SEP 18, 2019 12:27 PM PDT

The history behind Navajo sandstone

New research published in the journal Geology sheds light on the early history of the picturesque Navajo Sandstone. The swirling red and tan sediment that graces postcards of the southwestern US in Arches, Canyonlands, Capitol Reef, and Zion national parks was here long before the people that have inhabited its landscapes. But what can these beautiful rocks teach us about the future of our deserts?

Scientists hoping to gain insight on the process of desertification used carbonates and correlation of rock layers to determine age dates. Desertification refers to the process by which fertile lands become desert and it may be stating the obvious, but understanding that process is particularly relevant in our current climate crisis.

The geologists were able to figure out the numerical ages of the sediments in the biggest known sand sea (erg) during the Early Jurassic in southern Utah using a radiometric method of uranium-lead (U-Pb) to look at calcium carbonate rock layers. The layers come from lake deposits that once were in interdune areas, where there were watering holes for dinosaurs and small theraspids (relatives of mammals). The numerical ages that they found were 200.5 ± 1.5 million years (Ma) and 195.0 ± 7.7 Ma.

What do those numbers mean? Basically, that parts of the Navajo desert in eastern Utah are a lot older than we thought. And that when we look at other age dating information that we have from Arizona, we can see that the giant sand sea (erg) became younger to the south. And to add to that, as Science Daily reports, “The lake and associated spring deposits also show that this vast desert, at times, had a wetter climate and more active hydrologic cycle than had been previously assumed.”

Geologists hope to discover more about Navajo sandstone like this, which was found in Canyonlands National Park. Photo: Pixabay

All in all, it’s pretty neat that scientists are able to use sand deposits in order to understand what the land went through millions of years ago. Questions like, “How did this landscape lose its water bodies, vegetation, and animals? How long did desertification take to happen? How long did it last? What amount of time is actually represented by these deposits?” are now suddenly a lot clearer…although many questions remain.

Although the researchers were studying what happened to the land and groundwater long, long ago, they believe that their findings can help act as a model for the continental interior hydroclimates of today. We already know that the predicted rise in temperatures will put more stress on arid regions, as well as make semi-arid and non-arid regions even more dry. The authors say that marginal zones are especially vulnerable, pointing towards places in Africa and Asia that have so many people living on the land, such that the land cannot keep up with food and water demand. They hope their conclusions can be used to extrapolate from the Navajo erg to better understand desertification around the globe.

Sources: Science Daily, Geology

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
OCT 21, 2019
Earth & The Environment
OCT 21, 2019
Lightning strikes in the Arctic
The US National Weather Service has reported some unusual weather in the Arctic circle. The NWS station in Fairbanks, Alaska, detected several lightning st...
OCT 21, 2019
Plants & Animals
OCT 21, 2019
This Mantis Uses Kung Fu Stances to Intimidate Predators
Virtually all mantids are known to science as carnivores, but perhaps unsurprisingly, some other creepy crawlies, such as jumping spiders, will also try to...
OCT 21, 2019
Earth & The Environment
OCT 21, 2019
What to expect from the Climate Action Summit
The climate summit is just around the corner and Greta Thunberg isn’t the only one gearing up for the event. Since Thunberg’s arrival on the ze...
OCT 21, 2019
Earth & The Environment
OCT 21, 2019
Get ready for it to be hotter and drier
New research published in Proceedings of the National Academy of Sciences (PNAS) highlights a recently discovered feedback mechanism that is going to make...
OCT 21, 2019
Plants & Animals
OCT 21, 2019
Watch a Hungry Polar Bear Respond to an Opportunity to Eat
Polar bears necessitate lots of food to ensure their long-term survival, but many times, hunting prey isn’t easy. It’s estimated that one in tw...
OCT 21, 2019
Earth & The Environment
OCT 21, 2019
Researchers Discover "Stormquakes"
Researchers have discovered a new geophysical occurrence—the “stormquake.” A stormquake occurs when a hurricane or similarly strong storm...
Loading Comments...