Frequent impacts prevented solid crust formation
Recent geophysical simulations indicate that during the Hadean eon the young Earth endured a relentless barrage of asteroid collisions. The kinetic energy released by these events penetrated deep into the mantle, raising surface temperatures substantially.
Radiogenic heating added to the thermal budget
In parallel, the decay of radioactive isotopes generated additional internal heat. The synergy of external impact energy and internal radiogenic heating kept the planet in a largely molten state for several hundred million years.
Consequences for continent development
Under such conditions a thick, stable crust—necessary for later continental growth—could not develop. Instead, the surface remained liquid or only thinly solidified, postponing the emergence of sizable landmasses.
Implications for early Earth history
These findings clarify why the first continents appeared only after the Hadean and illustrate how frequent extraterrestrial events can shape the geological evolution of nascent planets.