1. Your title
page for
knowledge
section

2. Grade 7 Vocabulary List 1
1. resource
2. atom
3. element
4. isotope
5. compound
6. density
7. mineral
8. crystal
9. silicate
10. fracture
11. ore
12. intrusive
13. extrusive
14. sediment
15. fossil fuel
16. hydroelectric
17. geothermal
18. biomass
19. pollutant
20. landfill
21. conservation
22. compost
23. sewage
24. smog
** Need to write for each word:
1. Definition
2. Your own sentence

3. Reading Link - http://news.discovery.com/earth/what-are-tar-sands-110902.html
The Sticky Problems With Tar Sands
Actress Darryl Hannah and NASA scientist James Hansen are just two of
the more than 800 environmental protesters that have been arrested in front
of the White House this week.
The crowd has been demonstrating against the proposed Keystone Pipeline
XL project, which involves building a 1,700-mile (2,735-kilometer) heavy-oil
pipeline from the tar sands of Alberta, Canada, to oil refinement facilities
along the Gulf Coast of the United States.
The decision to allow TransCanada Corp. to go through with the $7 billion
Keystone XL pipeline rests with the U.S. government, and protesters are
hoping to sway Obama to veto the permit.
Aside from the environmental disruption caused by constructing the underground pipeline, the
environmentalists’ opposition to Keystone hinges on the hydrocarbon chemistry of tar sands and how
they’re converted into crude oil.
To understand what tar sands are and why they have a slippery reputation with environmentalists,
here’s a cheat sheet on these unconventional oil fields:
WHAT: Tar sands, also known as oil sands, are a mixture of roughly 90 percent sand, clay and water
and 10 percent bitumen, a thick hydrocarbon liquid. After extracting that 10 percent of bitumen from the
tar-sand mixture, the bitumen can be purified and refined into crude oil.
WHERE: In North America, tar sands are concentrated in the Athabasca Oil Sands in Alberta, Canada.
Because of Canada’s vast oil deposits, it's the top supplier of crude oil to the United States. Saudi
Arabia is the second-largest supplier.
Tar sands are also found in Venezuela and the Middle East.
The proposed Keystone XL pipeline would run from the Alberta tar sands down the middle of the United
States through Montana, North Dakota, South Dakota, Nebraska and Oklahoma, all the way to Texas,
where it will be refined and converted into gasoline. That's longer than the Trans Alaska Pipeline, which
stretches 800 miles. Currently, there are around 55,000 miles of oil pipeline crisscrossing the United
States.
HOW: Squeezing oil out of tar sand is an extremely wasteful process: it takes between 2 and 4 tons of
tar sand and two to four barrels of water to produce a single barrel of oil. Rather than drilling for oil,
enormous shovels carve out open pits in the tar sands, scooping out the greasy interior to be hauled to a
processing facility.
There, the tar sand is combined with water to form a slurry, which forces the sand to sink to the bottom
of the mixture while the bitumen floats to the top. Once the bitumen is extracted, the run-off is piped into
large, stagnant tailing ponds of sand, water, and bitumen impurities.
To make it to the pump, refined bitumen heads to an oil refinery where it’s converted into gasoline. And
since bitumen is a highly viscous “heavy” oil that doesn’t flow as easily as lighter crude, it requires more
processing to facilitate its flow through the oil pipelines.
Overall, mining tar sands, extracting bitumen and converting it to gasoline releases three times more
carbon dioxide than typical oil production. In addition to massive amounts of tar sand needed to extract

4. oil and the carbon emissions generated, the tar sand mining operation takes places in Alberta's boreal
forest, a relatively untouched ecosystem prized for its biodiversity. But the habitat destruction has
threatened the livelihood of various native species, and the Alberta
Water Research Institute is currently
spending $15 million to prevent runoff toxins collected in tailing pools from entering nearby water
supplies.
WHY: As the price of crude oil has risen and relations with the oil-rich Middle East have deteriorated, tar
sands close to American borders have become a more attractive option in the past decade.
Those in favor of the Keystone XL pipeline argue that importing tar sands oil from Canada, a political ally,
will move the country toward more energy independence. However, those opposing the pipeline counter
that reducing reliance on fossil fuels like tar sands oil is the only long-term path toward energy
independence.
HOW MUCH: Tar sands around the world also collectively represent 3 trillion barrels of oil. But a
majority of that tar sand bitumen lies too deep in the earth for recovery with today’s mining technology.
Nevertheless, Canadian tar sands produce more than 1 million barrels of crude synthetic oil every day.
If completed, the Keystone XL pipeline would allow up to 830,000 barrels of crude oil to flow daily to the
Gulf Coast. In June 2011, the U.S. imported just over 2 million barrels of crude oil from Canada every
day, followed by 1.1 million barrels from Saudi Arabia and Mexico each.
The U.S. government should reach a decision on the Keystone XL by the end of the year. The U.S.
State Department has already issued a report on the pipeline’s potential environmental effects and
found “no significant impact on most resources along the proposed pipeline corridor.”
Yet, the report did raise concern about the potential of pipeline leaks in "environmentally sensitive
areas," such as the Ogallala Aquifer, a primary freshwater source for the Plains regions.
NASA scientist James Hansen, who was arrested at the Keystone XL protests in front of the White
House, commented that if the government approves the project, it's "game over" for curbing climate
change.
Meanwhile, in Alberta, enormous dump trucks keep hauling payloads of tar sands to be sifted, sloshed
and siphoned, eventually, into our gas tanks.
Questions –
A. Reading
1. What is the main idea of the reading?
2. What are the pros (good points) for getting oil from the tar sands in Canada?
3. What are the cons for getting oil from the tar sands in Canada?
4. What is one big reason why people are so concerned with getting oil from the tar sands?
B. You
1. How much oil do you think you use in your life?
2. Now look at the bottom words. They represent some of the many things that contain oil?
Do you want to change your answer in question 1 now?
Ammonia, Anesthetics, Antihistamines, Artificial limbs, Artificial Turf, Antiseptics, Aspirin, Auto Parts, Awnings, Balloons, Ballpoint pens, Bandages, Beach
Umbrellas, Boats, Bubble Bath, Bubble Gum, Cameras, Candles, Car Battery Cases, Carpets, Caulking, Combs, Cortisones, Cosmetics, Crayons, Credit
Cards, Curtains, Deodorants, Detergents, Dice, Disposable Diapers, Dolls, Dyes, Eye Glasses, Electrical Wiring Insulation, Facial Cleanser, Faucet
Washers, Fishing Rods, Fishing Line, Fishing Lures, Food Preservatives, Food Packaging, Garden Hoses, Glue, Hair Coloring, Hair Curlers, Hearing Aids,
Heart Valves, Heating Oil, Ink, Insect Repellant, Insecticides, Linoleum, Lip Stick, Milk Jugs, Moisturizer, Nail Polish, Oil Filters, Panty Hose, Plastic Bags,
Perfume, Petroleum Jelly, Rubber Cement, Rubbing Alcohol, Shampoo, Shaving Cream, Shoes, Toothpaste, Tires, Trash Bags, Upholstery, Vitamin
Capsules, Water Pipes, Yarn.

5. Understanding Oil – Investigation
• This activity will help you to understand what oil is better and have fun
• Follow the instructions carefully and write a short paragraph at the end
to communicate any discoveries or other ideas
What You Need-
1. Tall clear cup
2. Short cup
3. Cold water
4. Cooking Oil
5. Liquid Food Coloring
6. Dropper
Instructions –
1. Fill the TALL GLASS with cold water.
2. Don’t fill it all the way – Leave at least an inch of space at the top.
3. Pour about an inch of cooking oil into the SHORT GLASS. Then, put two or three
small drops of the food coloring into the cooking oil.
4. Stir the oil/coloring mix slightly, just enough to break up the globs of color a little bit.
5. Slowly pour the oil from the short glass into the tall glass.
6. Write below any discoveries or other ideas and thoughts.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
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___________________________________________________________________________________

6. _______________________________________
______________________________-
Coal is the first resource to study for our science unit. What is it exactly? Well… broadly speaking, oil is
a kind of ____________ that contains a large amount of ___________and does not dissolve (mix with)
in water. (ex. cooking oil, oils in plants)
In the case of _______________, oil is often used to describe crude petroleum, a thick, black modified
form of a special oil found in the upper layers of the earth. (ex. the substance we use to run cars). This
kind of oil is also classified as a fossil fuel because of the way it has been formed. And it is a valuable
energy resource in today’s world.
Let’s learn more…
___________________________?
A fossil fuel is a kind of fuel that is from the ______________ of dead plants and other organisms that
were buried and changed over a very long time (millions of years!). A fuel is kind of material that is
burned to produce power or heat for various uses. (ex. energy for cars, heat for homes).
___________________________
A. _______________– is a rock that contains at least 50 % plant remains. Coal is formed in swamps.
Plants die there and get covered and protected from the air by other plants, water and sediment. As well,
bacteria grow in the dead plants and cause them to break down in a special way that leaves mostly
carbon. Over a very long time, this altered substance gets pushed further down into the warm depths of
the earth. This added pressure and heat also causes changes and eventually a new product is formed:
coal. (see figure 2, pg. 22 in your textbook)
Coal is commonly removed from the ground by _____________ There are various ways. In the case of
_______________ the entire soil and rock above the coal is removed so that the coals is exposed. This
is a good method for coal that is close to the surface. If the coal is too deep, drift mines or slope mines
are made. In this case, an opening is made into the side of a mountain to access the coal.
B. ____________(more) – oil is formed in a very similar way to coal. However, it does not form in
swamps from dead plants. It forms at the bottom of oceans from the buried remains of very tiny marine
(ocean) organisms called plankton. As well, it often gets trapped under rocks. Oil is less dense that
water and tends to move up until hard enough rocks stop and trap it. The rock found right underneath
trapped oil is called reservoir rock.
Oil is commonly removed by drilling. Humans __________a hole from the surface all the way to the
location of the oil. A ____________is inserted and the oil is pumped up and out.
C. ___________________ – natural gas is formed just like oil except that it forms as a gas and not a
liquid.
Natural gas is also removed by drilling and pumping with a pipe like oil.
D. __________________- these fuels are __________natural originally. They are just modified forms of
other naturally occurring fossil fuels like coal or oil. Humans change thinks like coal or oil using special
treatment reactions. For example, _________________is synthetic fuel. It is refined from oil.

7. ___________________________-
It is important to remember that fossil fuels will not last forever. In fact, humans are removing huge
reserves of coal, oil and natural gas every day. A reserve is any fossil fuel amount that can be removed
easily enough to make money in the process. Human predict that coal will run out in 200 years. Natural
gas will only last for 60 more years.
This will be a big problem for the people of the future. What can we do?
1. __________________________ Instead of using coal or oil, we might be able to use methane
hydrates. They are another kind of fossil fuel found on the ocean floor from ice. It may also be better to
use other kinds of resources. Nuclear energy is another important source of electrical energy that is
obtained by a process called fission. It involves the decay of radioactive substances like uranium.
Energy sources that work by fusion may be another solution. Solar energy occurs by fusion reactions in
the sun. It may be possible to use hydrogen located on Earth to produce energy by fusion.
2. ____________________ – another way to conserve fossil fuels is to change _____________ habits
or even way of life. If humans do simple things like turning off the lights, it can make a big difference in
the total amount we use every day

8. SUMMARY – Organizer Handout
Reading Notes
Step 1: Read one time. * Take notes too if you want! 
Step 2:
Write the Main Idea (1-2 sentences) –_________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
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Step 3: Write the supporting ideas. Write in the small boxes first!
Step 4: Write the supporting details. Write in the bigger boxes later!
Supporting Idea 1 (1-2 sentences)
Supporting Details 1 (1+ sentences)
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Supporting Idea 2 (1-2 sentences)
Supporting Details 2 (1+ sentences)
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9. Supporting Idea 3 (1-2 sentences)
Supporting Details 3 (1+ sentences)
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Supporting Idea 4 (1-2 sentences)
Supporting Details 4 (1+ sentences)
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Supporting Idea 5 (1-2 sentences)
Supporting Details 5 (1+ sentences)
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10. Supporting Idea 6 (1-2 sentences)
Supporting Details 6 (1+ sentences)
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Supporting Idea 7 (1-2 sentences)
Supporting Details 7 (1+ sentences)
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Supporting Idea 8 (1-2 sentences)
Supporting Details 8 (1+ sentences)
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11. _____________________________
(Chapter 3, Section 1 Summary Note)
Before you learned about fossil fuels. Fossil fuels are one kind of natural resource and they come from
organic things. (living things that died a long time ago)
Now, you will learn about ________________ Minerals are also natural resources but the come from
____________________things. (things that cannot live). As well, they have many other interesting
features and qualities.
What is a Mineral?
A mineral is a _________________ occurring ______________ ________________.It also has an
__________________________ and a ____________________________
Characteristics of Minerals
1. All minerals are formed by _________________ If a human makes something, it can’t be a
mineral.
Ex. salt is formed by seawater so it is mineral. Steel is NOT a mineral because it is made by
humans. (but iron is which steel comes from)
2. All minerals are ____________________ If something is or was living, it can’t be a mineral. It can
have organic elements in it as long there are inorganic elements as well.
Ex. Aluminum is a mineral because aluminum is an inorganic element.
Coal is NOT a mineral because it comes from dead plants.
3. All minerals are either made of a _____________________ or a ____________________ and
thus have a definite chemical composition.
Ex. Salt is a mineral because it is completely made of NaCl compounds and nothing else.
4. All minerals are crystalline solids. Gasses and liquids are NOT minerals.
NOTE- all solids are not necessarily minerals. The first 3 features above must apply!
The Structure of Minerals
All minerals are _________________.. A crystal is a solid with the same kind of atoms or
compounds. These atoms and compounds are also arranged in an orderly, repeating pattern. Ex.
See Figure 2 and 3 on pg. 63,64 in your textbook
Crystals can be formed in 2 ways-
1. _____________________- when hot magma eventually cools later, some of the atoms in it
loose heat energy and move close together in an orderly and repetitive way. As a result, very
large crystals get formed. The type of mineral crystal created depends on what atoms are in
the magma at the time. Ex. Labradorite
2. _______________________- sometimes minerals dissolve in water naturally. Then later the
water evaporates. The remaining ions of the mineral then move close together in an orderly
and repetitive way. As a result, another kind of crystals are made. Ex. salt (sodium chloride)

12. SUMMARY – Organizer Handout
(For Chapter 3, Section 3) Reading Notes
Step 1: Read one time. * Take notes too if you want! 
Step 2:
Write the Main Idea (1-2 sentences) –_________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
Step 3: Write the supporting ideas. Write in the small boxes first!
Step 4: Write the supporting details. Write in the bigger boxes later!
Supporting Idea 1 (1-2 sentences)
Supporting Details 1 (1+ sentences)
_______________________________________________________________________________
_______________________________________________________________________________
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Supporting Idea 2 (1-2 sentences)
Supporting Details 2 (1+ sentences)
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13. Supporting Idea 3 (1-2 sentences)
Supporting Details 3 (1+ sentences)
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Supporting Idea 4 (1-2 sentences)
Supporting Details 4 (1+ sentences)
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Supporting Idea 5 (1-2 sentences)
Supporting Details 5 (1+ sentences)
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14. Supporting Idea 6 (1-2 sentences)
Supporting Details 6 (1+ sentences)
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Supporting Idea 7 (1-2 sentences)
Supporting Details 7 (1+ sentences)
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Supporting Idea 8 (1-2 sentences)
Supporting Details 8 (1+ sentences)
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15. Uses of Minerals
(Chapter 3, Section 3 Summary Note)
Many kinds of minerals are used by people. The following categories outline some of the main kinds of
minerals used and some of their uses
A. Gems-
A gem is a cut mineral that looks very precious. Usually, a gem is a slightly more beautiful
sample among some other more average looking samples for some kind of mineral. A number of
specific properties can often be noted to identify a gem. First, gems are often are clearer, brighter
and/or more colourful than other samples of the same mineral. They can also be polished to a
higher quality than the other samples. For example, amethyst is a gem form of quartz. It just
contains small amounts of iron but other (more common) samples of quartz do not. So it looks
nicer and thus is considered to be a gem. (see Table 2 for gem examples compared to more
common samples)
Gems are often prized which means they have been used and are used in some important
cultural artifacts. For example, many gems are used in jewelry. Then, the gems are called jewels.
The Imperial State Crown of England contains thousands of gems. Diamonds, a kind of gem are
also used in many kinds of jewelry such as wedding rings.
In addition, certain gems can be used as cutting tools especially diamonds. Other gems are
used to produce lasers such as rubies. Some timepieces use quartz crystals to control the
frequency.
B. Ores-
Many other minerals are used in large quantities to make thousands of things in the world. Such
minerals are called ores. They are also obtained from the earth by mining and sold for profit. A good
example is iron. Iron is a single element. It is mined and then sold to make so many things such as
frying pans and even ships. Other minerals may contain useful elements that have to be separated.
Bauxite is mined for the element, aluminum which can be extracted from it by a special refining
process. Then the aluminum is used to make and sell various products including bicycles, pop cans and
even car parts.
C. Vein Minerals – certain minerals can get deposited in spaces between rocks call veins.
Sometimes, these minerals dissolve in fluids and then are carried to certain weak areas of rocks
or empty spaces left by rocks when they collapse. A good example is the mineral, sphalerite
which contains the element zinc. Zinc is extracted and used to coat products with iron to prevent
them from rusting.
D. Titanium – other minerals contain the element titanium including ilmentite and rutile. These 2
minerals are commonly formed when magma cools and solidifies. After mining them, the titanium
is extracted and used for various important products as it is very durable but light. For instance,
racing bicyles as well as suspension parts in cars and even parts of wheelchairs are all made
using titanium.

16. Mineral Identification
(Chapter 3, Section 2 Summary Note)
How can you recognize if something is a mineral or find a mineral already present in
something else? Remember that most minerals share certain characteristics that help to
identify them from other things as follows:
Mineral Appearance – minerals have a particular appearance. For instance, they look
nicer than other similar resources. They could vary in colour (a lot) of even their location
( a little)
Hardness – is a measure of how easily a mineral can be scratched. Some minerals can
be very soft such as talc. Many substance will make scratches in them. Other minerals
are extremely hard such as many diamonds. Few or no other minerals will scratch them.
The Mohs Scale can be used to compare hardness. You can used it to approximate a
hardness value for an unknown mineral. You scratch it with different known minerals.
When you find one mineral can make a scratch but the another mineral cannot than the
unknown mineral’s hardness must be between the hardness for the 2 known minerals.
Luster – the way a mineral reflects light is called luster. Luster can be metallic or non-
metallic. Metal luster comes from minerals that shine a lot like metals. If the mineral does
not shine much, is luster is nonmetallic.
Specific Gravity- is the ratio of a mineral’s weight compared to the weight of an equal
volume of water. It is very similar to a mineral’s density (mass divided by volume). This
number is good for comparing how heavy minerals are.
Streak- A streak is the portion of a mineral that is rubbed off and remains when the
mineral is scratched against some other material. A mineral will only make a streak if it is
softer than the other material. Some minerals will even make streaks against paper such
as graphite. (found in pencils).
Cleavage and Fracture – both of these terms are used to describe the way a mineral
breaks (if even possible). If a mineral breaks into smaller pieces with smooth, flat
surfaces, we say the mineral has cleavage. But if it breaks into pieces that are uneven,
rough or jagged, we say the mineral has facture. Quartz is a mineral with fracture.
Other Properties – some minerals have special other properties that can be useful to
identify them. For instance, certain minerals have magnetic properties such as magnetite.
Some minerals can separate light rays or fizz when acid is added such as calcite.

17. The Rock Cycle
(Chapter 4 – Section 1 Summary Note)
Believe It! # 1 – A rock is actually just a bunch of other things mixed together. Commonly, a rock
contains many different kinds of minerals but it also can contain other things too like volcanic matter,
organic matter and other special natural materials.
Believe It! #2 – A rock never remains the same over time! It is always changing but often very slowly
over time. How the rock changes from one form into another is known as the rock cycle or you could
even say it is a rock process (like our problem solving process!)
General Features of the Rock Cycle-
1. There are 3 main kinds of forms a rock can be in:
a. Metamorphic rock – this rock has been put under a lot of pressure and heat. It can
eventually become magma with enough heat and pressure
b. Igneous rock – when metamorphic rock (or even magma) gets cooled down (for various
reasons), it become igneous rock.
c. Sedimentary rock – Igneous rock can also be exposed to certain elements (ex. weathering
and erosion) that break it down into smaller pieces. Then these smaller pieces can get
compacted into the ground or other medium and become a more dense form. This form of
rock is called sedimentary rock
2. A rock can change from one form into another form by various processes. For example, a
rock could be heated up by magma or it could heated up in a laboratory. Strong winds could blow
at a rock over time causing it to be compacted but water waves could also keep hitting the rock
until it becomes more compacted too.
3. A rock can change to any other form depending on the situation – there is NO single
direction in the rock cycle. Sedimentary rocks could be “loosened” by wind or water to become
eventually igneous rock. Similarly the same sedimentary rocks could get heated up and put under
pressure to become metamorphic rocks. It all depends on the situation the rocks are exposed to.
The Rock Cycle

18. Other Notes-
1. During the rock cycle, matter is never destroyed or created. The rock’s materials are just
recombining with other things to make new forms of matter. OR. Certain rocks are just getting
broken down into separate components. The fact that matter is neither created or destroyed is
called the principle of conversation of matter
2. The rock cycle was first identified and later established by James Hutton, a Scottish scientist.

19. More on the Rock Cycle: Types of Rocks
(Chapter 4- Sections 2,3 and 4)
A. Igneous Rocks-
Igneous rocks are a form or that rocks take when cooled from magma. In other words, under certain
conditions that require extreme temperatures (over 650 degrees Celsius) rocks exist in the form of hot
liquid called magma. This occurs naturally deep below Earth’s surface. When conditions change, the
magma may cool and when it does it changes into a solid rock called an igneous rock. For example,
magma gets pushed out of the earth from volcanoes and flows as lava. The lava then cools once it is
above the Earth’s surface and forms igneous rocks.
Types of Igneous Rocks
1. Intrusive Rocks – Sometimes, (under the right conditions) magma can cool –under- Earth’s
surface and changed into igneous rocks. Such rocks are also called intrusive rocks because they
are formed –under- Earth’s surface. They are only found at the surface when another process
“moves” there such as by erosion. These rocks cool slowly and have large grains (crystals) of
rock.
2. Extrusive Rocks – when magma cools at Earth’s surface (and is really called lava), the igneous
rocks formed are called extrusive rocks. These rocks cool quickly and have very small grains
(crystals) of rocks.
3. Volcanic Glass – sometimes magma cools extremely quickly. As a result, few or not mineral
crystals get formed. This kind of igneous rock is called volcanic glass. Sometimes, gases can get
trapped inside when the new rock form is created causing holes in the rock after the gas
eventually escapes later.
In addition, magma exists as different types depending on what types of minerals are in it. As a result,
the igneous rocks that it changes into when it cools can also be of various types. Basaltic rocks form
from magma that has a lot of iron and magnesium. They are dark in colour. Granitic rocks are formed
from magma that contains a lot of silica (a compound with silicon and oxygen). They are stiff and often
released violently from volcanoes as they are formed. Andesitic rocks have some combination of
minerals from both basaltic rocks and granitic rocks.
B. Metamorphic Rocks-
For a number of reasons, rocks can experience high levels of heat and pressure. (ex. when buried
deeply under Earth or when magma touches them and its hot fluids react with rocks). When this
happens, their physical makeup gets altered by the heat and they change form. The new form of rock is
called a metamorphic rock.
Also note that there are different kinds of metamorphic rocks depending on the rocks that form them and
the heat and pressure conditions. As well, any kind of rock can change into a metamorphic including
igneous rocks, sedimentary rocks and even other metamorphic rocks.
Types of Metamorphic Rocks-
1. Foliated Rocks – sometimes, a high temperature and/or pressure causes other rocks to arrange
into layers as they change into metamorphic rocks. These rocks are called foliated rocks. Their

20. minerals are also pressed together very tightly so that water cannot pass very easily through
them. Examples include slate and gneiss.
2. Nonfoliated Rocks- some metamorphic rocks are not formed as layers. The mineral grains
(crystals) in rocks just get rearranged into some other form to make metamorphic rocks. These
rocks are called nonfoliated rocks. Sandstone and marble are two examples.
C. Sedimentary Rocks-
At other times on Earth, pieces of rocks can get broken off from the main rocks. These loose materials
are called sediments. Then, various processes (ex. the wind, water, ice, gravity, coming out of solution)
can move some of these rock pieces together to become tightly packed. New rocks get formed as a
result and they are classified as sedimentary rocks. These rocks also often form as layers which is a
result of the way they get packed together: often in stacks.
Types of Sedimentary Rocks-
1. Detrital Sedimentary Rocks – these sedimentary rocks are formed by weathering and erosion.
Rocks are broken down by chemical and mechanical actions (ex. by exposure to water or wind)
through a process called weathering. Then, the resulting rock pieces are moved together (Ex. by
the wind or water pushing or picking them up) through a process called erosion. Then, they
become stuck together to form a new solid rock by a process called compaction. Sometimes,
certain large pieces require help to stay stuck together. Sometimes, water and other minerals it
picks up move through open spaces created when large sediments are pushed together. The
water eventually moves on but some of the mineral in the water remain and act like a cement to
help hold the rock pieces together. Such a process is called cementation.
Different rocks are given specific names based on the size and shape of the sediments that form
the sedimentary rocks. For example, conglomerate is formed form round large sediments and
breccia is formed from large sediments with sharp angles. Sandstone is formed from smaller
sediments of almost any kind of mineral but often quartz and feldspar.
2. Chemical Sedimentary Rocks-
These sedimentary rocks form when certain dissolved minerals come out of solution. Rock salt is
a good example. It if formed from compounds containing halogens such as sodium chloride.
Limestone is another good example. It is formed from calcium carbonate that comes out of
solution and is called calcite.
3. Organic Sedimentary Rocks-
Certain organisms (Ex. clams, corals, snails) have hard shells that contain minerals such as
calcite too. When they died, their shells accumulate on the ocean floor and can get packed
together to form rocks such as the rock called coquina. Chalk and coal are another two good
examples or rocks that are formed dead organisms.