Question

what happens to temperature in earth the deeper in earth

Answer 1

Temperature generally increases as you go deeper into the Earth — this is called the geothermal gradient — but the rate and details depend on depth and location.

Key points
- Near-surface (crust): temperature rises fairly quickly with depth by conduction. Typical continental values are about 20–30 °C per kilometer (average ~25 °C/km). So at 1 km you might be ~20–30 °C warmer than surface; at 5 km a few hundred °C warmer.
- Lithosphere vs. mantle: the rigid lithosphere (crust + uppermost mantle) conducts heat. Below it, the mantle convects, and heat follows a near-adiabatic profile rather than the steep conductive gradient. That means temperature continues to increase with depth but the rate (°C/km) is smaller.
- Typical deeper values (approximate ranges):
- ~100 km depth: ~1,000–1,400 °C (upper mantle / asthenosphere beginning)
- 410 km and 660 km: phase-transition depths in the mantle where mineral structures change and temperatures are roughly 1,500–2,000 °C (varies)
- Core–mantle boundary (~2,900 km): ~3,000–4,000 °C (estimates vary)
- Inner core center: ~5,000–7,000 °C (comparable to the surface of the Sun in some estimates)
- Local variations: temperatures are higher near magma chambers, mid-ocean ridges, and mantle plumes (hotspots), and lower in cold subducting slabs. Geothermal gradients can be much steeper in volcanic or hydrothermal areas.

Why it gets hotter
- Leftover heat from Earth’s formation (accretion and core formation)
- Radioactive decay of elements in rocks (U, Th, K)
- Heat released by crystallization of the core and other internal processes

How heat moves
- Conduction dominates in the crust and near-surface rocks.
- Convection dominates in the convecting mantle (solid rock flows over long times).
- In some places fluids (groundwater, magma) transport heat rapidly.

Consequences
- Increasing temperature controls rock strength (brittle near surface, ductile at depth), melting (volcanism), and supports geothermal energy resources.

If you want, I can show a simple temperature vs. depth plot with typical numbers for continental crust and mantle, or give numbers for a specific location.