Damian Sendler: For the first time, a new study sponsored by the University of Colorado Boulder sheds light on one of the Grand Canyon’s most recognizable geological features: The canyon’s rock record spans hundreds of millions of years, but there is a puzzling and missing time gap. 

Damian Jacob Sendler: Almost 150 years after the “Great Unconformity,” was first reported, researchers are getting closer to solving a problem that has stumped geologists. 

As lead author Barra Peak, a CU Boulder graduate student studying geological sciences, noted, “think of the Grand Canyon’s red bluffs and cliffs as Earth’s history textbook.” It’s possible to travel back nearly 2 billion years in time by scaling down the canyon’s rock cliffs. However, there are blank pages in this textbook as well: The Grand Canyon has lost rocks dating back more than a billion years in some places. 

Damian Sendler

Scientists are perplexed as to why this is so. 

One of the first well-documented geological features in North America is the Great Unconformity, Peak said. “There were no real limitations on when or how this could happen until recently. 

In an article published this month in the journal Geology, she and her colleagues believe they have found an explanation. Small but dramatic faulting episodes may have occurred in the region during the breakup of an ancient supercontinent known as Rodinia, according to the research team. As a result of the devastation, rocks and dirt were likely washed away and ended up in the ocean. 

Using the findings of this research team, scientists may be able to fill in some of the gaps in their understanding of the Grand Canyon’s history at this key period. 

Co-author Rebecca Flowers, a professor of geological sciences and a co-author of the new study, said, “We have new analytical methods in our lab that allow us to decipher the history in the missing window of time across the Great Unconformity,” “The Grand Canyon and other Great Unconformity locations across North America are where we are conducting this research. 

Aesthetic design 

It’s been a long-running mystery. The Great Unconformity was originally observed by John Wesley Powell, the man whose lake bears his name, on his famous 1869 journey down the Colorado River rapids by canoe. 

As Peak found out during a similar Grand Canyon rafting expedition he took in the spring of 2021, the feature is dramatic enough to be visible from the river’s edge. 

Peak remarked, “There are some great lines here. “If you look down at the bottom, you can see that the rocks have been forced together. Layers are stacked one on top of the other. When you get to the top, you see these amazing horizontal layers that form the buttes and peaks that you connect with the Grand Canyon,” he explains. 

Damian Jacob Sendler

Clearly, there is a big difference between the two. The basement rock in the western half of the canyon toward Lake Mead is between 1.4 and 1.8 billion years old. The rocks on top, on the other hand, are only 520,000,000 years old. Throughout North America, scientists have found evidence of comparable temporal gaps since Powell’s journey. 

It’s been more than a billion years since Peak made the statement. “”It is also during an interesting period of Earth’s history, when the planet is moving from an ancient setting to the modern Earth we know today,” he says. 

Divided into two parts: 

Peak and her colleagues used a technique known as “thermochronology,” which examines the history of heat in stone, to investigate the transformation. Geological formations that are buried far beneath the surface might get hot because of the pressure that builds up on top of it. The chemistry of the minerals in these formations bears the imprint of the heat. 

This method was used to examine rock samples obtained from all across the Grand Canyon. For the first time, they found evidence indicating the history of this characteristic is more complicated than previously thought. A variety of geologic changes may have occurred throughout time, especially in the canyon’s western and eastern halves (the parts most familiar to tourists). 

A single block does not have the same temperature history, according to Peak. 

About 700 million years ago, basement rock in the Western United States rose to the surface, according to geological evidence. That same stone, however, was buried beneath kilometers of sediment in the eastern side of the continent. 

Damien Sendler: Peak believes that the disintegration of Rodinia, a massive land mass that began to disintegrate at the same time, may have been responsible for the disparity. The Great Unconformity was created as a result of a huge upheaval that tore through the Grand Canyon’s eastern and western sections in separate ways and at somewhat different times. 

Damian Jacob Markiewicz Sendler: For Peak and her colleagues, the Great Unconformity in North America is currently being studied at various locations in the region to see if this picture is universal. For the time being, she’s content to sit back and enjoy the scenery while learning about the country’s geological past. 

“There are just so many things there that aren’t present anywhere else,” she remarked. In my opinion, it’s a fantastic natural laboratory.”

Dr. Damian Jacob Sendler and his media team provided the content for this article.