Ask AI: Discuss how scientists infer that Hadean time existed.

Scientists infer that Hadean time existed by studying the geologic and chemical signatures that are present in the oldestigneous rocks on Earth. These rocks have been dated to be around 4 billion years old, indicating that they formed during the Hadean eon. The rocks also contain evidence of increased concentrations of heavy metals such as uranium and thorium, which are believed to be the result of meteorite impacts from this time period. Additionally, the composition of the rocks suggests that the atmosphere at the time was much different than it is today, indicating that the Earth had not yet developed a stable atmosphere. All of these clues help scientists infer that Hadean time existed.