On average every 15 million years between 2.5 and 3.5 billion years ago, the early Earth had asteroid collisions equivalent to those that extinguished the dinosaurs. This translates into a number of impacts ten times higher than what had been previously calculated .
This is what a new study presented at the Goldschmidt geochemistry conference suggests, which also indicates that some of these asteroids would be the size of cities or even small provinces.
Chemical evolution of the surface
Earth’s early years were unimaginably violent compared to today. Scientists believe it was hit by a significant number of large asteroids (over 10 km in diameter), which would have had a significant effect on the near-Earth surface chemistry and its ability to host life. The researchers are also studying the effect the impacts may have had on the evolution of the planet’s surface chemistry .
The huge impacts spewed molten particles and vapors that then cooled and fell to the ground to embed themselves in the rock as small spherical glassy particles, called spherules. Researcher Simone Marchi , from the Southwest Research Institute, in the United States, explains that they have developed:
A new model of impact flow and we have compared it with a statistical analysis of the data from the old layer of spherules. Using this approach, we found that current models of Earth’s first bombardments seriously underestimate the number of known impacts, as recorded by spherule layers.