Researchers Explain the 'Curious Bend' in Appalachian Mountain Chain

A new study explains why the Appalachian mountain chain bends in Pennsylvania and New York State.

The Appalachian Mountains, also called the great highland system of North America, run nearly 1500 miles along the eastern part of the U.S. The range is a straight line from Alabama to Newfoundland, but bends Pennsylvania and New York State. Now, researchers from the University of Rochester, have an explanation for this turn.

Millions of years ago, a dense, underground block of rigid, volcanic rock forced the chain to shift eastward, researchers said.

According to Cindy Ebinger from the University of Rochester, scientists knew that there was volcanic rock beneath the range.

"What we didn't understand was the size of the structure or its implications for mountain-building processes," she said in a news release.

The research team also included Margaret Benoit, an associate professor of physics at the College of New Jersey, and graduate student Melanie Crampton at the College of New Jersey

Data for the study came from Earthscope project, which makes use of 136 GPS receivers along with 400 portable seismometers located in the northeast United States. The project is funded by the National Science Foundation.

Researchers also used data from the American Gravity Database, which is a collection of data from the U.S. and its neighbours Canada and Mexico. This data has information about gravitational pull over North American terrain. According to researchers, contrary to popular belief, gravitational pull varies depending on the location from where it was measured. The difference is due to the variation between density and thickness of the Earth's rocky layers.

According to the researchers, the North American and African continental plate collided some 300 million years ago. The collision led to folds in the North American plates as it was pushed westwards into the underground rock structure. The underground rock structure is what is now known as the northeastern U.S. The dense rock acted as a barricade and forced the Appalachian mountain range to form with the bend.

The two datasets helped researchers develop a model that explains the curious bend in the Appalachian Mountains ranges. Researchers estimate that the underlying volcanic rock is dimensions of 450 kilometers by 100 kilometers.

Ebinger said that the study was "foundation study" that will help scientists understand Earth's underlying structure. The research could also provide information about the possible challenges associated with hydraulic fracking in the region.

The study is published in the journal called Earth and Planetary Science Letters.