1 00:00:01,901 --> 00:00:06,964 Imagine if you could halt the constant march of time. 2 00:00:11,644 --> 00:00:15,171 ...if you could slow it down... and speed it up. 3 00:00:17,550 --> 00:00:21,748 Imagine if you could stop time... or even reverse it. 4 00:00:23,790 --> 00:00:26,452 The world about us would look quite different. 5 00:00:31,031 --> 00:00:35,092 Imagine no longer... come with us as we go on a journey through time. 6 00:00:46,479 --> 00:00:49,414 The earth is full of surprises. 7 00:01:09,002 --> 00:01:12,301 What is this sea creature doing on Mount Everest? 8 00:01:15,008 --> 00:01:18,705 Why will East Africa end up under the sea? 9 00:01:20,246 --> 00:01:24,148 And how did river crocs get stranded in the Sahara desert? 10 00:01:26,119 --> 00:01:30,249 We can get answers, but ONLY if we play with time. 11 00:01:38,465 --> 00:01:44,062 We will show you the hidden forces that build mountains and tear our world apart. 12 00:01:47,807 --> 00:01:51,573 We will show you the planet as you have never seen it before. 13 00:02:06,359 --> 00:02:10,989 When we sit down in front of the telly we aren't expecting the earth to move. 14 00:02:11,197 --> 00:02:14,655 But the ground beneath us IS shifting. 15 00:02:15,235 --> 00:02:18,398 You'd only notice it if you could travel through time, 16 00:02:18,605 --> 00:02:22,564 if the sofa could become your very own time machine. 17 00:02:27,447 --> 00:02:28,675 Over millions of years 18 00:02:28,882 --> 00:02:33,216 the ground beneath your feet has gone through some extreme changes. 19 00:02:46,799 --> 00:02:51,133 It is still going on - but on a massive time scale. 20 00:02:56,476 --> 00:03:00,207 We'll travel through the past, present and future. 21 00:03:00,580 --> 00:03:04,277 Get ready for a wild ride through time. 22 00:03:13,259 --> 00:03:18,458 We are so wrapped up in the day to day that we don't even notice time passing. 23 00:03:18,665 --> 00:03:20,997 We're taken aback when people change or 24 00:03:21,201 --> 00:03:24,364 when we suddenly realize how much we've aged. 25 00:03:25,205 --> 00:03:29,539 So it's hardly surprising we don't clock change in the wider world. 26 00:03:30,210 --> 00:03:33,907 It's so creepingly slow we don't see a thing. 27 00:03:37,984 --> 00:03:44,048 Hidden in this icy landscape there lies a powerful force that's shaping our planet, 28 00:03:44,257 --> 00:03:47,749 but we only notice it when something extraordinary happens. 29 00:03:51,464 --> 00:03:54,763 In 1950 a hiker in the mountains of New Zealand 30 00:03:54,968 --> 00:03:57,129 discovered some large pieces of metal 31 00:03:57,337 --> 00:04:00,704 under the icy foot of the Franz Josef Glacier. 32 00:04:02,542 --> 00:04:07,411 The glacier is in the middle of nowhere, so how they got there was anyone's guess. 33 00:04:09,249 --> 00:04:12,980 They turned out to be pieces in a very strange puzzle. 34 00:04:13,419 --> 00:04:15,649 It all started six years earlier... 35 00:04:20,860 --> 00:04:23,556 On October 29th 1943 36 00:04:23,763 --> 00:04:26,755 a light aircraft took off on a sightseeing trip. 37 00:04:27,133 --> 00:04:31,297 It was a tour over the icescapes of New Zealand's South Island. 38 00:04:43,383 --> 00:04:48,320 The tourists on-board were to get a lot more drama than they'd bargained for. 39 00:04:53,393 --> 00:04:56,692 Technical problems forced the pilot to crash-land. 40 00:04:59,899 --> 00:05:01,662 The passengers were rescued 41 00:05:01,868 --> 00:05:03,995 and even the wreckage was recovered, 42 00:05:04,203 --> 00:05:07,297 all except a few pieces of fuselage. 43 00:05:11,077 --> 00:05:16,037 It was these missing pieces that the walker discovered six years later, 44 00:05:16,249 --> 00:05:18,080 melting out of the glacier. 45 00:05:19,385 --> 00:05:22,377 But the REALLY strange thing was that they were found 46 00:05:22,588 --> 00:05:25,716 over three kilometers from where the plane crashed. 47 00:05:27,093 --> 00:05:29,960 How on earth did they move so far? 48 00:05:32,899 --> 00:05:37,768 The only thing linking the two sites was the Franz Josef Glacier. 49 00:05:40,707 --> 00:05:42,971 So what secrets could it hold? 50 00:05:48,081 --> 00:05:50,743 Glaciers look solid and immovable... 51 00:05:52,885 --> 00:05:56,048 But if you throw a fast forward switch they perk up. 52 00:06:03,563 --> 00:06:06,225 They turn into dynamic rivers of ice. 53 00:06:13,806 --> 00:06:16,934 Deep inside the ice it's way below freezing, 54 00:06:17,143 --> 00:06:19,134 yet there's water racing through. 55 00:06:24,417 --> 00:06:29,514 Its own massive weight and pressure causes the lower layers of ice to melt. 56 00:06:29,722 --> 00:06:33,818 This meltwater acts like a smear of slippery oil 57 00:06:34,227 --> 00:06:35,956 gravity does the rest. 58 00:06:41,934 --> 00:06:45,392 These frozen juggernauts grind down mountains, 59 00:06:45,638 --> 00:06:48,106 crumbling rock like biscuit crumbs. 60 00:07:00,620 --> 00:07:03,418 This glacier might only move two metres a day. 61 00:07:03,623 --> 00:07:07,184 But over six years that adds up to three kilometres... 62 00:07:08,928 --> 00:07:12,489 ...the same distance the plane parts travelled down the mountain. 63 00:07:16,736 --> 00:07:19,967 Remarkably the plane has been put back together. 64 00:07:20,873 --> 00:07:24,206 A long, drawn-out pause in its flight-path. 65 00:07:24,777 --> 00:07:27,644 But nothing in the life of a glacier. 66 00:07:28,915 --> 00:07:32,373 The rocky valley below tells an even longer story, 67 00:07:32,652 --> 00:07:34,210 one that affects us all. 68 00:07:34,887 --> 00:07:37,355 When glaciers melt back they reveal the way 69 00:07:37,557 --> 00:07:39,957 they've clawed at the rocks underneath. 70 00:07:40,193 --> 00:07:42,320 These marks read like a book. 71 00:07:42,562 --> 00:07:46,965 They tell us how glaciers ebb and flow over many centuries. 72 00:07:48,868 --> 00:07:53,862 To see the plot unfold we have to watch the Franz Josef glacier in action, 73 00:07:54,073 --> 00:07:55,836 thirty thousand years ago. 74 00:07:57,510 --> 00:08:02,948 Over this period it grew - not just down the valley, but out of the mountains. 75 00:08:16,095 --> 00:08:17,722 This was going on everywhere. 76 00:08:17,930 --> 00:08:21,696 Glaciers from Norway to Chile were advancing 77 00:08:21,901 --> 00:08:23,869 because the world was freezing up. 78 00:08:32,678 --> 00:08:35,010 This was the great Ice Age. 79 00:08:41,521 --> 00:08:47,721 Just 20,000 years ago almost half of the land was covered in ice. 80 00:09:06,746 --> 00:09:08,873 Today we're concerned about global warming, 81 00:09:09,081 --> 00:09:12,244 but this could all be over-ridden by bigger changes... 82 00:09:12,451 --> 00:09:16,046 which could send the glaciers on the march once again. 83 00:09:22,828 --> 00:09:25,888 When we squeeze thousands of years into seconds, 84 00:09:26,098 --> 00:09:27,895 glaciers spring to life. 85 00:09:28,134 --> 00:09:33,162 But time travel also allows us to throw new light on age-old secrets. 86 00:09:43,849 --> 00:09:49,185 The Ancient Egyptians left some stunning reminders of their wealth and power. 87 00:09:49,455 --> 00:09:55,394 But when the sun set on their civilization they also left a huge mystery behind. 88 00:10:01,233 --> 00:10:04,862 A grumpy camel ride can take us back to the heart of it - 89 00:10:05,071 --> 00:10:08,268 to the Sphinx and the Pyramids at Giza. 90 00:10:09,775 --> 00:10:12,801 We can only imagine what these immense monuments 91 00:10:13,012 --> 00:10:15,913 would have looked like at the height of the Egyptian empire. 92 00:10:21,087 --> 00:10:25,956 We've always assumed the sphinx was built at the same time as the pyramids, 93 00:10:26,659 --> 00:10:28,650 but maybe it wasn't. 94 00:10:30,663 --> 00:10:34,099 The Pyramids entombed the dead kings of Egypt. 95 00:10:34,967 --> 00:10:38,459 There are good records to show how and when they went up. 96 00:10:39,305 --> 00:10:43,571 What's missing is anything about the origins of the Sphinx. 97 00:10:47,613 --> 00:10:50,639 No-one can even agree on how old it is. 98 00:10:51,050 --> 00:10:54,383 There is now a shocking suggestion that this half-man, 99 00:10:54,587 --> 00:10:59,081 half-lion wasn't started by the Egyptians at all. 100 00:11:07,133 --> 00:11:09,226 But if they didn't build it, who did? 101 00:11:12,238 --> 00:11:15,537 500 kilometres to the south of the sphinx 102 00:11:15,775 --> 00:11:21,338 the desert is full of natural monuments that might offer some clues. 103 00:11:24,016 --> 00:11:28,953 On a fine day it's hard to imagine how this magical place came to be. 104 00:11:30,056 --> 00:11:32,889 It becomes easier when the wind gets up. 105 00:11:39,932 --> 00:11:46,201 The wind picks up loose sand and catapults it across the landscape for miles. 106 00:11:46,439 --> 00:11:48,464 It's like being in a firing range. 107 00:11:50,843 --> 00:11:55,439 Each grain of sand becomes a tiny, stinging missile. 108 00:12:02,655 --> 00:12:06,250 A single, blowing sand grain doesn't do a thing. 109 00:12:06,525 --> 00:12:13,192 But combine it with eons of time and you have a force that can carve rock itself. 110 00:12:15,267 --> 00:12:19,931 Believe it or not this is how these bizarre rocks were blasted into shape. 111 00:12:22,208 --> 00:12:25,302 But when the wind blows from just one direction 112 00:12:25,544 --> 00:12:29,241 the rock gets whittled into something even more distinctive, 113 00:12:29,448 --> 00:12:32,178 something remarkably sphinx-like. 114 00:12:40,192 --> 00:12:47,758 Did the force that created this also have a hand in creating the great sphinx? 115 00:12:56,542 --> 00:13:01,070 In their minds, these tourists are re-visiting Egypt's heyday - 116 00:13:01,280 --> 00:13:03,407 over three thousand years ago. 117 00:13:03,783 --> 00:13:06,513 But if they really want to get to grips with the sphinx 118 00:13:06,719 --> 00:13:09,882 they'd need to go back fifty thousand years. 119 00:13:16,595 --> 00:13:19,530 They'd be transported in front of a single giant rock 120 00:13:19,732 --> 00:13:22,963 outcrop jutting over the desert at Giza. 121 00:13:23,269 --> 00:13:24,827 No pyramids to be seen. 122 00:13:29,008 --> 00:13:31,306 The wind was already hard at work. 123 00:13:35,748 --> 00:13:39,582 Travelling now through thousands of years of fast forward, 124 00:13:39,852 --> 00:13:44,152 those tourists might watch the sand grains eating away at the rock - 125 00:13:44,456 --> 00:13:47,016 sculpting that distinctive shape. 126 00:13:53,833 --> 00:13:56,927 The early Egyptians may just have happened upon this rock 127 00:13:57,136 --> 00:14:00,537 and been inspired to add some finishing touches. 128 00:14:02,875 --> 00:14:06,311 They gave this rock a name and found it a job - 129 00:14:06,645 --> 00:14:09,876 guard duty for the pyramids which were built behind it. 130 00:14:26,899 --> 00:14:30,767 They added detail and dazzling paintwork. 131 00:14:33,739 --> 00:14:35,934 And they made it part of their culture. 132 00:14:43,215 --> 00:14:48,016 For thousands of years the Sphinx DID guard the pyramids of Egypt. 133 00:14:48,954 --> 00:14:50,945 But those days are over. 134 00:15:01,233 --> 00:15:05,101 The wind is a sculptor that never knows when to stop. 135 00:15:23,956 --> 00:15:29,019 This monumental rock is now a shadow of its former self. 136 00:15:29,261 --> 00:15:33,391 It needs high maintenance to fight the ravages of time. 137 00:15:43,475 --> 00:15:48,378 The modern stonemasons at Giza work year-round to shore it up, 138 00:15:48,747 --> 00:15:55,619 but in the end they are powerless against tiny grains of sand... and time. 139 00:16:06,765 --> 00:16:09,757 Time-travel can show us the big picture. 140 00:16:10,069 --> 00:16:15,837 What happens as huge natural forces change the shape of the world around us? 141 00:16:17,476 --> 00:16:20,843 Everything can and does change. 142 00:16:29,054 --> 00:16:30,578 Take the Sahara desert. 143 00:16:30,990 --> 00:16:34,289 It would cover the United States of America, 144 00:16:34,593 --> 00:16:38,324 but even something this big cannot be taken for granted. 145 00:16:48,407 --> 00:16:52,002 Temperatures regularly peak at 50 degrees. 146 00:16:52,211 --> 00:16:56,341 There are places where no rain has fallen for years. 147 00:16:57,649 --> 00:17:01,141 And yet living things attempt to cross it. 148 00:17:08,027 --> 00:17:12,930 The Paris-Dakar rally is one of the world's great endurance tests. 149 00:17:15,300 --> 00:17:20,363 Swallows cross it when they fly from South Africa to breed in Europe. 150 00:17:41,460 --> 00:17:43,189 Bikers do this for kicks. 151 00:17:43,429 --> 00:17:45,954 But it's no fun-run for the swallows. 152 00:17:46,665 --> 00:17:50,294 How did they end up with the journey from hell? 153 00:17:54,173 --> 00:17:56,869 In the middle of the Sahara is a rock - 154 00:17:57,076 --> 00:18:00,341 and on it are paintings which might tell us. 155 00:18:03,182 --> 00:18:05,514 They were done five thousand years ago 156 00:18:05,717 --> 00:18:10,017 and show animals that couldn't possibly survive in a desert. 157 00:18:10,222 --> 00:18:13,316 Was this the scene from the artist's back door? 158 00:18:13,659 --> 00:18:16,127 It is certainly not the Sahara we know. 159 00:18:21,633 --> 00:18:25,831 To see for ourselves, let's go back five thousand years... 160 00:18:39,651 --> 00:18:41,346 Unrecognisable! 161 00:18:41,553 --> 00:18:47,458 This Sahara had vast lakes, forests and abundant wildlife, 162 00:18:47,659 --> 00:18:50,059 where today you'd be dying of thirst. 163 00:18:56,602 --> 00:19:01,096 It was like this when swallows began their inter-continental flights - 164 00:19:01,440 --> 00:19:03,305 a much easier route. 165 00:19:07,880 --> 00:19:11,407 But then, rather suddenly, it all went pear-shaped. 166 00:19:13,819 --> 00:19:16,151 It began five thousand years ago 167 00:19:16,355 --> 00:19:21,019 with a small shift in the way our planet orbits the sun. 168 00:19:22,161 --> 00:19:27,690 Even a small change like this results in massive climate change. 169 00:19:31,103 --> 00:19:35,062 Rainfall dropped off and this triggered a dramatic chain reaction, 170 00:19:35,274 --> 00:19:37,401 which left plants gasping. 171 00:19:45,417 --> 00:19:50,252 The swallows' migration was turning into an endurance test of its own. 172 00:19:56,962 --> 00:20:00,762 In some places the change from forest to desert may have happened 173 00:20:00,966 --> 00:20:03,696 in the space of just one hundred years. 174 00:20:08,173 --> 00:20:12,075 That's why swallows still struggle across the Sahara. 175 00:20:12,844 --> 00:20:15,642 They haven't had enough time to change their route. 176 00:20:17,649 --> 00:20:22,177 It's the type of journey that sorts the men from the boys. 177 00:20:25,691 --> 00:20:30,458 Something this small really needs the right stuff to get to the other side. 178 00:20:30,829 --> 00:20:33,889 Their prize lies beyond the Mediterranean. 179 00:20:39,705 --> 00:20:43,505 Here it is - the insect-rich meadows of Europe. 180 00:20:51,883 --> 00:20:55,910 Swallows have a few short months swooping over the English countryside 181 00:20:56,121 --> 00:21:00,615 and raising their young before they have to do the whole thing over again. 182 00:21:06,365 --> 00:21:10,927 Their marathon journey back to South Africa is no less easy. 183 00:21:11,136 --> 00:21:13,468 But time offers a glimmer of hope. 184 00:21:16,575 --> 00:21:20,409 In the heart of the desert lies the Ennedi Gorge. 185 00:21:23,548 --> 00:21:27,541 This is not just an oasis. It's a time warp. 186 00:21:29,321 --> 00:21:33,314 Deep in its shade is a tiny remnant of those vast lakes 187 00:21:33,525 --> 00:21:35,425 that once covered this region. 188 00:21:35,894 --> 00:21:38,988 It's the only water for hundreds of kilometres. 189 00:21:40,232 --> 00:21:45,898 And it shelters one of the most unlikely survivors of the Sahara's wetter past... 190 00:21:47,306 --> 00:21:48,967 Nile Crocodiles. 191 00:21:53,745 --> 00:21:56,578 They are playing a waiting game. 192 00:21:58,383 --> 00:22:02,513 The Earth's orbit is changing constantly, like a pendulum. 193 00:22:02,788 --> 00:22:07,020 It goes through cycles every 20,000 years, like clockwork. 194 00:22:07,292 --> 00:22:12,855 This means that the Sahara regularly alternates between dry and wet. 195 00:22:17,135 --> 00:22:22,573 If they can just hang on here for another 14,000 years, 196 00:22:22,841 --> 00:22:24,934 they may get a proper lake to swim in. 197 00:22:28,347 --> 00:22:30,975 And the swallows might have an easier ride. 198 00:22:50,502 --> 00:22:54,939 As for the Paris-Dakar rally... well, it'll be a picnic! 199 00:22:58,710 --> 00:23:00,871 We've travelled through thousands of years 200 00:23:01,079 --> 00:23:03,843 to see the morphing of the Sphinx and Sahara. 201 00:23:04,116 --> 00:23:07,017 But now we're going to shift up several gears. 202 00:23:07,285 --> 00:23:10,118 It's time to fasten seatbelts. 203 00:23:10,355 --> 00:23:15,588 We're accelerating into deep time - through millions of years. 204 00:23:16,128 --> 00:23:20,963 Only then will we have enough time to witness the creation of the Grand Canyon. 205 00:23:29,975 --> 00:23:34,275 It is one of the world's greatest natural wonders. 206 00:23:53,565 --> 00:23:57,467 Visitors can be silenced by its sheer scale. 207 00:23:57,836 --> 00:24:00,498 But it's almost impossible to get your head around 208 00:24:00,705 --> 00:24:03,173 how long it's been in the making. 209 00:24:14,186 --> 00:24:19,351 It's taken 5 million years and it isn't even finished yet! 210 00:24:19,691 --> 00:24:22,785 The creator of this canyon is still at work - 211 00:24:22,994 --> 00:24:25,724 a force that will take your breath away. 212 00:24:28,767 --> 00:24:30,962 Enter the canyon at your peril. 213 00:24:53,258 --> 00:24:55,954 The Colorado River at the foot of the canyon 214 00:24:56,161 --> 00:24:58,629 will certainly get your heart racing. 215 00:25:05,370 --> 00:25:07,531 But these rafters aren't in real danger. 216 00:25:07,772 --> 00:25:13,074 The steady flow of even white-water isn't enough to carve out these walls. 217 00:25:14,379 --> 00:25:17,542 This is the work of something much scarier. 218 00:25:17,749 --> 00:25:22,516 A force that can really let rip through these narrow canyons. 219 00:25:26,958 --> 00:25:30,519 It's these people who should stay on the alert. 220 00:25:30,795 --> 00:25:34,629 The danger signs are written all over the walls. 221 00:25:44,709 --> 00:25:48,736 These beautiful shapes have been sculpted by water - 222 00:25:48,947 --> 00:25:52,644 a huge amount of it and at phenomenal speed. 223 00:25:57,522 --> 00:25:59,319 But where is the water? 224 00:25:59,624 --> 00:26:02,252 This place seems as dry as bone. 225 00:26:04,262 --> 00:26:08,028 The Grand Canyon lies at the heart of the Arizona Desert. 226 00:26:08,233 --> 00:26:11,464 Most of the year it doesn't rain at all. 227 00:26:11,937 --> 00:26:14,462 But when it does you'd better watch out. 228 00:26:27,018 --> 00:26:29,213 This is where timing comes in. 229 00:26:31,523 --> 00:26:33,548 Timing is everything. 230 00:26:38,096 --> 00:26:40,155 A single raindrop is nothing - 231 00:26:40,365 --> 00:26:43,801 it's when they join forces that things get serious. 232 00:26:55,046 --> 00:26:59,608 The ground is so sun-baked that the raindrops just don't soak in. 233 00:26:59,818 --> 00:27:02,616 They glance off it and stream across the surface. 234 00:27:24,743 --> 00:27:27,769 The thin desert soils put up little resistance - 235 00:27:27,979 --> 00:27:31,142 the floods simply sweep up everything in their path. 236 00:27:31,683 --> 00:27:35,551 From all over the desert the floods race towards the canyon. 237 00:27:36,154 --> 00:27:39,282 And then they begin to carve downwards. 238 00:28:00,111 --> 00:28:04,571 Tourist attraction becomes hellhole in a matter of minutes. 239 00:28:14,759 --> 00:28:19,059 In 1997, eleven visitors were swept to their deaths. 240 00:28:20,999 --> 00:28:22,227 That was one flood 241 00:28:22,434 --> 00:28:25,164 but imagine if we could watch the effect of thousands 242 00:28:25,370 --> 00:28:29,864 of similar cataclysmic floods over millions of years. 243 00:29:07,712 --> 00:29:11,978 The Grand Canyon is a powerful reminder that the world can change, 244 00:29:12,183 --> 00:29:15,846 not gradually, but in short, sharp shocks. 245 00:29:24,596 --> 00:29:29,329 This is how one of the most terrifying forces on the planet is unleashed - 246 00:29:29,534 --> 00:29:33,436 not in days or even hours, but in seconds. 247 00:30:08,573 --> 00:30:14,705 The duration of an average earthquake is less than sixty seconds. 248 00:30:15,046 --> 00:30:17,640 Seconds filled with utter terror. 249 00:30:21,853 --> 00:30:27,291 They look like acts of God, but in fact they're not random strikes at all. 250 00:30:28,626 --> 00:30:32,426 If we whip over to Wellington, New Zealand we'll see what's going on. 251 00:30:33,231 --> 00:30:37,327 It's a city that seems on sure enough ground. 252 00:30:37,569 --> 00:30:41,903 But not if we travel back to a precise point in time... 253 00:30:47,779 --> 00:30:53,479 Nine fifteen on the night of January 21st, 1855. 254 00:30:55,720 --> 00:30:59,451 At this moment Wellington is just a small town. 255 00:30:59,757 --> 00:31:02,021 The coastline is made of steep cliffs, 256 00:31:02,227 --> 00:31:04,718 which plunge straight into the Pacific Ocean. 257 00:31:12,237 --> 00:31:14,728 The next few seconds were earth-shattering. 258 00:31:20,445 --> 00:31:24,643 A violent quake heaved the whole of this coastline upwards. 259 00:31:42,100 --> 00:31:47,697 As the cliffs rose, they pulled a whole new area of land out from under the waves. 260 00:31:56,147 --> 00:31:59,048 The sun rose on a different landscape. 261 00:32:04,489 --> 00:32:10,052 Where fish had swum and surf had pounded there was now dry land. 262 00:32:14,999 --> 00:32:19,663 It was on this newly exposed land that today's city, 263 00:32:19,871 --> 00:32:25,002 its airport and roads were all built. 264 00:32:27,879 --> 00:32:32,043 But the 1855 earthquake was not a one-off. 265 00:32:32,450 --> 00:32:34,680 By racing through centuries we can see 266 00:32:34,886 --> 00:32:38,845 they've wrenched up the coast, over and over again. 267 00:32:39,257 --> 00:32:40,622 There's a pattern. 268 00:32:41,726 --> 00:32:47,562 And it's a pattern that's repeated in very particular places all around the world. 269 00:32:50,301 --> 00:32:53,930 The earth's crust is not one solid piece of rock. 270 00:32:54,305 --> 00:32:58,469 It's broken up - like crazy paving on a grand scale. 271 00:32:59,510 --> 00:33:03,173 The edges of these slabs are constantly grinding, 272 00:33:03,381 --> 00:33:07,442 and when they suddenly jolt past each other - that's an earthquake. 273 00:33:08,019 --> 00:33:11,750 To live along one of these edges is asking for trouble. 274 00:33:16,294 --> 00:33:19,855 Wellington sits slap, bang on one of the boundaries. 275 00:33:20,064 --> 00:33:24,125 But then so do San Francisco, Tokyo and Istanbul; 276 00:33:24,335 --> 00:33:27,736 millions of people sitting on borrowed time. 277 00:33:28,840 --> 00:33:32,640 An earthquake is bound to hit them sooner or later - 278 00:33:32,944 --> 00:33:35,378 there is no if here, it's when. 279 00:33:46,057 --> 00:33:50,391 Within seconds these immense forces can tear open the earth's crust. 280 00:33:50,628 --> 00:33:56,123 Over much, much longer time frames they can change the entire map of the world. 281 00:34:02,440 --> 00:34:06,035 But how can we possibly look so far back into the past? 282 00:34:06,277 --> 00:34:11,476 It's possible because some things can travel through vast amounts of time. 283 00:34:14,652 --> 00:34:18,110 This fossil is the remains of a sea creature 284 00:34:18,322 --> 00:34:22,816 that's travelled through 150 million years of earth history. 285 00:34:25,563 --> 00:34:30,193 What it has told us about the past has rocked the way we see the world. 286 00:34:30,401 --> 00:34:33,996 It's turned our view of this mountain upside down. 287 00:34:41,813 --> 00:34:46,546 At eight and a half thousand metres, Mount Everest is so high 288 00:34:46,751 --> 00:34:51,916 that a cruising jumbo jet would graze its wing tip on the summit. 289 00:34:55,326 --> 00:34:56,691 One of the first attempts to climb 290 00:34:56,894 --> 00:35:01,490 to the very top was made in 1924 by George Mallory. 291 00:35:02,934 --> 00:35:06,734 When asked why he was doing it, he quipped, "Because it's there". 292 00:35:12,143 --> 00:35:17,103 But what we now know is that it hasn't always been there. 293 00:35:17,315 --> 00:35:19,647 And we know because this fossil tells us. 294 00:35:23,788 --> 00:35:26,450 It was found high up in the Himalayan mountains, 295 00:35:26,657 --> 00:35:31,219 but it's the remains of a creature that lived only in the sea. 296 00:35:31,529 --> 00:35:35,124 These peaks are hundreds of kilometers from the nearest ocean, 297 00:35:35,333 --> 00:35:40,327 so how on earth were these sea creatures left high and dry? 298 00:35:42,807 --> 00:35:46,641 We need to go back 150 million years... 299 00:35:53,151 --> 00:35:57,918 to when ammonites were the most successful creatures in the world's oceans. 300 00:36:01,259 --> 00:36:02,920 The seas looked very different 301 00:36:03,127 --> 00:36:05,857 but then we wouldn't recognize the map of the world, either. 302 00:36:14,038 --> 00:36:18,532 It started to become more familiar about 100 million years ago... 303 00:36:24,282 --> 00:36:27,342 ...when a chunk of land ripped away from Africa. 304 00:36:27,552 --> 00:36:29,884 That chunk was to become India. 305 00:36:32,523 --> 00:36:36,118 If we watch at a million years per second, 306 00:36:36,561 --> 00:36:38,995 India appears to race across the ocean. 307 00:36:42,166 --> 00:36:44,396 At first nothing blocked its way. 308 00:36:47,872 --> 00:36:51,239 But over the horizon lay a huge obstacle. 309 00:36:53,411 --> 00:36:56,869 India was on a collision course with Asia. 310 00:37:03,454 --> 00:37:08,118 In earth-time this was the equivalent of a motorway pile-up. 311 00:37:08,459 --> 00:37:12,657 The force of impact thrust the seabed between them out of the water. 312 00:37:12,863 --> 00:37:15,798 It's been hurled skywards ever since. 313 00:37:35,653 --> 00:37:40,920 Everest, K2 and Annapurna are just part of a chain of wreckage 314 00:37:41,125 --> 00:37:42,820 along this crumple zone. 315 00:37:45,863 --> 00:37:47,956 They haven't been up here very long - 316 00:37:48,165 --> 00:37:53,159 they're raw, new mountains and animals have only just moved in. 317 00:37:55,172 --> 00:37:56,901 They may live on top of the world 318 00:37:57,108 --> 00:38:00,635 but they're walking on rocks from the ocean floor, 319 00:38:00,878 --> 00:38:03,745 and it's these rocks that contain the sea fossils. 320 00:38:11,455 --> 00:38:13,355 The collision is far from over. 321 00:38:13,557 --> 00:38:16,583 India is still ramming the mountains upwards. 322 00:38:19,130 --> 00:38:24,466 The world's highest mountain is being forced northwards 2 centimetres each year. 323 00:38:28,139 --> 00:38:31,540 Things have changed even since Mallory's first climb. 324 00:38:31,742 --> 00:38:34,210 Everest is not there any more - 325 00:38:34,412 --> 00:38:37,142 it's moved a metre away - over there! 326 00:38:43,521 --> 00:38:48,151 We've whizzed through the past, but time doesn't stop here, with the present. 327 00:38:48,459 --> 00:38:49,824 The earth's not finished yet! 328 00:38:50,227 --> 00:38:53,060 Let's travel on - to see what happens next. 329 00:39:03,274 --> 00:39:06,368 In the tiny African country of Djibouti 330 00:39:06,577 --> 00:39:10,343 a maintenance crew turns up to repair a crack in the road. 331 00:39:14,151 --> 00:39:17,279 This is not your average wear and tear. 332 00:39:17,722 --> 00:39:21,715 This is a crack that allows us to peer into the future. 333 00:39:25,496 --> 00:39:26,986 What they're about to shore up 334 00:39:27,198 --> 00:39:30,895 is the start of the biggest crack on the face of the planet. 335 00:39:37,641 --> 00:39:40,906 This is a crack that can be seen from space. 336 00:39:42,580 --> 00:39:45,174 It runs from that small road in Djibouti, 337 00:39:45,449 --> 00:39:48,350 widening out through Ethiopia and Kenya. 338 00:39:49,920 --> 00:39:53,083 It then spreads through Tanzania and Malawi. 339 00:39:54,759 --> 00:39:59,196 It ends in Mozambique, six thousand kilometres away. 340 00:40:07,638 --> 00:40:13,042 It's Africa's Great Rift Valley, and it's remarkable not just for its size. 341 00:40:20,885 --> 00:40:24,116 This long, cliff-bound valley provides a stage 342 00:40:24,321 --> 00:40:27,722 for the biggest gatherings of wildlife in the world. 343 00:41:05,763 --> 00:41:07,230 It looks rosy. 344 00:41:07,531 --> 00:41:11,297 But the trouble is, the future doesn't look bright at all. 345 00:41:13,337 --> 00:41:16,704 We know, because that Djibouti road crew at the north 346 00:41:16,907 --> 00:41:19,705 end of the crack is never out of a job. 347 00:41:21,412 --> 00:41:24,313 Every time they fix it, it ruptures again. 348 00:41:25,082 --> 00:41:27,710 So what's pushing the tarmac apart? 349 00:41:29,854 --> 00:41:31,321 Time to step back... 350 00:41:38,395 --> 00:41:41,387 ...back 30 million years... 351 00:41:42,132 --> 00:41:47,069 That's half way between now and the extinction of the dinosaurs. 352 00:41:54,979 --> 00:41:58,244 The world was then home to some strange beasts. 353 00:42:01,819 --> 00:42:05,016 East Africa has no mountains, no volcanoes 354 00:42:05,256 --> 00:42:07,588 just gently rolling hills. 355 00:42:07,958 --> 00:42:10,984 But pressure was building up from below, 356 00:42:11,328 --> 00:42:14,855 a force destined to change Africa forever. 357 00:42:16,901 --> 00:42:21,804 A huge abscess of molten rock from the centre of the earth oozed upwards. 358 00:42:22,006 --> 00:42:26,272 It stretched the crust under East Africa to breaking point. 359 00:42:35,252 --> 00:42:38,380 Molten rock was squeezed out to form new mountains. 360 00:42:38,822 --> 00:42:43,384 And in less than a million years Mount Kilimanjaro grew from nothing 361 00:42:43,594 --> 00:42:46,825 to become the tallest peak in Africa. 362 00:43:00,311 --> 00:43:03,974 Even today there's volcanic activity along the rift. 363 00:43:04,248 --> 00:43:07,615 There's a string of lakes along the valley fed from water 364 00:43:07,818 --> 00:43:10,753 bubbling up through the hot rocks below. 365 00:43:11,055 --> 00:43:14,923 They're so caustic that flamingos have it all to themselves. 366 00:43:25,069 --> 00:43:29,130 Periodic eruptions also come with the territory. 367 00:43:34,979 --> 00:43:39,177 The eruptions are proof that the valley is still rifting apart. 368 00:43:39,383 --> 00:43:44,116 It's an inconvenience, but nothing compared with what's going to happen next. 369 00:43:55,699 --> 00:43:58,167 In around ten million years time 370 00:43:58,469 --> 00:44:03,338 the crack will have become so wide that the ocean will breach in. 371 00:44:14,885 --> 00:44:18,480 All the wildlife in the Rift Valley will be destroyed 372 00:44:18,689 --> 00:44:23,422 and a new sea will be created as East Africa separates. 373 00:44:25,195 --> 00:44:28,028 No wonder these guys feel overwhelmed. 374 00:44:28,232 --> 00:44:33,226 But just because this seems a long time off, we shouldn't feel too safe. 375 00:44:41,211 --> 00:44:45,739 Given enough time, something huge will rear its ugly head. 376 00:44:48,919 --> 00:44:51,012 Something that could destroy us all. 377 00:44:51,321 --> 00:44:55,314 It could be in a thousand years, a hundred years, ten years. 378 00:44:55,592 --> 00:44:56,923 Or tomorrow. 379 00:45:02,366 --> 00:45:05,733 Take a look at this showstopper. 380 00:45:05,969 --> 00:45:10,303 It's lying in wait here... in Yellowstone National Park. 381 00:45:14,812 --> 00:45:19,249 Yellowstone is famous for its hot springs and geysers - 382 00:45:19,450 --> 00:45:23,352 where the earth's heat escapes as super-heated water. 383 00:45:26,323 --> 00:45:31,556 One in particular is renowned for the precision timing of its blowouts. 384 00:45:31,829 --> 00:45:33,160 Old Faithful. 385 00:45:33,363 --> 00:45:35,729 It goes off every 90 minutes. 386 00:45:42,740 --> 00:45:45,174 It's the ultimate visitor attraction - 387 00:45:45,375 --> 00:45:49,937 a spectacular natural event that goes off on schedule. 388 00:45:52,683 --> 00:45:59,486 But maybe Old Faithful is not so much loyal friend as a sinister watchman. 389 00:45:59,923 --> 00:46:05,156 Each time it goes off, we could be 90 minutes closer to Armageddon. 390 00:46:08,866 --> 00:46:12,529 Yellowstone is sitting over a ticking clock, 391 00:46:12,903 --> 00:46:19,399 one whose beat is so slow that until recently no-one even knew it existed. 392 00:46:23,280 --> 00:46:28,616 Yellowstone is astride one of the biggest volcanoes in the world. 393 00:46:31,722 --> 00:46:35,158 It's a volcano that's over 70 kilometres across, 394 00:46:35,359 --> 00:46:40,126 and potentially so lethal that it makes Vesuvius look like a roman candle. 395 00:46:41,231 --> 00:46:44,598 The last three times, it exploded with such force that 396 00:46:44,802 --> 00:46:48,260 its ash buried half of North America. 397 00:46:48,572 --> 00:46:52,406 It doesn't go off very often - but so far it's followed a pattern. 398 00:46:53,310 --> 00:46:57,508 The eruptions come at 600,000-year intervals. 399 00:47:00,350 --> 00:47:06,255 620,000 years have passed since the last eruption. 400 00:47:10,127 --> 00:47:14,723 So if it keeps to schedule, our time is up. 401 00:47:27,711 --> 00:47:31,875 No-one on the planet would escape this big smoker. 402 00:47:32,749 --> 00:47:36,947 It could trigger a chain reaction of volcanic winters and - 403 00:47:37,154 --> 00:47:40,282 for humans - potentially fatal climate change. 404 00:47:45,495 --> 00:47:46,962 Will it erupt soon? 405 00:47:47,664 --> 00:47:52,033 Or is there some other unseen time bomb due to go off? 406 00:47:53,370 --> 00:47:55,361 Only time will tell.