Convection currents, which move the tectonic plates, are found in which layer of the earth?

Convection currents, the primary driving force behind the movement of tectonic plates, are located in the Earth's mantle [2]. These currents are generated by thermal differences and geothermal gradients caused by radioactive decay and internal heat [3]. Specifically, these currents occur within the asthenosphere, which is the upper, semi-solid, and viscous part of the mantle [6]. As material near the core-mantle boundary heats up, it becomes less dense and rises toward the surface. Upon reaching the base of the lithosphere, these currents diverge, exerting a pulling force or tension that moves the overlying lithospheric plates [6]. This process, known as Convection Current Theory, was pioneered by Arthur Holmes in the 1930s to explain the mechanism of plate tectonics [4].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 7: Tectonics > Convection Current Theory (CCT) > p. 98
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 7: Tectonics > 7.4. Plate Tectonics > p. 102
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. [5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > 4.1. The Internal Structure of The Earth > p. 52
5. [6] https://education.nationalgeographic.org/resource/plate-tectonics/
6. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 7: Tectonics > 7.5. Comparison: Continental Drift – Seafloor Spreading – Plate Tectonics > p. 109