Two University of Arizona geosciences professors will be honored for their contributions and achievements during the Geological Society of America's annual meeting this Saturday.

Peter DeCelles, a professor of geosciences, has been selected for the Laurence L. Sloss Award, which is given to "a sedimentary geologist whose achievements contribute widely to the field of sedimentary geology and through service to GSA," according to the society. The Sloss Award is given annually to recognize the lifetime achievements of one sedimentary geologist.

Paul Kapp, an associate professor of geosciences, has been chosen to receive the society's Young Scientist Award, which is given to scientists 35 years old or younger for "outstanding achievement in contributing to geologic knowledge through original research that marks a major advance in the earth sciences."

The awards will be presented during the society's annual meeting in Houston.

"It's neat to have some recognition for things that one spends a long time doing," DeCelles said. "To receive an award like that is a strong validation of what you've been doing. It's pretty gratifying."

"The Sloss Award is recognition of Pete's research accomplishments and evidence of Pete's prominent standing in the geological community," said Karl Flessa, head of the UA's department of geosciences.

DeCelles credits some of his success to having good colleagues at the UA.

"Almost all of my work has involved strong collaborations, and I have benefited enormously from the collegiality and willingness of my students and colleagues to engage in multidisciplinary studies," DeCelles said.

His research focuses on the origins of major mountain ranges all over the world and the evolution of the sedimentary basins that form alongside them. His studies include the Himalayas, the Rocky Mountains, the Andes and the Apennines.

DeCelles studies how mountain ranges are formed by plate tectonics. The processes include giant pieces of the earth's crust colliding into each other, sliding past each other and plunging beneath each other.

As one plate dives beneath the other, the top plate scrapes sediment from the bottom plate into a huge pile, creating a mountain range. The piles of rock at the foot of the mountains are so heavy, the bottom plate flexes downward. Sediment accumulates in the resulting basin, hence the term sedimentary basin.

"Pete is extraordinarily skilled at reading the tectonic message contained in sedimentary rocks," Flessa said.

DeCelles uses structural geology and geological mapping to explain how mountain ranges and their basins developed. He takes rock and sediment samples from mountain tops and sedimentary basins to figure out the ages of the rocks and the time that certain geological processes happened. 

For almost 15 years, DeCelles has conducted fieldwork on treks that can last up to six weeks in the roadless areas of the Himalayas in Nepal.  

The steep inclines, landslides and avalanches make it extremely difficult to navigate the mountains. He said the monsoons from the Bay of Bengal "fire-hose" the mountain range, creating large, deep canyons and "gnarly, Wizard-of-Oz-type peaks."

"It's completely off the charts compared to any other mountain range on earth," DeCelles said. "Things like the Alps or Rockies, they're nothing. The Himalayas are so incredible, and there's so many big questions, and the processes are huge."

Rocks that originate at greater depths have been exposed to more heat and pressure and therefore record more processes, he said.

Rocks at the surface of the Himalayas come from depths of 35 kilometers (about 22 miles) below the surface, compared with rocks at the surface of the Andes that come from 10 kilometers (about 6 miles) deep.

Although the Sloss Award recognizes lifetime achievement, DeCelles has no plans to stop doing research.

"It's nice recognition," he said. "I take it as a sign to keep doing what I'm doing."

Kapp echoed those sentiments.

"It feels great to be recognized for my work, but I don't work for recognition at all. I work because I love it," Kapp, 34, said.

Kapp, who will receive the gold Donath Medal and $20,000, conducts research north of the Himalaya Mountains to figure out the different geological processes that formed the Tibetan Plateau.

"Paul is one of our own," said UA Regents' Professor George H. Davis, who was one of Kapp's instructors. "He received his undergraduate degree in geosciences here at UA and was exceptional; I mean, really exceptional."

Kapp's specialty is structural geology and geological mapping. Geological mapping identifies the different types of rocks and the nature of the boundaries between the rocks in order to reconstruct the geological history of the area.

He typically works on the Tibetan Plateau at elevations around 16,000 feet where the air is thin and the weather cold and windy. He and his UA research team, mostly graduate students, spend one to three months in the field at a time. 

The team also includes Chinese professors and students. Kapp also considers the Tibetan drivers an integral part of the team.

"We have this whole mix of cultures. We try to make a strong group," he said. "We're basically nurturing cross-cultural relationships in a positive way."

Despite his young age, Kapp starts any research project with a traditional approach. Initially, he makes basic field observations and maps them.  

"I'm like the most old-fashioned young geologist," he said. "It's very basic. We've been doing this forever. All you need is a pencil and a map."

Kapp has an insatiable desire to learn and discover new ideas. He considers himself more of a student of geology than a professor.

"I have also benefited from a great group of graduate and undergraduate students who keep me realizing that I first and foremost remain a student," he wrote in his acceptance speech. "Keeping me on a very steep learning curve is the geology itself."

This past year, Kapp began examining wind erosion and its effects on rock deformation and plate tectonics in the Qaidam basin, located on the northeast side of the Tibetan Plateau. One of the first steps he took was to read about wind patterns in an introductory textbook.

The Qaidam basin is shaped like a bathtub and is surrounded by mountain ranges on all sides. Many scientists believe that sediment is washing off the sides of the mountains and filling the basin, Kapp said. 

However, when he saw satellite images of the area, he recognized that a large part of the basin was not filled with sediment. Instead, part of the basin reveals folded rock that has wind-sculpted valleys and ridges called yardangs.

These enormous features are best seen from space, he said, adding that similar yardangs can be seen on Mars.

At times during the past 2.5 million years of the Earth's history, the region's climate was much colder and windier. Kapp hypothesizes those high winds eroded the rock layers above the folded rocks. The folding that results from the collision of two plates accelerated because the weight of the surface rocks was removed.

"In terms of science, it's a completely new direction to explore," he said.

Kapp will go to the Qaidam basin next spring to test his hypothesis. If he is correct, his research will provide the first documentation of the interplay between wind and the rock deformations caused by plate tectonics.