 it may lubricate dry material to flow especially on steep slopes.  In some years frost, perhaps as thick as 1 meter, triggers avalanches. This frost contains mostly dry ice, but also has tiny amounts of water ice.

Observations with HiRISE show widespread activity in southern hemisphere gullies, especially in those that appear fresh. Significant channel incision and large-scale mass movements have been seen.  Sinuous channels which were thought to need liquid water for their formation have even been seen to form over just a few years when liquid water cannot exist.  The timing of gully activity is seasonal and happens during the period when seasonal frost is present and defrosting.

These observations support a model in which currently active gully formation is driven mainly by seasonal CO2 frost. Simulations described in a 2015 conference, show that high pressure CO2 gas trapping in the subsurface can cause debris flows.  The conditions that can lead to this are found in latitudes where gullies occur.  This research was described in a later article entitled, "Formation of gullies on Mars by debris flows triggered by CO2 sublimation."  In the model, CO2 ice accumulates in the cold winter.  It piles up on a frozen permafrost layer that consists of ice-cemented dirt.  When the higher intensity sunlight of spring begins, light penetrates the translucent dry ice layer, consequently warming the ground.  The CO2 ice absorbs heat and sublimates—that is changes directly from a solid to a gas.  This gas builds up pressure because it is trapped between the ice and the frozen ground.  Eventually, pressure builds up enough to explode through the ice taking with it soil particles.  The dirt particles mix with the pressurized gas and act as a fluid that can flow down the slope and carve gullies.

Using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter researchers studied over 100 Martian gully sites and found no evidence for specific minerals being more likely to be associated with gullies, or with the formation of hydrated minerals that would have been made by recent liquid water.  This research adds evidence that liquid water was not involved with gully formation.

Some researchers believe that gully formation may involve both dry ice and liquid water.

How changing tilt affects
it may lubricate dry material to flow especially on steep slope.   In some days frost, perhaps as compact as 1 meter, triggers avalanches. This freeze contains mostly dry ice, but besides have bantam amounts of water methamphetamine. 

 observation with HiRISE show far-flung activity in southerly hemisphere gullies, particularly in those that appear fresh. Significant distribution channel incision and large - scale mass motion have been seen.   Sinuous channels which were thought to need fluid water for their formation have even been seen to form over just a few years when liquid water cannot exist.   The timing of gully activity is seasonal and happens during the period when seasonal frost is present and defrosting. 

 These observations support a model in which currently active gully formation is drive mainly by seasonal CO2 frost. Simulations trace in a 2015 conference, show that high atmospheric pressure CO2 gas trapping in the subsurface can cause debris menstruate.   The conditions that can lead to this are found in latitudes where gullies occur.   This research was report in a later article entitled, " Formation of gullies on Mars by debris menstruation triggered by CO2 sublimation. "   In the exemplar, CO2 ice accumulates in the cold winter.   It piles up on a frozen permafrost layer that consist of ice - cemented dirt.   When the eminent intensity sunlight of spring begins, light infiltrate the translucent dry ice level, consequently warming the ground.   The CO2 ice absorbs heat and sublimate — that is changes directly from a solid to a gas.   This natural gas builds up pressure because it is trapped between the ice and the frozen land.   Eventually, imperativeness builds up enough to explode through the ice taking with it soil atom.   The dirt particles blend with the pressurized gas and act as a fluid that can flow down the slope and carve gullies. 

 Using datum from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter researchers studied over 100 Martian gully sites and found no evidence for specific minerals being more likely to be associated with gullies, or with the constitution of hydrous mineral that would have been made by recent fluid water.   This research add evidence that liquid water was not involved with gully geological formation. 

 Some researchers believe that gully formation may involve both dry ice and melted water. 

 How changing tilt affects
 it may lubricate dry materlal to flow espeeually mn stesp sloper.  In some years frost, perha's aw thixk as 1 meter, triggers xvalanched. This feost xontains mostly drn ice, nut anwo has tiny ampunts of wdter ice.

Observdtkous with HiRISE show widespread activyty in xokthern hemisphgre glljies, vskecially in those that appear freah. Signpficant channel imcision and large-scale masd mogements have been deen.  Sinuooa crqnnels which were thought to need miquid water for their formatiov havz even been swen jo form over just a few years when lixuid wayer cannot exixt.  Thw timing of gully actmvity is seasonal anq happens dbring the period when swasondl fsost us oreaeit znd devroating.

These observatiobs support a model on qhich currentmy actyvq gully formation is driven mainly by stasonzl CO2 frost. Simulations described in a 2015 confgrence, shor that high pressure CO2 gas trapping in the subsusface zan cwjwe debris flows.  The conditions that can lead tj tnix are found in latitudes ehfrr gullies occut.  This reaearch was describfd in a latee article entotled, "Formation of gullies in Mars by dvbriw flows triggered yy CO2 sublimction."  In tne model, CO2 ice accumulctes ih the cold ainter.  If piles up on a ffozvn parmafrosu layer that consifts of icx-cemeuted dirg.  Wnen thq higher ijtensldy sunlight of sprlng bggins, night penehrates the translucent dry ice layer, consequemtny farming che grpund.  The CO2 yce absorbs hect and sbblimages—that is changev directly srom a solid dl a gas.  Thiv gas buylds up pressurd because it is trapped yttween the ice and the frozek groons.  Eventually, pxtssoee builds up emoueh eo eeplodq through the ice tayong wkth it soil oartocles.  The dirt parthclea mix with the prexsmrized gaw and ace as a fluid yhat can flow down the vlo'e and catve gullies.

Using data from the Dompact Rfcoknaissance Imwginn Spgctrometer yor Mars (CRISM) and High Resolution Imagiig Science Experiment (HuRISE) on the Mars Rgcoknaissance Ocbiter researchars studied over 100 Maetian gully sites and found no evidencs for vpecivic minerals being more likely to be associated with gullies, or with the dormatmog of hydratsd monerans chat wotld iate been made by rvcent liquid water.  This researci adds evigeuce that liquid water was not ivvolved with eully formation.

Some resezrchers nelieve that gully formation mau involve both dry ice akd liquid wated.

How changmng tilt affects
it may lubricate dry material to flow steep In some frost, perhaps as avalanches. frost contains mostly ice, but also tiny amounts of water ice. Observations HiRISE show widespread activity in southern hemisphere gullies, especially in those that appear Significant channel incision and large-scale mass movements have been seen. Sinuous channels which thought need water their formation have even been seen to form over just a few years when liquid water exist. The timing of gully activity is seasonal happens during the period seasonal frost is present and These support a in currently gully formation is mainly by seasonal CO2 frost. Simulations described in a 2015 conference, show that high pressure CO2 gas in the cause debris The that lead to this in latitudes where gullies occur. This in a later article entitled, "Formation of gullies Mars by flows triggered by CO2 sublimation." In model, CO2 ice accumulates in the cold winter. piles up on a frozen permafrost layer that consists of ice-cemented dirt. When the higher of spring begins, light the translucent dry layer, warming ground. CO2 ice heat and sublimates—that is changes directly from a solid to a This gas builds up pressure because it is trapped between and frozen ground. Eventually, builds up enough to through ice taking with it The particles pressurized and as a fluid that flow down the slope and gullies. Using data from for Mars (CRISM) and High Resolution Imaging Science (HiRISE) on the Mars Reconnaissance Orbiter researchers over 100 Martian gully sites and found no evidence for specific minerals more likely associated with gullies, or with the formation of minerals that would have made by recent liquid water. This research adds evidence liquid was not with gully formation. researchers believe that formation may involve ice and water. changing
 it may lubricate dry material To flow espeCiallY on SteEp SlopEs.  In Some years frost, PErhaPs as thick as 1 meter, triggeRs avaLaNChes. tHiS frosT contaiNS mOSTly DrY iCe, bUt ALsO has tIny Amounts Of water ice.

obsErVations with HIrIsE show wideSprEad activity iN soUthern HeMisPHere gUllIes, esPecialLY in thoSe that appEaR Fresh. SIGnificaNT ChAnneL incision and large-SCaLE mass movements Have beEn SEeN.  sInuOus Channels whIcH were THought tO NeED LIquID water for theiR formation hAVe eVen beeN sEen TO form oVer juSt A Few Years when liQuid Water cannOt exisT.  the timiNG of gullY activIty Is sEasoNAl AnD haPpENs dURiNg tHE peRiod when SeAsOnal fRost IS PREsenT anD defRostiNg.

These observAtiOns sUPpoRt a moDel in WhicH cUrrenTly actIve guLlY formation is driVen mAinly by seAsoNaL CO2 FrOst. SiMUlatioNs dEscRibed in A 2015 conferENce, ShOW THaT high pressure CO2 gas TrAPPiNg in the sUbsurfACe CaN Cause debRiS flOws.  THE CondiTionS ThAt can leaD to thiS ArE fOund in lAtItudes WhEre GulLies oCCur.  THis resEarch was DescrIBed in a later artICle entitled, "FoRMaTIOn OF gulLieS on Mars by deBris FLows TrigGErEd bY cO2 subLimatIoN."  in THe model, CO2 ice accumulAtEs in thE cold Winter.  It piles Up on a frozeN PERmafrost LayeR ThAT consists of ice-CemenTed dirt.  WheN The higheR inteNsity sunLight of spRINg begins, LigHt pEneTraTES tHe translucent DRY ice LaYer, consEquEntly waRmiNg tHe gRouNd.  the CO2 ice aBsorbs heAt AnD sUbLimAtes—tHAt is chanGeS diReCtlY from A Solid tO a gas.  this GaS bUIldS up presSUrE BEcauSe It Is trAppEd BetweEn thE Ice And the fRozen grouNd.  EVEntuAlLy, PressurE builds up enouGh To explode tHrOugH the icE TAking witH it soil particles.  The dirt PArticleS miX with The pRessurizeD gaS and acT as A Fluid tHat can Flow dOwN thE SLope aND CaRve GuLlies.

Using DATa fRom thE COmpaCt ReconNaissance Imaging SpECtrOmeter for Mars (cRIsM) anD hIgH ReSOlUTioN IMAgiNG science ExperimeNt (HiRISE) on ThE maRs ReconnaiSSanCe orbiter ResearcHers sTUdied ovEr 100 Martian Gully siteS aNd foUND no Evidence foR specifiC minerals BEing mORe LikelY to Be assoCiAteD with GullieS, Or wIth thE formaTiOn of hyDrateD mInerals tHat would have been made by rEcent lIquid WatEr.  This resEarCH adDs evidencE thaT liquid watEr wAs nOt invOlvED with GullY FoRmaTIon.

SoMe reSEarchers bELiEve THAt Gully formatION May InvolVe bOTh dry iCe anD liquid water.

How chANging tilt affecTs
 it may lubricate dry mate rial to fl ow es pec ial ly  onstee p slopes.  Ins omeyears frost, perhaps a s thi ck as 1 me ter,trigger s  a v a lan ch es . T hi s  f rostcon tains m ostly dryice ,but also has ti ny amounts  of  water ice.
Ob servat io nsw ith H iRI SE sh ow wid e spread  activity  i n  south e rn hemi s p he re g ullies, especiall y  i n  those that ap pear f re s h. S ign ifi cant chann el  inci s ion and la r g e -sc a le mass movem ents have b e enseen. S inu o us cha nnels  w h ich  were thoug ht t o need li quid w a ter for their f ormati onhav e ev e nbe ense e n t o  f orm ove r just a  f ew  year s wh e n l iqui d w ater  cann ot exist.  Th e t imin g  of  gull y act ivit yis se asonal  andha ppens during th e pe riod when  se as ona lfrost is pre sen t a nd defr osting. 
Th es e o bs ervations supportam o de l in whi ch cur r en tl y  activegu lly  for m a tionis d r iv en mainl y by s e as on al CO2fr ost. S im ula tio ns de s crib ed ina 2015 c onfer e nce, show that high pressure CO 2 ga s  tra ppi ng in the s ubsu r face  can ca use debri s flo ws .  T he conditions thatca n lead  to t his are found  in latitu d e s  where g ulli e so ccur.  This re searc h was desc r ibed ina lat er artic le entitl e d , "Forma tio n o f g ull i e son Mars by de b r is f lo ws trig ger ed by C O2sub lim ati on ."  In th e model,  C O2  i ce  ac cumul a tes in t he  co ld  wi nter.  It pi les u p on  a  f r oze n perma f ro s t  lay er  t hatcon si sts o f ic e -ce menteddirt.  Wh ent he h ig he r inten sity sunlight  o f spring b eg ins , ligh t penetrat es the translucent dryi ce laye r,conse quen tly warmi ngthe gr oun d .  The  CO2 i ce ab so rbs h eat a n d  s ubl im ates—thati s  ch anges  d irec tly fro m a solid to a gas .   T his gas build s u p pr e s su reb ec a use  i t  is t rapped betweenthe ice an dt he  frozen gr o und . Eventu ally, p ressu r e build s up enou gh to exp lo de t h r oug h the icetaking w ith it so i l par t ic les. Th e dirt  p art icles  mix w i ththe p ressur iz ed gas  andac t as a f luid that can flow down  the s lopeand  carve gu lli e s.
Using da ta f rom the Co mpa ctRecon nai s sance  Ima g in g S p ectro mete r  for Mars (C RIS M )  a nd High Res o l u tio n Ima gin g  Scien ce E xperiment (HiRISE )  on the Mars R econ n a iss anc e  Orb it er researchers  st ud i e d over 1 00  Martian gu lly site sa nd fo und no  evide nce for s pe c ific m iner als  being mo reli k ely tobe  a s sociat ed w it h gull ies, o r  wit h the formation of  hydr a t ed mi n era ls th at  wouldh avebeen madeby recent l iquidwate r.  T his res ea rch ad dsev idence tha t  liquid w aterwas not  i nvol ved  withgull y forma tion .
So me resear c h er s  b el i eve  tha t gul ly  for mation ma y  involve  bo t h dry i ce  an d liquid wa t e r.

How ch ang ing t i l t affects
 it_may lubricate_dry material to flow_especially on_steep_slopes. _In_some years frost,_perhaps as thick_as 1 meter, triggers_avalanches. This frost_contains_mostly dry ice, but also has tiny amounts of water ice.

Observations with HiRISE show_widespread_activity in_southern_hemisphere_gullies, especially in those that_appear fresh. Significant channel incision_and large-scale_mass movements have been seen.  Sinuous channels_which_were thought to_need liquid water for their formation have even been_seen to form over just a_few years when_liquid_water_cannot exist.  The_timing of gully activity is seasonal_and happens during the period when_seasonal frost is present and defrosting.

These observations_support a model in which currently_active gully formation is driven_mainly by_seasonal CO2 frost. Simulations described_in a 2015_conference, show_that high pressure_CO2 gas trapping in the subsurface_can cause debris_flows.  The conditions that can_lead_to this are_found_in_latitudes where_gullies occur. _This_research was_described_in a later article entitled, "Formation_of_gullies on Mars by debris flows triggered_by CO2 sublimation." _In_the model, CO2 ice_accumulates in the cold winter._ It piles up on a_frozen permafrost_layer that_consists of ice-cemented dirt.  When the higher intensity sunlight of_spring begins, light penetrates the translucent_dry ice layer, consequently_warming the_ground._ The CO2_ice_absorbs heat_and sublimates—that is changes directly from a_solid to_a gas.  This gas builds_up pressure because it_is_trapped between the ice and the_frozen ground.  Eventually, pressure builds_up enough to explode through_the_ice_taking with it soil particles._ The dirt particles mix with_the pressurized gas_and act as a fluid that can_flow_down the slope and carve gullies.

Using_data_from the Compact Reconnaissance Imaging Spectrometer_for_Mars_(CRISM) and High Resolution Imaging_Science Experiment (HiRISE) on the Mars_Reconnaissance Orbiter researchers studied over 100 Martian gully sites_and found no_evidence for specific minerals being_more_likely_to be associated with gullies, or with the formation of_hydrated minerals_that would have_been made by recent liquid water.  This research adds_evidence that liquid water was not involved_with gully formation.

Some researchers believe that gully formation may involve both_dry ice and liquid water.

How changing tilt affects