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Like Pages in a Book: Utah’s Geologic History

BYU geology professor Dr. Thomas Morris is developing paleographic maps to understand how Utah’s geology has changed over millions of years.
Dr. Tom Morris.jpg

Utah used to have ocean front real estate. But that was 325 million years ago. One of the areas of research for Dr. Thomas Morris in the Department of Geological Sciences is developing paleographic maps, or “geological snapshots,” to understand how Utah’s geology has changed from then to now.

The process for creating these paleographic maps is complex and requires extensive field and library research. Morris and his students go all over Utah examining the layers of sedimentary rock. The San Rafael Swell, located eighty miles outside of Arches National Park, is an especially good location because it does not require them to do any digging. The layers of the earth are readily visible with little vegetation obscuring the rocks.

“There is a pile of sedimentary rock on the Colorado Plateau, and those rocks have been folded over big uplifts and then eroded, and that’s what the San Rafael Swell is,” Morris said. “The sedimentary rocks would be the pages of the book as to what the earth looked like . . . [so] you get a peek into that stratigraphic record and therefore the history of Utah.”

The Swell is approximately seventy-five miles by forty miles, has spectacular scenery, and is a popular location for outdoor enthusiasts. Morris, who has been studying these rocks for more than twenty years, said the research process takes time.

“It’s based on a lot of work examining stratigraphic sections. We don’t dig; we let Mother Nature do the digging in the exposure. We go to where the rocks are exposed, and then we measure them and take pictures and study bedforms and rock types.”

One purpose of these maps is to better predict where oil reserves are in Utah, but that is not the entire reason Morris and his students develop these maps.

“Our purpose wasn’t strictly to find oil and gas. We’re not out there trying to find oil and gas fields. We’re trying to understand the depositional system of everything that was going on around the state,” Morris said. “If you understand that, then you can get much more predictive [in spotting gas fields]. So we’re trying to give the oil and gas people tools so that they can then explore and drill oil and gas wells.”

In studying the exposed rock samples, Morris has found evidence that there was oil in certain areas of the Swell in the past. However, most of the oil is no longer there, but traces of its presence can still be found. Recently, Morris and his students were studying a section of rocks on the southeastern flank of the Swell, and they could see that some of the sandstone was very grey. Morris shaved a thin section of the rock and looked at it under a microscope.

“Tar was in the pore spaces of the sandstone, which means that at some point in its geologic past when it was buried, it was an oil reservoir,” Morris said.

As exciting as these discoveries are, Morris said the best part of his job is seeing his students go on to be successful in their careers post-graduation.

“They turn into your kids. You work with them for two and a half years—even longer when they’re your undergraduate students—and you get to know them as a person,” Morris said. “A lot of my students have been very successful, and it’s just rewarding. It’s rewarding to work with them on a daily basis.”