Interesting facts about the mirabilite spring mounds near Great Salt Lake Marina

What are these white mounds and when did they form?

In late October 2019, as air temperatures started to cool to near freezing, unique mineral mounds began forming on the south shore of Great Salt Lake, just east of the Great Salt Lake Marina. They are not composed of common table salt (sodium chloride—NaCl), but mirabilite (hydrated sodium sulfate—Na2SO4•10H2O), also known as Glauber’s salt.

How do mirabilite mounds form?

When the sodium-sulfate-rich spring water hits the cold winter air, mirabilite crystals form and build up a collection of small terraces, similar in appearance to the travertine rimstone and dam terraces that form at Mammoth Hot Springs in Yellowstone National Park.

What conditions are needed for the mounds to form?

In the 1940’s, researchers investigated this area and reported finding a 3-6 foot thick mirabilite layer 30 inches down in the subsurface. Groundwater seems to be partially dissolving this mirabilite layer, which is then reprecipitated at the surface as the spring water emerges. Additionally, mirabilite is most stable and precipitates in sub-freezing dry environments. When temperatures rise above freezing, the impressive clear mirabilite crystals that form the mounds will dehydrate to form a white, powdery, easily eroded mineral called thenardite (Na2SO4). Furthermore, the mounds will only form if the area (at about 4194 ft) is above lake level, a rare occurrence until the past few years.

Why are there multiple mounds?

It is hypothesized that as the mounds grow, they eventually seal off their spring water source, causing the groundwater to find a new pathway to the surface, and thus, a new mound begins to form a few dozen yards away. As of January 2020, the beach has four mounds that have grown up to 3 feet tall and several yards wide.

How rare are mirabilite mounds?

The mineral mirabilite is quite common and found in saline lakes around the world, including the north arm of Great Salt Lake. In saline lakes, mirabilite crystals form in the water column, float to the surface, and are washed ashore to form an amorphous, slushy slurry or dune-like accumulations of crystals. However, spring-fed crystalline mirabilite mounds are rare―they have never before been scientifically documented at Great Salt Lake. Mirabilite-precipitating springs and the formation of terraced mounds have been documented in the Canadian Arctic, central Spain, and the Antarctic. These features are ephemeral; warmer spring temperatures will eventually turn the mirabilite to the powdery, easily eroded thenardite, if the rising lake level doesn’t erode the mounds first. These features may or may not reform again next winter.

Is there a Mars connection?

While Mars has conditions conducive to the formation of mirabilite (dry, cold, etc.), the mineral has not yet been documented there. Mars does have topographic mounds that some researchers believe may be related to saline groundwaters. In addition, orbital spectrometers have suggested the presence of sulfates on the surface. Because of these similarities, some researchers are interested in the growth of mirabilite mounds on Earth because they may serve as analogues for understanding geologic processes on Mars.

Don’t tread on me.

These mirabilite mounds are fragile and researchers are still actively studying them. Please do not walk on the mounds or collect samples. Besides, mirabilite is unstable at temperatures above freezing and dehydrates to form a white powder (thenardite), so the samples would not last more than a day.



Riverdale landslide now just 6.5′ from home

RIVERDALE, Utah (News4Utah) Some Riverdale homes are closer than ever to falling off the edge of a steep bluff. New measurements taken this week show it’s likely to happen sooner rather than later.


Op-ed: The clock is ticking until Utah faces a major natural disaster

While hurricanes were devastating Texas, Florida and Puerto Rico, fires were wreaking havoc in California and other global natural disasters were delivering widespread destruction, some here in Utah expressed relief to live in a place where we do not face such devastating natural hazards.


Man excavating Utahraptor herd turns to public for donations

LEHI — Scott Madsen has been working on one particular job for more than 15 years.

He’s had a long career as an expert in preparing fossils. His work is exceptionally delicate and he often spends hours at a time peering through a microscope, peeling back layers of rock one layer at a time.


PRESS RELEASE: Major Oil Plays in Utah and Vicinity



Media Contact

Utah Geological Survey
Tom Chidsey


New Report Provides Information and Maps to Help Keep Utah “The Place” to Find Oil

Salt Lake City (Jan. 18, 2017) — A new study by the Utah Geological Survey (UGS), Major Oil Plays in Utah and Vicinity, contains the critical maps, data and information to help Utah remain a significant petroleum contributor to the nation while reaping major benefits to the State’s economy for years to come.

The study comes at time of low drilling activity in Utah, and elsewhere, due to current low oil prices. However, oil prices change depending on the economics of global market supply and demand. History has shown that oil prices always rebound and are predicted to rise soon. The UGS study will help petroleum companies, both those already operating in Utah and others considering operations in the state, determine land-acquisition, new exploration, and field-development strategies.

It will also help pipeline companies better plan future facilities and routes. Additionally, landowners, bankers and investors, economists, utility companies, county planners, and numerous government resource management agencies now have the additional data, information, and maps they need to assist with the decisions and evaluations they face.

“One of the benefits of Utah’s diverse geology is a wealth of petroleum resources,” said UGS geologist Tom Chidsey. “Utah’s proven oil reserves have risen significantly to more than 812 million barrels, indicating significant oil remains to be discovered and produced. This study will help increase recoverable oil reserves from existing fields and encourage new discoveries while reducing risk.”

Utah oil fields have produced about 1.6 billion barrels since production began in the late 1940s. Among oil-producing states, Utah ranks eleventh in domestic oil production, having over 150 active oil fields. The 2004 discovery of Covenant oil field in central Utah, a region that had never produced oil or gas, has yielded over 23 million barrels of oil.

Three major oil-producing provinces exist in Utah—the thrust belt, Uinta Basin, and Paradox Basin, in the northern and central, eastern, and southeastern parts of the state, respectively. Utah produces oil from eight major “plays” within these provinces. The UGS study provides “stand alone” play portfolios that describe concisely these major oil plays.

The play portfolios include oil reservoir thickness and rock types; type of oil traps; rock properties; oil and gas chemical and physical characteristics; oil and gas source rocks; exploration and production history; case-study oil fields and exploration potential and trends. Maps of each of the play and sub-play areas are also included.

The study also includes descriptions of Utah’s rock outcrops that are analogs for the producing underground reservoirs. Utah’s incredible exposures of the same rocks that produce from deep in the subsurface provide templates to better understand how to produce oil here and from similar reservoirs throughout the world.

The 293-page Utah Geological Survey Bulletin 137, Major Oil Plays in Utah and Vicinity, is available (PDF) for free download from the UGS website at Print-on-demand copies are available for purchase from the Utah Department of Natural Resources Map and Bookstore, 1-888-UTAHMAP, This research was funded by a grant from the U.S. Department of Energy, National Energy Technology Laboratory under the Preferred Upstream Management Program with additional support from the Utah Geological Survey. The Utah Geological Survey, a division of the Utah Department of Natural Resources, provides timely scientific information about Utah’s geologic environment, resources, and hazards.

For more information about major oil plays in Utah, please contact:

Utah Geological Survey
Tom Chidsey

Map from the new Utah Geological Survey study showing various oil play areas and major oil and gas fields in the Uinta Basin of eastern Utah. 










Major Oil Plays in Utah and Vicinity

Major Oil Plays in Utah and Vicinity

By: Thomas C. Chidsey, Jr., Compiler and Editor

One of the benefits of Utah’s diverse geology is a wealth of petroleum resources. Three oil-producing provinces exist in Utah and adjacent parts of Wyoming, Colorado, and Arizona—the thrust belt, Paradox Basin, and Uinta Basin. Utah produces oil from eight major “plays” within these provinces. This 293-page bulletin describes concisely and in new detail each of these major oil plays. It provides “stand alone” play portfolios which include the following descriptions: (1) tectonic setting; (2) reservoir stratigraphy, thickness, and lithology; (3) type of oil traps; (4) rock properties; (5) oil and gas chemical and physical characteristics; (6) seal and source rocks including timing of generation and migration of oil; (7) exploration and production history; (8) case-study oil field evaluations; (9) reservoir outcrop analogs; (10) exploration potential and trends; and (11) maps of play and subplay areas. The bulletin will help petroleum companies determine exploration, land-acquisition, and field-development strategies; pipeline companies plan future facilities and pipeline routes; and assist with decisions and evaluations faced by landowners, bankers and investors, economists, utility companies, county planners, and numerous government resource management agencies.


The latest issue of Survey Notes is here!

Our latest issue of Survey Notes is here! Find articles on mapping Utah wetlands & UGS’s role in contributing water-quality data to the National Ground-Water Monitoring Network, and more among our regular featured columns.



Check out past issues of Survey Notes

POTD October 19, 2016: White Rock Bay, Antelope Island State Park, Davis County

White Rock Bay, Antelope Island State Park, Davis County
Photographer: Ken Krahulec © 2016


Earth Science Week 2016

Earth Science Week is in full swing at the Utah Geological Survey this week.

Our stream trailer allows students to create and destroy a river landscape while learning about deposition and erosion.


Survey Notes September 2016 Issue is Here!

Our latest issue of Survey Notes is here!

Find articles on the salt crust on Great Salt Lake’s north arm, the geothermal project near Milford, Utah and more among our regular featured columns.



Check out past issues