The climate of early Earth was no day at the beach, with stinging acid rains and an intensely warm surface, a new study suggests. These harsh conditions could explain why geologists today have found no rocks more than 4 billion years old: They were all weathered away.
Geologists from the University of Wisconsin-Madison examined zircon crystals, the oldest known materials on Earth, to shed light on the fate of rocks from the early Earth. Zircons, which are smaller than a speck of sand, can offer a window back in time to about 4.4 billion years ago, when the Earth was a mere 150 million years old because they are extremely resistant to chemical changes.