Geothermal gradient
Topic: Interior of the Earth: Earthquakes, Volcanoes and the Layered Earth · NCERT: Class 11, Ch 3 "Interior of the Earth"; Class 11, Ch 5 "Geomorphic Processes"
Meaning
The geothermal gradient is how fast temperature rises as you go deeper into the earth. In the upper crust it is about 25-30 °C per km. Deeper down it slows, and the centre of the earth is about 5,000-6,000 °C. The heat comes from inside the earth. Differences in this heat flow drive endogenic processes, the forces that work from inside the earth, such as diastrophism (the bending and breaking of the crust) and volcanism. The gradient is one of the indirect clues to what the interior is like.
Example
The gold mines of South Africa go only 3-4 km deep, because below that the rock is too hot for people to work in. The Kola Superdeep Borehole in Arctic Russia found about 180 °C at a depth of about 12.2 km. That was far hotter than scientists expected.
Related concepts
- Direct sources of information about the interior
- Indirect sources of information about the interior
- Kola Superdeep Borehole
- Gravity anomaly