Multiple ancient volcanic ash beds (the lighter color on the cliff) are exposed at Scotts Bluff National Monument in Nebraska.
Research by Huiming Bao, a geologist at Louisiana State University, at Scotts Bluff and surrounding areas found the remains of eruptions deposited in layers of rock from volcanoes located on North America's northern high plains. These volcanos spewed massive amounts of sulfate aerosols into the atmosphere 40 million years ago.
"Combining measurements of the sulfate in ancient volcanic ash beds with a detailed atmospheric chemistry model, we found that the long-ago chemistry of volcanic sulfate gases is distinct from that of more modern times," said Bao. "This is the first example showing that the history of massive volcanic sulfate emissions, and their associated atmospheric conditions in the geologic past, may be retrieved from rock records."
This research was funded by the National Science Foundation's Division of Earth Sciences. To read more about this study, see the Epoch Times news story Ancient North American Volcanic Eruptions Were More Explosive. (Date of Image: 2005)
Credit: Huiming Bao, Louisiana State University