Earth’s continents are like giant rocky rafts floating on a thick, solid-but- slowly-flowing layer, so “how deep is it below the continents” depends on what layer you mean and where you measure.

Continental thickness in a nutshell

  • The continents themselves (crust plus the uppermost rigid mantle, called continental lithosphere) are typically about 150–200 km thick, and can reach roughly 250–300 km beneath the oldest, most stable continental interiors called cratons.
  • Beneath that lithosphere is the asthenosphere , a hotter, weaker part of the upper mantle that can flow very slowly over millions of years.

So if you stand on a continent and ask “how deep is it below the continents until the next major layer?”:

  • From the surface down to the base of the continental lithosphere : ~150–200 km in most places, up to ~300 km beneath old cratons.
  • From the surface down to the core–mantle boundary (where the rocky mantle gives way to the liquid outer core): about 2,900 km.
  • From the surface down to Earth’s center : about 6,371 km.

Layer-by-layer below a continent

Think of it as stacked shells under your feet:

  1. Continental crust
    • Thickness: ~30–50 km on average; under big mountain ranges it can exceed ~70 km.
 * This is the granite-rich, lower-density rock that makes continents “float higher” than ocean basins.
  1. Uppermost mantle (lithospheric mantle)
    • Extends from the base of the crust down to ~150–200 km depth in many continental regions, deeper under cratons.
 * Together with the crust, this forms the rigid tectonic plate.
  1. Asthenosphere (upper mantle, weaker zone)
    • Roughly from ~100–200 km down to about 400–660 km, with exact depths varying by region.
 * Rocks here are solid but hot and weak enough to flow very slowly, allowing continents and ocean plates to move over geologic time.
  1. Lower mantle
    • From about 660 km down to ~2,900 km depth.
 * Solid but extremely hot, under enormous pressure; convects on long timescales and helps drive plate tectonics.
  1. Outer core and inner core (much deeper but still “below the continents”)
    • Outer core (liquid iron–nickel): ~2,900–5,150 km depth; motion here generates Earth’s magnetic field.
 * **Inner core** (solid iron–nickel): ~5,150 km down to Earth’s center at ~6,371 km depth.

Why depth varies from place to place

  • Old, stable continents (cratons) have especially thick, cold lithosphere that can reach ~250–300 km deep, so “how deep it is below the continent” to the softer asthenosphere is greater there.
  • Younger, tectonically active regions often have thinner lithosphere (closer to ~100–150 km), so the transition to the weaker mantle is shallower.

Put simply, below a continent you have tens of kilometers of crust, then around a hundred or more kilometers of rigid mantle, then thousands of kilometers of deeper mantle and core before ever reaching Earth’s center.