Introduction: Layers of the Earth With Playdough
Earth, the third planet from the sun, but what do you think the Earth is made of? What is at the center?
Geologists help us figure that out! Geology is an earth science concerned with the solid Earth, the rocks which make up its composition and the processes by which they change over time. One topic geologists’ study is the layers of the earth.
For this project we will be making a playdough model of the Earth, complete with its layers.
Our Earth is made of layers. It has, overall, four layers based on chemical variations: the solid crust on the outside, the mantle, the outer core and inner core.
Crust: Earth’s outermost surface, usually made from dense, solid rock.
Mantle: The thick layer of the Earth beneath its outer crust. The mantle is semi-solid and generally divided into an upper and lower mantle.
Core: Something, usually round-shaped, in the center of an object. Earth’s innermost layer. Divided into inner and outer layers.
● Playdough (can also be made using supplies below)
○ Food Coloring
○ Mixing bowl
○ Measuring cups
● A small marble or ball
● Rolling pin
● Knife (Used only by ADULT)
● Table covering/cutting board (to protect table)
Step 1: Prepare Your Playdough
Using this link: https://www.instructables.com/id/No-Bake-Playdough/ for a large batch made for 4+ people see below for smaller batch measurements. .
Follow the directions on how to mix, but with the modified measurements below to make smaller batches per color. Remember, you might need to add more or less of each ingredient depending on your brands of supplies or what color you are mixing. Red dye makes the dough sticky sometimes, if your dough is sticky add extra flour. If your dough is dry add oil.
Medium batch For 2+ people
● ½ cup of water
● 8+ drops of food coloring
● 1 cup of flour
● ¼ cup of salt
● 2 tbs of oil
Small For 1+ people
● ¼ cup of water
● 5+ drops of food coloring
● ½ cup of flour
● 4 tbs of salt
● 1 tbs of oil
I made 6 small batches of the following colors: white (no food coloring), green, blue, red, yellow, and mixed all to make a brown. Each color will be a different layer of the earth.
Step 2: Prepare the Core
To make the inner core of your Earth, roll out your white playdough and put your small ball/marble in the middle and carefully wrap the white playdough around the ball. Remember to distribute evenly. After you have your inner core, roll out your yellow playdough, this will be your outer core! Repeat the process of wrapping playdough to make your full inner and outer core. Distribute as even as possible.
Some things about our Earth’s Core:
The Earth’s core is the very hot and dense center of our planet. The core lies beneath the crust and the mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface and is made of two layers: the outer core, which borders the mantle, and the inner core. The boundary separating these regions is called the Bullen discontinuity.
Both are hot! Very hot! The temperature of the inner core is far above the melting point of iron. The outer core has a liquid metal with very low viscosity. This means it is easily deformed and malleable.
However, unlike the outer core, the inner core is not liquid or even molten. The intense pressure of the inner core, that is the entire rest of the planet and the planet’s atmosphere, prevents the iron from melting. Because of this, some geophysicists prefer to refer to the inner core not as a solid, but as a plasma behaving as a solid.
The hottest part of the core is actually the Bullen discontinuity, where temperatures reach 6,000° Celsius (10,800° Fahrenheit)—as hot as the surface of the sun.
Step 3: Add More Layers! the Mantle and Crust.
Roll out your mantel, using red, and your crust, using brown. You will notice that your Earth is getting bigger with each layer you add, So, remember as you add layers you will need to roll them out bigger each time, making the layer thinner as you go.
Some Info about the Mantle and Crust:
Made mostly of iron, magnesium and silicon, the mantle is Earth’s thickest layer. It is dense, hot and semi-solid. The mantle forms a layer of partially melted rock known as the asthenosphere. Geologists believe this part of the mantle is what Earth’s tectonic plates ride upon and slide across.
Unlike the other layers of the Earth, the crust is extremely thin, cold and brittle. It is made of relatively light elements, especially silica, aluminum and oxygen. It’s also highly variable in its thickness. Under the oceans, it may be as little as 5 kilometers (3.1 miles) thick. Beneath the continents, the crust may be 30 to 70 kilometers (18.6 to 43.5 miles) thick. What a difference!
Step 4: Add the Ocean and Land Formations
Roll your blue playdough as big and thin as you can make it. This time, instead of wrapping the playdough, you will drape it over your crust. You can use a bowl or plate to help with this. Once your crust is draped over with the blue playdough (ocean) as much as possible.
Tear the excess blue playdough around the bottom and rotate your Earth to the uncovered crust. Using the torn blue pieces of playdough, carefully patch together to cover the rest of your Earth.
Your Earth is covered and ready for land mass! Cut your green playdough into pieces and press onto your ocean firmly to help it stick. You now have your own Playdough Earth!
Step 5: Cut Open Your Earth to See the Layers!
Ask an adult (or have an adult supervise) and carefully cut open your Earth! If you used a ball in the middle, only cut to the edge of the ball (I used a Styrofoam ball and cut all the way through).
You should see 4 layers underneath the ocean and land mass. The crust, the mantle, the outer core, and the inner core.
Remember to look at our other instructables for more science activities and experiments!
https://www.instructables.com/member/Sciencecityed/ And for more information about Science City, visit https://www.unionstation.org/sciencecity or follow us on Facebook @ScienceCityKC. Remember, to tag us or hashtag #ScienceCityKC.