Geography
The Role of Geothermal Gradients in Continental Crustal Heat Flow
Quick fact
On average, continental geothermal gradients increase about 25-30°C per kilometer of depth, but in volcanic regions they can be much steeper, reaching 40°C or more per kilometer.
Why this is interesting
Mine shafts get hotter the deeper you go, but have you ever wondered why? And why does the temperature rise faster in some places than in others?