that geologic
formations, like mountain ranges, on the two continents also
matched up
What was Pangaea?
Wegener suggested that the earth's continents were once
joined together in one large mass. He called the original
landmass (or supercontinent) "Pangaea," the Greek word for
"all the earth." According to Wegener, over time "Pangaea" split
apart and the different landmasses, or continents, drifted to
their current locations on the globe.
Tectonic Plates
Pangaea begins to
break up and splits
into two major
landmasses —
Laurasia in the north,
made up of North
America and Eurasia,
and Gondwana in the
south, made up of the
other continents.
Gondwana splinters
further — the South
America-Africa
landmass separates
from the AntarcticaAustralia landmass.
The Indian
landmass breaks
away from the
AntarcticaAustralia
landmass.
Major rifting of
Laurasia, with the
North American
landmass separating
from Eurasia.
South America and
Madagascar
separate from
Africa.
Greenland separates
from North America.
Australia separates
from Antarctica and
moves north.
The Indian landmass
collides with Asia.
Continents Over Time
Click the link above. In the instruction box you will see
directions printed in red. Read over carefully and then click
“Begin” After you have the correct order of the continents,
answer the bonus question.
When you have completed the question, return to this
presentation and go to the next slide.
Plate Boundaries
What is the difference between continental crust and oceanic crust?
Using the map above, identify each of the plates on the
Plates and Boundaries Handout.
Completely copy the table below in your science notebook. Use the information from the Plate
Boundaries Chapter to complete the table. Be sure you have a clear understanding of the 3 different
boundaries as well as some examples. When you have completed the table go to next slide.
Carefully study the map you filled in of the plate locations below,
click the map and play Plate Boundaries Challenge
End of lesson