If the Earth were an onion, peeling away each layer would reveal an amazing new material the deeper and deeper you get. You would find a variety of rock, flowing magma, and a metallic inner core. Our planet’s interior is full of mysterious substances and behaviors.
Geophysicists study the layers and find a lot of evidence about the formation of the Earth. This evidence is important if we want to preserve life on our delicate planet. So I designed this article to be a guide to our layers of the Earth felt board and if you’d like the printable 3-part Montessori cards you can find them here.
By the end, you and your child will gain a new understanding of our planet and how our learning materials can assist you. You’ll get some great resources and activities for continued study too. I’m certain it will inspire your kids to learn more about our wonderful world.
The majority of the information here is academic and at times a bit dense, but I did my best to put it into layman’s terms. The activities are ideal for kids in many age groups, depending on the child’s affinity for science.
How to use our felt boards and cards
First, lay out all the felt pieces, put the cards into separate baskets, and start with a conversation. Use the information below as a guide. It’s a simplified scientific explanation of the layers and their compositions. Once you have gone through this section you can start with the puzzle and cards.
How did they find the layers?
Man has never actually seen all the layers of the Earth. In fact, the deepest we have ever penetrated is 12.2 kilometers (7.6 miles) at the Kola Superdeep Borehole in Russia. But, the Earth is around 13,000 Km (8,000 miles) in diameter, so peeking inside is sure to uncover some mysteries.
The actual way we know anything about the layers of the Earth is due to the discovery of seismic waves. They are sound waves that come from volcanic eruptions, earthquakes, and ocean currents.
There are two types of seismic waves: a pressure wave and a shear wave. A pressure wave can move through both liquid and solids, and a shear wave can only travel through solids. This is what has helped geologists deduce that the Earth is actually a mix of solid and liquid layers.
Many believe these layers are quite simple. There’s a core, a mantle, and a crust. But this assessment would be an oversimplification. Scientists have created subdivisions that kids should profit from. But what are these divisions?
Chemical vs. Mechanical layers
Geologists discovered that pressure and temperature influence the behavior and properties of Earth’s layers. So they made these subdivisions: chemical and mechanical. They based these divisions on their fundamental properties and compositions.
But what’s the difference between mechanical properties and chemical composition?
Here’s an example to illustrate:
Water and oil have the same mechanical properties, a liquid state. Water and ice have the same chemical composition, H2O, but one is a liquid and the other a solid. So materials can have the same chemical composition yet different mechanical properties. This’s what’s happening in the Earth’s interior.
With a range from 5 to 70 kilometers the crust is the outermost layer of the planet. There are two types of crust: the oceanic crust and the continental crust. The ocean floor is thinner but harder and made of basalt. The continental crust contains softer rocks, like granite.
Reaching depths of 3 kilometers the mantel is the thickest of the interior layers. As with the core, it has two subdivisions: the upper and lower. They both contain silicate rocks that are rich in magnesium and iron. Though they are both solid, the upper mantel is more elastic due to high temperatures. The rock in the lower mantle is rigid because of the intense pressure.
Most geophysicists postulate that this part of the core has the metals nickel and iron in it. Though there is no direct evidence to back it up, seismic wave behavior helped determine this based the speed that waves pass through metal.
In contrast to the outer core, many scientists believe that the inner core has a variety of metals. This is why our puzzle has two chemical cores.
The outermost mechanical layer of the planet contains both the crust and the top of the mantel. It’s put together like a giant puzzle, with what’s called tectonic plates. These plates wander and change the surface of the planet over time. Their movement causes things like earthquakes, volcanic eruptions, and continental drift.
The asthenosphere is the soft layer of the mantel on which the lithosphere glides. Although it is a solid material, the high temperature makes it pliable, like chewing gum.
Otherwise known as the lower mantel, the mesosphere is the layer above the outer core. It’s different from the asthenosphere because of the intense pressure at this depth. There is still some movement of molecules here, but it’s quite restricted.
The outer core is molten metal due to its high temperatures and chemical composition. It’s the only true liquid within the Earth’s interior. Since the outer core is metal and liquid geophysicists believe its flow is responsible for the magnetic field that protects our planet.
Even with temperatures as hot as the surface of the sun, the metals of the inner core are completely solid. This is the result of the pressure that exists at about 6,400 Kilometers depth.
Below is a graph that gives you an idea of what depths and temperatures exist when we talk about these layers. It’s not hard to understand the immense pressures down there when you see this graph.
The layers depths and temperatures
Source: Temperature with depth in the Earth, By Bkilli1 creativecommons.org
via Wikimedia Commons
Using our materials, continued
As mentioned above, it’s important to go over this information before you break out our felt boards. It’s a complex topic with lots of chemistry and geology involved. So the more you lay the groundwork, the better their understanding will be.
Use the above definitions when you present a new card. Get your kids familiar with each layer’s properties before matching them to the felt. If you’re unfamiliar with Montessori 3-part cards, this is an in-depth article on the process.
More activities and resources [Disclaimer: As an Amazon Associate I earn from qualifying purchases at no cost to you from the affiliate links below]
There are so many resources on this topic that it’s hard to know which is the best. But the link below is in my opinion is the best at describing the activity with a wonderful result.
This is a fun messy <Earth layers activity> that gets the kids to be hand’s on with their learning. Soap is a wonderful alternative for those tired of always using play-doh. Once the soap is made they have a tool they can use while bathing or washing hands to reinforce the learning.
This activity is for arts and crafts lovers. It requires lots of drawing, cutting, and assembly. In the end, your little ones will have a load of fun learning this fascinating topic.
This wonderfully illustrated book is perfect for kids. It’s full of beautiful drawings, scientific background, and fun facts about our planet and its mysterious interior. It’s a must-read for science lessons.
This model of the Earth’s layers is a classic and can help in any lesson. It’s a foam cross-section that shows the four main compositional layers.
This fun geology set lets the kiddos get hands-on with their learning. They get to form the layers with moldable clay and even find rare gems stones while they go digging!