[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:07.20,0:00:08.26,Default,,0000,0000,0000,,Every spring,
Dialogue: 0,0:00:08.26,0:00:12.18,Default,,0000,0000,0000,,hundreds of adventure-seekers dream\Nof climbing Qomolangma,
Dialogue: 0,0:00:12.18,0:00:14.70,Default,,0000,0000,0000,,also known as Mount Everest.
Dialogue: 0,0:00:14.70,0:00:17.21,Default,,0000,0000,0000,,At base camp, they hunker down for months
Dialogue: 0,0:00:17.21,0:00:22.01,Default,,0000,0000,0000,,waiting for the chance to scale \Nthe mountain's lofty, lethal peak.
Dialogue: 0,0:00:22.01,0:00:26.16,Default,,0000,0000,0000,,But why do people risk life and limb\Nto climb Everest?
Dialogue: 0,0:00:26.16,0:00:27.58,Default,,0000,0000,0000,,Is it the challenge?
Dialogue: 0,0:00:27.58,0:00:28.67,Default,,0000,0000,0000,,The view?
Dialogue: 0,0:00:28.67,0:00:32.02,Default,,0000,0000,0000,,The chance to touch the sky?
Dialogue: 0,0:00:32.02,0:00:37.56,Default,,0000,0000,0000,,For many, the draw is Everest's status\Nas the highest mountain on Earth.
Dialogue: 0,0:00:37.56,0:00:40.33,Default,,0000,0000,0000,,There's an important distinction\Nto make here.
Dialogue: 0,0:00:40.33,0:00:44.51,Default,,0000,0000,0000,,Mauna Kea is actually the tallest\Nfrom base to summit,
Dialogue: 0,0:00:44.51,0:00:47.60,Default,,0000,0000,0000,,but at 8850 meters above sea level,
Dialogue: 0,0:00:47.60,0:00:51.17,Default,,0000,0000,0000,,Everest has the highest altitude \Non the planet.
Dialogue: 0,0:00:51.17,0:00:54.20,Default,,0000,0000,0000,,To understand how \Nthis towering formation was born,
Dialogue: 0,0:00:54.20,0:00:57.61,Default,,0000,0000,0000,,we have to peer deep \Ninto our planet's crust,
Dialogue: 0,0:00:57.61,0:01:00.02,Default,,0000,0000,0000,,where continental plates collide.
Dialogue: 0,0:01:00.02,0:01:03.41,Default,,0000,0000,0000,,The Earth's surface \Nis like an armadillo's armor.
Dialogue: 0,0:01:03.41,0:01:06.17,Default,,0000,0000,0000,,Pieces of crust constantly move over,
Dialogue: 0,0:01:06.17,0:01:07.01,Default,,0000,0000,0000,,under,
Dialogue: 0,0:01:07.01,0:01:08.100,Default,,0000,0000,0000,,and around each other.
Dialogue: 0,0:01:08.100,0:01:13.61,Default,,0000,0000,0000,,For such huge continental plates,\Nthe motion is relatively quick.
Dialogue: 0,0:01:13.61,0:01:16.51,Default,,0000,0000,0000,,They move two to four \Ncentimeters per year,
Dialogue: 0,0:01:16.51,0:01:18.92,Default,,0000,0000,0000,,about as fast as fingernails grow.
Dialogue: 0,0:01:18.92,0:01:20.52,Default,,0000,0000,0000,,When two plates collide,
Dialogue: 0,0:01:20.52,0:01:25.04,Default,,0000,0000,0000,,one pushes into or underneath the other,\Nbuckling at the margins,
Dialogue: 0,0:01:25.04,0:01:29.96,Default,,0000,0000,0000,,and causing what's known as uplift\Nto accomodate the extra crust.
Dialogue: 0,0:01:29.96,0:01:32.08,Default,,0000,0000,0000,,That's how Everest came about.
Dialogue: 0,0:01:32.08,0:01:36.81,Default,,0000,0000,0000,,50 million years ago, the Earth's \NIndian Plate drifted north,
Dialogue: 0,0:01:36.81,0:01:38.91,Default,,0000,0000,0000,,bumped into the bigger Eurasian Plate,
Dialogue: 0,0:01:38.91,0:01:42.87,Default,,0000,0000,0000,,and the crust crumpled,\Ncreating huge uplift.
Dialogue: 0,0:01:42.87,0:01:45.54,Default,,0000,0000,0000,,Mountain Everest lies at the heart\Nof this action,
Dialogue: 0,0:01:45.54,0:01:49.12,Default,,0000,0000,0000,,on the edge of the Indian-Eurasian \Ncollision zone.
Dialogue: 0,0:01:49.12,0:01:52.88,Default,,0000,0000,0000,,But mountains are shaped by forces\Nother than uplift.
Dialogue: 0,0:01:52.88,0:01:58.29,Default,,0000,0000,0000,,As the land is pushed up, \Nair masses are forced to rise as well.
Dialogue: 0,0:01:58.29,0:02:02.73,Default,,0000,0000,0000,,Rising air cools, causing any water\Nvapor within it to condense
Dialogue: 0,0:02:02.73,0:02:05.02,Default,,0000,0000,0000,,and form rain or snow.
Dialogue: 0,0:02:05.02,0:02:07.63,Default,,0000,0000,0000,,As that falls, \Nit wears down the landscape,
Dialogue: 0,0:02:07.63,0:02:12.68,Default,,0000,0000,0000,,dissolving rocks or breaking them down\Nin a process known as weathering.
Dialogue: 0,0:02:12.68,0:02:15.47,Default,,0000,0000,0000,,Water moving downhill carries\Nthe weathered material
Dialogue: 0,0:02:15.47,0:02:17.40,Default,,0000,0000,0000,,and erodes the landscape,
Dialogue: 0,0:02:17.40,0:02:20.66,Default,,0000,0000,0000,,carving out deep valleys and jagged peaks.
Dialogue: 0,0:02:20.66,0:02:25.58,Default,,0000,0000,0000,,This balance between uplift and erosion\Ngives a mountain its shape.
Dialogue: 0,0:02:25.58,0:02:28.03,Default,,0000,0000,0000,,But compare the celestial peaks\Nof the Himalayas
Dialogue: 0,0:02:28.03,0:02:30.38,Default,,0000,0000,0000,,to the comforting hills of Appalachia.
Dialogue: 0,0:02:30.38,0:02:33.02,Default,,0000,0000,0000,,Clearly, all mountains are not alike.
Dialogue: 0,0:02:33.02,0:02:35.98,Default,,0000,0000,0000,,That's because time \Ncomes into the equation, too.
Dialogue: 0,0:02:35.98,0:02:40.29,Default,,0000,0000,0000,,When continental plates first collide,\Nuplift happens fast.
Dialogue: 0,0:02:40.29,0:02:43.16,Default,,0000,0000,0000,,The peaks grow tall with steep slopes.
Dialogue: 0,0:02:43.16,0:02:46.80,Default,,0000,0000,0000,,Over time, however, gravity and water\Nwear them down.
Dialogue: 0,0:02:46.80,0:02:49.46,Default,,0000,0000,0000,,Eventually, erosion overtakes uplift,
Dialogue: 0,0:02:49.46,0:02:52.52,Default,,0000,0000,0000,,wearing down peaks \Nfaster than they're pushed up.
Dialogue: 0,0:02:52.52,0:02:55.96,Default,,0000,0000,0000,,A third factor shapes mountains: climate.
Dialogue: 0,0:02:55.96,0:03:00.77,Default,,0000,0000,0000,,In subzero temperatures, some snowfall\Ndoesn't completely melt away,
Dialogue: 0,0:03:00.77,0:03:03.86,Default,,0000,0000,0000,,instead slowly compacting \Nuntil it becomes ice.
Dialogue: 0,0:03:03.86,0:03:08.94,Default,,0000,0000,0000,,That forms the snowline, which occurs\Nat different heights around the planet
Dialogue: 0,0:03:08.94,0:03:11.23,Default,,0000,0000,0000,,depending on climate.
Dialogue: 0,0:03:11.23,0:03:14.93,Default,,0000,0000,0000,,At the freezing poles,\Nthe snowline is at sea level.
Dialogue: 0,0:03:14.93,0:03:19.34,Default,,0000,0000,0000,,Near the equator, you have to climb\Nfive kilometers before it gets cold enough
Dialogue: 0,0:03:19.34,0:03:21.40,Default,,0000,0000,0000,,for ice to form.
Dialogue: 0,0:03:21.40,0:03:24.81,Default,,0000,0000,0000,,Gathered ice starts flowing under\Nits own immense weight
Dialogue: 0,0:03:24.81,0:03:28.74,Default,,0000,0000,0000,,forming a slow-moving frozen river\Nknown as a glacier,
Dialogue: 0,0:03:28.74,0:03:30.90,Default,,0000,0000,0000,,which grinds the rocks below.
Dialogue: 0,0:03:30.90,0:03:33.64,Default,,0000,0000,0000,,The steeper the mountains, \Nthe faster ice flows,
Dialogue: 0,0:03:33.64,0:03:37.28,Default,,0000,0000,0000,,and the quicker it carves \Nthe underlying rock.
Dialogue: 0,0:03:37.28,0:03:41.03,Default,,0000,0000,0000,,Glaciers can erode landscapes\Nswifter than rain and rivers.
Dialogue: 0,0:03:41.03,0:03:45.13,Default,,0000,0000,0000,,Where glaciers cling to mountain peaks,\Nthey sand them down so fast,
Dialogue: 0,0:03:45.13,0:03:49.66,Default,,0000,0000,0000,,they lop the tops off\Nlike giant snowy buzzsaws.
Dialogue: 0,0:03:49.66,0:03:54.36,Default,,0000,0000,0000,,So then, how did the icy Mount Everest\Ncome to be so tall?
Dialogue: 0,0:03:54.36,0:03:57.80,Default,,0000,0000,0000,,The cataclysmic continental clash\Nfrom which it arose
Dialogue: 0,0:03:57.80,0:04:00.54,Default,,0000,0000,0000,,made it huge to begin with.
Dialogue: 0,0:04:00.54,0:04:03.16,Default,,0000,0000,0000,,Secondly, the mountain lies \Nnear the tropics,
Dialogue: 0,0:04:03.16,0:04:07.71,Default,,0000,0000,0000,,so the snowline is high,\Nand the glaciers relatively small,
Dialogue: 0,0:04:07.71,0:04:10.27,Default,,0000,0000,0000,,barely big enough to widdle it down.
Dialogue: 0,0:04:10.27,0:04:13.25,Default,,0000,0000,0000,,The mountain exists in a perfect storm\Nof conditions
Dialogue: 0,0:04:13.25,0:04:15.70,Default,,0000,0000,0000,,that maintain its impressive stature.
Dialogue: 0,0:04:15.70,0:04:17.70,Default,,0000,0000,0000,,But that won't always be the case.
Dialogue: 0,0:04:17.70,0:04:20.50,Default,,0000,0000,0000,,We live in a changing world \Nwhere the continental plates,
Dialogue: 0,0:04:20.50,0:04:22.08,Default,,0000,0000,0000,,Earth's climate,
Dialogue: 0,0:04:22.08,0:04:23.97,Default,,0000,0000,0000,,and the planet's erosive power
Dialogue: 0,0:04:23.97,0:04:28.13,Default,,0000,0000,0000,,might one day conspire to cut \NMount Everest down to size.
Dialogue: 0,0:04:28.13,0:04:32.41,Default,,0000,0000,0000,,For now, at least, it remains legendary\Nin the minds of hikers,
Dialogue: 0,0:04:32.41,0:04:33.50,Default,,0000,0000,0000,,adventurers,
Dialogue: 0,0:04:33.50,0:04:35.14,Default,,0000,0000,0000,,and dreamers alike.