"Spot the Rock" for Thursday, March 27, 2014

It’s Thursday, and that means “Spot the Rock”!

Can any of you geo-sleuths tell us where this is?

"Spot the Rock" March 20, 2014

Can you “Spot the Rock”? This tucked away sight is no castle of rocks, though its immensity is quite spectacular.
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UPDATE: Location Revealed

Last week’s “Spot the Rock” photo was of a sinkhole in Big Round Valley, Washington County, just north of the Arizona state line. Can you spot the person for scale in this closeup view of the sinkhole?

This hole formed when the roof of an underlying cave collapsed, but what created the underlying cave? It was likely created when ground water dissolved and carried away the mineral gypsum. The Harrisburg Member of the Kaibab Formation underlies the sinkhole and is known for such gypsum “karst” features elsewhere in the area. Alternatively, or in conjunction with gypsum dissolution, ground water may have dissolved and carried away part of an underlying limestone layer.

A third possible scenario involves a process called sediment piping, where ground water traveling along initially small cracks carries away clay and silt-size particles. In this scenario, fine sediment is carried away in suspension by flowing ground water, and the small cracks can grow to large channels, or pipes. For piping to occur, the removed silt and clay needs a place to be deposited. Therefore, piping features usually end at the base of a river bank or other steep slope. However, the bed of the adjacent Virgin River is about 20 feet (6 meters) higher in elevation than the bottom of the sinkhole. Thus sediment cannot be piped to the river channel. This brings us full circle to needing a cave in limestone or gypsum bedrock to collect sediment.

More information on this location can be found here-http://geology.utah.gov/surveynotes/geosights/sinkhole.htm

"Spot the Rock" March 13, 2014

Can you “Spot the Rock”? It’s time for a new mystery geologic location—tell us where these bumpy rocks are found!

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UPDATE: Location Revealed
For those of you who follow our GeoSights (http://1.usa.gov/1dqnUJo), last week’s “Spot the Rock” was probably very easy. For those who don’t (you should), the answer is Fantasy Canyon.

Fantasy Canyon is approximately an hour’s drive southeast of Vernal. Even though it’s only 28-miles (as the crow flies) in distance, the labyrinth of oil company service roads quickly lengthen the drive.

You’ll find that Fantasy Canyon is crowded with intricate and peculiar stone figures that are a unique expression of rock weathering and erosion. Covering only a few acres, this miniature canyon can be viewed up-close on a short 0.6-mile loop trail. The dull, light khaki gray color of Fantasy Canyon sandstone transforms to a glowing pale orange at sunset. More information about Fantasy Canyon can be found at http://1.usa.gov/1l4cbs7.

"Spot the Rock" March 6, 2014

Here’s another installment of “Spot the Rock”! Can you guess where this is? Like us on FACEBOOK or follow us on TWITTER to participate!

UPDATE: Location Revealed
Crystal Geyser is located on the eastern bank of the Green River approximately 3.5 miles downstream from Interstate 70. It is a geologically unusual site to visit, as it is a cold-water, carbon-dioxide-driven geyser as opposed to the geothermal geysers you would see at Yellowstone. In the past, Crystal Geyser’s eruptions were notably higher and more frequent than what they are today. As seen in the video the entire area is draped with beautiful travertine (calcium carbonate) which makes it a gem of a place to put on your bucket list.

"Spot the Rock" February 27, 2014

“Spot the Rock” is back this week with these towering giants. Can you guess where in Utah this feature is found?

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"Spot the Rock" February 20, 2014

It’s time again for another round of “Spot the Rock”! Can you guess where this interesting sight is located?

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UPDATE: Location Revealed
This “Spot the Rock” photo was taken in northwestern most part of Utah, at the southern end of the Grouse Creek Mountains, Box Elder County. As was correctly guessed it is in the area of the Devils Playground.

Devils Playground consists of Tertiary-age (approximately 38 million years old) granitic rock formed from a cooling magma body that intruded overlying Paleozoic (400 to 300 million years old) sedimentary rocks. Known as the Emigrant Pass pluton, this intrusion covers an area of approximately 10 square miles. For more information including directions, visit our GeoSights article-http://geology.utah.gov/surveynotes/geosights/devils_playground.htm

"Spot the Rock" February 13, 2014

It’s Thursday, and time for another “Spot the Rock” challenge! Let’s see how many of you can guess where this is!

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UPDATE: Location Revealed

Alhambra Rock is a diatreme seen to the west of Scenic Byway 163 is southeastern Utah just south of Mexican Hat. Explosive Tertiary volcanic events created diatremes, which are volcanic necks or plugs. Small vents erupted pulverized rock and gas from the magma chamber to the earth’s surface. The magma-filled vents cooled and hardened, and were covered by sediments that later eroded. The remaining volcanic necks now stand in stark outline above the surrounding landscape. Diatremes are present along Comb Ridge, and are also in adjacent states, and include the famous Shiprock in northwestern New Mexico. You can read more about the surrounding area in our “Canyon County” pamphlet (pdf) here: http://1.usa.gov/1cqMLQ9

"Spot the Rock" February 6, 2014

Happy Thursday, everyone! The weekend is almost here, and with it, another round of “Spot the Rock.” Tell us below where in Utah you think this rockin’ site is found!

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UPDATE: Location Revealed

Step Mountain is a Tertiary-aged (dated at 36 million years) andesitic dike in Rose Canyon, three miles southwest of Herriman. The summit is at 6109 feet above sea level. The mountain is a fine example of columnar jointing, typically associated with basalt, but also found in andesites. Columnar jointing is found below the surface of thick lava flows, sills, and dikes, and is caused by the cooling and contracting of the lava creating long vertical joints that form slender polygonal columns, typically pentagonal or hexagonal in shape. In the case of Step Mountain dike, magma filled a crack in the pre-existing rock and the joints formed horizontal to the surface, so the columns act as “steps.” The weathering-resistant dike now has a prominent relief due to the erosion of the softer surrounding volcanic rock.

"Spot the Rock" January 30, 2014

Well we hope your January has really rocked! And on that note— it’s another great Thursday. Time for another round of “Spot the Rock”! Let us know where you think this geologic site is found.

Down and down it goes, where it stops, no body knows! Tell where this stuff flows!

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UPDATE: Location Revealed
Last week’s “Spot the Rock” photo shows natural oil seeps (black) and salt (white) at Rozel Point about ½ mile southeast of the Spiral Jetty on the shore of Great Salt Lake, Box Elder County. Miocene to Pliocene (24 to 1.8 million years old) organic-rich lake sediments probably generated the oil. From these source beds, the oil migrated upward along faults and fractures to a porous basalt layer that comprises a main reservoir. Some of the oil in this basalt reservoir leaks to the surface through faults and fractures, emerging as thick, sticky, tar-like oil.

Rozel Point is one of the oldest (if not the oldest) fields to produce oil in Utah. The seeps have been known since the late 1800s and production attempts began in 1904. The field produced an estimated 10,000 barrels of oil from 30 to 50 wells, but has been inactive since the mid-1980s due to extremely difficult production, very high refining costs, and rising lake levels.

"Spot the Rock" January 23, 2014

It’s another wonderful Thursday…and time for “Spot the Rock” again!

Though this red rock may look familiar, something tells me it’s quite peculiar. If you know where this slot canyon hides, try your luck and tell us where it resides.

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UPDATE: Location Revealed
This Spot the Rock photo was taken in Quail Creek Canyon, roughly 15 miles northeast of Saint George, Washington County. This section of Quail Creek Canyon is located within the Red Cliffs Desert Reserve, Red Cliffs National Conservation Area, and Cottonwood Canyon Wilderness. The trailhead for this site is found in the Red Cliffs Campground.

The red rocks of the Red Cliffs are composed primarily of Jurassic age Navajo Sandstone. The towering Pine Valley Mountains, which provide the water for the creek, are a volcanic feature called a laccolith.

This area of Utah is unique in that it is a transition zone between the Great Basin, Colorado Plateau, and Mojave Desert.