Which two types of text features are used in the passage?
2.glossary 5.index
Children sometimes talk about digging a tunnel to the other side of the world. Of course, that’s impossible! Earth’s core, or center, is almost 4,000 miles underground, which means it’s nearly 8,000 miles to the other side of the world. These thousands of miles are divided into many layers of rock. Even if someone could somehow dig deep enough, reaching Earth’s core is nearly impossible. This is because the core is so hot that it’s liquid! When Earth’s surface cooled down, it turned into a shell-like layer called the crust. The oceans and continents lie on top of this crust. Under the ocean, the crust isn’t that thick. However, below dry land, the crust is more than 50 miles deep. Underneath the crust is another layer, the mantle. The rocks in the crust and in the mantle are different. In deeper parts of the mantle, the temperature of the rock increases. At the bottom of the mantle, the temperature is high enough to melt iron. Below the mantle is a layer of melted metal. Scientists believe the metal to be iron and nickel. The metal is so hot that it is like thick syrup. This layer is known as the outer core. At the center of Earth is the inner core. This inner core is the hottest part of Earth. Thus, what lies beneath Earth’s surface is much more complicated than you’d think. It’s no wonder that it would be impossible to dig to the opposite side of the planet!
