0:00:18 > 0:00:22Europe three billion years ago.
0:00:22 > 0:00:26Born of violence and upheaval.
0:00:30 > 0:00:33Scoured by wind-blasted deserts.
0:00:33 > 0:00:36Swallowed by the oceans.
0:00:39 > 0:00:42And cloaked in tropical swamps.
0:00:46 > 0:00:52These sweeping changes lay the foundations for the most diverse of continents.
0:01:00 > 0:01:07But then some two and half million years ago, this virgin world faced a fresh assault.
0:01:10 > 0:01:16Triggered by the most unusual combination of cosmic and global events,
0:01:16 > 0:01:21Europe was now confronted by a radical change in climate.
0:01:47 > 0:01:51The landscape was transformed beyond recognition.
0:01:54 > 0:01:58Locked in a tomb of ice.
0:02:01 > 0:02:06These were the ice ages - a raw, challenging time.
0:02:14 > 0:02:20This onslaught of climatic change had a profound impact on the land.
0:02:23 > 0:02:28How did this new era of extremes shape the Europe we know today?
0:02:57 > 0:03:02The Alps - the very heart of Europe.
0:03:02 > 0:03:08Millions of visitors come here every year to enjoy the exhilaration of winter.
0:03:23 > 0:03:28A glimpse of a time when much of Europe was gripped in the big freeze.
0:03:29 > 0:03:37Remnants of the ice ages are found right across the continent, but this is the most spectacular -
0:03:37 > 0:03:39the Matterhorn.
0:03:39 > 0:03:46An iconic pyramid of rock jutting almost 4,500m into the sky.
0:03:48 > 0:03:52Travel back through time over a period of just 20,000 years,
0:03:52 > 0:03:56and the landscape was very different indeed.
0:04:03 > 0:04:07An island in a sea of ice.
0:04:09 > 0:04:12Only its tip would have been visible.
0:04:16 > 0:04:20Back then, conditions in the Alps and in northern Europe
0:04:20 > 0:04:22were extremely harsh.
0:04:25 > 0:04:29Relentless icy storms swept the land.
0:04:34 > 0:04:39Temperatures plunged to well below minus 50 degrees Celsius.
0:04:45 > 0:04:48What triggered this climatic onslaught?
0:04:51 > 0:04:56As the earth goes about its orbit, its pathway periodically shifts
0:04:56 > 0:05:00taking it closer to or further away from the sun.
0:05:04 > 0:05:10As well as this, in a rhythm of its own, the earth's axis tilts.
0:05:10 > 0:05:18About two and a half million years ago, these factors combined to cause cooling in Europe's higher latitudes.
0:05:24 > 0:05:26Summers became shorter.
0:05:29 > 0:05:32And winters more severe.
0:05:34 > 0:05:39But cold alone does not constitute an ice age.
0:05:39 > 0:05:43This chill was dramatically intensified by a range of other events.
0:05:43 > 0:05:49One of which happened thousands of kilometres away on the far side of the Atlantic.
0:05:52 > 0:05:59As North and South America began to join they blocked the flow of water from the Atlantic to the Pacific,
0:05:59 > 0:06:04diverting a warm tropical current back towards Europe.
0:06:04 > 0:06:07The gulf stream was born.
0:06:07 > 0:06:10With it came masses of moisture-laden air.
0:06:27 > 0:06:32When these clouds reached the colder atmosphere of northern Europe
0:06:32 > 0:06:35they delivered enormous quantities of snow.
0:06:53 > 0:06:57As temperatures plummeted, survival became increasingly hard.
0:07:01 > 0:07:05A whole new caste of cold-adapted animals moved in,
0:07:05 > 0:07:10rather like today's musk oxen with their shaggy windproof coats and stocky frames.
0:07:19 > 0:07:22In the ever shortening summers, animals like reindeer too
0:07:22 > 0:07:26would have eked out a living on lichens and mosses.
0:07:27 > 0:07:32But as temperatures dropped below minus 40 degrees Celsius,
0:07:32 > 0:07:37even these hardy creatures would've been forced south to warmer climes.
0:07:44 > 0:07:50Year after year snow built upon snow compacting into solid ice.
0:07:51 > 0:07:53Engulfing the continent.
0:08:02 > 0:08:05Even the sea began to freeze.
0:08:15 > 0:08:19The expansive ice acted like a giant mirror
0:08:19 > 0:08:23reflecting the sun's warmth back into space.
0:08:26 > 0:08:31Colossal ice sheets up to 2,000 metres thick
0:08:31 > 0:08:37spread across the continent covering Siberia, Scandinavia and Scotland.
0:08:44 > 0:08:48We now know how far south the ice sheet reached,
0:08:48 > 0:08:52thanks to evidence found in some surprising places.
0:08:58 > 0:09:03During the construction of the London underground in the late 19th century,
0:09:03 > 0:09:09scientists unearthed unusual sediment patterns in the very centre of London.
0:09:17 > 0:09:24They revealed that the edge of the northern ice sheet was more of less here
0:09:24 > 0:09:27at the Finchley Road tube station.
0:09:30 > 0:09:35Just imagine how London might have looked half a million years ago
0:09:35 > 0:09:38when the ice ages were at their most extreme.
0:09:44 > 0:09:50Other glacial deposits indicate that the edge of the ice spanned the European continent.
0:09:53 > 0:09:56Touching on Amsterdam.
0:09:59 > 0:10:02And also Berlin.
0:10:02 > 0:10:07A freeze-up of this scale would change the whole shape of a continent.
0:10:19 > 0:10:24This is the North Sea off the coast of Holland.
0:10:24 > 0:10:32Although this may seem a normal fishing trip, these Dutch trawlermen aren't after sole or plaice.
0:10:32 > 0:10:40They're actually scientists on an unusual mission in search of a far more intriguing catch.
0:11:02 > 0:11:05Among the piles of starfish, crabs and driftwood
0:11:05 > 0:11:11they find the long-submerged remains of a far larger animal.
0:11:15 > 0:11:20When bones like these were first hauled out more than a century ago,
0:11:20 > 0:11:24they were presented to a local doctor for identification.
0:11:24 > 0:11:29He declared them to be clear evidence of Noah's flood.
0:11:30 > 0:11:35Whatever your belief about Noah, the doctor was right about the flood
0:11:35 > 0:11:38because these are the bones of land animals.
0:11:40 > 0:11:41Massive ones at that.
0:11:43 > 0:11:44Woolly mammoths.
0:11:50 > 0:11:53What are they doing in the middle of the North Sea?
0:11:57 > 0:12:03During the ice ages, the sea level was around 100m lower than today.
0:12:03 > 0:12:07Back then, the North Sea was all dry land.
0:12:07 > 0:12:13Its water locked up in the ice sheets to the north and in mountain glaciers.
0:12:13 > 0:12:16These mammoth bones tell us something else.
0:12:16 > 0:12:19Not all of Europe was buried in ice.
0:12:19 > 0:12:24The North Sea was one vast green valley - a tundra.
0:12:31 > 0:12:34Standing three metres tall and wrapped in dense fur,
0:12:34 > 0:12:39woolly mammoths were well adapted to life on these cold, grassy plains
0:12:39 > 0:12:44which they shared with relatives of today's saiga antelopes.
0:12:46 > 0:12:50Their oversized noses help to warm the chilly air as they inhale
0:12:50 > 0:12:53and to preserve precious moisture as they breathe out.
0:12:56 > 0:13:00Saigas came to Eurasia from North America across the Bering Straits -
0:13:00 > 0:13:05an important land bridge when sea levels were lower.
0:13:05 > 0:13:09And with them came Przewalski's horses -
0:13:09 > 0:13:11the ancestors of our modern horse.
0:13:13 > 0:13:15As the climate kept changing,
0:13:15 > 0:13:21the edge of the ice sheets shifted, and so did entire ecosystems.
0:13:21 > 0:13:26But the most surprising ice-age immigrants came from the south.
0:13:46 > 0:13:48Here in London during the 1830s,
0:13:48 > 0:13:54builders constructing Nelson's column in Trafalgar Square made some extraordinary discoveries.
0:13:54 > 0:14:02They unearthed the bones of some very un-ice age and indeed un-European animals.
0:14:02 > 0:14:06Hippos, rhinos, hyenas and even lions.
0:14:17 > 0:14:24Around 120,000 years ago, Western Europe must have looked more like East Africa.
0:14:45 > 0:14:48Over the past two and a half million years,
0:14:48 > 0:14:55the climate has see-sawed from subtropical to Arctic and back again.
0:14:55 > 0:15:02These warm interglacial periods, lasting as long as 100,000 years,
0:15:02 > 0:15:08have allowed plenty of time for new ways of life to establish themselves on the continent
0:15:08 > 0:15:12before being driven back again by the next cold spell.
0:15:45 > 0:15:53This thermal pulsing was rapid and extreme with at least 20 different climatic cycles.
0:15:59 > 0:16:04Right now, we're enjoying one of the warmer periods in between.
0:16:04 > 0:16:12It's a sobering thought that this extreme climatic change has not been an exception but the rule.
0:16:19 > 0:16:23The last major glacial period began 115,000 years ago.
0:16:26 > 0:16:31It was to have an immense impact in shaping the continent we know today.
0:16:31 > 0:16:36Back then much of the land would have been inhospitable.
0:16:36 > 0:16:39Natural shelters were highly prized.
0:16:45 > 0:16:50One ice-age creature totally depended on these caves.
0:16:53 > 0:16:55The cave bear.
0:17:00 > 0:17:06In an ice-age winter, deep caves were vital for hibernating bears.
0:17:06 > 0:17:10But their peace and indeed their future
0:17:10 > 0:17:14was about to be shattered by others who also sought refuge here.
0:17:45 > 0:17:48BEAR ROARS
0:17:48 > 0:17:50BEAR FALLS SILENT
0:18:00 > 0:18:03Neanderthals.
0:18:03 > 0:18:06Ice-age specialists, like the cave bear.
0:18:06 > 0:18:09They braved the continent's harshest climate ever.
0:18:19 > 0:18:26For over 150,000 years, Neanderthals remained Europe's top predators.
0:18:35 > 0:18:39But now a new force was on the move.
0:18:41 > 0:18:46A force destined to have a profound impact on the continent -
0:18:46 > 0:18:49modern humans.
0:18:49 > 0:18:52Our ancestors.
0:18:54 > 0:18:57Some 40,000 years ago,
0:18:57 > 0:19:03Homo sapiens began to advance into Asia and Europe from their homelands in Africa,
0:19:03 > 0:19:06living a nomadic existence
0:19:06 > 0:19:10following the migratory herds.
0:19:17 > 0:19:21For these inventive and adaptable hunters,
0:19:21 > 0:19:26this new land, in spite of its harsh climate, offered a wealth of big game.
0:19:32 > 0:19:36Although Neanderthals and modern humans certainly crossed paths,
0:19:36 > 0:19:41in this vast continent encounters between them must have been rare.
0:19:49 > 0:19:53Yet for Neanderthals, time was running out.
0:19:56 > 0:19:59Their populations were shrinking.
0:20:00 > 0:20:05About 30,000 years ago, they vanished from the face of the land,
0:20:05 > 0:20:12possibly decimated by disease or conflict or an inability to deal with climate change.
0:20:19 > 0:20:2515,000 years ago, the shape of the earth's orbit and the tilting of its axis
0:20:25 > 0:20:29would come to spell the end of the last great ice age.
0:20:31 > 0:20:36In the northern hemisphere summers now became longer
0:20:36 > 0:20:39and winters less severe.
0:21:05 > 0:21:08As temperatures rose rapidly in northern Europe,
0:21:08 > 0:21:15by as much as ten degrees Celsius in less than a century, the melt gathered momentum.
0:21:32 > 0:21:35Massive volumes of water.
0:21:35 > 0:21:41100,000 years' worth of snowfall cascaded off the ice sheets.
0:21:49 > 0:21:53This great melt swelled vast river networks.
0:21:53 > 0:21:57Old rivers found new courses where the ice had once been.
0:21:57 > 0:22:00Violent torrents carried a massive cargo of debris
0:22:00 > 0:22:05filling low-lying valleys with rubble, thus creating Europe's plains.
0:22:07 > 0:22:10Rivers like the Elbe and Volga
0:22:10 > 0:22:14would have been many times their current size and power.
0:22:16 > 0:22:20From the smaller ice caps of the Alps and Pyrenees
0:22:20 > 0:22:24to the great northern ice sheets, rivers flowed in spate.
0:22:32 > 0:22:36Much of this meltwater was trapped before it reached the sea.
0:22:36 > 0:22:39Tens of thousands of new lakes were created.
0:22:40 > 0:22:46The most impressive of them all, 18,000 square kilometres,
0:22:46 > 0:22:50is Lake Ladoga on the Finnish / Russian border.
0:22:52 > 0:22:55Europe's largest body of fresh water.
0:22:58 > 0:23:01Free from the weight of the Scandinavian ice cap,
0:23:01 > 0:23:06the land began to rise, cutting Lake Ladoga off from the sea.
0:23:11 > 0:23:16Today, it is a remote natural refuge.
0:23:16 > 0:23:18One of the wild fringes of Europe.
0:24:01 > 0:24:06Lake Ladoga is also home to a rare animal which became trapped here
0:24:06 > 0:24:12about 9,000 years ago when the lake was finally isolated from the sea.
0:24:15 > 0:24:19Ladoga ringed seals.
0:24:19 > 0:24:22Today, just a couple of thousand of them remain.
0:24:27 > 0:24:31They once inhabited the open sea,
0:24:31 > 0:24:34but have adapted to life in this freshwater lake.
0:24:38 > 0:24:45Ice-age relics like these are found in cold enclaves across the continent.
0:24:46 > 0:24:54As the climate warmed up, they retreated to Europe's highest latitudes and highest altitudes,
0:24:54 > 0:24:56wherever the Arctic climate lingers on.
0:25:02 > 0:25:05From the Alps to the Highlands of Scotland,
0:25:05 > 0:25:10mountain ranges across Europe are Arctic islands.
0:25:24 > 0:25:29Ibex are ice-age immigrants from the mountain ranges of central Asia.
0:25:32 > 0:25:36Ibex would have followed the edge of the ice sheets to the west
0:25:36 > 0:25:39and remained here after the ice retreated.
0:25:47 > 0:25:54During the cold periods, some of these ice-age immigrants were spread across most of the continent.
0:25:56 > 0:26:01Now remnant populations are thousands of kilometres apart.
0:26:09 > 0:26:14The ptarmigan, a bird of the Arctic tundra,
0:26:14 > 0:26:19now inhabits the Alps, northern Scandinavia and Scotland.
0:26:22 > 0:26:28Their winter plumage, perfect camouflage and insulation, is an echo of the icy past.
0:26:32 > 0:26:36Ptarmigans share these mountain tops with another ice-age character -
0:26:36 > 0:26:39the mountain hare.
0:26:39 > 0:26:44It has shorter ears than brown hares, helping reduce heat loss,
0:26:44 > 0:26:47and its broad feet make perfect snow shoes.
0:27:00 > 0:27:06Snow buntings nest both in the high Arctic and 3,000km south in the high Alps.
0:27:08 > 0:27:13But it's not only ice-age animals that remind us of our frozen past.
0:27:16 > 0:27:24Europe still bears the scars of the mightiest, most dynamic ice-age force of all.
0:27:24 > 0:27:28A force that created much of the landscape we're familiar with today.
0:27:30 > 0:27:33Glaciers.
0:27:33 > 0:27:38This is how Europe may have looked tens of thousands of years ago.
0:27:43 > 0:27:48Glaciers may appear rigid and sedentary but they're quite the opposite,
0:27:48 > 0:27:52particularly those on steep mountain slopes.
0:27:52 > 0:27:54CREAKING
0:27:57 > 0:27:59By condensing time
0:27:59 > 0:28:01they come to life.
0:28:03 > 0:28:07Glaciers slip and slide at a surprising rate,
0:28:07 > 0:28:10up to 20m a week.
0:28:13 > 0:28:16Like a river of ice.
0:28:25 > 0:28:31The glaciers' enormous weight makes the ice masses glide on a film of water.
0:28:31 > 0:28:35As it glides, it rips rocks and boulders from the ground
0:28:35 > 0:28:37and pulls them along.
0:28:39 > 0:28:45Like giant sandpaper, the glacier smoothes its rocky bed.
0:28:47 > 0:28:52The impact of glaciers on the landscape is all too clear.
0:28:52 > 0:28:55From the wide, U-shaped valleys of Scotland...
0:28:57 > 0:29:00..to the deep fjords of Norway.
0:29:03 > 0:29:06And from Spain's Picos de Europa...
0:29:08 > 0:29:11..to the gorges of the Alps.
0:29:16 > 0:29:20But glaciers do more than carve out valleys.
0:29:20 > 0:29:26Like super-sized conveyer belts, they carry massive loads of rocky debris
0:29:26 > 0:29:30sometimes hundreds of kilometres from their source.
0:29:31 > 0:29:38This rocky load piles up where the glacier ends, or is left behind when it melts...
0:29:39 > 0:29:44..forming distinctive piles of rubble known as moraines.
0:29:50 > 0:29:55Some of the best evidence of this can be found here at Segonzano
0:29:55 > 0:29:58in the Dolomites of Italy.
0:29:58 > 0:30:03Lurking in the forest is a bizarre collection of pillars.
0:30:05 > 0:30:11Legend has it that once these were trolls punished for their carelessness.
0:30:14 > 0:30:20They're actually the remains of moraine dumped here by an ice-age glacier.
0:30:20 > 0:30:25Over thousands of years, rain has washed away the soft clays and gravels,
0:30:25 > 0:30:29except where it was protected by a hard-stone cap.
0:30:47 > 0:30:52Strangely enough, even some seemingly desert landscapes
0:30:52 > 0:30:56owe their whole existence to the last ice age.
0:30:58 > 0:31:01Where has all this sand come from?
0:31:14 > 0:31:16When the Baltic ice sheet melted,
0:31:16 > 0:31:20an enormous heap of rubble was dropped into the sea,
0:31:20 > 0:31:25eroded into sand and then washed ashore along the northern flanks of Poland,
0:31:25 > 0:31:27like here at Slowinski national park.
0:31:33 > 0:31:35The process continues today.
0:31:35 > 0:31:42The glacial dunes are expanding by nine metres a year and swallowing everything in their path.
0:31:46 > 0:31:53During the last ice age, mineral- rich glacial dust known as loess,
0:31:53 > 0:31:57was blown from the Alpine ice cap as far as the Black Sea.
0:32:01 > 0:32:06Millions of tons of it was spread across Eastern Europe along the Danube valley,
0:32:06 > 0:32:12laying the foundations for what has now become a rich agricultural landscape.
0:32:13 > 0:32:18These super fertile plains are the largest on the continent.
0:32:18 > 0:32:23Almost 50,000 square kilometres of crop land
0:32:23 > 0:32:26yielding wheat, rye, barley and oats.
0:32:26 > 0:32:29The bread basket of Europe.
0:32:29 > 0:32:32All this productive land we're so familiar with today,
0:32:32 > 0:32:38only exists because the peaks of the Alps were ground to dust by glaciers
0:32:38 > 0:32:40and carried here by the ice-age winds.
0:32:48 > 0:32:54After the great melt, when the ice sheets covering most of northern Europe had disappeared,
0:32:54 > 0:32:58they left behind a barren, rocky moonscape.
0:33:08 > 0:33:13But as temperatures rose, pioneering plants and lichens,
0:33:13 > 0:33:18which can cling to bare rock, began to recolonise the land.
0:33:26 > 0:33:30Gradually, in sheltered spots, more complex plants took hold,
0:33:30 > 0:33:34their seeds carried on the wind.
0:33:35 > 0:33:39In time, the soils were restored
0:33:39 > 0:33:44and the re-greening of Europe had begun.
0:33:49 > 0:33:55Soon the continent lay swathed in grassland, peat bog and tundra.
0:34:02 > 0:34:06For a while, animals like reindeer were in their element,
0:34:06 > 0:34:09exploiting these verdant pastures.
0:34:30 > 0:34:35But as temperatures continued to rise, the reindeer retreated north.
0:34:35 > 0:34:39The tundra on which they depended would soon be forest.
0:34:48 > 0:34:52Conifer trees like larch, spruce and juniper
0:34:52 > 0:34:58rapidly advanced north across the continent at about 500m a year.
0:35:04 > 0:35:10Europe became cloaked in forest and echoed to a new chorus of life.
0:35:14 > 0:35:17BIRD MAKES CLICKING SOUND
0:35:19 > 0:35:25The spring mating dance of the capercaillie - a sure sign the seasons were in full swing.
0:35:45 > 0:35:49With the trees came new settlers who also found their niche here.
0:35:49 > 0:35:54From tree climbers like pine martens to birds of prey.
0:35:54 > 0:35:58All seeking out the small mammals sheltering in the forest.
0:36:12 > 0:36:17Red deer, grazers of the open tundra, now browsed in the woods.
0:36:20 > 0:36:26Around 10,000 years ago, these early coniferous woodlands were at their peak.
0:36:28 > 0:36:34By then, the flanks of Europe had also undergone a radical transformation.
0:36:35 > 0:36:39Sea levels had risen and risen by 100m or more,
0:36:39 > 0:36:44defining the outline of the continent as we know it today,
0:36:44 > 0:36:48with around one and half million kilometres of coastline.
0:37:02 > 0:37:09One of the most impressive new coastal landscapes of all lies in northern Norway.
0:37:09 > 0:37:13Here, deep valleys were scoured out by glaciers
0:37:13 > 0:37:17and then drowned by rising seas,
0:37:17 > 0:37:20creating a network of fjords.
0:37:20 > 0:37:26These waterways are as deep as the mountains are high.
0:37:26 > 0:37:30Blessed by the nutrients and warmth carried here by the gulf stream,
0:37:30 > 0:37:34they teem with life and remain ice free all year round.
0:37:40 > 0:37:43Each year, the north Norwegian fjords
0:37:43 > 0:37:46lure hundreds of killer whales.
0:37:52 > 0:37:58They come for the enormous shoals of herring that overwinter here.
0:38:18 > 0:38:23The impact of the gulf stream and the rising seas
0:38:23 > 0:38:27is felt right across Western Europe.
0:38:27 > 0:38:30From Norway all the way to Ireland,
0:38:30 > 0:38:33France and Scotland.
0:38:35 > 0:38:42Pounded by the Atlantic, this rugged coastline is home to some unique concentrations of life.
0:38:43 > 0:38:49Around 120,000 grey seals inhabit these waters,
0:38:49 > 0:38:52also exploited by otters.
0:38:58 > 0:39:05In the British Isles alone, some 6,000 new islands were born during the post-glacial melt.
0:39:12 > 0:39:18The remote, craggy cliffs offer perfect nest sites for birds like fulmars, guillemots and gulls.
0:39:32 > 0:39:38These are some of the most impressive sea bird colonies in the world.
0:39:38 > 0:39:42And because they're so inaccessible, predators pose little threat.
0:39:46 > 0:39:50In the summer, the skies come alive.
0:40:07 > 0:40:12Along the northern rim of Germany is a very different wildlife haven.
0:40:12 > 0:40:16These are some of Europe's youngest coastlands
0:40:16 > 0:40:20and a vital stopover for birds migrating up and down the east Atlantic.
0:40:20 > 0:40:24More than two million visit every year.
0:40:28 > 0:40:34For waders, they offer a gastronomic treat of shellfish and worms.
0:40:37 > 0:40:42But feeding here is always a race against time and tide.
0:40:45 > 0:40:48And there's another drawback.
0:40:49 > 0:40:55All this commotion attracts one of the fastest and most agile hunters in the world -
0:40:55 > 0:40:58the peregrine falcon.
0:41:31 > 0:41:37After the last glacial period, these new coastal fringes with their prolific supply of food,
0:41:37 > 0:41:43were also vital corridors for new arrivals making their way up the Atlantic coast.
0:41:45 > 0:41:48Here from around 10,000 years ago,
0:41:48 > 0:41:53Stone Age people began to find a foothold along Europe's shores.
0:42:01 > 0:42:04This was a brand new way of life.
0:42:04 > 0:42:08A diet based almost entirely on protein-rich shellfish.
0:42:10 > 0:42:14Scallops, limpets, dogwelks and winkles.
0:42:28 > 0:42:34And with food so readily available, they had time to develop cultural pursuits -
0:42:34 > 0:42:37making music and decorative jewellery.
0:42:57 > 0:43:05While the northern margins of the continent remained a bleak place, the interior was changing radically.
0:43:07 > 0:43:10Unsuited to the warming climate,
0:43:10 > 0:43:15the coniferous forests were now retreating, replaced by seasonal deciduous woodland.
0:43:51 > 0:43:58A diverse mix of trees like hazel, oak, elm, lime and beech spread their way north.
0:44:11 > 0:44:15All sorts of different animals aided this reforestation
0:44:15 > 0:44:18by overstocking their winter stores.
0:44:45 > 0:44:48For a time, access to the interior
0:44:48 > 0:44:54was only open to those that could fly or take advantage of the waterways.
0:44:54 > 0:44:58Fish like Atlantic salmon moved upriver from the sea to spawn.
0:45:32 > 0:45:39This was now a pristine wilderness of endless forest broken only by rivers and lakes.
0:45:47 > 0:45:50Soon the rivers would provide access to the forest.
0:45:50 > 0:45:55It wasn't long before coastal dwellers began to head inland
0:45:55 > 0:46:00to find a wild new world to explore and exploit.
0:46:06 > 0:46:11Mature silver eels were another enticing lure.
0:46:19 > 0:46:23The most efficient way of catching the eels was by intercepting them
0:46:23 > 0:46:26during their autumn migration to the sea.
0:46:29 > 0:46:36People constructed elaborate basket traps of stakes and wickerwork to divert the large shoals.
0:46:40 > 0:46:44Eels provided them with a reliable and highly nutritious source of food.
0:46:44 > 0:46:49Large quantities could be kept alive or smoked for later.
0:46:53 > 0:47:00While these corridors offered a reasonably safe access to the fringes of the forest,
0:47:00 > 0:47:04the deep interior must have seemed a very foreboding place.
0:47:07 > 0:47:09Impenetrable,
0:47:09 > 0:47:12gnarled and twisted.
0:47:12 > 0:47:15And roamed by dangerous predators.
0:47:32 > 0:47:35But in time, it would be conquered.
0:47:39 > 0:47:43For now, as the climate released its grip,
0:47:43 > 0:47:47a new force was on the rise.
0:47:47 > 0:47:51One which was destined to tame and transform Europe
0:47:51 > 0:47:55more rapidly than ever before.
0:48:19 > 0:48:23Subtitles by BBC Broadcast - 2005
0:48:23 > 0:48:26E-mail us at subtitling@bbc.co.uk