Name:____________________________________________ Homeroom:____________ Date:__________
MCAS HW#3 – The Earth!
Massachusetts State Learning Standards
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Describe the layers of the earth, including the lithosphere, the hot convecting mantle, and the dense metallic core.
Describe how the movement of the earth’s crustal plates causes both slow changes in the earth’s surface (e.g., formation of
mountains and ocean basins) and rapid ones (e.g., volcanic eruptions and earthquakes).
Describe and give examples of ways in which the earth’s surface is built up and torn down by natural processes, including
deposition of sediments, rock formation, erosion, and weathering.
Instructions
- Read the following text
- Highlight and underline important information throughout this HW.
- Use the information to fill out the remaining packet
Earth’s surface is constantly changing. Earth looks different today from the way it did millions of years ago. People
wonder, “What’s inside Earth?” The extreme conditions in Earth’s interior prevent exploration far below the
surface. Geologists have used two main types of evidence to learn about Earth’s interior: direct evidence from rock
samples and indirect evidence from seismic waves.
Rocks from inside Earth give geologists clues about Earth’s structure. Geologists can make inferences about
conditions deep inside Earth where these rocks formed. Using data from seismic waves produced by earthquakes,
geologists have learned that Earth’s interior is made up of several layers. The three main layers of Earth are the
crust, the mantle, and the core. These layers vary greatly in size, composition, temperature, and pressure. Beneath
the surface, the temperature decreases for about 20 meters, then increases until the center of Earth is reached.
Pressure results from a force pressing on an area. Pressure inside Earth increases as you go deeper. The crust is the
layer of rock that forms Earth’s outer skin. The crust is a layer of solid rock that includes both dry land and the
ocean floor. Oceanic crust consists mostly of rocks such as basalt, dark rock with a fine texture. Continental crust,
the crust that forms the continents, consists mainly of rocks such as granite. Granite is a rock that usually is a light
color and has a coarse texture.
Below a boundary 40 kilometers beneath the surface is the solid material of the mantle, a layer of hot rock. Earth’s
mantle is made up of rock that is very hot, but solid. Scientists divide the mantle into layers based on the physical
characteristics of those layers. The uppermost part of the mantle and the crust together form a rigid layer called
the lithosphere. Below the lithosphere is a soft layer called the asthenosphere. Beneath the asthenosphere, the
mantle is solid. This solid material, called the lower mantle, extends all the way to Earth’s core. The core is made
mostly of the metals iron and nickel. It consists of two parts—a liquid outer core and a solid inner core. The outer
core is a layer of molten metal that surrounds the inner core. The inner core is a dense ball of solid metal. Scientists
think that movements in the liquid outer core create Earth’s magnetic field. Because Earth has a magnetic field, the
planet acts like a giant bar magnet.
1. How do pressure and temperature change as you go deeper into the Earth?
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2. What is the name of the layer makes up tectonic plates (hint: it is made up of the uppermost layer of the mantle
and the crust) _____________________________________.
3. In the picture to the right, label
each layer of the Earth with the
correct term. [try and do it without a
word bank, but if you need one, see
the bottom of this page
TECTONIC PLATE BOUNDARIES MAP
Word bank for #3: mantle, inner core, outer core, crust
Tectonic (crustal) Plates
The lithosphere on the earth is not solid. It is cracked. In fact it is broken into eight major, and several smaller,
pieces that we call “tectonic plates” or “crustal plates”(see image on previous page). Because these plates sit on top
of the hot, convecting mantle, they slowly move. Their movement varies between 1-20 cm/year – that’s slow!
Tectonic plates are responsible for many features on Earth, and all of the features they create occur along the
boundaries between two moving plates. Earthquakes are common along all plate boundaries, because they are
caused by abrupt motion and grinding between plates. Volcanoes, mountains and trenches are other features
found along plate boundaries.
Tectonic Plates have been moving for hundreds of
millions of years, and they have helped change
the arrangement of the continents. 250 Million
years ago, the world looked very different. All of
the land on the planet was stuck together in one
massive continent called Pangaea. Slow
movement of the plates broke up the continent
and lead to the current formation of land that we
have today.
Scientists first came up with the idea for Pangaea
by comparing the similarities in shape between
South America and Africa – they almost look like
puzzle pieces! Scientists found further evidence
by comparing the types of fossils and rocks found
on South America, Africa, North America, and
Europe. Many of them matched up! The only
explanation was that they were once connected.
4. What features occur along tectonic plate boundaries?
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5. How fast do tectonic plates move? _________________________________________
6. Critical Thinking: Do you think tectonic plates are still moving today? What is some evidence that you can use to
support your answer (hint: find evidence in your everyday life, experience, and reading)
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Use the map of tectonic plate boundaries and the maps of Pangaea to help you answer the following questions.
7. On what plate are we (in Boston) located? _____________________________________________________
8. Describe the relative motion of the African Plate compared to the South American Plate? ______________
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9. In the last 250 million years, have North America and South America always been connected? Explain.
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10. Locate Japan and circle it on the Plate Tectonic Boundaries Map. Why do so many large earthquakes occur
here?_________________________________________________________________________________
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The diagram below shows two land masses separated by an ocean.
11. A scientist is studying these two land masses. The scientist hypothesizes that the land masses were once
together.
a. Using the diagram, identify two pieces of evidence that support the scientist’s theory that the land masses
were once together.
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b. Explain how each piece of evidence you identified supports the scientist’s hypothesis.
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