Sierra Nevada than expected

California's Sierra Nevada, an impressive mountain range that includes the popular Yosemite National Park, has done a great job of keeping its age a secret. But now a new study provides evidence that it's at least 40 million years old.

Scientists conducted a chemical analysis of ancient raindrops found in the Sierra during the California Gold Rush in the mid 1800's.

They figured out at what elevation a drop fell by looking at its molecules. In nature, hydrogen and other atoms can come in variations with slightly different masses.