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's outer core is most likely made up of an iron-nickel alloy while the inner core mostly iron and a bit of nickel and cobalt. This is due to inferences that iron, cobalt and nickel are denser than other materials found at different levels in the structure of Earth, such as magnesium in the mantle. The outer core is made up of liquid iron and nickel, along with lighter elements such as sulfur and oxygen. The inner core is made up of solid nickel and iron, and contains heavy and radioactive elements as well. There are two parts to the Earth's core: the inner and outer core.