Category: Geology

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Paleontological Paradise

Dinosaurs & Fossils
Photo Courtesy
Utah Geological Survey

Hi, I’m Holly Strand for Stokes Nature Center in beautiful Logan Canyon.

Mongolia, China, and United States have produced far more dinosaur fossils than any other countries in the world. And Utah is a prime dinosaur site within the United States. Scattered around Utah are several active quarries, including the world famous Carnegie Quarry in Dinosaur National Monument and the Cleveland-Lloyd Dinosaur Quarry outside of Price. Paleontologists are beginning to find that the Grand Staircase Escalante Area is another prolific boneyard. In their day, dinosaurs roamed almost all parts ofthe known world, so what makes Utah so exceptional for dinosaur discoveries?

First of all, it’s important to understand that the vast majority of dinosaurs lived and died without leaving any fossil traces. Thus, what we find today is an extremely small percentage of the total of all dinosaur matter. In order to be preserved a creature needs to be buried or frozen almost immediately upon death, Given that the world was pretty warm in the age of the dinosaurs, most of today’s fossils come from individuals that died in or near a sand dune, lake or sea and were then quickly covered by sand or mud. Dinosaurs lived in the late-Triassic, Jurassic and Cretaceous periods of the Mesozoic era –that is 225-65 million years ago. At that time, what-would-be-become Utah featured both a shallow inland sea and dunes.. So dinosaurs who lived and died here had a much better chance of being fossilized.

Once fossils are well preserved, certain conditions will increase the probability that they will be found. First of all, you want exposed Mesozoic rock, since dinosaurs lived and died in the Mesozoic era. The Morrison and Cedar Mountain Formation are both from the Mesozoic and are extremely rich in dinosaur fossils.. In fact, Utah has one of the most detailed Mesozoic rock records in the world. Certain types of sedimentary rock –including sandstones, mudstones and limestones –are most promising for fossils and Utah has plenty of these.

Another condition for good fossil hunting is a dry environment. Desert and semi-deserts are optimal for discovery, since decomposition is slowed. With little or no vegetation on the ground, wind and water erosion increases and more ancient fossils are uncovered. In this regard also, Utah is perfect, having just the right amount of water. There’s enough to cause occasional and severe erosion to expose new rock, but not enough to encourage the amount of plant growth that will anchor soil or reduce visibility of the ground.

In the past 2 decades, dinosaur discovery and research has been enjoying a renaissance with plenty of new species being unearthed.. In an upcoming episode, I”ll talk about some exciting new discoveries in our state.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:

Photo: Courtesy Geology.Utah.gov, https://geology.utah.gov/esp/paleo/images/dinodig.jpg

Text: Stokes Nature Center – Holly Strand

Sources & Additional Reading

Dodson, Peter. 1990. Counting dinosaurs: How many kinds were there? Proc. Natl. Acad. Sci USA. Evolution. Vol 87, pp. 7608-7612.

Handwerk, Brian. 2008. Amazing Dinosaur Trove Discovered in Utah National Geographic News June 17

Norman, David. 2005. .Dinosaurs A Very Short Introduction. Oxford Univ. Press

Utah Geological Survey/Dinosaurs and Fossils. https://geology.utah.gov/utahgeo/dinofossil/index.htm (accessed Sept 12, 2008)

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Are We in the Rockies?

Snow and the Rocky Mountains in Wyoming, Colorado, and Utah
Courtesy NASA Visible Earth,
Jacques Descloitres,
MODIS Land Rapid Response Team,
NASA/GSFC

Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

For awhile now, I assumed that living on a bench on the eastern edge of Cache Valley, meant that I was living on the very western edge of the Rocky Mountains. But is the Bear River Range really in the Rockies? Are the Wasatch Mountains in general?

Peakbagger.com, which features a hierarchical system of mountain range classification, says that the Utah Rockies are represented by two main mountain massifs the Uintas and the Wasatch.

But according to Halka Chronic, author of Roadside Geology of Utah, we are definitely out: The Wasatch Range, steeply faulted on its western side, was once considered to be part of the Rocky Mountains, formed in the late Cretaceous to early Tertiary period. The Wasatch is now known to be younger than the Rockies and is considered the easternmost part of the Basin and Range region. Chronic identifies Heber Valley as the easternmost basin of the Basin and Range. The Basin and Range is a huge arid region in Utah, Nevada and adjacent states. Within it, narrow north-south oriented mountain ranges alternate with valleys filled with erosional sediment.

I turned to some Utah State University geologists for help. As usual, the answer to what I think is a simple question turns out to be complicated. Sue Morgan considers the Wasatch to be the easternmost edge of the Basin and Range because the mountains were formed by normal faulting characteristic of the Basin and Range. But, she points out, that the Utah Geological Survey considers the Wasatch to be part of the Middle Rockies.

Dave Liddell says the answer to my question is a matter of scale. If you are looking at North America from space those of us on the Wasatch Front could justifiably consider ourselves located on the edge of the continental–scale Rocky Mountain system. However, the closer look, you have to start taking into consideration lots of fine scale variations and categorizations; this makes drawing a boundary between the Rockies and the Basin and Range province extremely complex. Liddell would put Cache Valley in the Basin and Range because of its formation by pull apart tectonics. The rest of the Wasatch Front is Basin and Range for the same reason. But most geologists put Bear Lake in the Rockies. So perhaps the Wasatch is a large transition zone.

Next time the subject comes up—and there’s no guarantee that it will ever come up—I’m probably going to favor the argument that the Wasatch Mountains are outside the Rockies and that most Utahns live in the Basin and Range region. But if some of you Wasatch Front residents really want to live at the foot of the Rockies, that’s fine too–you can cite the Utah Geological Survey. Now that I decided to go with Basin and Range, I’ll want to find out more about the plants and animals that live here. So you can expect to hear more about them in future programs.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:

Photo: Courtesy Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC https://visibleearth.nasa.gov/view.php?id=62272

Text: Stokes Nature Center: Holly Strand

Sources & Additional Reading

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Red Rock Country

Red Rock Country: Chinese Wall at Bryce Canyon National Park Courtesy NPS.gov https://www.nps.gov/brca/
Chinese Wall at Bryce Canyon National Park
Courtesy NPS.gov
https://www.nps.gov/brca/

Straddling the 4 corners region is a massive geologic province known as the Colorado Plateau. Varying from 5 to 10,000 feet in elevation the region covers an area larger than the state of New Mexico, and is composed of thick horizontal layers of sedimentary rock . Terrain here is flat compared with Basin and Range country to the west and the Rocky Mountains to the east. Yet wind and water have whittled Plateau rock into dramatic cliffs and steps as well as fanciful domes, towers, turrets, and arches. The Plateau is dissected by the Colorado River and its tributaries exposing a deep and colorful geologic history. A predominance of red bed deposits in the central area of the Plateau has prompted the nickname “red rock country.”

So what’s behind the spectacular hues for which Utah is so famous? The color of rock is primarily influenced by trace minerals. The red, brown, and yellow colors so prevalent in southern UT result from the presence of oxidized iron–that is iron that has undergone a chemical reaction upon exposure to air or oxygenated water. The iron oxides released from this process form a coating on the surface of the rock or rock grains containing the iron.

Just think of what happens to a nail when you leave it outside. Upon prolonged exposure, the iron in the nail oxidizes and rust is formed as a coating on the surface of the nail. So basically what we have in red rock country is a lot of rusting sandstones and shales. Hematite is an especially common mineral form of iron oxide in Utah, the name coming from the Greek word “heama” or red blood. It only takes a tiny bit of hematite make a lot of red rock.

Geologists refer to rock layers of similar composition and origin within a given geographic area as “formations.” Certain formations in Utah are especially known for their beautiful reds or pinks. The Permian Period gave us Organ Rock shale which caps the buttes and pinnacles of Monument Valley. The deep ruddy browns of the Moenkopi formation were formed in the Triassic. In the early Jurassic, eastern Utah was a vast sea of sand with wind-blown dunes. These dunes became the red bed deposits of the Wingate Formation which today forms massive vertical cliffs. Entrada sandstone, from the late Jurassic, forms the spectacular red, slickrock around Moab.

Well anyway, now you know what I’m thinking of when I hear Utah referred to as a Red State. I’m picturing the extraordinary beauty of the red, salmon and rust- brown rocks that help to form the massive geologic layer cake in the south and east of our state.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:
Photo: Courtesy NPS.gov: https://www.nps.gov/brca/
Text: Stokes Nature Center: Annalisa Paul

Sources & Additional Reading

Chan,Marjorie A. and William T. Parry Rainbow of Rocks . Public Information Series 77. Utah Geological Survey. https://geology.utah.gov/online/pdf/pi-77.pdf (Accessed July 2008)

Geology Underfoot in Southern Utah by Richard L. Orndorff, Robert W. Wieder, and David G. Futey, Missoula, MT Mountain Press Publishing Company, 2006, https://mountain-press.com/item_detail.php?item_key=366

Chronic, Halka. Roadside Geology of Utah. Missoula, MT Mountain Press Publishing Company, 1990 https://mountain-press.com/item_detail.php?item_key=48

Fillmore, Robert, The Geology of the Parks, Monuments and Wildlands of Southern Utah, University of Utah Press, 2000, https://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/upcat&CISOPTR=1328