No one has dug deep down enough to be sure, but scientists think the Earth is made up of 4 layers of rock and metal. The outer one is a layer of solid rock called the crust. Below it we find the mantle, this is solid at the top, but melts down as we go deeper because of the heat. Next is what we call the outer core and it is made up of hot liquid metal. At the center we find the inner core, which is solid metal. Scientists have worked this out by studying earthquakes.
Life on Earth only exists within the top layers of the crust. No one can dig a tunnel to the other side of the Earth because it is very hot inside. The temperature inside the core is over 9000o F (5000o C).
Under the continents the Earth’s crust is almost 40km (25 miles) thick. Under the oceans it is only 8km (5 miles) thick. The hard top layers of the crust are split into large pieces, called plates. These plates have been moving very slowly for millions of years, and have moved the continents around.
© 2005 Al Bawaba (www.albawaba.com)
