The tests used to determine whether brain stem death has occurred are outlined below: 1  A torch is shone into both eyes to see if they react to the light. 2  The cornea (transparent outer layer of the eye), which is usually very sensitive, is stroked with a tissue or piece of cotton wool to see if the eye reacts.
The inner core extends another 900 miles inward towards the center of the Earth. It is believed that this inner core is a solid ball of mostly iron, and nickel. The mantle is made of much denser, thicker material, because of this the plates float on it like oil floats on water.
The Earth is made out of many things. Deep inside Earth, near its center, lies Earth's core which is mostly made up of nickel and iron. Above the core is Earth's mantle, which is made up of rock containing silicon, iron, magnesium, aluminum, oxygen and other minerals. The rocky surface layer of Earth, called the crust, is made up of mostly oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium. Earth's surface is mainly covered with liquid water and its atmosphere is is mainly nitrogen and oxygen, with smaller amounts of carbon dioxide, water vapor and other gases.