In the interior of the Earth

In the interior of the Earth, both temperature and pressure increase with depth. Scientific analysis of mining activities and geothermal gradients confirms that temperature rises as one moves from the surface toward the core [2]. The average geothermal gradient in the crust is approximately 25-30°C per kilometer [2]. This heat is primarily generated by the radioactive decay of elements like uranium and thorium, as well as residual heat from the Earth's formation [3]. Simultaneously, pressure increases significantly due to the weight of the overlying rock layers, known as overburden pressure [4]. For example, temperatures in the mantle range from 200°C at the crustal boundary to nearly 4,000°C at the core-mantle boundary [5]. While some specific oceanic contexts might show localized temperature decreases in water columns [6], the geological interior consistently exhibits rising temperatures and pressures with increasing depth [7].

Sources

1. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 2: The Origin and Evolution of the Earth > Indirect Sources > p. 19
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > How is it captured > p. 295
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > The Force Behind Endogenic Movements > p. 79
4. [4] https://www.sciencedirect.com/topics/engineering/overburden-pressure
5. [5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > The Mantle > p. 54
6. [6] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 12: Water (Oceans) > Horizontal and Vertical Distribution of Temperature > p. 104
7. [7] https://pubs.usgs.gov/gip/dynamic/inside.html