In Canada, components of the earth's surface have been found for more than four billion years. The results of the research suggest that these are remnants of the land surface generated in the first hundreds of millions of years.
The practically totality of the earth's surface resulting from Earth's geological activity returns to the mantle. But there are exceptions and a few portions of land of 4,000 million years are known. On the other hand, the circus crystals that, despite passing through the mantle, remain unundone and emerge in new rocks can be even older.
This time, researchers have analyzed an area in the north of the Great Lakes. This area is composed mostly of granites of 2.7 billion years, but by its composition have come to the conclusion that they had to be created from other older rocks. Taking into account the time this process would take, and measuring samarium and neodymium isotopes of samples, it has been calculated that there is a land surface of more than 4.2 billion years mixed with 2.7 billion. The work has been published in the journal Science.