The Secrets of Death Valley Uncovered | How the Earth Was Made (S2, E9) | Full Episode | History

0:02earth a unique planet restless and dynamic

0:10continents shift and clash volcanoes erupt glaciers grow and recede titanic forces that

0:19are constantly at work leaving a trail of geological mysteries behind and there is

0:28nowhere more mysterious than death valley the hottest and driest desert in the united states

0:37this is a place where even 700 pound rocks appear to move by themselves

0:46it's the lowest point in the u.s and right here the earth's crust is thinner than almost

0:52anywhere else on the planet death valley is a dynamic laboratory for investigators

1:00who uniquely read rocks like x-rays to reveal the inner workings of the earth and its history

1:09adding to the continuing story of how the earth was made

1:22death valley is the largest national park in the lower 48 states

1:27more than three times the size of rhode island straddling the border of california and nevada and

1:35surrounded by towering mountain peaks 140 miles long and up to 15 miles wide with temperatures

1:45reaching a scorching 134 degrees fahrenheit this is one of the most inhospitable places on earth

1:57but for geologists death valley has a unique attraction

2:01here they can witness the interplay of the earth's most titanic geological forces

2:09when you look at death valley really you're looking at a battle a battle between processes

2:15that are occurring on the earth's surface and we can see the record of those forces of

2:19nature locked into the rocks death valley has an archive that is almost unrivaled worldwide

2:28to uncover death valley's earliest history brave is hunting for its oldest rocks he is searching in

2:38one of its most remote spots in the extreme south of the valley in the isolated alexander hills

2:48this is one of the oldest rocks in death valley it's 1.2 billion years old

2:52and given the color of this rock and the fact that it's quite soft it can powder when i scratch it

2:57these are all clues that tell me that this is a limestone

3:02the limestone is a major clue to revealing the way this arid desert used to look

3:09if we think about the type of environments

3:12that limestones can be deposited in the first that comes to mind is an underwater in a marine setting

3:21there is only one way to form limestone it is made from the tiny bones and shells of sea creatures

3:28they die and sink to the sea floor where the weight of further layers

3:33on top of them crushes them slowly into solid rock

3:42and prave has discovered other startling evidence that death valley had a watery past

3:49fossils are a major clue they are vital in the type of evidence that a geologist will use

3:56these are some very nice examples of the type of fossils you can find in these ancient rocks

4:03and you can see here these curving surfaces outlining what looked to

4:08be large cabbages that are sliced in half these were algae known as a stromatolite

4:15ironically these marine fossils have survived in the death valley desert

4:20only because there is so little water that might otherwise have washed them away

4:27but they would have originally looked like this when they flourished in the death valley waters as

4:34the limestone formed more than one billion years ago these tell us that the environment when this

4:40rock formed would have been a shallow sea if i'd been here when these rocks were first being formed

4:48i'd be sitting in my swimming trunks about waist deep in water very much like the bahamas today

4:54the stromatolites are some of the earliest signs of life on our planet to discover what happened

5:01over the next one billion years prague studies evidence in the surrounding hills the different

5:09bands of colors and the rock layers and the hills represent ancient seas that covered the death

5:14valley area the seas would deposit a layer of limestone move back across the land another layer

5:20of limestone would be deposited and so we have a history of the seas moving across the death valley

5:26region from the time of the stromatolites to these rock layers now more than a million years later

5:34geologists wanted to figure out what dramatic geological upheaval could have turned death

5:39valley from a shallow sea to the baking hot desert of today and brave has found clues

5:47in a rock that is entirely different from the marine limestones he has studied up until now

5:55this is a nice example of a rock type called a granite

5:59and it forms those veins that are in the hillside behind me

6:05you can think of these like the fingers of my hand

6:08they're fed upward from a much more larger massive area of granite sitting underneath

6:14the granite tells scientists the reasons why death valley's ancient seas vanished

6:22today it is solid rock but it was once hot molten magma from deep underground

6:31only one force of nature has the awesome power

6:34and 2000 degree fahrenheit heat to melt rock into magma and fire it to the surface

6:44volcanoes the seas here didn't just drain away they were pushed back by these mountains of fire

7:01it was only in the 1960s with the realization that earth's continents were drifting around the planet

7:07that scientists figured out why the volcanoes erupted under death valley

7:14the theory of plate tectonics revealed that around 100 million years ago

7:19an ancient oceanic plate began sinking under north america pushing up the land

7:27heat from the collision powered a coastal chain of volcanoes erupting on the land and finally

7:34driving away the seas submerging death valley this landscape would have been very explosive

7:41a hostile type of setting and that then set the stage for what was to become death valley

7:50still surviving in the valley to this day is the ghost town

7:54evidence of another substance far rarer than granite that the volcanoes brought to the surface

8:03gold although gold occurs naturally in more than 30 different u.s states

8:11the golden death valley was concentrated in veins in the rock as magma solidified near the surface

8:19it made it worth mining and millions of years after its formation it sparked the death valley

8:24gold rush it's a wonderful example of a gold mine shaft it's the eureka mine high up in the panama

8:32mountains associated with trying to find gold in the granites that were intruded into these

8:38rocks 100 to 200 million years ago the gold would have been in veins these fingers would

8:45have been injected up into these rocks and the gold would have been concentrated in these veins

8:55the gold rush here lasted just a few years miners often had to remove a ton of rock to

9:01recover only one tenth of an ounce of gold enough to produce just a single wedding ring

9:10today all that remains are empty tunnels and ghost towns

9:18it's interesting to consider that the frenzy of activity mining gold was actually a direct result

9:26of the kind of volcanic activity 100 to 200 million years ago

9:31geologists investigating the battle that raged in death valley between

9:36fiery volcanoes and ancient seas have found important evidence

9:44stromatolite fossils are proof that death valley was once submerged by the waters of a shallow

9:50sea veins of granite could only have formed in the fiery heat of the volcanoes that burst

9:57to the surface around 100 million years ago and drove that sea away

10:03the volcanoes built up the land that was to become death valley into peaks as high as

10:08the cascades mountain range but deep beneath the earth's surface awesome geological forces

10:15were about to destroy those peaks stretch the land apart and transform the mountains of death valley

10:24into the lowest point in the u.s a billion years death valley remained a flat plain under the sea

10:38around 100 million years ago erupting volcanoes formed high mountain ranges

10:45but then the real geological mystery began the land here must have undergone an extraordinary

10:52transformation because today in death valley those high mountain ranges have vanished incredibly the

11:01one-time mountains have sunk below sea level to become the lowest point in north america

11:10yet all around the valley snow-capped peaks still soar up to 11 000 feet into the air

11:19the investigation digs deep under the landscape to discover what vast geological forces could have

11:25caused that huge difference in height between two places just 20 miles away from each other

11:33there are a lot of mysterious aspects about death valley it's a unique landscape because the valley

11:39floor itself is is very deep it's below sea level and the mountains rise up very steeply on

11:45either side clues to the power of these underground forces

11:50lie all over the valley if you know where to look many of the rock layers were originally

11:59deposited on the ancient flat seabed they can still be seen as horizontal layers

12:08but other nearby layers aren't horizontal at all they tilt downwards into the ground

12:19miller finds a further clue of earth's power in the unusual shape of this cinder cone

12:25a mound of ash and debris lying on death valley's floor it looks like it's two

12:31cinder cones but in fact it's really just one that's been pulled apart along a big fault zone

12:41this has moved some 700 feet in some 700 000 years so that's about a foot per thousand years which

12:49sounds like it's really really slow but if you look at it over a great length of geologic time

12:55you get quite a lot of slip and give it even longer time it'll be offset even more

13:03miller's next challenge is explaining what is making the fault line move for that she studies

13:11other ancient rock formations whose jagged outline has given them the name turtlebacks

13:18the turtlebacks are crucial to understanding death valley's early origins they have so much of the

13:26record here if you're willing to spend time to try to unravel it

13:32the real clue lies in the rock's distinctive texture

13:38if you just take a look at this rock closely you can see that it's very kind of strung out very

13:43stringy it tends to be a pretty fine grained this texture tells miller where these rocks came from

13:53we see evidence that these rocks were deformed just like if you take a piece of plastic and

13:58where to heat it up you could bend it it's the same thing with rock and so these rocks formed

14:03at high temperatures and pressures within the earth's crust at depths of about 10 miles or so

14:10and they have since been brought to the earth's surface concluded that

14:17some overwhelming underground force must have raised the turtleback rocks to the surface

14:22and stretched them out like warm toffee as death valley formed the final explanation

14:31of what happened here once again came back to the way continents drift around the globe

14:39as the collision of the plates that had forced ancient volcanoes to the surface slowed down and

14:45ceased the high mountains that once dominated the land were slowly pulled apart and tilted downwards

14:54gradually as the underlying crust grew thinner and thinner a deep basin formed between the

15:00mountain ranges death valley is the most extreme example of what such stretching forces can do

15:08by measuring seismic waves scientists discovered that here the continental crust is just 16 miles

15:15thick this might sound like a lot but it is far thinner than almost anywhere else on the planet

15:22around the globe the earth's continental crust averages 25 miles thick it's strongest beneath

15:29the himalayas at 43 miles thick enough to support the weight of massive mountains such as everest

15:45the turtleback rocks also offer miller evidence as to when death valley's stretching started

15:53dating these rocks reveals that the deformation started here around 13 million years ago although

16:00death valley did not take on its final shape immediately death valley is really young

16:06when you look at the whole geologic time scale modern death valley is

16:11probably three or four million years old at the most the stretching started before that but death

16:17valley itself is a very recent feature scientists know that the process is far from finished

16:26they've found irrefutable evidence in the alien death valley landscape known as bad water basin

16:36i'm standing here at bad water which is the lowest point in the western hemisphere it's 282 feet

16:44below sea level we're actually standing below sea level about the depth of a football field

16:53this floor has been sinking it's about a tenth of an inch per year which is

16:57about half of the speed at which your fingernail grows continual stretching of the earth's

17:06crust has turned bad water into one of the lowest spots on any continent on the planet

17:13yet its true depth is even lower still the surface that we see here is the present-day surface

17:21but what one has to realize is that beneath our feet we can go down through sediment that

17:26represents ancient periods of time when death valley was a surface that goes down three miles

17:34you would need to drill down through the sediment to a depth

17:37equivalent to 11 empire state buildings end to end before you hit the crustal bedrock

17:45the total volume of material in this basin would bury new york to the depth of nearly a mile

17:54the valley floor is constantly being covered with sediment cascading from the surrounding mountains

18:00but it can never fill up completely the sediment is coming in at a rate that is less than

18:08the rate of sinking of death valley itself so that we're always maintaining a surface

18:13here on the valley that is sitting below sea level and is continuing to sink

18:17through time this constant movement shows earth's geological forces at their most dynamic

18:24and makes death valley unique the allure is that nowhere on earth do we see continental crust

18:32being pulled apart at this rate or this magnitude the investigation into death

18:40valley's creation has established how it sank to become the lowest point in north america

18:48the turtleback rocks were deformed by the powerful tectonic forces

18:52pulling the mountains apart to form a wide valley floor

18:58the still sinking landscape of bad water currently 282 feet below sea level

19:03is proof that the crust here is still being stretched today

19:11but the sinking of death valley is just one part of the story geologists still need to

19:18investigate how one of the hottest places on earth was shaped by the power of moving ice

19:331.2 billion years ago death valley was submerged by ancient seas

19:40around a billion years later volcanic mountains drove the seas away

19:46thirteen million years ago the continental crust started stretching apart here

19:51and by three million years ago death valley was one of the lowest points on earth

19:59the clue that showed investigators what happened next was the discovery

20:04in the valley of a little-known but highly valued white crystalline rock

20:11when one thinks of prospectors in the death valley region one often thinks of them hunting for gold

20:16and for silver but there was one mineral that was much less glamorous much less sexy and exciting

20:21and that was borax but it was actually known as the white gold of the desert in 1880 borax was

20:28a rare but in demand mineral used in antiseptics and detergents one impoverished couple desperately

20:34trying to make a living in death valley was aaron and rosie winters they heard from a

20:40passing prospector that they could make good money from borax if they could find it they learned from

20:46their fellow prospector the then secret method of testing rock for borax anxious to keep potential

20:54profits for themselves the couple waited until the dead of night to perform the test in death valley

21:01you burn the mineral to see if the powder that we have in front of us here contains any borax

21:08now what the winters did is to add sulfuric acid to borax bearing mineral we'll add some alcohol

21:18the winters probably used cheap whiskey back in 1880 and the flame should burn hopefully a

21:25green color if borax is there and as we can see the flame is green in color and in 1880

21:36the winters knew that they would become wealthy because they had borax from these

21:44humble beginnings a whole industry grew in death valley it made the winter's fortune and also gave

21:52scientists a priceless clue in their quest to understand the geological history of death valley

22:01because borax deposits like these can only be found in the beds of ancient freshwater lakes

22:10the sea water that once covered this valley had long gone a billion or more years earlier

22:16but the presence of borax proves that fresh water must have flooded into the area when ice

22:23age glaciers started to melt from the surrounding mountains around two hundred thousand years ago

22:29as the glaciers melted rivers flowed towards the lowest point

22:34death valley gradually a vast lake spread out across the flooded valley floor

22:43the valley's catchment area was huge its rivers drained more than nine thousand square miles

22:50an area bigger than new hampshire the water pouring in from the surrounding mountains

22:58leeched minerals such as borax from the rocks and deposited them on the lake bed

23:06in a lot of the lake beds this mineral borax would appear as a kind of a white fuzzy mineral it's

23:12actually called cotton ball the borax proved that a lake existed here geologists called it

23:21lake manley after one of the pioneers william l manley who had named death valley in 1849

23:31but they had no evidence to tell them its depth and its size

23:38a solution to this puzzle is revealed in this small hill

23:42with a road cut straight through it near the valley's edge at a spot called beady junction

23:50it's very fortunate to have a road cut right through this gravel deposit so in the exposure

23:57we can see very well rounded pebbles we can also see some crude layering in the

24:03gravels and they're stacked in against each other and we call that shingling

24:09the shape and the smoothness of the stones tells caskey exactly how these pebbles got here

24:17the way their stack tells us that the direction of water flow that laid these pebbles down like this

24:24was from the right to the left so we know that this had to be wave action that strong evidence

24:29that this is a beach environment by looking at the height of this pebble beach above the valley floor

24:36caskey calculates the dimensions of the lake from this speech gravel bar that we're standing on

24:43the waves would have been crashing at our feet and as we look south it's hard to imagine a

24:48lake sitting out there across that vast salt pan but lake manly would have covered about

24:53600 square miles and it would have been about 450 feet deep it's odd mapping shorelines on

25:02a really hot day in death valley you kind of long for the the ancient days of yore

25:08when there were big lakes out here you imagine this was a beautiful place full of lush vegetation

25:15yeah it was quite a different place than it is today for caskey the next step is discovering why

25:22death valley no longer has a lake and there is evidence about that in one of its most unusual

25:29landscapes this twisted jagged field of white peaks that's called the devil's golf course

25:40even the sounds here are mysterious in the silence of the desert there is a faint

25:45popping noise as the relentless sun sucks every drop of moisture out of the parched surface

25:55the salt that we see here is the remains of an ancient lake it's called devil's golf

26:00course because it's probably the least likely surface that you would ever want to play golf on

26:07the surface is made up of rough salt crystals popping when they expand and contract in the

26:13searing heat but this salt did not come from the sea just like the borax the salt was leached

26:22from the rocks when fresh water started flowing into death valley two hundred thousand years ago

26:30the salt was originally dissolved in the freshwater lake manly

26:34and caskey has a simple experiment to show exactly how it ended up on the floor of death valley

26:42i'll pour the water and salt solution into this pan and as the water evaporates

26:47we should see salt forming and that's exactly how this salt crust forms

26:56it's hot enough out here today it should evaporate pretty quickly

27:05in fairly short amount of time some beautiful salt crystals formed along the edges

27:10but that's essentially how salt pan forms when the rain water comes in

27:15the salt goes into solution uh basically just like the water that we have in this water bottle

27:21and from the moment the water starts evaporating salt crystals start forming

27:29today death valley salt pans cover more than 200 square miles

27:34an area three times the size of washington dc they are the remnants of the ancient lake

27:41that finally disappeared two thousand years ago when earth's climate began to warm up

27:49from then onwards death valley's temperatures just kept on rising

27:56death valley is definitely one of the hottest spots in the world the record high

28:00was 134 degrees fahrenheit recorded back in july 10th 1913 and just to give you perspective on

28:07that the caretaker of the furnace creek ranch who actually was the one doing the recordings

28:11back then he describes that day as being so hot he saw the swallows falling dead in flight

28:21geologists today understand how death valley's unusual geology

28:26is responsible for the punishing climate that killed off its lake

28:31it stays so dry because there are three distinct mountain ranges between death valley

28:36and the moisture carried off of the pacific ocean over 200 miles away we have the sierra nevada to

28:44the west of us the storms come in from the west laden with moisture as they rise up they lose

28:49most of that moisture on the west side and each set of mountains wicks a little more moisture

28:55out of the clouds and here with our three sets of mountains in between us and the ocean by the

29:01time that moisture to get to death valley there's either all gone or we just get a few drops of rain

29:08almost all storms from the coast are stopped by the three mountain ranges each one in turn having

29:15an effect the scientists call a rain shadow so we are in the rain shadow of a rain shadow of a rain

29:23shadow an average less than two inches a year and there is another way that geology influences the

29:31desert climate air heated under the cloudless sky is trapped by the surrounding mountains

29:37in summer death valley becomes a deadly dangerous furnace

29:47the local weather station provides a graphic demonstration of how quickly that heat could have

29:52destroyed death valley's lake every day caligan checks the rate of evaporation the summer months

30:01it may take five of these containers here so i'm going to fill them up

30:05and dump them into the pond until it brings the water level up to the needle

30:11now our average rainfall is barely two inches a year but the evaporation pond records up to

30:17150 inches of evaporation that huge discrepancy between the amount of rainfall and the speed of

30:25evaporation means that a lake 12 feet deep and 30 miles long would evaporate in just a single year

30:33lake manley was bigger than that but over time it never stood a chance

30:42the scientists studies of death valley have solved the mysteries of its freshwater past borax

30:49discovered here in the 1880s proves that death valley was once filled with a freshwater lake

30:57pebbles unearthed on an ancient shoreline show the lake once covered 600 square miles

31:02an area three times the size of chicago when the last fresh water pools dried up here two thousand

31:11years ago death valley started its reign as the driest place in the u.s which makes it ironic

31:19that the investigation's next phase examining the valley's most recent geological upheavals

31:25involves scientists studying the awesome power of fast flowing water

31:37around 100 million years ago death valley's ancient seas gave way to exploding volcanoes

31:44whose peaks were then wrenched apart to create the lowest spot

31:47in america from around 200 000 years ago the valley filled with a freshwater lake

31:55but the rain shadow of surrounding mountains dried up the water

32:02for the past 2000 years death valley has been hotter

32:06and drier than anywhere else in north america

32:12which makes it all the more mysterious to find mosaic canyon

32:16a deep chasm seemingly cut by water in this parched and arid land

32:24especially when there is evidence of massive boulders having been pushed around like pebbles

32:34just look at the size of that boulder and look at how high above my feet it is it's about three feet

32:42in diameter and i can't even estimate what the weight of that thing is she may be in a

32:48desert but messina knows there is only one force that could have lifted the boulder up so high

32:55water brought it here and left it here the force of the water that came through here had to have

33:00been pretty severe in order to get that boulder up there plastered against the wall this boulder

33:08gives us evidence about the force of the water that comes down these canyons during flash floods

33:15a flash flood is one of nature's most lethal weapons

33:20if there were a flash flood coming down this canyon i wouldn't have enough time to run out

33:25of its path because the water flows down at an incredible velocity flash floods are among the

33:33most violent processes on the earth they can carry material the size of an suv without any problem

33:41at all in one of the driest places in the world the flood water comes from a surprising source

33:49rain

33:55on average death valley receives just two inches of rain a year

34:02this is less than half the rain that falls on new york in a single month

34:08but violent summer storms mean it can all fall in just a single day

34:16the floods transform the desert landscape in a number of ways one is known as the desert bloom

34:24where seeds and plants that may have lain dormant for up to 10 years

34:29burst into flower after a sudden rainfall this phenomenon might be

34:36beautiful but there is another deadlier side to these floods with a human cost

34:44in 2004 there was a flash flood that came down furnace creek it was just this muddy slurry that

34:51was dense enough to pick up a vehicle and carry it downhill and several people died in it the

34:592004 flash flood is small in comparison to some of the events that we see preserved here in the rocks

35:07flash floods happen all over the world but there's evidence here of their particular and rare

35:13geological effect in death valley this marble is very highly polished it's not scratched

35:21it's not gouged it's been polished by very fine grain material it comes down as part of

35:27a flash flood so it's really smooth and it's fluted it's really unique

35:34to uncover how these unusual polished walls were formed messina takes a closer look at

35:40what geologists term the badlands i think it's called bad because nothing will grow on it

35:47there's just this very loose material out here and it erodes so readily that plants can't even

35:54take root so this is bad land the rock that makes up the badlands is the dried-up remains

36:02of the two thousand-year-old lake bed that once submerged death valley this is nothing more than

36:08desiccated mud it's called mudstone because it's slightly lithified meaning it's turned into rock

36:19the mudstone's minerals are arranged in tightly packed flat sheets the rain can't penetrate the

36:27mudstone and therefore the rain picks up a lot of particles and carries them downhill

36:34these particles are the key to the canyon's smooth polished walls

36:41it flows through here so laden with sediment that it causes a lot of polishing

36:48and incision so every time a flash flood comes through

36:52this canyon gets deeper the walls get higher and the rock gets more polished

36:59the sediment-laden floods can carve into death valley's rocks with tremendous speed and force

37:06these canyons have been gouged out where the rocks

37:09here have been fractured and weakened by the continuous stretching the valley is undergoing

37:17this is up front in your face geology happening right here death valley is dynamic this is a

37:23place where things are happening in a human lifespan in this arid desert the investigation

37:31has identified water as the latest factor in death valley's continuing geological evolution

37:39the giant boulders plastered high on the canyon walls illustrate the

37:43power of flash flooding in the desert the smooth walls of mosaic canyon show how the

37:50dried mud from an ancient lake still affects how death valley is being shaped to this day

37:58and yet some mysteries remain unsolved

38:02including one of the world's most intriguing geological riddles

38:07the rocks that seem to walk by themselves moving thousands of feet across the floor of death valley

38:20over 1.2 billion years death valley has been transformed from a watery

38:24landscape to a barren desert even though geologists now understand the processes

38:34that have shaped this extraordinary region there are still mysteries to be solved

38:42and there is no part of death valley more mysterious than an area known as the race track

38:51this parched cracked lake basin just two and a half miles long and a mile wide is the setting

38:58for one of death valley's most intriguing geological puzzles it's sliding stones

39:06i love this place because it's odd i could come here 100 more times and

39:10every time there'll be something different something i didn't see

39:15stretching behind these rocks are long grooved trails in the earth

39:21it is clear that they are tracks left behind as the rocks move across the valley floor

39:29the puzzle is to work out how the rocks can slide uphill against this slightly tilted surface

39:38these are no mere pebbles some of these rocks are over 700 pounds and some of the trails are

39:48nearly 3 000 feet long the phenomenon was first recorded here by scientists

39:55some 100 years ago and yet in this remote location no one has ever seen the rocks moving

40:04messina has been tracking the movement of each individual rock on the racetrack since 1996.

40:10her gps readings are accurate to within a single inch geology is really nothing more than

40:20detective work and rather than looking for evidence of things that took place a long time ago

40:27what i really like about working on the racetrack is you're looking at things that are happening

40:31right now it's an ongoing process her first clue is the surface on which the rocks slide

40:38if i try to move my hand over it i could probably file my nails right now however after it rains

40:45there's so much clay in the lake bed sediments that it gets slick it's almost like teflon you

40:53wouldn't need very much force to set even a very large rock into motion just because the

40:58friction on the surface is almost nil but water alone isn't enough to make these rocks move

41:08messina has identified a second factor at work you can have rain but if you don't have wind a couple

41:16of days later i don't think these rocks are going anywhere the racetrack is a natural wind tunnel

41:25the wind funnels into the valley from the south

41:29close to the ground the winds can exceed hurricane strength reaching speeds of over 90 miles per hour

41:36enough to push the rocks into action if you have wind and there is no friction

41:43all you'd need to do is hit a rock with your finger like that and it would go into motion

41:49when all these elements are in place the rocks can begin their mysterious journey

41:59since no one has ever seen the rocks in motion we can only guess how fast they go but based on some

42:06of the evidence that i've seen these rocks aren't inching along by any means and the best estimate

42:12we have is about three to four miles an hour so a nice brisk walk but until this phenomenon is

42:20witnessed the mystery of death valley's sliding rocks will remain i hope that this mystery

42:27isn't solved it's what keeps me interested and i think it's what keeps a lot of people interested

42:37geologists studying death valley have figured out its extraordinary geological evolution

42:46stromatolite fossils show that this area was once covered by

42:49seas turtleback rocks proved that the land was stretched apart by tectonic forces

42:57dropping the valley floor down to the lowest point in america

43:02pebbles at bd junction proved that death valley was once covered with a freshwater lake

43:11and the smooth polished walls of mosaic canyon show that water is still at the heart of death

43:18valley's modern evolution death valley remains one of the most extreme geological wonders on earth

43:27and it's still evolving its valley floor is being constantly pushed apart by forces deep within the

43:34earth this means that the crust here will continue to stretch and thin one day tens of millions of

43:43years into the future death valley could be separated by the sea from the rest of the u.s

43:52today death valley continues to sink at a steady rate of one-tenth of an inch a year

43:58while its surface continues to be sculpted by water living proof that the earth is never at rest