Scientists have discovered methane gas bubbling from the seafloor in an unexpected place: off the East Coast of the United States where the continental shelf meets the deeper Atlantic Ocean.

The methane is emanating from at least 570 locations, called seeps, from near Cape Hatteras, N.C., to the Georges Bank southeast of Nantucket, Mass. While the seepage is widespread, the researchers estimated that the amount of gas was tiny compared with the amount released from all sources each year.

In a paper published online Sunday in the journal Nature Geoscience, the scientists, including Adam Skarke of Mississippi State University and Carolyn Ruppel of the United States Geological Survey, reported evidence that the seepage had been going on for at least 1,000 years.

They said the depths of the seeps suggested that in most cases the gas did not reach the atmosphere but rather dissolved in the ocean, where it could affect the acidity of the water, at least locally.