Unit 5 Geology Day 6: Crayon Rock Cycle Investigation

BIG Idea

v  The physical structures______ and chemical properties_____ of the solid Earth provide evidence of Earth’s evolution over time. Investigation of Earth’s layers, tectonic activity, and the rock cycle­­­__ reveals Earth’s history. As rocks move through the rock cycle their mineral compositions and physical structures change to reflect the processes under which they are formed.

v  Over time through the various Earth processes of weathering_________, erosion_________________ & deposition__________, melting & crystallization and_______ heat & pressure, Earth’s rocks change from one type into another as described in the rock cycle.

v  Igneous rocks____________ are formed when lava or magma cools and solidifies. They are characterized by interlocking mineral crystals that vary in size depending upon how rapidly they cooled.

v  Sedimentary rocks______ are formed when particles of other rocks are deposited in layers and undergo compaction (crushing together), and cementation (binding of the sediments). Some sedimentary rocks contain fossils.

v  Metamorphic rocks______ are formed deep underground where heat and pressure cause existing rocks to be altered. Metamorphic rocks are often characterized by wavy layers of mineral crystals or by the presence of unusual minerals.

How? - Procedure

Step I: To form SEDIMENTS

1. Put on your goggles.

2. Place a sheet of paper in front of you.

3. Each group member take a wax crayon of a different color and remove the wrapper.

4. Use a pencil sharpener to WEATHER your crayon to form a pile of crayon chips and flakes on the sheet of paper. Use a plastic knife to chop the last bit of crayon as needed. Clean bits of crayon from the sharpener with a straightened paperclip. Your group will have four piles of different colored SEDIMENTS.

5. Use the knife to chop up the shavings into small bits.

Step 2: The sediments are ERODED and DEPOSITED

1. Have a group member hold a plastic bag open and at a slight angle.

2. Take turns to ERODE and DEPOSIT your color of SEDIMENTS into the bag. Do this by gently pouring your color of scrapings into the bag such that layers of colors form in one corner of the bag.

3. Add a cementing solution by asking your teacher to spray one spritz of water into your bag.

4. Try not to disturb your LAYERS OF DEPOSITED SEDIMENTS as you gently press the air out of the bag while sealing it.

Step 3: To form the SEDIMENTARY ROCK

1. Place the bag of LAYERED SEDIMENTS on your chair and sit on the bag of sediments to model COMPACTION and CEMENTATION of the sediments.

2. While sitting on the bag, read the Background and answer the

Background questions in your Student Journal.

3. Retrieve and open the bag to observe the “sedimentary rock.” Break the rock in half and observe the edges.

4. Compare your “rock” with a sample of the sedimentary rock sandstone. Record your comparison in your Student Journal.

Complete the Sedimentary Rock section for Part I in your Student Journal.

5. Place an approximately 3 cm piece of the rock on the group paper plate labeled Rock Samples and label the section sedimentary. Place the rest into the plastic bag.

6. Once solid, take your “igneous rock” out of the tin and observe before placing on the group paper plate labeled Rock Samples. Label the section igneous.

Step 4: To form the METAMORPHIC ROCK

1. Take the plastic bag with your sedimentary rock and reseal the bag while pushing out all excess air.

2. Apply EXTREME HEAT to your rock by dunking the bag into a cup of 45oC tap water for 2:00 minutes. Wrap the wet bag with a paper towel.

3. Next, set the paper towel wrapped bag on the floor. Place a large, heavy book on top of the bag and take turns standing on the book to apply EXTREME PRESSURE to your rock.

4. Remove the book, open the bag and observe the “metamorphic rock.”

5. Break the rock in half and observe the edges.

6. Compare your “rock” with a sample of the metamorphic rock, schist. Record your comparison in your Student Journal. Complete the Metamorphic Rock section for Part I of your Student Journal.

7. Place an approximately 3 cm piece of the rock on the group paper plate labeled Rock Samples and label the section metamorphic.

Place the remainder into the small aluminum pan.

Step 5: To form the IGNEOUS ROCK

1. Put on your goggles.

2. Turn the hot plate to low heat.

3. Place the small aluminum tin with the metamorphic rock on the hot plate to MELT the rock and turn it into MAGMA.

4. While waiting, get a 500 mL glass beaker with ice.

5. When the rock completely melts to MAGMA, turn off the hot plate. Use either the tongs or a safety mitt to remove the hot tin and place the tin on top of the ice so the wax can COOL and SOLIDIFY.

Now You Try With a Shoulder Buddy