Ogres, Onions, and the Earth
Ogres, onions, and the Earth are really all one in the same…if you think about it. Ogres and onions have layers just like this very Earth that we live on! You might think that you are standing on a giant pile of rocks, which is probably true, but the below all of those rocks there are even more layers to our magnificent planet.
Now let’s start with that pile of rocks we were talking about, geologists (scientists who study the Earth and its processes) call this outermost layer of the the Earth our crust. Just like a pizza, but probably not as tasty and definitely not as cheese! We have two different types of crusts here on Earth: oceanic and continental. Oceanic crust is the layer of rock that sits beneath our big beautiful oceans. This layer is made up of basalt, an igneous rock formed the cooling of lava. Basalt rock is composed mostly of silica, magnesium, and iron. This crust ranges from roughly 3 to 5 miles in thickness. Our continental crust on the other hand, is made up mostly of granite, an igneous rock formed from the cooling of magma. Granite rock is composed mostly of silica, aluminum, potassium and calcium. This crust can is made up of valleys and mountains so it can reach thicknesses up to 25 miles! Much like how our pizza crust is broken into different slices, Earth’s crust is broken into pieces we call tectonic plates. We have seven major, large, plates and many minor, small, plates, that pieced together make up the crust of our Earth.
As we continue to peel back the layer of our Earth we make our way to the mantle. Unlike a mantle you might find in your house above your fireplace, this mantle is viscous, meaning it moves around like a thick liquid, maybe even a little jelloy! The viscosity, or jelloyness, of the mantle allows heat to travel in convection currents, just like an oven. Convection currents occur when hotter matter rises, pushing down cooler matter, which is heated and the process continues. Our tectonic plates which rest on top of our mantle move as these currents circulate. Our mantle is composed of silica, magnesium, and iron, similar to the rocks found in our crust. This layer is very important as it makes up 80% of Earth volume and is roughly 1,800 miles thick!
Next we have Earth’s core which, just like an apple core is located in the middle of our Earth. Our core is divided into two parts: the outer core and the inner core. The outer core is made of liquid iron and nickel and is about 1,400 miles thick. While the inner core is composed of solid iron and nickel and has a radius of about 760 miles. The iron in Earth’s core generates 90% of the Earth’s magnetism.
Just like ogres and onions beneath each layer is another one, containing new questions and discoveries. The more layers we peel back the better we are able to understand the Earth we live on!
Earth’s layers- https://phys.org/news/2015-12-earth-layers.html