Geography Reference
In-Depth Information
Figure 6-1:
A
cut-away view of
the Earth.
The composition and temperature of Earth's interior are the reasons nobody has ever gone there and
probably never will. Most of that realm is molten or almost molten. Thankfully, not only is it out of
sight and out of mind, but also out of touch. Were it not for the insulating crust, life as we know it
simply would not exist.
Directly beneath the lithosphere lies the
asthenosphere
. Measured in the thousands of degrees
Fahrenheit, its rock assumes a plastic, almost molten quality. Directly beneath the astheno-
sphere is a vast volume of somewhat stronger rock and below that liquid iron of the outer core
and solid iron of the inner core that is hotter still (as shown in Figure 6-1).
Altogether, that vast volume of incredibly hot stuff is a powerful source of pressure — tectonic force.
Indeed, it is mighty enough to create and rearrange continents, and in the process build mountains
and cause earthquakes to occur and volcanoes to erupt. This knowledge has been available for only a
couple of decades. But the idea of a force powerful enough to move continents has been around for
centuries.
