ROCKY RELICS: AN UNKNOWN CHAPTER OF EARTH'S PAST

Canada's Hudson Bay has revealed a treasure: it may contain the oldest known rocks on Earth.

- ABHIJEET KABAD

A study of streaky gray rocks from the Nuvvuagittuq Greenstone Belt dates them to 4.16 billion years ago. These rocks are remnants of the Earth's earliest crust, which formed around 4.57 billion years ago. Scientists dated the rocks using two methods based on the decay of radioactive isotopes. These techniques analyzed ancient magma trapped inside the rocks, helping determine their age.

Earth began as a ball of molten lava. During its first 600 million years—known as the Hadean Eon—it cooled, forming small pockets of solid rock. The Hadean lasted from about 4.5 billion to 4.03 billion years ago, a period marked by asteroid bombardments and the formation of the Moon.