A new analysis of ancient minerals called zircons suggests that earth's earliest continents were probably destroyed by an extremely harsh climate. Zircons, the oldest known materials on earth, offer a window in time back as far as 4.4 billion years ago, when the planet was a mere 150 million years old. As these crystals are exceptionally resistant to chemical changes, they have become the gold standard for determining the age of ancient rocks, ScienceDaily reported.