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hiker rambling through Utah ’s confect - despoil canyons sometimes come across a strange - looking sight . Where the Navajo Sandstone loses its iconic apricot , orangish and scarlet stripe , hundreds of round , iron - surface stones often litter the terra firma .
The stony spheres are concretions — sandstone balls cemented by a hard eggshell of iron oxide minerals . Often hollo moqui wits , Accho of the chocolate - colour rock-and-roll are scatter across Utah and Arizona . They crumple from the pallid , pick - coloredNavajo Sandstonebeds , when wind and weewee wash away the softer rock .
Moqui marbles on a sandstone slope.
For decades , the rocks were just a geological oddity . Then , face - alikes were discovered on Mars ( the so - calledMartian blueberries ) . The milepost — among the former evidence for water supply on Mars — encourage involvement in Earth ’s iron baubles . [ Photo Gallery : See Fantastic Moqui Marbles ]
Now , a Modern study expose that the moqui marbles are no more than 25 million year old — a shrill direct contrast to the 190 - million - yr - honest-to-goodness Navajo Sandstone . Marbles scattered on sandstone side in Grand Staircase - Escalante National Monument are only 2 million to 5 million years sure-enough . And on Arizona ’s Paria Plateau , the marbles ' iron oxide rind is as young as 300,000 years old , researchers account in the September 2014 issue of the Geological Society of America Bulletin .
" They really correspond a record of how water moved the rock millions of long time ago , and the next genesis can use them to understand water supply and life on other planets , " said Marjorie Chan , cobalt - author of the new study and a geologist at the University of Utah in Salt Lake City .
Red and white Navajo sandstone in Zion National Park.
unmated ball
The moqui marbles ' accurate long time derive from a radioactive clock . The Fe oxide mineral check traces of radioactive atomic number 92 and thorium , and these decay by expelling helium . Tallying the component reveals the time since the minerals formed . The innovative proficiency may help resolve different simulation of how the stone field formed . Scientists accord that the iron comes from the os - lily-white Navajo Sandstone layer , leach nude of their mineral rouge by percolating groundwater . A insidious film of hematite , oriron oxide , distort the iconic red-faced cliff and canyons .
chemical substance reaction fused the moqui marbles with iron , but the details have n’t been settled . Some researchers now think tiny germ spurred the chemical operation , and that alike concretion on Mars may one day expose sign of ancient lifespan . [ The 7 Most Mars - Like place on land ]
The spheres grew layer by layer, making contact with others nearby until many spheres became one large ball.
" Thediscoveries on Marshelped push us to well understand the context here on Earth , and what we do on Earth feeds back into helping read Mars , " Chan order Live Science .
Concretions of all form and sizes are found all over the world . The curious rocks have inspired fantastic tarradiddle of fairies , meteorites and dinosaur ballock , but their ancestry is jolly mundane . Water hang through sedimentary rock forget behind minerals that paste together mountain of George Sand , clay or other subatomic particle . Sometimes , a treasure — like a bone or a shield — shroud inside .
The moqui marble work up in the Navajo Sandstone in Arizona and in Utah ’s public lands , eroding from the spectacular livid cliffs in Zion National Park and theGrand Staircase - Escalante National Monument . Collecting concretions in the parks is prohibited .
The iron Stone seem almost black , with a pitted open polished by blowing sand . Other rust structures formed too , including discs , " flee dish aerial , " pipes and flat plates . Spiritualists have endowed the marbles with " energy " and dub the typical shapes as male and female , making them among the only rocks with a sexuality . Quietly sitting and hold one in each bridge player is said to settle down the spirit , just like meditation .
" I do n’t believe that , " Chan said . " I do think these are important resourcefulness , and the geological landscape painting is our heritage . "
cloak in branding iron
The Navajo Sandstone was once the biggest expanse of dunes on Earth . Its colour comes from eccentric of iron - rich mineral blown in and buried with the quartz sand . After the dunes were blanket and buried by young geological layers , the iron enrobed the guts caryopsis , give the Navajo Sandstone its astonishing colors and convention . [ Image Gallery : Majestic Monument Valley ]
Eons after , the moqui marble were born . The coalescence owe their existence to massive tectonic work shift in the Southwest , researchers think . Some 20 million years ago , the Colorado Plateau start to bob up like a bobfloat . The intact tableland has lift about 1.2 mi ( 2 klick ) .
The tectonic upliftwarped its rock layers , trapping rock oil and gas pedal . When a mixture of water and innate gas flowed through the Navajo Sandstone , it stripped away the rusty coating , bleaching the rock candy from red to creamy white . Chan thinks this iron - full-bodied water crept through the sandstone until it reached a cracking , hole or bed where the water alchemy was unlike and iron settled out of the urine .
The chemic chemical reaction first cover each sand grain with smoothing iron , creating petite spheres . The sphere grew , stratum by level , make tangency with others nearby until some spheres tie into one large mass . collector on private place sometimes find left over , knobby lump that come along to be part shape vault of heaven , where the process may have halted halfway through .
" These round concretions have a self - organizing form , like people at a political party , " Chan suppose . " The natural pattern is for masses to collect together in conversation chemical group , and the chemical group are extend to be round . "
The outcome of the raw work hint that the first branding iron - oxide batch forge 20 million to 25 million years ago , and the next lot was added 2 million to 3 million years ago . This unseasoned group matches up with another major event : It ’s when theColorado Riverstarted cutting through the Navajo Sandstone near the lip of the Escalante River , which likely transfer groundwater period through the region . These youthful marbles are mostly goethite instead of hematite , which may reflect the changing interpersonal chemistry of the groundwater .
Fe eater
The younger age also plunk for a dissimilar model for how the concretions formed , according to David Loope , a geologist at the University of Nebraska - Lincoln , who was not involved in the study . Loope thinks the moqui marbles were translate by germ , morphing from one kind of mineral to another as the region ’s groundwater chemistry changed .
agree to Loope ’s model , the marbles were originally siderite , an smoothing iron carbonate mineral . The same fluid Chan said had bleached the sandstone posit the carbonate spheres , only with an tally boost of carbon copy dioxide accelerator dissolved in the piss . When the Colorado River slice into the Navajo Sandstone 2 million years ago , the groundwater stream and the mineral stage shifted .
The researchers think bacteria helped convert the siderite into hematite . With a sinewy microscope , the researchers also discovered midget structures indicatory of microbic life inside the concretions , standardized to tube seen inMartian meteorite . Some of the hematite rind resemble siderite crystals — a clue that one mineral throw out the other , Loope and his colleagues reported in August 2012 in the journal Geology . " We are wholly convinced the densification had siderite precursors , " Loope said .
Link to the past
" Moqui " is a Hopi word that means " near departed ones . " According to Hopi tradition , spirit of the dead would run with the marbles at night , leave alone them behind in the sunup to reassure the bread and butter that they were happy in the hereafter .
Just as the moqui marbles embody the Hopi idea of life after demise , the branding iron stones are tie to ancient environments on the Colorado Plateau . With the Modern dating technique , Chan has shown that scientists can start to nail where and when water flow through rock . The hunt for historic water road in the Southwest has engage researchers for more than century , since the first geologist tried to stick outhow the Colorado River carved the Grand Canyon .
" A lot of citizenry are just fascinated by these compaction , and maybe geologists have n’t been able to take them seriously in the yesteryear , " Loope told Live Science . " I think they somewhat clear curb a luck of information . "
