Massive Crater 3x Larger Than the Grand Canyon Discovered in the U.S.

Imagine a crater so massive it could swallow the Grand Canyon three times over. Now, what if I told you this behemoth lies hidden beneath the United States’ own backyard?

That’s right, the Chesapeake Bay Crater, spanning a whopping 52.8 miles in diameter and 0.8 miles deep, has been lurking under Virginia’s coastal plain for 35 million years.

The Chesapeake Bay Crater

The Chesapeake Bay Crater’s story begins 35.5 ± 0.3 million years ago when a massive bolide, estimated to be around 1.86 miles wide, slammed into the shallow shelf on the western margin of the Atlantic Ocean at a speed of approximately 11.1 miles per second.^(ref)

The impact unleashed an explosion equivalent to millions of nuclear bombs, vaporizing the bolide, fracturing basement rock to depths of 5 miles, and raising a peak ring around the crater.

The entire circular crater is an area twice the size of Rhode Island, and nearly as deep as the Grand Canyon. However, numerical modeling techniques indicate that the post-impact diameter was likely around 24.9 miles rather than the observed 52.8 miles.

The crater is one of the best-preserved “wet-target” impact craters in the world.

Shaping the Landscape & Waterways

The impact’s effects were far-reaching and long-lasting. Within minutes, millions of tons of water, sediment, and shattered rock were cast high into the atmosphere for hundreds of miles along the East Coast. An enormous megatsunami likely engulfed the land and possibly even reached the Blue Ridge Mountains.

The crater’s formation disrupted coastal aquifers, altering groundwater flow and salinity. The present freshwater aquifers lie above a deep salty brine, remnants of 100- to 145-million-year-old Early Cretaceous North Atlantic seawater, making the entire lower Chesapeake Bay area susceptible to groundwater contamination.

Rivers like the Susquehanna, once flowing southeast to the Atlantic, were diverted northeast into the crater depression. Over millions of years, erosion and sea-level rise conspired to obscure the crater’s surface expression, but its influence on the landscape remained. 

Its long-lasting topographic depression helped predetermine the course of local rivers and the eventual location of the Chesapeake Bay itself.

A Window into Earth’s Past

Beyond its geological significance, the Chesapeake Bay Crater offers a unique window into Earth’s tumultuous past. The crater’s buried layers hold valuable clues about the impact event and its environmental consequences.

The impact has been identified as the source of the North American tektite field, namely the Georgiaite and Bediasite fields. 

By studying the crater’s structure, rock fragments, and ejecta layer containing tektites and shocked quartz grains, scientists can piece together a detailed picture of that fateful day 35 million years ago and its aftermath. This knowledge not only enriches our understanding of Earth’s history but also helps us better prepare for potential future impacts.

A Global Perspective

While the Chesapeake Bay Crater is an awe-inspiring testament to the power of cosmic collisions, it is far from alone. Earth bears the scars of numerous impact events, from the 186-mile-wide Vredefort Crater in South Africa to the 0.75-mile-wide Barringer Crater in Arizona. Each of these craters tells a unique story of our planet’s dynamic past and the forces that have shaped it over billions of years.

By studying these cosmic scars, we gain a deeper appreciation for the interconnectedness of Earth’s systems and the role of celestial events in our planet’s ever-evolving story.