What America Really Looked Like When Sea Levels Were 400 Feet Lower Than They Are Today?

20,000 years ago, sea levels were roughly 400 feet lower than they are today—and the map of America looked dramatically different. Vast stretches of today's ocean floor were dry land, while immense ice sheets covered much of northern North America. In this Planet Beneath documentary, we explore what America really looked like during the last Ice Age and reconstruct the coastlines that disappeared as the oceans rose. Discover how lower sea levels exposed the continental shelves along the Atlantic coast and Gulf of Mexico, why ancient rivers crossed landscapes that now lie underwater, and how the Bering Land Bridge connected Alaska with Asia. We also examine the powerful geological and climatic forces of the Last Glacial Maximum, when enormous ice sheets trapped enough water to reshape the world's shorelines. As the climate warmed and glaciers retreated, rising seas flooded coastal plains and river valleys, helping create the bays and estuaries we recognize today. From submerged river channels off North Carolina to the once-exposed land near Cape Cod, evidence of this vanished geography is still preserved beneath the ocean. Subscribe to Planet Beneath for more documentaries about American geology, prehistoric landscapes, Earth history, and the hidden forces that shaped our planet. #AncientAmerica #IceAge #SeaLevelChange #Geology #PlanetBeneath 🌎 Welcome to Planet Beneath — The Secrets of Earth Run Deep. Discover the extraordinary forces shaping our planet, from powerful earthquakes and volcanic eruptions to shifting tectonic plates, ancient continents, and mysterious geological formations. At Planet Beneath, we explore Earth's hidden history through immersive, science-based documentaries that reveal the fascinating processes taking place above and beneath the surface. Explore the mysteries of geology, Earth's interior, natural disasters, ancient landscapes, and billions of years of planetary evolution. 🔔 Subscribe to Planet Beneath for fascinating Earth science documentaries and incredible discoveries about the world beneath our feet. Planet Beneath — The Secrets of Earth Run Deep. #PlanetBeneath #Geology #EarthScience