The heat produced by geothermal energy is created by the interaction between the molten mantle of the Earth and the Earth's crust. When this heat breaks through the crust it erupts in the form of steam, water geysers or lava.
When the Earth was formed, a large amount of energy was released. This energy is responsible for the tightly bound molecules of iron and nickel that form the Earth's core. This inner core is surrounded by a liquid outer core made of the same elements, which extends for about 1,410 miles. The outer core is surrounded by another liquid layer called the mantle, which extends to about 1,790 miles. This mantle has an average temperature of about 3,300 degrees Fahrenheit. The Earth's crust was formed by the cooling of the topmost layers of this mantle. All the land on earth and the ocean floor consists of this crust.
Geothermal energy is produced by the interaction of the crust with the heat of the molten mantle under it. This intense heat sometimes breaks through the thin parts of the crust. These become known as hot spots. Hot spots on dry land release the heat through lava in volcanic eruptions. When the mantle's heat comes into contact with water in oceans, lakes or rivers, it causes geothermal hot springs or geysers of boiling water or steam. Sometimes minute cracks in the Earth's crust can cause water in lakes and springs to be continually heated by geothermal energy.