Earth's internal temperature increases with depth towards the core, a well-established geophysical fact demonstrated by geothermal gradients and borehole thermometry.
The claim states that Earth's internal temperature increases with depth towards the core. This is a fundamental geological fact taught at an introductory level and supported universally by borehole thermometry, geothermal gradients, and geodynamics (as reflected in multiple geothermal papers). Consequently, it is classified as common knowledge requiring no citation.