New technology captures 3-D views of Twin Sisters formation

A new technology is giving the world a fuller view of a famous set of local twins.

When you take a closer look at the state-of-the-art image of the two sisters, you can’t help but notice they are not truly identical. One is a little wider and more weathered.

Then again, most twins of their class aren’t identical. But there aren’t many in their class.

That’s because these twins are rock formations in western Walla Walla County above the Columbia River, basaltic towers known as the Twin Sisters.

There are at least two other similar sets of geological twin sisters in the United States — one in Mississippi and the other in Idaho.

The Idaho pair, it turns out, really aren’t twins because one sister is believed to be 100 times older than her younger sibling.

And the Mississippi towers don’t look anything alike.

Perhaps that is why neither of them was chosen as the subject of a new 3-D imaging technique being developed by Whitman College assistant geology professor Lyman Persico.

“I really like the Twin Sisters because it has both cultural and geological significance,” Persico said during a phone interview last week, while taking a break from a summer geology field trip in the Adirondacks of New York.

The Twin Sisters — the subject of Persico’s new 3-D image — are the same age, are made of the same stuff and are in the same spot they’ve stood exposed for some 10 millennia.

Located just off Highway 730 in the Wallula Gap National Natural Landmark, the Twin Sisters rock formations — also known as Two Sisters on some maps — jut up to form a landmark that has been known and used by local inhabitants for eons.

Last month, Persico posted what is believed to be the first-ever 3-D image of the Twin Sisters — and possibly the first large-scale 3-D geological image captured with a high-definition camera carried by a drone.

“We have had to learn how to do this because there are no instruction books,” Persico said, adding they are still “fine-tuning” their technique.

The fine tuning has included taking images of a flat subject to contrast with the techniques used for high-relief subjects.

Being a Whitman professor, for his flat 3-D subject Persico chose Whitman’s Ankeny Field. But it’s the majestically rising Twin Sisters that are getting all the attention.

“Really, as geologists, we are very much interested in changes of elevation,” Persico said, adding in particular “how rocks break down” to form elevation.

The Twin Sisters, he said, was the perfect subject.

Formed during the last of the great Missoula Floods more than 10,000 years ago, the Sisters have been a landmark for Native Americans and settlers, and they have Native American folklore connected with them.

To get his 3-D image of the sisters, Persico made two runs with the drone camera — one at 164 feet and the second time at 262 feet above the peaks.

Also captured in the image was Persico’s car at the base of the Twin Sisters.

Once the images were captured, Persico headed back to his Whitman lab, where it took a beefed-up computer with 64 gigabytes of RAM about 16 hours to create the image, viewable online at a 3-D image sharing site: bit.ly/2bhXnse.

“For geologists, what this does is provides us with a baseline,” Persico said, adding the image can be used to study erosions or find earthquake faults.

But it can also be used to plan a hiking trip or enjoy the beauty and intrigue of how geological structures are created.

“You can kind of look at it from a natural history perspective of how they formed and why they look the way they do,” he said.

The geologist plans to release another 3-D image this fall, with the subject being the Mojave Desert.

As for other twins, so far there are no plans to take images of the Twin Sisters of Palisades State Park in Mississippi or the Twin Sisters of City of Rocks National Reserve near Alamo, Idaho, both of which pale in comparison to the Twin Sisters of the Wallula Gap.

“We are in the perfect part of the world to do something like this,” Persico said, “and I have had great support from Whitman.”

This story was originally published August 18, 2016 at 4:30 AM with the headline "New technology captures 3-D views of Twin Sisters formation."