That Time America Almost Split In Half

That Time America Almost Split In Half

The Ancient Wound Beneath America That Never Fully Healed

About a billion years ago, America tried becoming two continents.

Enormous forces began pulling the crust apart from deep beneath what is now the American Midwest. The crack stretched for nearly 1,200 miles, from present-day Kansas, through Iowa and Minnesota, and down into Michigan.

It wasn’t caused by a single eruption…it was something closer to a volcanic tantrum that lasted millions of years. Scientists think enough lava erupted to bury Texas beneath several miles of rock.

Before the rifting stopped, insane amounts of lava poured out of the Earth’s crust, filling the rift valley with thousands of feet of flood basalts over a period of about twenty million years.

Then, just as suddenly as it began, the process stopped. It might’ve been a continental collision elsewhere that reversed the compression, but no one really knows.

The continent was literally in the middle of tearing itself apart, then changed its mind. It failed before it could form another ocean, leaving behind Lake Superior and the area’s rich copper deposits.

The entire thing is buried beneath your feet. You can even see parts of the exposed ancient lava flows in Kennesaw National Historic Park. The southern arms of the rift are entirely buried by younger sedentary rock — but can be tracked by their bizarrely strong gravity signature.

It stretched, cracked, then failed — much like some of my old relationships. Image credit: Geo.mtu.edu

The Midcontinent Rift never finished what it started. It began yanking the continent apart, poured out unimaginable amounts of lava, and carved a wound thousands of miles long. Today that scar remains buried beneath farms, forests, cities, and the Great Lakes.

Usually when rifts succeed, the evidence is destroyed or buried deep underwater. Because this rift failed, it left behind a perfectly preserved terrestrial record of how continents begin to tear apart.

It acts as a fossilized snapshot of plate tectonics; had the process been completed, the North American continent would have split into two pieces separated by a wide ocean.

The continent survived, the rift failed, and most of us go about our lives completely unaware that one of Earth’s geological near-disasters is still hiding beneath America.