How to Study Earth
geology, core sampling, sequence, layer
Earth and Life History Unit
Did you know you are walking on stories? The crust of our Earth can tell us about times past: what the land used to look like, what lived here, and how the ground you are standing on right now has grown and changed over millions of years. The answers to the past are buried beneath your feet. All you have to do is dig.
It isn't easy to see the stories that rocks have to tell. It is easier to see things in the dirt. You could look at the ground in a forest to see where deer have walked, where a river has dried up, and where a tree has tipped over and died. It's much harder when mud turns into rock and then is buried deep beneath the earth. Some stories will be easy to see, like fossils, but other things take many years to figure out. Geology is the science that studies the history of our Earth through rocks. If you were to find some blocks of salt and some shells buried in rock, what would you think had been there? An ocean, of course. See? You are almost a geologist already.
The Grand Canyon - the ultimate study in geology.
Let's make a cake. Let's go crazy and make a chocolate, raspberry, vanilla, and strawberry cake. Why not? We'll pour it into a tall round pan so the batter won't leak out everywhere. We'll pour in the chocolate first, then the raspberry, and then the vanilla. Oops! You drop your comb inside! That's okay, we'll eat around it And at last, we pour in strawberry. This last flavor is like the earth that is right under your feet. One layer was added on top of the next until the last layer. The last layer is the soil that you are standing on now. A sequence is the order in which something happens. As far as the earth (or our cake) goes, the newest is on top (strawberry) while the oldest is on the bottom (chocolate). Yum.
Now, let's bake the cake. You can think of this as the millions of years it takes for the dirt beneath your feet to turn into rock. For every minute we spend baking, we can think of it as a million years of pressure on the dirt. When you take it out of the oven, you will see all the parts we put into the cake. They are no longer the liquid that they were when we poured them in. They have grown very hot and then very cold, becoming solid, just like the dirt you are standing on. A layer is one of many things that are stacked on top of each other. At the top is the pink layer, then a white layer, then a red layer and at the bottom is the dark brown layer. Just like in the cake, as we move farther down the earth's layers, we find new things. Let's go ahead and spread some frosting on top of our layers of cake. This frosting is kind of like the layers of sand, dirt, and snow that sit on the top layer of the earth.
Now comes the fun part: cutting the cake! Slice it with a knife and set one piece on a plate. Look at it from the side. You can see all the layers. Oh! There's the comb buried in the vanilla. That will be our fossil. When geologists study the earth, they can't just use a knife because the earth is made up of rock and is not very soft. They use a circular drill that's hollow in the center. It's kind of like cutting off the top of a soda can and plunging it into our cake. Core sampling is when we drill out a piece of rock from the earth that shows many layers. The sample is shaped like a cylinder or a fatter, longer can of soda. These are the rocks they use to read the past. The lowest parts are mud or sand that gathered, settled, and then became hard, just like in our cake.
Core samples are like a slice of earth's history.
Geology is the study of rocks in order to see the Earth's past. Cakes are not exactly the same, but they can be a faster, softer way to see how the layers of the earth came to be. Instead of a seven inch cake slice, the pieces of earth we dig up can be as deep as seven miles! And instead of taking minutes to bake, the Earth took millions of years to form. And there's no question that our cake is a lot tastier.
Kids Geo. "The Earth - Inside Out." Kids Geo, 2011. <http://www.kidsgeo.com/geology-for-kids/0019-inside-of-earth.php>
Science Kids. "Geology for Kids." Science Kids, 2012. <http://www.sciencekids.co.nz/geology.html>
Learner. "Interactives - Dynamic Earth: Earth's Structure." Learner, 2013. <http://www.learner.org/interactives/dynamicearth/structure.html>