geothermal gradient

American  

noun

1. the increase in temperature with increasing depth within the earth.

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Etymology

Origin of geothermal gradient

First recorded in 1935–40

Example Sentences

That's called the geothermal gradient.

From National Geographic

The typical geothermal gradient increases at a rate of just 30 °C per kilometre below ground, and a shallow borehole that the team drilled nearby in 2011 had a gradient of twice that.

From Nature

Both these methods depend on how fast the earth is losing heat, that is on the geothermal gradient.

From Project Gutenberg