Why do we know that the geothermal gradient near the surface ...

[ashley]

Why do we know that the geothermal gradient near the surface cannot continue very deeply into
  Earth? What will be an ideal response?

Question 2

What is Earth's average density, what are the average surface rock densities, and what does this tell us
  about the interior of Earth? What will be an ideal response?

[dmurph1496]

Answer to Question 1

If the geothermal gradient near the surface continued at depth, the temperature at only 100 km depth
would be so high that all known rocks would melt despite the high pressure.

Answer to Question 2

Earth's average density is 5.5 g/cm3, surface rocks range between 2.5 and 3.0 g/cm3, and, therefore, the
interior must be denser than the crust.

[ashley]

Thank you

[dmurph1496]

No problemo