Fossil Formation

Fossilized fish
Mioplosus labracoides
Copyright 2013 Stokes Nature Center
Andrea Liberatore, Photographer

Fossilized fish
Copyright 2013 Stokes Nature Center
Andrea Liberatore, Photographer

Horn Corals from Logan Canyon
Copyright 2013 Stokes Nature Center
Andrea Liberatore, Photographer

Fossilized leaf
Copyright 2013 Stokes Nature Center
Andrea Liberatore, Photographer

Fossilized shells
Copyright 2013 Stokes Nature Center
Andrea Liberatore, Photographer

The most popular school program that the Stokes Nature Center offers is a geology lesson for second grade. I’m not sure what happens between second grade and adulthood to make our general perception of geology go from exciting to boring, but you would be amazed at how excited second graders get over rocks, and especially, over fossils.

Fossils are really quite rare – a very specific set of conditions have to be met in order to create one. Most living things decompose fairly rapidly upon death, leaving no trace of their existence behind. In order to create a fossil, this process of decomposition needs to be halted fairly rapidly, which typically means that the body is quickly covered by some kind of sediment – like sand, or soil or mud. For this reason, most fossils are found embedded in sedimentary rock. If pressure and moisture levels are just right, over the course of millions of years the organism’s molecules will slowly be replaced by minerals from the surrounding sediments – eventually turning bone into stone.

Only somewhere around one in a billion bones will make it through this process. From there the fossil has to remain intact and identifiable through eons of tectonic plate movement, earthquakes, and mountain uplift. Then, in order to be found it has to be located near enough to the earth’s surface, and in such a place where a human might come across it. Some geologists estimate that only 1 in 10,000 species that have ever lived have made it into the known fossil record, which makes me wonder what discoveries still await us.

Fortunately for us, prehistoric Utah was a place where fossilization happened with some regularity, as evidenced by places like Dinosaur National Monument and the Escalante Petrified Forest. Did you know that Utah has a state fossil? That distinction goes to the allosaurus, a predatory dinosaur that thrived during the Late Jurassic period. Numerous skeletons found in east-central Utah range in size from 10 – 40 feet in length, meaning this fearsome creature may have rivaled it’s more famous cousin Tyrannosaurus Rex for top predator status.

With such a rich fossil history, it’s not out of the question that you might stumble onto something truly amazing during a routine hike. Can you keep your find? Well, that depends on two things: the type of fossil, and whose land it was found on. On public lands in Utah, fossils of vertebrates cannot be collected, while fossils of invertebrates and plants can be. Private land owners have full rights to the fossils found on their property. With all fossils, it’s a great idea to report your find to the US Geological Survey so that your discovery can be documented for public or scientific research, display or education.

Fossil creation is an incredible phenomenon that has allowed us to glimpse the earth’s history in ways that would otherwise be completely hidden. Thanks to fossils, we can envision a prehistoric landscape filled with giant ferns, enormous dragonflies, long-necked allosauruses, and flying pterodactyls. Without the evidence in the fossil record, I doubt that even the most imaginative person among us could have envisioned such an amazing array of life.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

Credits:

Photos: Courtesy & © Stokes Nature Center, logannature.org
Text:    Andrea Liberatore, Stokes Nature Center, logannature.org

Additional Reading:

State of Utah, Utah Geological Survey, Dinosaurs & Fossils (2011) https://geology.utah.gov/utahgeo/dinofossil/index.htm

McCalla, Carole and Eldredge, Sandy (2009) What should you do if you find a fossil? Utah Geological Survey. Accessible online at: https://geology.utah.gov/surveynotes/gladasked
/gladfossil_collecting.htm

Trefil, James (1996) 101 Things You Don’t Know About Science and Nobody Else Does Either. Houghton Mifflin Company: New York, NY, https://www.amazon.com/Things-Dont-About-Science-Either/dp/0395877407

Bryson, Bill (2003) A Short History of Nearly Everything. Broadway Books. New York, NY, https://www.amazon.com/Short-History-Nearly-Everything-Illustrated/dp/0307885151

Oolites

Click to view larger image of the Utah's Oolitic Sand, Photo Courtesy and Copyright Mark Larese-Casanova
Utah’s Oolitic Sand, Photo Courtesy and Copyright Mark Larese-Casanova

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Imagine if prehistoric brine shrimp were responsible for one of the finest examples of architecture in Salt Lake City today.

Okay, so it may be a bit of a stretch, but let me explain. In a previous episode of Wild About Utah, I discussed the life cycle of brine shrimp and the important role that they play in the Great Salt Lake Ecosystem. Well, as the billions of brine shrimp feed on bacteria in Great Salt Lake, they excrete waste in the form of tiny fecal pellets. These pellets, along with sand grains and other bits of debris, eventually settle to the bottom of Great Salt Lake.

In shallow areas of the lake, where wind and waves routinely mix the water, these small particles gradually accumulate layers of calcium carbonate, forming an oolite (spelled o-o-l-i-t-e). This is very similar to how a pearl, also layers of calcium carbonate around a small particle, is formed within the shell of an oyster or mussel. The main difference, aside from a pearl being much larger, is that oolites are typically oblong, rather than round. The beaches on the west side of Antelope Island are a great place to find oolitic sand, which will look and feel as though you have a handful of tiny pearls.

Click to view larger image of the Utah's Oolitic Sandstone, Photo Courtesy and Copyright Mark Larese-Casanova
Utah’s Oolitic Sandstone
Photo Courtesy & Copyright
Mark Larese-Casanova

Around 50 million years ago, large fresh- and salt-water lakes covered parts of Utah, and in these areas, vast amounts of sediments, including oolites, were deposited. Over time, these oolites were compressed and cemented together into limestone.

A quarry near Ephraim in Sanpete County supplied oolitic limestone for the construction of the Governor’s Mansion in 1902 and the original Salt Lake City Public Library in 1905. The Library building, located at 15 South State Street, eventually housed the Hansen Planetarium and is now home to the O.C. Tanner flagship store. The building underwent an extensive restoration just a couple of years ago, and now serves as a shining example of neoclassical architecture in our capitol city.

The truth is, there are tens of millions of years separating oolitic limestone from our modern-day brine shrimp. So, we can’t exactly say that prehistoric brine shrimp were responsible for the existence of the O.C. Tanner building. But, it’s fun to imagine precious gems from around the world housed in a beautiful building constructed from the ‘pearls’ of Great Salt Lake.

Click to view larger image of the historic OC Tanner building made from oolitic sandstone (This building formerly housed the Salt Lake Library and Hansen Planetarium), Photo Courtesy and Copyright Mark Larese-Casanova
Historic OC Tanner Building
(formerly the Salt Lake Library
and later the Hansen Planetarium)
Photo Courtesy & Copyright
Mark Larese-Casanova

For Wild About Utah, I’m Mark Larese-Casanova.
Credits:

Images: Courtesy and copyright Mark Larese-Casanova

Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Utah Geological Survey https://geology.utah.gov/utahgeo/rockmineral/collecting/oolitic.htm

Utah Division of Wildlife Resources, Great Salt Lake Ecosystem Program
https://wildlife.utah.gov/gsl/facts/oolitic_sand.php

Salt Lake Brine Shrimp, https://saltlakebrineshrimp.com/harvest/

Gypsum Dreams

Gypsum Dreams: Shallow briny lagoon on the Great Salt Lake where salt deposits are accumulating. Courtesy & Copyright, David Roubik, Photographer
Shallow briny lagoon on the
Great Salt Lake where
salt deposits are accumulating
Courtesy and Copyright David Roubik, Photographer

Gypsum deposits seen off the tour route in Lehman Caves, Great Basin National Park (Along the Western Utah/Nevada border) Courtesy NPS, NPS PhotoGypsum deposits seen off the tour route in Lehman Caves, Great Basin National Park (Along the Western Utah/Nevada border)
Courtesy US NPS, NPS Photo

Sheetrock manufactured from Gypsum near Sigurd, UT by US Gypsum (USG), Courtesy USGSheetrock manufactured from Gypsum
near Sigurd, UT by US Gypsum (USG)
Courtesy USG

Gypsum sand from White Sands National Monument, New Mexico
Courtesy
Mark A. Wilson, Photographer,
Department of Geology, The College of Wooster
Public Domain
Courtesy Wikipedia

Many of us slumber nightly amid the mineral sediments of ancient oceans. The Sheetrock walls of your home are made from the marine mineral gypsum. Along with rock salt, gypsum forms as a precipitate from salty brines. In deep stagnant waters, these minerals are concentrated by settling. More commonly, evaporative precipitates accumulate beneath shallow lagoons like those of the Great Salt Lake. Long ago, under a shrinking Lake Bonneville, such evaporates produced the Bonneville Salt Flats.Gypsum Dreams

Gypsum is a pale, soft mineral composed of hydrous calcium sulfate. Both gypsum and rock salt, or halite, are geologically peculiar. Pressed under the weight of overlying rock strata, they become plastic and mobile. Gypsum and halite are light compared to other rock layers and so are squeezed upward to form massive salt domes. The arches of Arches National Park were molded by an underlying gypsum salt dome that bowed the sandstone layers above.

Gypsum can be found in diverse forms. Glass Mountain in Capitol Reef National Park consists of massive translucent slabs of crystalline gypsum, called selenite. As alabaster, it is readily sculpted and carved. Gypsum sand comprises the white dunes southwest of Fillmore Utah, as well as those of White Sands Missile Range in New Mexico. Dehydrated in kilns, gypsum becomes plaster of Paris. Most gypsum is quarried, however, to make wallboard.

Near Sigurd, gypsum-bearing strata are mined and made into Sheetrock. These strata were laid down in the Jurassic when dinosaurs roamed. You can see a surface quarry of gypsum on a hillside just east of Nephi. Precipitated in briny lagoons, buried under rocks, squeezed upward into salt domes, perhaps blown about and sculpted by wind, the gypsum in your Sheetrock walls had a long and active history whose transformative stages you can witness right here in Utah.

Credits:

Images: Courtesy David Roubik
            Courtesy US NPS
            Courtesy USG, Usg.com
            Courtesy Mark A. Wilson
Text: Jim Cane, Bridgerland Audubon Society https://www.bridgerlandaudubon.org

Additional Reading:

Ralph Walter Stone. 1920. Gypsum deposits of the United States – Issues 697-701, pages 261-283, https://books.google.com/books?id=k1CsW4ux0-kC

Ege, Carl, The amazing monoliths and “mountain” of gypsum at Lower Cathedral Valley, Capitol Reef National Park, Wayne County, Utah, Utah Geological Survey https://geology.utah.gov/surveynotes
/geosights/cathedralvalley.htm

Chronic, Halka, Roadside Geology of Utah, https://www.amazon.com/Roadside-Geology-Utah-Series/dp/0878422285

Utah’s Glacial History

Moraine with erratics, Photo Courtesy and Copyright Mark Larese-Casanova, Photographer
Moraine with erratics
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Little Cottonwood Canyon, Photo Courtesy and Copyright Mark Larese-Casanova, PhotographerLittle Cottonwood Canyon
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

It is amazing to see just how much of an impact the large amount of snowfall from last winter still has on the annual cycle of nature. Of recent note, wildflower blooms in the mountains seem to be at least 2-3 weeks behind normal schedule. Hiking through snow in late July had me thinking about colder times when Utah’s mountains were covered with ice that flowed as glaciers.

The most recent period of glaciation in Utah occurred between 30,000 and 15,000 years ago when Utah’s climate was, on average, up to 30?F cooler. At times during this period, much of the western half of Utah was covered by Lake Bonneville, which contributed tremendous amounts of moisture as snow throughout Utah’s mountain ranges. As the snow accumulated at high elevations, its sheer weight caused it to recrystallize into ice. Once the masses of ice became heavy enough, gravity pulled them down slope, carving out characteristic U-shaped valleys.

At the top of the valleys, where the glaciers formed, we can often find large, bowl-shaped cirques. In the Wasatch Range, the Little Cottonwood Canyon glacier formed at the top, creating Albion Basin, and reached the mouth of the canyon where calved icebergs into Lake Bonneville. The Uinta Mountains contained such large glaciers that even many of the mountain peaks are rounded.

As temperatures warmed during the end of the last ice age, glaciers receded and left behind large piles of soil and rocks, known as moraines. Terminal moraines at the end of a glacier’s path, can act as natural dams to create lakes. Enormous boulders, known as glacial erratics, can often be found discarded along canyons.

While glaciers don’t currently exist in Utah, there are several permanent snowfields in shaded high mountain areas. So, if you’re feeling a little nostalgic and missing that extra long winter we had this year, you still a chance to hike up above 9,000 feet and cool your toes in the snow.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Courtesy & Copyright Mark Larese-Casanova
Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.

Additional Reading:

Utah Geological Survey https://geology.utah.gov/surveynotes/gladasked/gladglaciers.htm

Parry, William T. 2005. A Hiking Guide to the Geology of the Wasatch and Uinta Mountains. University of Utah Press.

Stokes, William Lee. 1986. Geology of Utah. Utah Museum of Natural History.