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More than bodies: Lake Mead gives up a 12 million year discovery

Volcanic ash revealed in dwindling Nevada reservoir

SHARE More than bodies: Lake Mead gives up a 12 million year discovery
A buoy sits high and dry on cracked earth previously under the waters of Lake Mead.

A buoy sits high and dry on cracked earth previously under the waters of Lake Mead at the Lake Mead National Recreation Area near Boulder City, Nevada, on June 28, 2022.

John Locher, Associated Press

The shrinking waters of Lake Mead are giving up her dead. It is more than just a mob-driven hit of a body in a barrel, sunken boats or stark white shorelines suffering from a lack of water from the shrinking Colorado River.

Now it is volcanic dust that tells the tale of what happened 12 million years ago, deposited from Idaho, Wyoming and California that rained down on southern Nevada in a time we cannot even imagine.

What it means: The Colorado River is shriveling due to drought and diversions. The U.S. Bureau of Reclamation has taken drastic steps to save its flows and all seven states in the Upper and Lower Colorado River basins that share its resources are trying to arrive at solutions.

In the interim, the stark reality of drought and a drying Southwest is giving ominous signs of what nature can tell man about its past, or about the earth’s gyrations when it comes to adjusting to climate.

What the research shows: Those sedimentary rocks have not been visible at Lake Mead since it started to fill in the 1930s. A new report by the University of Nevada, Las Vegas peels back the layers of what generations have been missing.

Some revelations:

  • Ash from even moderately explosive eruptions can travel hundreds of miles from the source, blanketing entire areas with anywhere from a centimeter to several meters of the heavy material.
  • Even a couple of millimeters of ash, when wet, is incredibly heavy and can take down power and telecommunications lines and block roadways. When inhaled, the incredibly tiny but sharp glass grains in the ash can cause significant chronic lung conditions such as silicosis.
  • UNLV’s team says studying the ash layers helps determine how often the Las Vegas area was inundated with ash over time, and may help prepare for future events from active volcanoes from far away.

Eugene Smith, an emeritus professor at UNLV, said the study provides revealing insights into the geography of the West.

“It is pretty exciting,” he told KSL NewsRadio, adding that the low levels at Lake Mead prompted the study.

Smith said the researchers found “rock ash outcrops” deposits descended on Lake Mead hundreds of miles away, adding to the science.