sciencetech-blog

comments

Archaeologists have uncovered one of the biggest landslides ever found on earth.

The huge collapse took place in southwestern Utah more than 21 million years ago.

It covered about 1,300 square miles, and the ground shifted 55 miles in minutes, killing animals as it went. 

The landslide took place in an area between what is now Bryce Canyon National Park and the town of Beaver, Utah. It covered about 1,300 square miles, an area as big as Ohio's Cuyahoga, Portage and Summit counties combined.

Kent State geologists had known about smaller portions of the Markagunt slide before the recent mapping showed its enormous extent.

Its rival in size, the 'Heart Mountain slide,' which took place around 50 million years ago in northwest Wyoming, was discovered in the 1940s and is a classic feature in geology textbooks.

The Markagunt could prove to be much larger than the Heart Mountain slide, once it is mapped in greater detail.

'Large-scale catastrophic collapses of volcanic fields such as these are rare but represent the largest known landslides on the surface of the Earth,' the authors wrote.

The landslide took place in an area between what is now Bryce Canyon National Park and the town of Beaver, Utah.

It covered about 1,300 square miles, an area as big as Ohio's Cuyahoga, Portage and Summit counties combined. 

David Hacker, Ph.D., associate professor of geology at the Trumbull campus, and two colleagues discovered and mapped the scope of the Markagunt slide over the past two summers.

Hiking through the wilderness areas of the Dixie National Forest and Bureau of Land Management land, Hacker identified features showing that the Markagunt landslide was much bigger than previously known.

Evidence of the slide is not readily apparent to visitors today. 

'Looking at it, you wouldn't even recognize it as a landslide,' said Hacker.

But internal features of the slide, exposed in outcrops, yielded evidence such as jigsaw puzzle rock fractures and shear zones, along with the pseudotachylytes. 

This map shows the area the landslide covered (shaded grey).It covered about 1,300 square miles, an area as big as Ohio's Cuyahoga, Portage and Summit counties combined.

The length of the landslide - over 55 miles - also shows that it was as fast moving as it was massive, Hacker said. 

Evidence showing that the slide was catastrophic - occurring within minutes - included the presence of pseudotachylytes, rocks that were melted into glass by the immense friction. 

Any animals living in its path would have been quickly overrun. 

The collapse may have been caused by the vertical inflation of deeper magma chambers that fed volcanoes.

Hacker has spent many summers in Utah mapping geologic features of the Pine Valley Mountains south of the Markagunt where he has found evidence of similar, but smaller slides from magma intrusions called laccoliths.

What is learned about the mega-landslide could help geologists better understand these extreme types of events.