Geology Archives - Page 13 of 17

March 7, 2013August 3, 2020

Gypsum Dreams

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

Sheetrock 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

September 27, 2012July 13, 2026

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 & Copyright
Mark Larese-Casanova, Photographer

Little Cottonwood Canyon, Photo Courtesy and Copyright Mark Larese-Casanova, Photographer — Moraine with erratics
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Little 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.

June 28, 2012June 27, 2016

Cryptobiotic Soil Crusts

Click to view larger image of Cryptobiotic Soil Crust, Photo Courtesy and Copyright Mark Larese-Casanova — Cryptobiotic Soil Crust
Photo Courtesy & Copyright 2009
Mark Larese-Casanova

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

Looking out over a Utah desert, we might see relatively few plants- perhaps some sagebrush, maybe a few junipers or Joshua trees, or even some small wildflowers or cacti. What is less noticeable, though, is the living soil crust that holds this entire landscape together. It’s not just sand, but rather an important and vast partnership between bacteria, lichens, algae, and fungi. These soil crusts are often referred to as ‘cryptobiotic’, which means ‘living in suspended animation’. This is a fitting description, considering that water can be so rare in Utah’s deserts.

Cyanobacteria, which is often called blue-green algae, is the backbone of cryptobiotic soil crust. Vast networks of long, microscopic filaments of cyanobacteria and fungi grow in length when they are wet, and leave behind a casing that literally binds the soil together. So, what might otherwise be loose sand not only is less likely to be washed away by water or blown away by wind, but also is able to hold much more water for plants.

Cyanobacteria is also extremely useful to desert landscapes for its ability to take Nitrogen out of the air and make it available to plant roots in the soil. Desert soils typically have relatively low nutrients, so this is especially important to desert plants.

In many Utah deserts, cryptobiotic soil crusts can cover up to 70% of the ground surface. Old soil crust can often look like small mountain ranges with black or white peaks inhabited by lichens or mosses. The little valleys in between the tiny mountains of crust are perfect spots for the seeds of desert plants to grow. Over time, the above ground crust can grow up to ten centimeters, or four inches, thick!

However, cryptobiotic soil crust grows at an alarmingly slow rate of about one millimeter per year. So, any soil crust that is disturbed can take a very long time to recover. Depending on the amount of moisture a desert receives, it can take anywhere between 20 and 250 years for soil crust to grow back.

Next time you’re out in the desert, kneel down and have a close look at the telltale peaks and valleys of cryptobiotic soil crust. If you bring a magnifying glass, you just might be able to see some of the lichens and mosses. Be sure to stay on trail, though, and whatever you do, don’t bust that crust!

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:

US Department of Interior. 2001. Biological Soil Crusts: Ecology and Management. Bureau of Land Management Technical Reference 1730-2., https://www.blm.gov/nstc/library/pdf/CrustManual.pdf
Rosentreter, R., M. Bowker, and J. Belnap. 2007. A Field Guide to Biological Soil Crusts of Western U.S. Drylands. U.S. Government Printing Office, Denver, Colorado., https://www.soilcrust.org/

August 18, 2011February 22, 2018

Stromatolites

Hi I’m Holly Strand.

Shark Bay in Northwest Australia is on my “places to see before I die” list. In a section of the bay called Hamelin Pond, colonies of microbes form hard, dome-shaped, deposits. Called stromatolites, these structures embody one of the oldest forms of life on earth. The fossil record of microbes in older stromatolites date back 3.5 billion years. Their antiquity, abundance, and persistence to modern times make stromatolites a fascinating subject for scientific inquiry.

Basically, stromatolites are layered structures formed primarily by cyanobacteria. This photosynthesizing bacteria changes the pH of the water causing calcium carbonate to precipitate over a mat of bacterial filaments. The minerals, along with grains of sediment in the water, are trapped in a layer of goo that surrounds the bacterial colonies. Then the lower layer bacteria grows upward and penetrates the most recent mineral and sediment layer. When this process is repeated over and over, a stromatolite is formed.

For over 2 billion years stromatolites dominated the shallow seas and formed extensive reef tracts rivaling those of modern coral reefs. However, today, stromatolites are relatively rare. You will usually find them growing in extreme environments, such as hypersaline water or thermal springs.

While Shark Bay boasts a stunning example of a modern stromatolite colony, you don’t have to go all the way to Australia. When lake levels are low, you can easily see them in the Great Salt Lake. They span hundreds of square kilometers in shallow shoreline waters. Some say that the Great Salt Lake contains some of the most extensive areal coverage of living stromatolites in the world.

One of the best places to view them is from the shore near Buffalo Point on Antelope Island. When conditions are clear, you can see them underwater at the mouth of the Great Salt Lake Marina.

More than just memorials to ancient life, the stromatolites also play a vital role in Great Salt Lake ecology. They are the principal habitat for the brine fly larvae and pupae. In turn, brine flies are a critical diet for goldeneye ducks, American avocets and many other water birds.

Thanks to Wayne Wurtsbaugh, from Utah State University’s College of Natural Resources for his support in developing this Wild About Utah episode.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy Utah Division of Wildlife Resources, Wayne A. Wurtsbaugh and Linda L’Ai
Text: Holly Strand

Sources & Additional Reading:

National Park Service. Stomatolite Fossils. https://www.nps.gov/care/naturescience/stromatolite.htm [Accessed August 16, 2011]

Schopf, J.William. Anatoliy B Kudryavtsev; Andrew D Czaja; Abhishek B Tripathi. 2007. Evidence of Archean life: Stromatolites and microfossils. Precambian Research, 158. No. 3-4 pp. 141-155.

UNESCO Shark Bay Western Australia https://whc.unesco.org/en/list/578 [Accessed August 16, 2011]

University of California Museum of Paleontology. Cyanobacteria: Fossil Record https://www.ucmp.berkeley.edu/bacteria/cyanofr.html [Accessed August 16, 2011]

Walter, M R. 1983. Archean stromatolites – Evidence of the earth’s earliest benthos
Earth’s earliest biosphere: Its origin and evolution. Princeton, NJ, Princeton University Press.

Wurtsbaugh, W.A. 2009. Biostromes, brine flies, birds and the bioaccumulation of selenium in Great Salt Lake, Utah. Pp. 1-15 In: A. Oren, D. Naftz, P. Palacios & W.A. Wurtsbaugh (eds). Saline Lakes Around the World:Unique Systems with Unique Values. Natural Resources and Environmental Issues, volume XV. S.J. and Jessie Quinney Natural Resources Research Library, Logan , Utah. URL: https://www.cnr.usu.edu/quinney/files/uploads/NREI2009online.pdf