Geology Reference
In-Depth Information
Heavy metal: The earth's core
At the center of the earth is its
core.
Scientists have not been able to sample it directly,
but based on their laboratory experiments and interpretations, they believe the core is
composed of massive, heavy metal elements such as nickel and iron. The core itself has
two layers:
Inner core:
The inner core at the very center of the earth is probably solid and
starts at approximately 5,150 kilometers (about 3,200 miles) from the earth's sur-
face.
Outer core:
Surrounding the inner core is a liquid layer of heavy metals called the
outer core.
The study of seismic waves and shadow zones allows scientists to de-
termine that the outer core begins at approximately 2,890 kilometers (1,795 miles)
into the earth.
There is no way to measure the temperature of the earth's core. Scientists called
geo-
physicists
use laboratory studies of iron under conditions of extreme pressure to estim-
ate how hot it may be at such depths. Their estimates range from 5,000 degrees F to
15,000 degrees F. More accurate measurements cannot be made because the conditions
of temperature and pressure at the earth's core are much too intense to be recreated in
a laboratory setting.
Flowing and solid: The earth's mantle
Outside the earth's metal core is a layer of rock composing the
mantle.
Mantle rocks are
made of minerals that combine light elements (such as silica and oxygen) with heavier
elements (such as iron and magnesium).
