Recently, researchers at Monash University and the University of Queensland in Australia found that the first continents on earth should have been born 3 billion years ago, 500 million years earlier than the previous research estimated < p > as we all know, the land we live on only accounts for 30% of the total area of the earth's surface, and the rest is covered by oceans. But billions of years ago, the earth was almost a "water world", and the birth of the first continents can be regarded as the most critical moment in the history of earth's life. They have become the humble habitat of land life < p > by studying the age of rocks in the oldest continental fragments in India, Australia and South Africa, researchers found that the sand that shaped these rocks formed the world's earliest beach about 3 billion years ago < p > when the continents rise to the sea level, they begin to be eroded, and the rocks are broken down into sand particles, which are washed downstream by the river and accumulated along the coastline to form beaches. This process lasted billions of years. By searching rock records and looking for signs of ancient beach deposition, researchers can study and confirm the formation period of continents in the distant past < p > < / P > < p > an ancient continental crust in the east of the Indian subcontinent. The singhbhum craton contains several ancient sandstones. These strata were initially formed from sand deposited on beaches, estuaries and rivers, and then buried and compressed into rock < p > by studying the microscopic particles of minerals called zircon preserved in these sandstones, researchers can determine the age of these sediments. This mineral contains trace amounts of uranium and is very slowly converted to lead by radioactive decay. This allows researchers to estimate the age of these zircon particles using a technique called uranium lead dating, which is very suitable for dating very old rocks < p > zircon particles show that singhbom sandstone was deposited about 3 billion years ago, making them one of the oldest beach sediments in the world. This also shows that at least 3 billion years ago, there was a continent in India. In addition, in the oldest ancient platforms in Australia and South Africa, researchers also found sedimentary rocks of about this age, indicating that many continents may have appeared in the world at that time. (small) < / P > < p >