New England, like the rest of the eastern United States, does not contain any active volcanoes in the present era. However, the White Mountains region of New Hampshire contains strong evidence of volcanic activity approximately 145 million years ago. Volcanic formation in the White Mountains has been estimated to have occurred between the late Jurassic and early Cretaceous periods, and would have coincided with the separation of Pangaea. As Pangaea broke apart and land masses were shifting, large features like the White Mountains were formed; at the same time, as this multitude of cracks was occurring, magma rose up and filled many of these voids. In this manner calderas were formed throughout the White Mountains as magma receded; these calderas then subsequently erupted on a scale dwarfing the 1980 eruption of Mount St. Helens. The results of these massive eruptions can be found in such places as the Ossipee Mountains, which are located proximal to the White Mountains. The Ossipee Mountains contain substantial amounts of volcanic rock, and the many ring dikes across the region indicate that there was once an active volcano on the site. Volcanic rocks can also be found throughout the White Mountains beyond the Ossipee region, further confirming that eruptions occurred across the area millions of years ago.