The Earth’s Crust

Name:

Class: 7-

Name:

Name:

The Earth’s Crust Textbook Scavenger Hunt

Use the index, glossary and table of contents to fill in the blanks.

Unit 4 in our textbook in entitled . This unit starts on page

. There are sections in this unit. There are layers to the Earth. They

are called , ,

, . Information of volcanoes can be

found on page and . There are types of volcanoes. They are

called and . The rock cycle contains

different types of rocks. These are , , and

. This information can be found on page . There are

different layers in soil. They are , , , and

. This information can be found on page .

Minerals are

.

Four main characteristics of minerals include , ,

and . This information can be found on

page . Erosion is

_.

The causes of erosion include , , and

. There are different types of mountains. They

include mountains, mountains and mountains.

According to page 228, the Earth is not one continuous piece, but is made of several huge, solid

sections called . Whenever plates meet, they cause .

Canada and the United States of America, as well as Mexico are all part of the

plate. Page 244 contains the .

Name:

Earth: A Layered Planet - Notes

Just over years ago, Earth was being formed. According to

astronomers, many , large and small, were in orbit around the newly forming

sun. As the rocks collided, they joined together to form even larger rocks, and planets like

began to form. Because the rocks in space were travelling at high speed,

each collision generated huge amounts of . This caused the rock to become

so hot that it melted. Heavy materials such as , sank to the core of the growing Earth.

As Earth grew larger, more rocks collided with it. Once most of the rocks near Earth were gone,

Earth was left about the size it is now. It was also very .

Layers of the Earth

The Crust

The Earth’s Crust is a thin layer of . It is the only layer of the Earth

to have cooled enough to form solid rock. It measures between and Kms depending

on where you measure. The material that makes up the Earth’s crust is than the

other materials that make up Earth. It is °C.

The Mantle

Just below the crust is a hot, partly molten layer called the . The mantle is made

up of a thick, material. When it cools it forms rock. The mantle moves

like thick syrup. It is approx. Kms thick. It is °C at the top of the

mantle and °C towards the outer core.

Name:

The Outer Core

Toward the of the Earth is the core. The outer core has a mass of

mostly with some in the mix. Like the mantle, material within the outer

core . The outer core is approx. Kms thick. It is °C.

The Inner Core

At the very centre of the Earth is the , a large ball of and

. Despite the heat (almost as hot as the surface of the ), the inner

core is , crushed under the enormous weight of the outer core and mantle. It

has a radius of of approx. Kms. It is °C.

Name:

Technology and Tectonic Plates

Theory of plate tectonics:

The theory of plate tectonics is generally accepted among scientists. This means that over time, there have been discoveries made to support this scientific idea. Scientists use different technologies to make their findings, and over time, technologies have advances (or improved).

The article “Technology and Tectonic Plates” discusses discoveries that help prove that our Earth’s crust is in fact changing.

Year Discovery How was this discovered?1872 – 1875,and 1908

1950’s

1960’s

Today

I

•

•

•

•••

••I

I

I

•

•

••

•••

•

'•• Alfred Wegener's Continental CluesWhen looking at a map of the world, it is not difficult to see that some of the continents look as if they could fit together like pieces of a giant puzzle. Alfred Wegener (1880-1930), a German meteorologist, saw this connection and found that if he included the continental shelves (the part of each continent that Is covered by shallow ocean water), the fit of the puzzle was

I even better. He believed that millions of years ago all of the continentswere joined together. He named this super-continent Pangaea, which is Greek for "all the land." At some point, Pangea split and began to move apart, settling Into the continents that we know today. His theory was called "continental drift."

Alfred Wegener found several other clues to support his theory. In places where the shape of the continents matched up, for example, between Brazil and part of Africa, the sequence in the layers of rocks (sandstone, shale, coal) also matched. He also observed that the same types of fossil remains of plants and animals, including dinosaurs, were found on different continents, even though they are separated by vast distances.

IThe weakest part of Wegener's argument was his explanation of why and

I how the continents moved. He suggested that the rotation of Earth and the gravitational pull of the moon caused the movement. Thirty years afterWegener's death, scientists found evidence of the sea floor spreading, which was undeniable proof that Earth's crust does split and move, and carries the continents with it. At this point, Alfred Wegener's theory and his

• life's work were finally substantiated.

••'200 million years ago 140 million years ago

I

••

••I65 million years ago Present day

It

••

•

•••

4.1.2 - 305

Technology and Tectonic PlatesDiscoveries, through experimentation and observation, are the foundations of knowledge and technological advances. Such is the case with research of Earth's oceans and continents. One of the first major discoveries were those of the scientists aboard The British H.M.S. Challenger expedition. The expedition lasted from 1872 to 1875. The ship sailed 111, 000 kilometres, measuring ocean depth and characteristics of the ocean floor throughout its journey.The results of this expedition showed that an extensive north to south ridge ran down the middle of the Atlantic Ocean between the Americas and Europe and Africa. Frank Taylor analyzed the data more than thirty years later, in 1908. He proposed that the ridge was evidence that the continents had been pulled apart by tremendous forces.

In the 1950s, two British geophysicists, Fred Vine and Drummond Matthew, discovered that the ocean floor was made up of younger rock than that of the continents. Using deep-sea drillingtechnology, Vine and Matthew were able to analyze core

:I!

samples. They found that the oldest oceanic crust is less than200 million years old. Continental rocks, on the other hand, were tested and found to be up to 4. l billion years old. One important question remained: Where had the old ocean floor gone?

With the introduction of computers in the 1960s, a greater understanding of the ocean floor emerged. It was discovered that the youngest ocean floor is in the middle of the Atlantic and the oldest is at the edges, proving that the sea floor is spreading.Sonar imaging used echo sounding to map the ocean floor. Later, remote-controlled submarines recorded data in depths of 6000 metres. Today, satellites are able to detect minute movements on

4.2.1 - 311

the earth. The new technology used to study the earth shows that continents and oceans are made of over 15 different tectonicplates. The boundaries of the plates are found mainly in the ocean. In some areas the plates are being forced apart, while other plates are being forced down, back into the centre of the earth. The movement of tectonic plates proves that the continents are moving and helps explain the volcanic eruptions and earthquakes that affect our world.

Sonar Imaging

«s

t:a0.

@

312 - 4.2.1

depressor weight

towing cable

mother ship marine seismicsurvey boat

t,-1 Continental Drift and Plate Tectonics

Divergent

nt

Dive

,

Continental Drift and Plate Tectonics

Continental Drift is a scientific theory that states the Earth's continents move relative to each other. The hypothesis that continents 'drift' was fully developed by Alfred Wegener in 1912. He suggested that the present continents once formed a single land mass that drifted apart. It was not untilthe development of the theory of plate tectonics in the 1960s, that a sufficient geological explanation of that movement was found.

Plate Tectonics is a scientific theory which describes the large scale motions of Earth's Crust {lithosphere). The lithosphere is broken up into what are called tectonic plates. There are about seven to eight major plates and many minor plates.

The main features of plate tectonics are:

• The Earth's surface is covered by a series of crustal plates.• The ocean floors are continually moving,spreading from the center,

sinking at the edges, and being regenerated.• Convection currents beneath the plates move the crustal plates in

different directions.• The source of heat driving the convection currents is radioactivity deep

in the Earths mantle.

Plate Boundaries

Convergent (Subducting Plate)

Volcanic ate

The earth's surface is broken into seven large and many small moving plates. These plates, each about 80 kilometers thick, move relative to one another an average of a few centimetres a year. There are three types of movement at the boundaries between plates: convergent, divergent and transform-fault.

At convergent boundaries, plates move toward each other and collide. Where an oceanic plate collides with a continental plate, the oceanic plate tips down and slides beneath (subduction) the continental plate forming a deep ocean trench where continental plates collide, they form major mountain systems such as the Himalayas.

At divergent boundaries, plates move away from each other such as at the Mid-Atlantic Ridge. Where plates diverge, hot, molten rock rises and cools adding new material to the edges of the oceanic plates. This process is known as sea-floor spreading.

At transform-fault boundaries, plates move horizontally past each other.

http://earthquakescanada.nrcan.gc.ca/recent_ eq/maps/index_ e.php

Name:

Mountains from Magma: Volcanoes (p. 240/241)

lava:

magma:

volcanic cone :

Volcanoes

- Do not erupt

- Can be found anywhere in a

- Formed above , where magma collects and pools

- Magma warms the above it and pours through a hole in the Earth

- Lava is and pours out like a

- Hardens into

- These volcanoes have a gently

Volcanoes

- Erupt

- Blow ash, rock and many km into

- Formed where two , one sliding on top of the other.

- Bottom (descending) plate has sediments containing .

- Magma is and , and made of melted .

- The combination of thick and steam under enormous causes a violent eruption.

Types of Volcanoes

Name:

Mountains Rock (p. 222/223)

1. breaks down mountains into carried by rivers and streams.

2. The particles of pebbles, soil and settle at the bottom of and because currents slow down.

3. Gradually, the piles up in and is compressed by enormous over millions of years.

4. While the layers are under pressure, water is slowly .

5. The lower layers form .

Why are there different types of sedimentary rocks?

In many parts of North America, there are large areas of sedimentary rock. What does this tell you about the ancient history of these areas?

Rock Mountains (p. 236/237)

Mountains are associated with the edges of , and form where two of the Earth’s platesmeet.

Fold Mountains Block Mountains Dome Mountains

Types of Sedimentary Rock

Types of Mountains

Name:

The Rock Cycle

Characteristics of Rocks

Igneous Sedimentary Metamorphic

Name:

Characteristics of Minerals

StreakStreak is the color of the mineral in powder form. Streak shows the true color of the mineral. Metallic minerals tend to streak a darker color. Non-metallic minerals tend to streak lighter colors. Streak is more reliable property to identify minerals than color.

HardnessHardness is one of the best properties for identifying minerals. The Mohs scale isused to test hardness of minerals, based on 10 minerals whose hardness is already known. Softer minerals can be scratched by harder minerals.

Cleavage and FractureCleavage is the way a rock breaks apart. Cleavage depends on how easily the rock is broken and the direction in which the rock breaks. Fracture is the quality of the cleavage surface.

LusterLuster is how much the surface of the rock reflects light. Metallic means the mineral is opaque and reflects light like a metal would. Non-metallic would not reflect light like metal.

Name:

Weathering and Erosion (pages 206 -209)

Definitions

erosion:

mechanical weathering:

moraines:

biological weathering:

chemical weathering:

Three Types of Erosion

3.

2.

1.

Name:

Layers of Soil (pages 210 -211)

Definitions:

horizons:

humus:

Four Layers of Soil

(Diagram and Notes)

#1: :

#2: :

#3: :

#4: :

Name: What makes good soil? (pages 214 -215)

Key Question: What makes good soil? look for soil dark in equal parts of , , and made up of different textures and sizes spaces for other “ingredients”: and minerals and other are food for plants good farming soil is about 50% and 50%

Fact: Fertile soil is essential for farming, yet less than 1% of Canada’s land is ideal for farming!

The components of soil and their effect on plant growth…

CLAY SILT SAND HUMUS WATER AIR

“The rock particles (of soil) have different names, depending on how large they are.” (p.214)