By: Crystal Gammon, OurAmazingPlanet Contributor
Published: 05/04/2012 12:27 PM EDT on OurAmazingPlanet
If it's true that a lady never reveals her age, then the Sierra Nevada mountain range, with its rich wilderness and snow-capped peaks rising above California and Nevada, is quite the lady. Researchers still don't know exactly how or when those rocky summits got there.
Now, new research has uncovered a clue in this geologic puzzle. Using GPS and space radar technology, scientists found that the range — which includes Lake Tahoe and the highest peak in the contiguous United States, the 14,505-foot-tall (4,421 meters) Mount Whitney — is growing by about a millimeter each year. At this rate, the entire Sierra Nevada could have been built in just the last 3 million years, the researchers say.
"There's a surprisingly wide variety of opinions about how and why the Sierra Nevada goes up, and about the ages and timing of all the events that contribute to the uplift," said William Hammond, a geophysicist at the University of Nevada, Reno, who led the study. "These findings suggest that whatever mechanism is at play, it's acting on the entire range."
Geologists say there are two possible, and wildly different, ages for the Sierra Nevada range: either 40 million to 80 million years old, or only about 3 million years old. [50 Amazing Facts About Earth]
That's a big difference, Hammond said, because it means the mountains are either very old and no longer growing, or they're quite young and still growing at a measurable rate.
To figure out the Sierra Nevada's current growth rate, Hammond's team combined GPS data with measurements from interferometric synthetic aperture radar, or "InSAR," a type of space radar.
In this radar technique, a satellite whizzes over the Earth and uses microwave energy to take snapshots of features like mountain ranges and earthquake faults. The satellite then revisits the same spot every month or so to take more microwave snapshots. Because it can monitor large swaths of landscape over long periods of time, InSAR data is particularly useful for measuring slow and steady changes in the shape of the Earth's surface.
"Most of the seismic cycle is made up of periods of time where the Earth is not shaking, but it is deforming," Hammond told OurAmazingPlanet. "We're getting better at measuring that slow shape change as a way of understanding, for example, where the Earth might break in future earthquakes."
His team analyzed 18 years of Sierra Nevada InSAR images, along with precise measurements from GPS stations, to zero in on a growth rate of about 0.04 to 0.08 inches (1-2 millimeters) per year for the mountains.
This means the entire range, which has an average high elevation of about 6,500 to 8,200 feet (2,000 to 2,500 meters), could have been built in less than 3 million years.
How did the mountains get there?
Exactly how the Sierra Nevada range was built is still a mystery, though, and theories abound.
The mountains lie just west of the Basin and Range Province in Nevada, where east-west tectonic forces are in the process of ripping the Earth's crust apart. Some geologists think this stretching might be causing the eastern side of the Sierra Nevada to grow upwards.
Another idea comes from seismologists, who believe they see a weighty blob in the Earth's mantle that may have been attached to the base of the Sierra Nevada tectonic block. They think this dense blob used to weigh the block down, like a keel on the bottom of a ship. Then, sometime between 3 million and 10 million years ago, this keel peeled off and sank down deeper into the Earth, and the Sierra Nevada block popped up.
Whichever it was, Hammond's team found that the process affected nearly the entire range — from Lake Tahoe to the Mojave Desert — and is still building up the Sierra Nevada today.
The team's findings were published on April 27 in the journal Geology.
Copyright 2012 OurAmazingPlanet, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.