“They may have documented [the United States’] oldest known rock,” he says, “but the challenge to young readers will be to discover an even older rock.” Frost agrees. The 3.8-billion ...

The oldest rock in the United States has been discovered in Michigan, with zircons dating back 3.82 billion years.

The Search for America’s Oldest Rock: The Watersmeet Gneiss The new title-holder for the oldest rock in the United States is the Watersmeet Gneiss in Michigan, which dates back 3.6 billion years ...

"Taken together, the Archean rocks of the Wyoming-Minnesota-Michigan block represent the oldest continental crust in the United States, the nucleus around which the younger rocks of the nation ...

"Taken together, the Archean rocks of the Wyoming-Minnesota-Michigan block represent the oldest continental crust in the United States, the nucleus around which the younger rocks of the nation ...