The sequoia trees of California's Sierra Nevada mountain range are obvious marvels. But according to new research, an unlikely and far-off source deserves a significant portion of the credit for allowing them to stand tall. The mineral that helps trees grow, phosphorus, is actually found in short supply in the granite formations of the region, so scientists have wondered how the monster trees were able to thrive, reports Seeker. Researchers, however, had a theory involving dust. To see if their theory was correct, they collected dust from four sites of varying elevations in the Sierra Nevada mountains—using a trap consisting of a bundt cake pan filled with marbles on a six-foot-tall post—then studied its isotopes to determine where the dust originated.
Of no surprise, especially as the study took place in the middle of California's drought, was that the majority of dust came from the state’s Central Valley, per Popular Science. But 20% of dust at the lowest elevation and 45% at the highest elevation came from Asia—more specifically, the Gobi Desert—and carried more phosphorus than the area's bedrock. Researchers explain specks of dust fly around the world at high elevations, falling only when they hit something. This dust was already known to replenish the soil of tropical ecosystems as rainfall washes nutrients away. But this study suggests dust is also "fertilizing way more of the world than we had ever anticipated," says the study author. "Without tiny particles from Asia," Popular Science notes, California's sequoias might be lost. (The trees may still be in danger.)