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UA researcher develops new methods to reconstruct ancient landscapes

A UA geosciences researcher is using a small-scale helicopter to photograph sand dunes as he tries to improve modern methods of reconstructing past landscapes.

Jon Pelletier, a professor and researcher in geosciences, is creating models to study river and canyon formation.

In the early evolution of rivers, narrow canyons are formed and over time they expand into wider canyons. Pelletier is working with computer models that can route sediments in landscapes and explain this transformation.

Pelletier's current project involves studying the formation of sand dunes - specifically, the factors that govern the dunes' spacing.

This research will lead to a great deal of data that can potentially answer many questions that have been researched by geoscientists for years, Pelletier said.

"We have these orders of magnitude more data than anyone can analyze in a lifetime," he added.

Pelletier proposes that the three recognized scales of dunes - ripples, dunes and megadunes - are caused by variations in grain size and wind velocity.

In order to gain precision, Pelletier is planning to use a miniature, remote-controlled helicopter to study sand dunes. It would be equipped with two different cameras that would allow for better depth perception by using over-lapping fields, a method similar to that used in the human eyes.

This method will allow for a one centimeter resolution in elevation data.

With the mounted cameras, this helicopter costs about $4,500. Pelletier is currently using a smaller $300 model to practice his control skills.

This helicopter was originally designed by a man in Kingman to sell real-estate, but geoscientists quickly realized that it was an easy way to obtain high-resolution pictures.

Using standard software programs, it is possible to convert the photographs obtained by the helicopter into computer images.

This data, along with sand collections and wind measurements, may answer questions about dune formation.

The computer programs also allow for a manipulation of the data so different hypothesis and variables may be tested in attempting to determine how they may have formed.

This work will allow for the creation of superb elevation maps as well as computer models to understand formation processes.

"Ideally, what we want to do is use that (the helicopter), to create this (the topographical map)," Pelletier said.

Pelletier's sand dune research may also lead to new information about Arizona's most famous landmark - the Grand Canyon.

"One question that you might address with this (landform evolution modeling) is the formation of the Grand Canyon," Pelletier said.

The canyon was formed 5 million years ago and it is not currently known whether the plateau dropped or was raised to create the canyon.

Pelletier joined the University of Arizona six months ago, and currently teaches a geomorphology course in the fall and a field course in the spring.

Pelletier was brought to UA's geosciences department - one of the most respected programs in the country - because of his expertise in the field and his teaching abilities, said Joaquin Ruiz, geosciences department head.

"There are not a lot of trees to get in the way of geomorphology here, which is cool," Pelletier said.

Pelletier was hired after a very long, competitive process, according to Ruiz.

During the interview process, Pelletier gave a lecture about the origination of streams.

"It was one of the most fascinating lectures I have ever heard," Ruiz said.

Pelletier was originally a math student but he found geosciences to be a "more down-to-earth" field. He said he believes that this background gives him a unique perspective on geomorphological research.

He said he is fortunate to be at the UA.

"This is a great place to do geomorphology," he said. "There is a great legacy."