At 11:05 on the morning of 4 December 2013, two rocks on a dry lakebed in Death Valley started moving at the same moment. Sixteen minutes later one had travelled 65.6 metres and the other 64.1. The wind was blowing at four to five metres a second — a gentle breeze. Both rocks were carrying GPS loggers, and a camera was watching.
Silence Index — D-147
Quiet, but findable
Ranks 71 of 99 scored dossiers — quieter than 29% of the others we have scored. A low score is not a warning; it describes who else will be standing next to you.
How the total is weighted. These are the fixed weights of the four inputs, the same on every dossier — not this place’s scores. We do not publish per-input bars, because the per-input values were never recorded article by article and inventing four plausible numbers that sum to the total would be a fabrication dressed as a chart.
This dossier was scored before 2 September 2026, when the fourth input became night darkness. It keeps the input it was reasoned with until it is re-scored at its next source re-check; the methodology page records the change.
The index is a desk instrument scored by this publication, not a field measurement. How it is calculated, and where it fails.
What this dossier is built from
This is desk research. Nobody from this publication has driven the Racetrack Valley Road. What follows is assembled from the peer-reviewed paper reporting the first direct observation and its discussion-stage companion; the 2011 physics paper that predicted the mechanism; earlier work in the Journal of Geology and Geomorphology; National Park Service visitor pages, news releases and natural resource pages; United States Geological Survey publications, captions, volcano records and elevation services; National Weather Service climate material; and DarkSky International's certification record.
It is not a story about an unsolved mystery. It is a story about a solved one still being sold as unsolved, and about how much smaller the true answer is than the answer people wanted.
11:05, 4 December 2013
Between 21 and 24 November 2013, 3.61 centimetres of rain and about twenty centimetres of snow fell on Racetrack Playa. The water gathered at the southern, lower end and made a pond ten centimetres deep at most, which lasted until the second week of February 2014.
Sitting in that pond were fifteen rocks carrying custom-built GPS loggers. Each recorded its position and temperature hourly, and switched to continuous one-second logging the instant it was pulled off a magnetic trigger buried in the mud beneath it. A weather station stood beside the playa at 36.6823°N, 117.5515°W, sampling wind every second, and time-lapse cameras watched the surface. The array had been going in, in one form or another, since 2007.
On the morning of 4 December the pond froze overnight and then began to break up in sunshine. At 11:05, rock A3 — 16.6 kilograms — and rock A6 — 8.2 kilograms — started moving together. Sixteen minutes later A3 had covered 65.6 metres and A6 had covered 64.1, beginning at five to six metres a minute and slowing to three or four by the sixth. The wind was blowing at four to five metres per second.
On 20 December, rock A11 moved 39.1 metres in 12.3 minutes from 11:37, and more than sixty rocks moved. On 9 January 2014 two of the authors watched a rock move in front of them at one to two metres a minute for about eighteen seconds, pushed by an ice panel they estimated at five to eight metres upstream. Across the season one rock, A5, accumulated up to 224 metres of travel; two recorded trails ran 157.5 and 162.4 metres. The paper is Norris, Norris, Lorenz, Ray and Jackson, Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion, in PLOS ONE, 27 August 2014.
The mechanism, and why it is the opposite of dramatic
The ice that moves the rocks is 3 to 6 millimetres thick. The paper's own word for it is windowpane. It forms overnight across the shallow pond, and in the late morning, as the sun works on it, it breaks into floating panels tens of metres across. The wind pushes the panels; the panels push the rocks.
That is the whole thing. The rocks are not lifted, floated or carried. In the companion paper the same group put it plainly: wind stress on a wide floating ice sheet bulldozes rocks. The ice gets behind the stone and shoves it.
Three numbers are worth holding together. The ice is millimetres thick. The wind is four to five metres a second — about nine to eleven miles an hour, Beaufort force 3, a gentle breeze on the National Weather Service's own scale. And the rocks move at two to five metres a minute. Watched from the shore this would not look like a phenomenon. It would look like a pond thawing.
What makes it rare is not the force but the coincidence: enough rain or snow to fill a pond a few centimetres deep on a surface that receives very little of either; a night cold enough to freeze it thin; morning sun to break the sheet up; and a breeze while the fragments are still floating. Lorenz and colleagues calculated that across close to a decade of instrumentation the rocks were in motion for a few minutes in total — about one millionth of the time. The Norris paper says the same thing from the other end: motion years to decades apart follows from the infrequency of rain or snow sufficient to form winter ponds.
What popular coverage gets wrong
Three claims travel with this place, and all three fail against the literature.
The first is that science cannot explain it. This was already false long before the 2014 paper, and the clearest evidence is a United States government publication. USGS Open-File Report 99-153, the proceedings of a 1999 conference on geologic research in Death Valley, describes the playa's tracks as caused most likely by ice-rafted rocks occasionally pushed across the playa during winter windstorms. Fifteen years before anybody filmed it, a federal publication stated the mechanism that turned out to be right.
The framing is durable even inside government. A Federal Highway Administration National Scenic Byways photograph of the site still captions it one of the apparent mysteries of Death Valley whose mechanism is the subject of countless hypotheses, and a USGS caption still hedges between ice-rafting and direct wind. If the agencies that own the ground are still writing it up as a mystery, the travel press was never going to stop.
The second is hurricane-force winds. This one is the most interesting, because it did not come from nowhere. It came from the scientific literature, and the numbers there were larger than the popular version suggests. Shelton in 1953 used an aircraft propeller and concluded that winds above 20 metres per second could move natural rocks. Sharp in 1960 put the requirement at 33 to 45. Bacon, Cahill and Tombrello, in the Journal of Geology in 1996, worked from wind-shear data at Owens Dry Lake about eighty kilometres away and found figures above 40 metres per second consistent with moving thirty of the thirty-one rocks they had data for. Reid and colleagues needed up to 80.
Beaufort force 12 — hurricane — begins at 64 knots, about 33 metres per second. So the older literature was not exaggerating when it implied hurricane winds; it was calculating them from a model in which the rock sits on mud and the air pushes the rock. The 2014 observation did not find a stronger wind. It found a wind roughly one-tenth of the smallest of those figures, acting through a completely different intermediary. The popular version kept the drama and threw away the correction.
The third is that a 300-kilogram rock has been recorded sliding. The mass figure itself is fine: Lorenz and colleagues describe rocks up to about 300 kilograms, the Park Service says up to 320, and a USGS caption estimates the block named Karen, one of the largest of the sliding rocks, at seven to eight hundred pounds. What is not established is that anyone has watched one of those move. The instrumented rocks whose motion was logged in December 2013 weighed 8.2 to 16.6 kilograms. The trails behind the big stones are real; the direct observations are of small ones.
Magnetism and extraterrestrial intervention circulate too. We will not cite a content farm to prove a rumour exists. What we can report is what the peer-reviewed literature contains: across every paper we opened, the word magnetic appears exactly once, and it refers to the triggers the researchers buried under each rock to start their GPS loggers.
The prediction that arrived three years early
The 2014 result is usually called a solution. It is more precisely a confirmation, and being accurate about that is the point of this dossier.
In January 2011, Ralph Lorenz, Brian Jackson, Jason Barnes, Joe Spitale and John Keller published Ice rafts not sails: Floating the rocks at Racetrack Playa in the American Journal of Physics. Their argument was that ice does not help by catching wind, as a sail would; it helps by reducing the reaction and friction forces at the bed. Reduce the normal force enough and the wind needed to start a rock falls away toward nothing.
The experiment they used to make the case is one of the most economical in the recent literature. They froze a 64-gram basalt pebble into a layer of water in a plastic food container, turned out an ice raft about three centimetres thick and twenty across, and floated it in a baking tray of coarse sand. A very gentle push — they estimate a few millinewtons — or simply blowing across the surface moved it. From that they argued that rafts a few centimetres thick and a few tens of centimetres wide could reduce the necessary wind speed to arbitrarily small values. Three years later a field campaign measured four to five metres per second and watched it work.
But the confirmation was not exact, and printing the difference matters more than claiming a clean win. Lorenz's 2011 mechanism was buoyancy: ice lifting the rock and unweighting it. What the cameras recorded in 2013 was ice panels fracturing and bulldozing rocks that stayed in contact with the bed, and the ice was far thinner than the centimetres the paper had modelled. The prediction was right about the agent — ice, and light winds — and wrong about the physics by which ice does the job. Lorenz is a co-author on the observation paper and lead author on the companion, which is the ordinary and unglamorous way this is supposed to work.
Nor was he first to reach for ice. Stanley proposed it in 1955. Sharp and Carey, in 1976, drove stakes into the playa around several rocks — the corral experiment — and reported that one rock left the corral while another stayed inside, which they read as evidence against a single ice sheet carrying everything at once. Messina and Stoffer mapped 162 rocks and trails with submetre differential GPS in July 1996, to about thirty centimetres, and found trails deviating from one another in ways suggesting rocks moving independently rather than as one raft. Both results fit what was eventually filmed: not one great sheet, but panels, breaking up, moving separately.
The playa itself, and how flat it really is
The playa lies in the southern Cottonwood Mountains, within the Panamint Range. Ubehebe Peak, 5,678 feet, rises along its western side, and the USGS notes that the valley follows an active fault system whose rift Racetrack Road runs along. The rocks are mostly a dark grey dolomite with a few granite boulders, off the slopes at the margins — Racetrack Dolomite, which the Park Service's formation list places in the Middle Cambrian.
Its dimensions depend on who you ask, and we are not going to average them. The Lorenz group's paper calls it a nearly flat lakebed of 4.5 by 2 kilometres; the Park Service says about three miles by two, over beige mud at least a thousand feet thick; a USGS caption gives about five square miles. Elevation is equally unsettled: just over 3,800 feet in the USGS caption, 1,300 metres in the Lorenz paper. We queried the USGS 3DEP elevation service at the published station coordinate and got 1,135.95 metres, or 3,727 feet.
The flatness claim deserves the same treatment. A widely repeated line has the playa level to within an inch or two end to end. A USGS caption says something different and more useful: the south end is a couple of feet lower than the north, which is why water gathers there and why the sliding rocks are found mostly at the lower southern end. Queried at two points on the surface, 3DEP returned 3,721 feet in the north and 3,708 in the south. That is an elevation model rather than a survey and should not be pressed to the inch, but the direction is unambiguous and it matches the physics: ponds need somewhere to pool.
One detail worth knowing before repeating any claim about which rock moved: to avoid disturbing the playa's own stones, the team imported theirs from the Panamint Springs Member of the Permian-aged Darwin Canyon Formation.
The wider reason anyone funds work here is not geological. Lorenz has also published on Racetrack and the nearby Bonnie Claire playa as analogues for Ontario Lacus on Titan — a basin at Saturn's moon that NASA's Cassini team concluded drains and refills from below, and compared to the Etosha Pan in Namibia. A shallow, seasonally flooded flat is useful to have on Earth when you are trying to read a radar image of one at Saturn.
The road, and what it costs in tyres
No permit, no quota, no guide, no booking. The friction here is mechanical.
The Racetrack Valley Road leaves the pavement near Ubehebe Crater and runs 26 miles to the Grandstand parking area; Teakettle Junction is at 20 miles, and the sliding rocks are a further two miles south. The Park Service's own wording is not soft: the road is rough, good tyres, four-wheel drive and high clearance are usually required, and standard rental vehicles are not recommended and often get flat tyres. It advises at least three and a half hours each way from Furnace Creek and states that there is no mobile coverage. Its backcountry roads page adds that flat tyres are common, that towing charges are high, and that motoring-club membership often does not cover tows on dirt roads.
The road is also not permanent. The remnants of Hurricane Hilary closed much of the park's network in August 2023; ninety-five miles of flood-damaged roads, Racetrack Road among them, reopened on 23 December that year on federal disaster and emergency-relief money. It was open as of the park's 18 August 2026 alerts page. Check it on the day.
What visitors do to it
The playa records everything. The Park Service's instruction is to keep vehicles off it entirely, to move or remove no rock, and to stay off the surface when it is wet, because muddy footprints disrupt the rocks' movement and leave scars for years.
The scale of the problem is documented rather than rhetorical. After illegal off-road driving on the surface, nineteen people from Friends of the Inyo and the Park Service spent a weekend repairing 512 feet of tyre tracks with garden tools and 750 gallons of water, described in a park news release of 15 March 2018. Off-road driving is prohibited park-wide, and the Park Service notes that tracks in fragile desert soils may be visible for decades.
The thing being damaged is also the instrument. Every published account of this phenomenon since the 1940s has been read off the trails, and a trail crossed by a tyre or a boot is a data point destroyed. Sharp and Carey's corral, Messina and Stoffer's 162 mapped tracks and the 2013 GPS record all sit on the surface a visitor is standing on.
Why the Silence Index is 61
Footfall pressure keeps this out of the seventies. Death Valley recorded more than 1.32 million visits in 2025, its fourth-highest year, and the Racetrack is one of the park's named destinations and a well-known photographic subject. Nothing caps it: no permit, no quota, no ranger, no season. That pressure lands on a surface of nine to fifteen square kilometres that holds a footprint for years.
Access friction is real but it is the kind money solves. Twenty-six miles of gravel, three and a half hours each way, routine punctures and no signal will turn most people back; a high-clearance rental and two spare wheels will not, and our methodology page is explicit that a filter sorting by wealth is not protection.
The acoustic floor is genuinely high: the Park Service describes parts of the park as some of the most naturally quiet places in the continental United States, and the nearest pavement is hours away. Darkness is higher still — an International Dark Sky Park since February 2013, Gold Tier across 13,848 square kilometres, with the Park Service's lightscape page naming the Racetrack area specifically among its best places to look up.
What pulls the score down is the fourth input, for a reason peculiar to this dossier. Our index gives a fifth of the weight to unresolved questions, on the argument that certainty is a form of erosion. Racetrack Playa is one of very few places in this archive whose central question was answered on camera. The trails are still there. The thing that used to be there with them — not knowing — is not.
What is still open
The first open question is frequency. In Geomorphology in 2014, Lorenz and Jackson reported that across seven years of monitoring they saw fewer movement events than the historical record implied, and a Monte Carlo analysis put roughly four-to-one odds on the movement probability having systematically declined — attributed to fewer occurrences of strong wind together with freezing temperatures. The sources disagree on when the previous movement was: the companion paper says the 2013 events were the first since about 2005, the Park Service's 2014 release says movement was last suspected in 2006. We print both.
The second is everything the fifteen loggers did not catch. The record covers a handful of events in one winter on a playa that has been accumulating trails for a very long time, and the largest stones remain unwatched.
None of that restores the mystery, and it should not be made to. The honest summary is narrow: the sailing stones move because thin ice breaks up in the morning sun and a light wind pushes the pieces. That was proposed in the 1950s, called most likely by the USGS in 1999, predicted with a food container and a baking tray in 2011, and photographed, timed and satellite-logged in December 2013. Anyone still telling you nobody knows why the rocks move is telling you something that stopped being true before most of the people repeating it were online.
Corner Codex — D-147
- Place
- Racetrack Playa, Death Valley National Park, Inyo County, California
- Coordinates
- About 36.68°N, 117.55°W. West longitude, so negative
- Size of the playa
- Disputed: 4.5 × 2 km (Lorenz et al.) or 3 × 2 miles (NPS) or 5 sq mi (USGS)
- Elevation
- 1,136 m at the research met station, per the USGS 3DEP elevation service
- Access
- 26 miles of rough gravel from Ubehebe Crater; at least 3.5 hours each way
- The mechanism
- Wind pushing thin floating ice panels that shove the rocks from behind
- Ice thickness
- 3 to 6 mm — the paper calls it windowpane ice
- Wind speed observed
- About 4 to 5 m/s. Beaufort force 3, a gentle breeze
- Rock speed
- 2 to 5 metres per minute
- Best-documented event
- 4 December 2013: two rocks moved 65.6 m and 64.1 m in 16 minutes
- Largest event
- More than 60 rocks moved on 20 December 2013
- Silence Index
- 61 / 100
The Traveler's Panel · checked
Changing information. Prices, permits, seasons and road access change, sometimes at short notice. Everything here is a starting point for your own confirmation — not a quote, and not a guarantee. Verify with the operator and the relevant official body before you book.
| Is it a mystery | No. Filmed, timed and GPS-logged in December 2013; published August 2014 |
| The mechanism | Wind pushing 3-6 mm floating ice panels that shove the rocks from behind |
| The wind needed | About 4-5 m/s. A gentle breeze, not a hurricane |
| How often | Years to decades apart. Movement occupied about one millionth of a decade |
| The road | 26 miles of rough gravel; 4x4, high clearance and good tyres usually required |
| Permit | None. No quota, no guide, no booking, no ranger at the playa |
| Entrance | USD 30 per vehicle for seven days. The park does not accept cash |
| Signal | None. The Park Service states there is no mobile coverage in the area |
Getting there — Las Vegas or Furnace Creek → Ubehebe Crater (pavement ends) → Teakettle Junction, 20 miles of gravel → The Grandstand, 26 miles → the sliding rocks, 2 miles further south
- The turn-off is at Ubehebe Crater, in the north-west of the park, where the pavement ends. From there the Racetrack Valley Road runs 26 miles of rough gravel to the Grandstand parking area, passing Teakettle Junction at 20 miles. The sliding rocks are a further two miles south of the Grandstand, at the lower end of the playa, and the trails are best seen there.
- The National Park Service's own wording is the wording to plan against: the road is rough; good tyres, four-wheel drive and high clearance are usually required; standard rental vehicles are not recommended and often get flat tyres. Allow at least three and a half hours each way from Furnace Creek.
- Carry two spare wheels rather than one, and the tools to fit them. The park's backcountry roads page states that flat tyres are a common problem, that towing charges are high, and that motoring-club membership often does not cover tows on dirt roads. The nearest help is hours away and there is no mobile phone signal in the area.
- There are no services of any kind on the road or at the playa: no fuel, no water, no toilets, no ranger station, no shade. Carry enough water and food to sit out an overnight breakdown, because that is the realistic failure mode.
- Check the park's alerts and conditions page on the day you travel. Racetrack Road was among 95 miles of park roads closed by the remnants of Hurricane Hilary in August 2023 and did not reopen until 23 December that year. It was open as of the park's 18 August 2026 update, but a single storm changes that.
- Go in winter or early spring if you want to understand what you are looking at. The mechanism needs standing water and a freezing night, and the surface is at about 3,720 feet, high enough to freeze when the valley floor 4,000 feet below does not. Do not walk on the playa while it is wet.
Indicative costs — verify before booking
| Park entrance | USD 30 private vehicle, USD 25 motorcycle, USD 15 on foot or bicycle, all valid seven days. USD 55 for the park annual pass |
| Payment | Card or digital only. The park states it does not accept cash |
| The Racetrack itself | Free. No permit, no reservation, no timed entry, no separate fee |
| The real cost | Tyres, and a vehicle that can carry two spares. We will not quote a figure: it depends entirely on what you arrive in |
| Recovery | Towing charges in the park are high and motoring-club cover often excludes dirt roads. Budget for a self-recovery, not a rescue |
What to pack
- Two full-size spare wheels, a jack that works on soft ground, a lug wrench and a compressor. One spare is the standard mistake here.
- More water than the drive appears to justify. The failure mode on this road is an overnight wait, not a walk out.
- Warm layers if you go in the season when the phenomenon happens. Ice forms at this elevation on nights when Furnace Creek does not come close to freezing.
- A paper map and a downloaded offline map. There is no mobile coverage on the road or at the playa.
- A long lens, and the discipline to use it. The best trails are the ones nobody has walked beside, and the way to keep them that way is to stay back.
Where to stay
There is nowhere to stay at Racetrack Playa and no facility of any kind on the road to it. Backcountry camping in the park is regulated and the playa itself is closed to vehicles entirely, so the practical options are the developed areas far to the east — Furnace Creek and Stovepipe Wells, both of which have lodging, fuel and water and both of which are a long way from the turn-off at Ubehebe Crater. That distance is the main reason the day is a seven-hour round trip on gravel before you have looked at anything. Some visitors base themselves in Beatty, Nevada, or in Lone Pine on the other side of the Sierra approach; we have not tested either and will not recommend a specific property. Whatever you choose, plan the day around leaving the playa with enough light to fix a puncture.
Safety & responsible travel
- Do not drive on the playa. It is prohibited, and the damage is documented: after one episode of illegal off-road driving, nineteen people from Friends of the Inyo and the National Park Service spent a weekend repairing 512 feet of tyre tracks with garden tools and 750 gallons of water. The Park Service notes that tracks in desert soils can remain visible for decades.
- Do not move or remove any rock. The instruction is explicit on the Park Service's own page, and it is not only about souvenirs: a rock lifted out of its trail destroys the record of a movement event, and the entire scientific literature on this site since the 1940s has been read off those trails.
- Stay off the surface when it is wet. The Park Service states that muddy footprints disrupt the rocks' movement and leave scars for years. The mud that records a stone also records a boot, and it does not distinguish between them.
- Do not rebuild the trails for a photograph, and do not repeat the mystery framing when you post the picture. The mechanism has been published, filmed and measured; presenting it as unexplained is what makes the site attract the kind of visit that damages it.
- Everything here is inside designated wilderness or beside it — Death Valley holds over 3,190,400 acres of it, about 93% of the park and the largest wilderness in the contiguous United States. Camp only where the park permits it, and pack out everything.
Nearby, and quieter
Ubehebe Crater, where the pavement ends, is worth the stop rather than the glance: a maar about half a mile across, formed when rising magma met groundwater, and the youngest of thirteen overlapping craters in a field whose most recent eruption the USGS dates to 2,100 years ago. Its depth is given as 600 feet by one Park Service page, 500 to 777 feet by another and 250 metres by the USGS. Teakettle Junction, twenty miles down the gravel, is a signpost hung with kettles left by passing drivers and is the only landmark on the road. The Grandstand, an outcrop of quartz monzonite at 3,781 feet, sits at the playa's northern end and is where the parking area is; the trails are two miles south of it. Ubehebe Peak, 5,678 feet, rises along the western side of the valley. And the Park Service points visitors who cannot manage the road toward Bonnie Claire Playa, which is easier to reach and shows the same phenomenon.
Getting there, in order
- 1Las Vegas or Furnace Creek
- 2Ubehebe Crater (pavement ends)
- 3Teakettle Junction, 20 miles of gravel
- 4The Grandstand, 26 miles
- 5the sliding rocks, 2 miles further south
Each leg is a separate booking and a separate chance to be weathered out. Build spare days into the chain, not onto the end of it.
Where it is
Racetrack Playa, Death Valley National Park, California · 36.6823°N 117.5515°W · Open in Google Maps · OpenStreetMap
Key locations
- Racetrack Playa research station — the met station in Norris et al.; the only coordinate here from a peer-reviewed paper
36.6823°N 117.5515°W - Racetrack Playa, southern end — approximate; where the trails are, and 3DEP returns 3,708 feet
36.6660°N 117.5566°W - The Grandstand, northern end — approximate; playa level beside the quartz monzonite outcrop USGS puts at 3,781 feet
36.7019°N 117.5719°W - Ubehebe Craters — the USGS volcano observatory coordinate; the pavement ends here
37.0200°N 117.4500°W - Furnace Creek climate station — NOAA station USC00042319, 59 m below sea level and 3.5 hours from the playa
36.4626°N 116.8672°W
Coordinates are for orientation and are accurate to roughly the width of the feature named, not to a doorway. Several of these points are inside protected areas or need a permit, a guide or a boat — read the access notes above before you plan a route to any of them.
Sources & further reading — checked
- PLOS ONE — Norris, Norris, Lorenz, Ray and Jackson, Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion (27 August 2014). The primary observation: ice 3 to 6 mm thick, winds of about 4 to 5 m/s, rock velocities of 2 to 5 m/min, the 4 December 2013 movements of 65.6 m and 64.1 m in 16 minutes from 11:05, the 20 December 2013 event in which more than sixty rocks moved, and the custom GPS loggers recording at one-second intervals
- PubMed Central — full text of Norris et al. (2014), PMC4146553. The masses of the instrumented rocks (A3 at 16.6 kg, A6 at 8.2 kg, A10 at 15.6, A11 at 15.4); the weather station at 36.6823N 117.5515W; the November 2013 rain of 3.61 cm and about 20 cm of snow; the pond at about 10 cm maximum depth from late November to early February; the windowpane wording; the 9 January 2014 direct sighting; the 224 m maximum seasonal travel; the rocks sourced from the Panamint Springs Member of the Darwin Canyon Formation; and the earlier wind-speed estimates of Shelton, Sharp, Bacon and Reid
- Earth Surface Dynamics Discussions — Lorenz, Norris, Jackson, Norris, Chadbourne and Ray, Trail formation by ice-shoved sailing stones observed at Racetrack Playa (2, 1005-1022, 2014). The bulldozing description of the mechanism; the estimate that rocks moved for a few minutes in close to a decade, about one millionth of the time; the movement dates of 4, 20 and 21 December 2013 and 5 and 9 January 2014; the playa given as a nearly flat 4.5 by 2 km lakebed at 1300 m; rocks up to about 300 kg, mostly dark grey dolomite with a few granite boulders; and the statement that these were the first movements since about 2005
- American Journal of Physics 79(1), 37-42 — Lorenz, Jackson, Barnes, Spitale and Keller, Ice rafts not sails: Floating the rocks at Racetrack Playa (January 2011). The prediction three years before the observation: that ice works by buoyantly reducing the reaction and friction forces at the bed rather than by increasing wind drag; the 64 g basalt pebble frozen in a plastic food container into a raft about 3 cm thick and 20 cm across, moved in a sand-filled baking tray by a push of a few millinewtons; and the claim that modest rafts can reduce the required wind speed to arbitrarily small values
- NASA Astrophysics Data System — Lorenz and Jackson, Declining rock movement at Racetrack Playa, Death Valley National Park: An indicator of climate change? (Geomorphology 211, 116, 2014). Seven years of monitoring finding fewer movement events than the historical record implies, and a Monte Carlo analysis giving roughly four-to-one odds that the movement probability has systematically declined, attributed to fewer occurrences of strong winds with freezing temperatures
- USGS Publications Warehouse — Messina and Stoffer, Terrain analysis of the Racetrack basin and the sliding rocks of Death Valley (Geomorphology 35(3-4), 253-265, 2000). The first comprehensive mapping of the trails: 162 rocks and trails surveyed with submetre differential GPS in July 1996 to about 30 cm accuracy; the finding that trail character relates more to where a rock rested at the onset of motion than to the rock itself; and only four rocks repositioned during the 1997-98 El Nino winter
- USGS Open-File Report 99-153 — Slate (ed.), Proceedings of Conference on Status of Geologic Research and Mapping in Death Valley National Park (1999). The single most important source for this dossier's correction: a USGS publication stating in 1999, fifteen years before the filming, that the trails were caused most likely by ice-rafted rocks occasionally pushed across the playa during winter windstorms
- The Journal of Geology 104(1), 121-125 — Bacon, Cahill and Tombrello, Sailing Stones on Racetrack Playa (1996). The wind-only case: wind-shear and gust data from Owens Dry Lake about 80 km SSE, argued as consistent with static-friction thresholds allowing motion of 30 of the 31 rocks for which data were available — the position the 2013 observations superseded
- National Park Service — Death Valley's Moving Rocks. The Park Service's own account: rocks weighing as much as 320 kilograms or 700 pounds, trails stretching for hundreds of metres, remote observations from 2011 to 2013 showing a rare combination of water, ice and wind, the prohibition on driving on the playa or moving any rock, and the alternative of Bonnie Claire Playa
- National Park Service — Mystery Solved: mysterious sailing stones of Death Valley seen in action for the first time (27 August 2014). The park's release figures, which differ slightly from the paper's: water about 7 cm deep, ice under 5 mm, winds of 3 to 5 m/s described as about 10 mph, rocks at 2 to 6 m/min, movements of a few seconds to 16 minutes and over 60 m; the statement that movement was last suspected in 2006; and Richard Norris's remark that the team expected to wait five or ten years without anything moving
- National Park Service — The Racetrack (visitor page). The road: 26 miles to the Grandstand, Teakettle Junction at 20 miles, the sliding rocks two miles south of the Grandstand parking, good tyres and 4x4 and high clearance usually required, standard rental vehicles not recommended and often getting flat tyres, at least 3.5 hours each way, no mobile phone coverage; the playa given as about 3 miles by 2 miles over mud at least 1,000 feet thick; and the rules on driving, rock removal and wet-surface footprints
- National Park Service — Restoration Work at Death Valley Racetrack (15 March 2018). The documented vehicle damage and its repair: 512 feet of tyre tracks worked on by nineteen people from Friends of the Inyo and the National Park Service using garden tools and 750 gallons of water, restoring the playa's natural polygon patterning
- National Park Service — Off-Road Driving in Death Valley. That off-road driving is prohibited park-wide, that 785 miles of established open roads are available instead, and the caption statement that tyre tracks from illegal off-road travel may be visible for decades in fragile desert soils
- National Park Service — Backcountry Roads, Death Valley. That flat tyres are a common problem for backcountry visitors because of rough road conditions, that towing charges are high and motoring-club cover often excludes tows on dirt roads, and that mobile reception is non-existent in most areas of the park
- National Park Service — Alerts and Conditions, Death Valley (checked 22 August 2026; page last updated 18 August 2026). The live road-status picture used in this dossier: Racetrack Valley Road not listed among current closures, Titus Canyon Road closed 1 October 2026 to 30 September 2027 for a second phase of repairs, and Darwin Falls likely closed until summer 2027
- National Park Service — Additional areas opening 12/23: North Highway, Ubehebe Crater and The Racetrack (December 2023). The reopening of 95 miles of roads damaged by the remnants of Hurricane Hilary, including Racetrack Road, on 23 December 2023, funded through an NPS Disaster Supplemental and Federal Highway Administration Emergency Relief for Federally Owned Roads
- National Park Service — Geologic Formations of Death Valley. The Racetrack Dolomite placed in the Middle Cambrian and described as nearly black to grayish-yellow dolomite with some chert nodules, within a rock record running from 1.8 billion-year-old metamorphic rocks to modern playa sediments
- National Park Service — Lightscape and Night Sky, Death Valley. That the park holds some of the darkest night skies in the United States and that the Racetrack area in particular is named by the Park Service as an excellent place to observe them
- National Park Service — Death Valley National Park's dark, starry nights earn international dark sky recognition (20 February 2013). The February 2013 certification as the third International Dark Sky Park in the National Park System and the largest at the time, and the lighting retrofits at Furnace Creek and Stovepipe Wells that were required to qualify
- DarkSky International — Death Valley National Park. The Gold Tier Dark Sky Park designation, the 2013 certification date, the 13,848 km2 certified area, and the note that the lights of distant Las Vegas and other cities still reach the park's skies
- National Park Service — Soundscapes, Death Valley. That portions of the park are among the most naturally quiet places in the continental United States, and that road noise spreads deep into canyons and wilderness far from the road itself
- National Park Service — Road Maintenance Includes Acoustic Research (2018). The 2018 pavement-noise study on Badwater Road, Beatty Cutoff and Mud Canyon Road with the US Department of Transportation's Volpe Center, and the park's statement that road noise carries surprising distances in Death Valley because it is so quiet
- National Park Service — 2025 Visitation, Death Valley. More than 1.32 million visitors in 2025, the park's fourth-highest year on record, despite a 43-day government shutdown and flash-flood closures
- National Park Service — Wilderness, Death Valley. Over 3,190,400 acres of designated wilderness, roughly 93% of the park, described as the largest wilderness in the contiguous United States
- National Park Service — Death Valley FAQs. More than 300 miles of paved roads, 300 miles of improved dirt roads and several hundred miles of unmaintained four-wheel-drive roads in the park
- National Park Service — Fees and Passes, Death Valley. Entrance at USD 30 per private vehicle for seven days, USD 25 per motorcycle, USD 15 per individual on foot or bicycle, and a USD 55 park annual pass; and that the park does not accept cash
- National Park Service — Weather and Climate, Death Valley. Average rainfall of less than 2 inches at Furnace Creek with an annual figure of 1.94 in; the 134F record of 10 July 1913; and the lapse rate of 3 to 5F per thousand feet gained, which is why the Racetrack at about 3,720 feet freezes when the valley floor does not
- National Weather Service, Las Vegas — Weather and Climate of Death Valley National Park. The record extremes: 134F on 10 July 1913 and 15F on 8 January 1913; the wettest year on record in 2005 at 4.73 inches or 120.1 mm; years with no rain at all in 1929, 1953 and 1989; and the only measurable snow at Furnace Creek, half an inch on 29 January 1922
- National Weather Service — Beaufort Wind Scale. That force 12, hurricane, begins at 64 knots — about 33 m/s — and that 8 to 12 mph, the band the observed 4 to 5 m/s falls into, is force 3, a gentle breeze
- NOAA National Centers for Environmental Information — station GHCND:USC00042319, Death Valley National Park, CA. The park's long-record climate station at 36.46263N, 116.8672W, elevation -59.1 m, with a period of record running from 26 April 1961
- USGS — Racetrack Playa (photograph caption, playa description). The playa placed in the southern Cottonwood Mountains of the Panamint Range at just over 3,800 feet, covering about 5 square miles, slightly higher at its north end near the Grandstand, with the sliding rocks found mostly at the lower southern end — and the still-open framing that the mechanism has been investigated for nearly a century
- USGS — Racetrack Playa (photograph caption, ponding at the south end). That the south end of the playa is a couple of feet lower than the north end and that water there is typically only a few inches thick — and a caption that still hedges between ice-rafting and direct wind, citing Messina and Stoffer 1999
- USGS — The Grandstand (photograph caption). The Grandstand as a large outcrop of quartz monzonite at an elevation of 3,781 feet rising above the mud at the playa's northern end
- USGS — Karen, a sliding rock (photograph caption). Karen described as a block of Racetrack Dolomite and one of the largest of the sliding rocks, estimated at between 700 and 800 pounds
- USGS — Ubehebe Peak (photograph caption). Ubehebe Peak at 5,678 feet rising along the western side of the Racetrack Playa valley, and the active fault system whose rift valley Racetrack Road follows
- USGS California Volcano Observatory — Ubehebe Craters. The coordinate used in this dossier's panel, 37.02N 117.45W, with an elevation of 752 m; thirteen overlapping craters of maar and tuff ring type; the main crater about 800 m wide and 250 m deep; an ejecta blanket of about 40 km2; and a most recent eruption 2,100 years ago
- USGS 3DEP Elevation Point Query Service — Racetrack Playa research station. An elevation of 1,135.95 m at the published coordinate of the research weather station, against the 1,300 m given in the Lorenz group's paper and the just-over-3,800-feet figure in the USGS caption
- USGS 3DEP Elevation Point Query Service — northern playa. An elevation of 3,721.5 feet at the northern end of the playa beside the Grandstand outcrop
- USGS 3DEP Elevation Point Query Service — southern playa. An elevation of 3,708.2 feet at the southern end of the playa, about thirteen feet below the northern reading and consistent with the USGS caption placing the south end lower
- National Park Service — Ubehebe Crater (visitor page). The crater given as 600 feet deep and half a mile across, formed possibly as recently as 2,100 years ago when rising magma met groundwater — the point at which the pavement ends and the Racetrack road begins
- National Park Service — Ubehebe Crater (places entry). A different depth from the same agency: 500 to 777 feet, or 152 to 237 m, depending which ridge it is measured from, with a diameter of about 0.5 miles, and the crater set about 8 miles west of Scotty's Castle
- NASA Jet Propulsion Laboratory — Cassini Finds Titan Lake is Like a Namibia Mudflat (19 April 2012). The planetary-science reason a Death Valley playa is studied at all: Cassini radar work led by Thomas Cornet concluding that Ontario Lacus on Titan drains and refills from below, with the Etosha Pan in Namibia used as the terrestrial analogue
- Federal Highway Administration, National Scenic Byways — Sliding Rocks at Racetrack Playa (photograph caption). A United States federal page still describing the sliding rocks as one of the apparent mysteries of Death Valley whose mechanism is the subject of countless hypotheses — evidence that the unsolved framing survives inside government, not only in the travel press
Official and scientific bodies are the authority for safety, regulatory and scientific claims. Commercial operators are used only for practical detail such as tour length, meeting points and indicative pricing — never for a safety or scientific statement.
How this was made
Desk research. Compiled from official bodies, scientific and conservation sources, established journalism and licensed operators. Not based on a personal visit.
Editor’s method note — what we checked, corrected and could not verify
- Desk research only. Nobody from this publication has been to Racetrack Playa, and nothing in this dossier is a first-hand observation of the road, the surface or the sky.
- Every URL cited was opened and read before citation. Sources we could not open are listed below and are not cited anywhere in the piece.
- We correct the commission brief in one direction. It is not accurate to say the phenomenon was solved in 2014 if solved implies that nobody had an explanation before. Stanley proposed ice in 1955; the USGS called ice-rafting the most likely cause in a 1999 conference volume; and Lorenz and colleagues published a quantitative ice-raft mechanism in the American Journal of Physics in January 2011. What happened in December 2013, published in August 2014, was the first direct observation and measurement. That is what we say throughout.
- We also print where the 2011 prediction was wrong. Lorenz's mechanism was buoyant flotation unweighting the rock; the observation found thin ice panels bulldozing rocks that stayed in contact with the bed, and the ice was millimetres rather than centimetres thick. The prediction was right about the agent and wrong about the physics, and merging the two would misrepresent both papers.
- Where the sources disagree we print both and name them. On the date of the previous movement: the Earth Surface Dynamics paper says the first since about 2005, the Park Service's 2014 release says movement was last suspected in 2006. On ice thickness: the PLOS paper says 3 to 6 mm, the Park Service says under 5 mm. On wind: the paper says about 4 to 5 m/s, the Park Service says 3 to 5 m/s. On the size of the playa: 4.5 by 2 km in the Lorenz group's paper, about 3 by 2 miles on the Park Service visitor page, about 5 square miles in a USGS caption. On elevation: just over 3,800 feet in a USGS caption, 1,300 m in the Lorenz group's paper, and 1,135.95 m returned by the USGS 3DEP elevation service at the published station coordinate. On Ubehebe Crater's depth: 600 feet on one Park Service page, 500 to 777 feet on another, 250 m in the USGS volcano record.
- The mass figures are not corrected, because they hold up. Rocks up to about 300 kg are described in the peer-reviewed literature and up to 320 kg by the Park Service. What we do correct is the implication that one has been watched moving: the instrumented rocks whose movement was logged weighed between 8.2 and 16.6 kg, and we found no measured record of a 300 kg rock in motion.
- The flatness claim was checked rather than repeated. Instead of the widely circulated line about the playa being level to within an inch or two, we cite the USGS caption stating the south end is a couple of feet lower than the north, and we queried the USGS 3DEP elevation point service at two coordinates on the surface, which returned 3,721.5 feet in the north and 3,708.2 feet in the south. 3DEP is a national elevation model, not a survey, and we do not press it below the metre.
- Coordinates. The only point in the panel that comes from a peer-reviewed source is the research weather station at 36.6823N, 117.5515W, published in Norris et al. Ubehebe Craters uses the USGS California Volcano Observatory's own published value of 37.02N, 117.45W, padded to four decimals rather than refined. The Furnace Creek point is NOAA's station metadata. The two playa points are approximate positions we checked against the 3DEP elevation service to confirm they fall on the lakebed rather than the surrounding slopes. Teakettle Junction is deliberately absent from the points list: we could not obtain an official coordinate for it, the USGS Geographic Names Information System web application requires JavaScript and would not render, and its bulk download host was blocked by our egress policy. We would rather describe the junction in the panel text than pin it in the wrong wash.
- Sources we could not read, and therefore did not cite: the Geological Society of America Bulletin page for Sharp and Carey (1976), which returned 403, so their corral experiment is reported only as the 2014 authors describe it; the Geology comment-and-reply on sliding rocks at the Racetrack, also 403; the Journal of Applied Meteorology and Climatology paper on meteorological conditions at Racetrack Playa, 403 on both the article and PDF routes, which is why no measured gust statistics appear here; the ScienceDirect records for Kletetschka and for Messina and Stoffer, blocked by robots.txt, the latter read instead through the USGS Publications Warehouse; the USGS Geolex entry for the Racetrack Dolomite, 403; and the NPS IRMA visitation report viewer, which serves its figures through a JavaScript report tool we could not render, so visitation is cited from the park's own news release instead.
- Things we could not verify: an official coordinate for Teakettle Junction or the Grandstand; any published record of a rock heavier than about 17 kg being observed in motion; the total number of rocks and trails on the playa, which no source we opened gives; the current condition of the Racetrack Valley Road, which is not in the park's alert list but changes after every storm; whether any movement has occurred since the 2013-14 season, on which we found no primary source at all; the outcome or prosecution of the off-road driving incidents the 2018 restoration release responds to, the release naming no date, vehicle or person; whether Racetrack Valley Road is 26, 27 or 28 miles long, the Park Service's own pages and its trailhead sign not agreeing; and any measured decibel figure for the playa, the Park Service publishing its Death Valley acoustic data only as a dataset we could not open.
AI is used to draft this text, and a human checks it. Every figure, date and quotation above was verified by Tony Hall against the source cited for it in the reference list; where sources disagree, the disagreement is shown rather than resolved, and where a claim could not be confirmed it is either marked unverified or left out. The illustrations are AI-created and labelled as such — no photograph on this site is presented as a record of a real place. Full disclosure · Editorial policy.
Access details change — recheck before you travel. Found an error? Tell us — corrections are dated and shown in place.
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