During Earth’s very early history, our planet was crashed by meteorites large and small, and eventually grew to its current size. Earth probably went through a period in which it was molten from near the surface to its center. Throughout its history, Earth has been hotter at its center than at its outer surface
In caves just below Earth’s ground surface in continental crust, the temperature tends to be a constant That’s why people use caves for wine storage. The deepest mine on Earth is currently the Mponeg gold mine just southwest of Johannesburg, South Africa, which reaches just over 4 km below the surface. At the bottom of that mine, the rock temperature reaches. Using the cave temperature to represent the surface temperature of the crust at depth, what is the rate at which temperature changes in Earth between 0 and 4 km—the near-surface geothermal gradient?
Celsius/km:
The temperature at the bottom of the lithosphere in Earth is often inferred to be around If we assume a depth to the base of the lithosphere of 100 km, what is a reasonable estimate for the geothermal gradient between 0 km and ~100 km?
Celsius/km
c. The center of Earth at an average depth of 6371 km below the surface has a temperature that has been estimated to be approximately What is the average geothermal gradient from Earth’s surface to its center?
Celsius/km:
Write a brief statement of a hypothesis you think might best explain the variation in the geothermal gradient within Earth.