Prehistoric rain: The 1,000-foot-deep secret under the Great Plains that took millions of years to build

Beneath America's seemingly simple Great Plains lies a colossal underground freshwater body, the High Plains aquifer, larger than California. This "invisible ocean," primarily the Ogallala formation, sustains the region's fertility and agriculture. However, this vital resource faces immense strain, with water levels declining rapidly in some areas, threatening the heartland's future.