1 00:00:02,269 --> 00:00:05,205 Ireland. 2 00:00:05,205 --> 00:00:08,508 The most westerly country in Europe. 3 00:00:08,508 --> 00:00:11,645 An outpost in the North Atlantic, 4 00:00:11,645 --> 00:00:16,717 it is the final landfall for thousands of miles, 5 00:00:16,717 --> 00:00:21,788 and towers above the sea. 6 00:00:21,788 --> 00:00:24,691 You have the ocean, the sky, the light, 7 00:00:24,691 --> 00:00:26,226 the wind even in your hair. 8 00:00:26,226 --> 00:00:31,331 You couldn't be closer to nature than here. 9 00:00:31,331 --> 00:00:35,535 Here, land and sea clash endlessly. 10 00:00:35,535 --> 00:00:39,406 The rock of Ireland, bitten and scoured by glaciers, 11 00:00:39,406 --> 00:00:44,878 is constantly being shaped and reshaped by water: 12 00:00:44,878 --> 00:00:49,816 pounding waves below, and driving rain from above. 13 00:00:49,816 --> 00:00:51,652 It's a very dynamic landscape. 14 00:00:51,652 --> 00:00:53,420 It's very rugged. 15 00:00:53,420 --> 00:00:56,223 It evolves day and daily. 16 00:00:56,223 --> 00:01:02,663 From the rugged Antrim coast, to the Wild Atlantic Way, 17 00:01:02,663 --> 00:01:06,566 this is Ireland. 18 00:01:09,403 --> 00:01:19,446 (♪♪♪) 19 00:01:19,446 --> 00:01:42,436 (♪♪♪) 20 00:01:59,119 --> 00:02:04,758 The Cliffs of Moher, a steep and sweeping precipice 21 00:02:04,758 --> 00:02:10,430 on Ireland's jagged west coast. 22 00:02:10,430 --> 00:02:16,169 The cliffs tower more than 700 feet above the stormy Atlantic 23 00:02:16,169 --> 00:02:19,339 and present real danger to those that fail 24 00:02:19,339 --> 00:02:24,478 to heed its warning signs. 25 00:02:24,478 --> 00:02:28,849 In the year 2000, two experienced climbers died 26 00:02:28,849 --> 00:02:34,421 and another was gravely injured when rocks above them gave way. 27 00:02:36,123 --> 00:02:39,359 And in 2015, a visiting photographer 28 00:02:39,359 --> 00:02:43,296 captured a spectacular rock fall in progress. 29 00:02:47,868 --> 00:02:51,238 It won't be the last time that these stunning cliffs 30 00:02:51,238 --> 00:02:57,377 crumble into the ocean, piece by piece. 31 00:02:57,377 --> 00:03:00,580 A powerful reminder that the geological violence 32 00:03:00,580 --> 00:03:05,285 that built Ireland is still very much alive here. 33 00:03:08,288 --> 00:03:11,158 But despite their many rock falls, 34 00:03:11,158 --> 00:03:17,431 the Cliffs of Moher aren't disappearing any time soon. 35 00:03:17,431 --> 00:03:20,400 They have stood here, in one form or another, 36 00:03:20,400 --> 00:03:25,639 for more than 300 million years, and greet visitors today 37 00:03:25,639 --> 00:03:31,611 coming east across the Atlantic. 38 00:03:31,611 --> 00:03:34,648 The Cliffs of Moher extend for five miles 39 00:03:34,648 --> 00:03:38,452 along Ireland's Wild Atlantic Way: 40 00:03:38,452 --> 00:03:41,688 a spectacular coastal route that winds 41 00:03:41,688 --> 00:03:46,193 for nearly 1,600 miles from Derry in the north 42 00:03:46,193 --> 00:03:52,699 to Cork in the south. 43 00:03:52,699 --> 00:03:56,136 The Cliffs of Moher draw close to one million visitors 44 00:03:56,136 --> 00:03:59,539 each year. 45 00:03:59,539 --> 00:04:05,645 This is one of the country's most breathtaking panoramas. 46 00:04:05,645 --> 00:04:09,716 The cliffs provide shelter for more than 30,000 birds 47 00:04:09,716 --> 00:04:14,654 from 29 different species. 48 00:04:14,654 --> 00:04:17,657 But the land on which they roost began to accumulate 49 00:04:17,657 --> 00:04:22,496 long before birds had evolved. 50 00:04:22,496 --> 00:04:25,732 Long before even their ancestors, the dinosaurs, 51 00:04:25,732 --> 00:04:30,103 had appeared on the planet. 52 00:04:30,103 --> 00:04:34,074 What you're looking at there is a cross section through time. 53 00:04:34,074 --> 00:04:36,543 You can see how the sediments have changed from the base 54 00:04:36,543 --> 00:04:37,711 right through the top. 55 00:04:37,711 --> 00:04:41,148 You can see each successive layer. 56 00:04:41,148 --> 00:04:42,816 The Cliffs Of Moher are the remains 57 00:04:42,816 --> 00:04:47,187 of an ancient river delta. 58 00:04:47,187 --> 00:04:51,625 Land created as flooded rivers dumped silt, sand, and mud 59 00:04:51,625 --> 00:04:54,761 into a shallow tropical sea. 60 00:04:58,698 --> 00:05:02,202 This sediment accumulated layer upon layer 61 00:05:02,202 --> 00:05:04,638 for millions of years. 62 00:05:09,442 --> 00:05:10,677 Those sediments are getting shallower and shallower 63 00:05:10,677 --> 00:05:13,213 because more and more sediment is pouring out and building out 64 00:05:13,213 --> 00:05:19,553 and making, essentially making land. 65 00:05:19,553 --> 00:05:21,488 Each of those layers may represent one storm event 66 00:05:21,488 --> 00:05:24,424 or one massive flood event. 67 00:05:24,424 --> 00:05:26,726 The fine shale layers then represent longer periods of time 68 00:05:26,726 --> 00:05:29,229 where sediment has collected more slowly over time 69 00:05:29,229 --> 00:05:31,765 then the next flood event will come along. 70 00:05:31,765 --> 00:05:36,102 New sediment deposited on top created crushing pressure 71 00:05:36,102 --> 00:05:38,672 on the sediment layers below, 72 00:05:38,672 --> 00:05:43,643 compacting them into the solid rock we see today. 73 00:05:43,643 --> 00:05:47,614 Over millions of years, earth's shifting tectonic plates 74 00:05:47,614 --> 00:05:50,383 carried these sediment deposits north 75 00:05:50,383 --> 00:05:53,520 from their point of origin south of the equator. 76 00:05:58,692 --> 00:06:02,062 But the story doesn't end there. 77 00:06:02,062 --> 00:06:05,599 Repeating layers of sandstone, siltstone and shale 78 00:06:05,599 --> 00:06:10,036 provide a clear view of an ancient sedimentary basin, 79 00:06:10,036 --> 00:06:15,242 something usually found underwater. 80 00:06:15,242 --> 00:06:18,478 Now above land, the Cliffs of Moher 81 00:06:18,478 --> 00:06:22,716 reveal their history inch by inch. 82 00:06:22,716 --> 00:06:25,685 This geological treasure has only been made visible 83 00:06:25,685 --> 00:06:32,125 by the constant, clawing waves at the base of the cliffs. 84 00:06:32,125 --> 00:06:35,662 Those waves come in, they will undercut the base of the cliffs, 85 00:06:35,662 --> 00:06:37,797 especially the shaley bits that will weaken it. 86 00:06:37,797 --> 00:06:40,634 And parts will fall into the sea. 87 00:06:40,634 --> 00:06:42,736 The clear shale, those dark, very dark rocks 88 00:06:42,736 --> 00:06:43,570 they've got fossils in them, 89 00:06:43,570 --> 00:06:45,071 they've got bits of plant material, 90 00:06:45,071 --> 00:06:46,439 they've got goniatites, but not much, 91 00:06:46,439 --> 00:06:48,508 they don't have the same variety of fossils 92 00:06:48,508 --> 00:06:49,709 that we get in the limestone. 93 00:06:49,709 --> 00:06:51,411 So it was a very difficult environment 94 00:06:51,411 --> 00:06:52,512 for things to live in. 95 00:06:52,512 --> 00:06:56,149 You've got rivers flowing on a swampy, marshy area 96 00:06:56,149 --> 00:06:58,785 and we get evidence of that from lots of tree material. 97 00:06:58,785 --> 00:07:00,787 We even find the roots of those trees in some of the sections 98 00:07:00,787 --> 00:07:04,257 so we know there was plants growing on essentially soil 99 00:07:04,257 --> 00:07:07,494 in that area. 100 00:07:07,494 --> 00:07:13,166 Just offshore, Branaunmore, a 220-foot-high sea stack, 101 00:07:13,166 --> 00:07:18,638 stands like an ancient guardian. 102 00:07:18,638 --> 00:07:20,173 The sea stack is a remnant actually 103 00:07:20,173 --> 00:07:22,709 of where the cliffs used to be. 104 00:07:22,709 --> 00:07:26,279 The Cliffs of Moher are eroding backwards. 105 00:07:26,279 --> 00:07:29,416 Due to these joints, due to the shaley nature of the cliffs, 106 00:07:29,416 --> 00:07:31,351 and mostly because of these fantastic waves that are 107 00:07:31,351 --> 00:07:36,656 coming in from the Atlantic pounding it every year. 108 00:07:36,656 --> 00:07:39,559 Those promontories can get isolated so either side of them 109 00:07:39,559 --> 00:07:42,228 will get eroded away more and eventually they get eroded away 110 00:07:42,228 --> 00:07:43,530 at the back. 111 00:07:43,530 --> 00:07:46,466 And that, sometimes they'll form arches initially and then those 112 00:07:46,466 --> 00:07:50,437 arches will collapse and be left with a sea stack. 113 00:07:50,437 --> 00:07:54,641 The rate of recession for the Cliffs hasn't been measured. 114 00:07:54,641 --> 00:07:58,778 But on the nearby Aran Islands the cliffs recede 115 00:07:58,778 --> 00:08:02,315 more than a foot-and-a-half each year due to erosion 116 00:08:02,315 --> 00:08:06,720 caused by battering waves. 117 00:08:06,720 --> 00:08:09,155 The Branaunmore sea stack is a reminder 118 00:08:09,155 --> 00:08:14,594 that nothing set in stone will remain forever. 119 00:08:14,594 --> 00:08:17,263 By the waves it was created. 120 00:08:17,263 --> 00:08:20,433 By the waves it will be consumed. 121 00:08:20,433 --> 00:08:21,668 Over time that sea stack is going to be eroded 122 00:08:21,668 --> 00:08:24,637 and that sea stack will fall and collapse into the sea as well. 123 00:08:24,637 --> 00:08:26,239 They come and then they go. 124 00:08:26,239 --> 00:08:29,309 There'll be new ones forming long after we're gone. 125 00:08:34,814 --> 00:08:36,750 The Cliffs of Moher. 126 00:08:36,750 --> 00:08:40,587 Not quite eternal, but immortalized in films 127 00:08:40,587 --> 00:08:43,156 such as The Princess Bride 128 00:08:43,156 --> 00:08:47,694 and Harry Potter and the Half-Blood Prince. 129 00:08:47,694 --> 00:08:49,429 And no wonder: 130 00:08:49,429 --> 00:08:54,100 they're a special effect 300 million years in the making. 131 00:09:07,180 --> 00:09:11,184 Eight miles north of the Cliffs of Moher in the region known as 132 00:09:11,184 --> 00:09:17,424 The Burren is the Ivy Cliff Cave, or as it's known today: 133 00:09:17,424 --> 00:09:21,027 Doolin Cave. 134 00:09:21,027 --> 00:09:24,731 Doolin Cave formed like every other cave in the Burren. 135 00:09:24,731 --> 00:09:27,066 It's on the limestone, so there was groundwater, 136 00:09:27,066 --> 00:09:28,234 there was water flowing, 137 00:09:28,234 --> 00:09:30,670 slightly acidic water, and over time 138 00:09:30,670 --> 00:09:34,741 that just eroded channels within the rock and the limestone. 139 00:09:34,741 --> 00:09:38,611 Hidden 80 feet beneath the entrance to Doolin Cave 140 00:09:38,611 --> 00:09:43,750 is its prized treasure: the Great Stalactite. 141 00:09:46,453 --> 00:09:49,456 At 23 feet, it is one of the longest 142 00:09:49,456 --> 00:09:54,260 free-hanging stalactites in the northern hemisphere. 143 00:09:54,260 --> 00:09:58,331 Limestone stalactites form as slightly acidic rainwater 144 00:09:58,331 --> 00:10:01,768 seeps through the bedrock, dissolving and eroding 145 00:10:01,768 --> 00:10:04,604 the minerals as it flows. 146 00:10:04,604 --> 00:10:08,741 Where water drips from the roof of a cave, dissolved limestone 147 00:10:08,741 --> 00:10:14,280 in the water precipitates out and hardens as calcite. 148 00:10:14,280 --> 00:10:18,485 Over time, minuscule amounts of calcite build up, 149 00:10:18,485 --> 00:10:21,254 eventually forming giant solid deposits 150 00:10:21,254 --> 00:10:24,090 that appear to drip from the cave ceiling. 151 00:10:24,090 --> 00:10:27,527 In most caves you'll get single, small, straw-like stalactites. 152 00:10:27,527 --> 00:10:29,229 They're quite common. 153 00:10:29,229 --> 00:10:30,697 It started forming almost certainly in the same way 154 00:10:30,697 --> 00:10:33,566 as all the others, but the water continued flowing there 155 00:10:33,566 --> 00:10:37,670 for a longer period of time. 156 00:10:37,670 --> 00:10:40,440 The Great Stalactite is a dramatic example 157 00:10:40,440 --> 00:10:46,346 of the geological processes that shape Ireland. 158 00:10:46,346 --> 00:10:50,116 It was created over hundreds of thousands of years, 159 00:10:50,116 --> 00:10:55,255 literally one drip at a time. 160 00:10:55,255 --> 00:10:58,691 But Doolin Cave and its remarkable stalactite 161 00:10:58,691 --> 00:11:03,429 are just one small feature in the Burren landscape. 162 00:11:03,429 --> 00:11:05,665 The Burren comes from the old Irish word bhoireann, 163 00:11:05,665 --> 00:11:09,836 which means rocky place. 164 00:11:09,836 --> 00:11:14,140 This rocky place, comprised of nearly 100 square miles 165 00:11:14,140 --> 00:11:16,776 of spectacular, rolling hills, 166 00:11:16,776 --> 00:11:23,116 was formed some 350 million years ago. 167 00:11:23,116 --> 00:11:26,786 It is a limestone pavement: layer-upon-layer 168 00:11:26,786 --> 00:11:30,189 of calcium carbonate sediment that was once at the 169 00:11:30,189 --> 00:11:34,561 bottom of the ocean, deposited by the skeletal remains 170 00:11:34,561 --> 00:11:38,464 of ancient marine organisms. 171 00:11:38,464 --> 00:11:42,268 The sea life that formed this pavement once lived in the 172 00:11:42,268 --> 00:11:46,606 same tropical sea, fed by the river that helped give rise 173 00:11:46,606 --> 00:11:50,643 to the Cliffs of Moher. 174 00:11:50,643 --> 00:11:53,813 The rock of the Burren was compressed and hardened 175 00:11:53,813 --> 00:11:59,586 by the weight of successive layers of calcium carbonate. 176 00:11:59,586 --> 00:12:03,323 This sea floor once occupied a place much farther south, 177 00:12:03,323 --> 00:12:07,493 at the same latitude where Egypt is today. 178 00:12:07,493 --> 00:12:12,265 As tectonic plates moved, these rocks drifted north, 179 00:12:12,265 --> 00:12:15,568 landing here when an ancient ocean closed 180 00:12:15,568 --> 00:12:18,338 and two plates of crust collided, 181 00:12:18,338 --> 00:12:23,776 forcing what was the seafloor to emerge high above the waves. 182 00:12:25,612 --> 00:12:28,348 In the south-eastern part of the Burren, 183 00:12:28,348 --> 00:12:32,452 an arresting 560-foot-high limestone hill 184 00:12:32,452 --> 00:12:35,755 bears the twists and bends of a landscape 185 00:12:35,755 --> 00:12:39,325 that was once under extreme pressure. 186 00:12:39,325 --> 00:12:42,161 It is Mullaghmore. 187 00:12:42,161 --> 00:12:46,232 In Irish, it means Great Summit. 188 00:12:46,232 --> 00:12:49,235 There's irregular curved folds in the limestone there 189 00:12:49,235 --> 00:12:50,570 and that's a result of compression. 190 00:12:50,570 --> 00:12:53,239 That's the result of a continent sliding along 191 00:12:53,239 --> 00:12:55,575 the surface of the earth, hitting another continent, 192 00:12:55,575 --> 00:13:00,079 the rocks buckle and they folded, nice and gentle. 193 00:13:00,079 --> 00:13:03,516 But this was far from the end of the geological story 194 00:13:03,516 --> 00:13:07,086 for this new piece of land. 195 00:13:07,086 --> 00:13:09,422 What is now Ireland was subjected 196 00:13:09,422 --> 00:13:14,160 to the unrelenting chill and crush of glaciers. 197 00:13:14,160 --> 00:13:17,397 This area has been subject to glaciation. 198 00:13:17,397 --> 00:13:20,166 Like most of Ireland it was covered by ice at some point. 199 00:13:20,166 --> 00:13:23,369 And once the ice travelled mostly from the north, northeast, 200 00:13:23,369 --> 00:13:25,705 it scraped off the surface, scraped off any soil 201 00:13:25,705 --> 00:13:30,543 that was there, and it exposed bare limestone. 202 00:13:30,543 --> 00:13:33,479 The last glacial period to affect the Burren 203 00:13:33,479 --> 00:13:37,517 ended 14,000 years ago. 204 00:13:37,517 --> 00:13:41,788 But while the landscape may have been scraped bare by ice, 205 00:13:41,788 --> 00:13:45,825 the land itself is far from barren. 206 00:13:45,825 --> 00:13:49,629 That then got colonized slowly afterwards by initially grasses 207 00:13:49,629 --> 00:13:54,200 and then more advanced trees and bushes. 208 00:13:54,200 --> 00:13:57,136 And then when humans came along, around about 5,000 years ago, 209 00:13:57,136 --> 00:13:59,739 they started cutting those trees down. 210 00:13:59,739 --> 00:14:03,810 The hunter-gatherers that cut down great swaths of forest 211 00:14:03,810 --> 00:14:09,449 for timber also raised cattle that devoured grasses, 212 00:14:09,449 --> 00:14:15,588 contributing to the current stark landscape. 213 00:14:15,588 --> 00:14:23,162 In 1651 an English Army Officer described the Burren as: 214 00:14:23,162 --> 00:14:27,100 "A country where there is not water enough to drown a man, 215 00:14:27,100 --> 00:14:32,538 wood enough to hang one, nor earth enough to bury them. 216 00:14:32,538 --> 00:14:36,008 And yet their cattle are very fat." 217 00:14:43,683 --> 00:14:47,653 Wildflowers and grasses take root in cracks and crevices in 218 00:14:47,653 --> 00:14:53,493 the limestone and flourish in the Burren's sweet, damp air. 219 00:14:55,228 --> 00:14:58,464 It's got grasses, it's got shrubs, it's got a fantastic mix 220 00:14:58,464 --> 00:15:00,700 of alpine and Mediterranean flowers. 221 00:15:00,700 --> 00:15:03,469 People come from all over the world to see that together 222 00:15:03,469 --> 00:15:05,605 in the same place, and it's not the Arctic and it's not 223 00:15:05,605 --> 00:15:10,042 the Mediterranean: it's in the west coast of Ireland. 224 00:15:10,042 --> 00:15:12,411 But underneath the surprising plant life 225 00:15:12,411 --> 00:15:17,617 there's the limestone, scrubbed and scratched by ice, 226 00:15:17,617 --> 00:15:22,722 stripped and depleted by man, and now eroded by water. 227 00:15:22,722 --> 00:15:25,224 Once this limestone has been exposed to the surface 228 00:15:25,224 --> 00:15:27,360 what happens is rain will fall on it, 229 00:15:27,360 --> 00:15:29,595 and we get a significant amount of rain here in the Burren, 230 00:15:29,595 --> 00:15:31,430 and that rain is very slightly acidic, 231 00:15:31,430 --> 00:15:34,433 a natural acidity from the carbon dioxide in the air, 232 00:15:34,433 --> 00:15:40,506 and when that hits the limestone it will start to dissolve it. 233 00:15:40,506 --> 00:15:46,112 This process creates what is known as karst topography. 234 00:15:46,112 --> 00:15:47,547 The limestone of The Burren 235 00:15:47,547 --> 00:15:52,418 is laced with a network of fissures called grikes. 236 00:15:52,418 --> 00:15:54,720 These fissures isolate blocks of stone 237 00:15:54,720 --> 00:15:58,324 at the surface known as clints. 238 00:15:58,324 --> 00:16:00,393 The irregular pits, the hollows, the curves, the grooves 239 00:16:00,393 --> 00:16:04,096 they're all a result of water flowing onto the surface 240 00:16:04,096 --> 00:16:05,431 and flowing maybe under the soil as well 241 00:16:05,431 --> 00:16:11,103 where it dissolves even further. 242 00:16:11,103 --> 00:16:14,540 As the limestone bedrock slowly breaks down, 243 00:16:14,540 --> 00:16:19,745 grikes grow wider and deeper, more water flows through them, 244 00:16:19,745 --> 00:16:25,651 and the grikes continue to grow larger. 245 00:16:25,651 --> 00:16:28,187 There are these fractures or joints all through the limestone 246 00:16:28,187 --> 00:16:30,356 here in the Burren, also out on the coast, 247 00:16:30,356 --> 00:16:34,727 and on the coast they're wonderfully exposed. 248 00:16:34,727 --> 00:16:40,099 They are exposed as lines of weakness in the limestone. 249 00:16:40,099 --> 00:16:44,670 About 20 miles from Mullaghmore, the cracked Doolin coast 250 00:16:44,670 --> 00:16:51,377 looks almost man-made with its precise, sharp lines. 251 00:16:51,377 --> 00:16:55,781 But it, too, is a result of the tectonic and erosive forces 252 00:16:55,781 --> 00:17:01,120 that shaped the rest of the Burren. 253 00:17:01,120 --> 00:17:03,623 We've got the water dissolving the limestone 254 00:17:03,623 --> 00:17:06,292 very gradually over a long period of time. 255 00:17:06,292 --> 00:17:08,527 On the coast it's much more dynamic, it's much more active, 256 00:17:08,527 --> 00:17:09,629 and every year you go back there 257 00:17:09,629 --> 00:17:14,267 you see the coast looks different. 258 00:17:14,267 --> 00:17:17,703 Cracks in the rock bear witness to the tremendous force 259 00:17:17,703 --> 00:17:21,741 generated far below by the grinding of what are now 260 00:17:21,741 --> 00:17:27,780 the North American and Eurasian continental plates. 261 00:17:27,780 --> 00:17:30,549 This is two huge plates crashing against each other, 262 00:17:30,549 --> 00:17:33,119 and when I say crashing that exaggerates a little bit. 263 00:17:33,119 --> 00:17:34,787 This is a slow process. 264 00:17:34,787 --> 00:17:36,489 A couple of centimeters a year these two continents 265 00:17:36,489 --> 00:17:40,192 are pushing into each other. 266 00:17:40,192 --> 00:17:42,495 But there's huge pressure behind that and this pressure 267 00:17:42,495 --> 00:17:48,634 builds up, builds up in rock and eventually something will give. 268 00:17:48,634 --> 00:17:52,305 Like miniature earthquakes, these rifts in the limestone 269 00:17:52,305 --> 00:17:57,743 are the visible evidence of that tectonic pressure. 270 00:17:57,743 --> 00:17:59,712 These might have been just like a millimeter, two millimeters 271 00:17:59,712 --> 00:18:02,214 wide these cracks, they popped open right through 272 00:18:02,214 --> 00:18:06,352 the whole Burren. 273 00:18:06,352 --> 00:18:09,689 But even a mere fraction of an inch is enough for water 274 00:18:09,689 --> 00:18:12,425 to exploit chinks in the limestone 275 00:18:12,425 --> 00:18:17,029 as rolling Atlantic waves pummel the Doolin coast below. 276 00:18:17,029 --> 00:18:18,798 These waves pack a huge punch. 277 00:18:18,798 --> 00:18:21,233 They're coming right across the Atlantic. 278 00:18:21,233 --> 00:18:24,070 And when it hits the rocks, especially at a high tide, 279 00:18:24,070 --> 00:18:26,472 these joints, these cracks that we talked about, 280 00:18:26,472 --> 00:18:29,442 are slightly open, the water whams against that. 281 00:18:29,442 --> 00:18:31,644 It pushes in the air that's already in there 282 00:18:31,644 --> 00:18:35,314 and it's like a pneumatic force pounding in against that rock. 283 00:18:35,314 --> 00:18:36,682 And it can actually fracture the rock. 284 00:18:36,682 --> 00:18:40,186 It'll fracture along lines of weakness already there. 285 00:18:40,186 --> 00:18:42,788 That makes it more susceptible to be moved during that storm 286 00:18:42,788 --> 00:18:46,726 or the next storm or subsequent storms. 287 00:18:46,726 --> 00:18:50,296 The waves of the Atlantic are even powerful enough to move 288 00:18:50,296 --> 00:18:55,501 entire blocks of limestone that have washed free from the shore. 289 00:18:57,336 --> 00:18:59,472 The rocks are being in some cases flipped over 290 00:18:59,472 --> 00:19:00,639 on top of each other, stacked up 291 00:19:00,639 --> 00:19:04,110 into piles of large lumps of limestone by these waves, 292 00:19:04,110 --> 00:19:06,612 and sometimes just dragged offshore and broken up. 293 00:19:06,612 --> 00:19:07,747 It's a great way to look at 294 00:19:07,747 --> 00:19:12,551 how the coast is actually eroding there. 295 00:19:12,551 --> 00:19:16,322 While the west coast of Ireland offers dramatic cliffs 296 00:19:16,322 --> 00:19:23,596 from which to gaze out over the tempestuous Atlantic Ocean, 297 00:19:23,596 --> 00:19:28,267 the east coast rewards visitors with panoramic views of peaks 298 00:19:28,267 --> 00:19:33,806 and glens steeped in rich history: 299 00:19:33,806 --> 00:19:36,642 the Wicklow Mountains. 300 00:19:40,413 --> 00:19:43,682 This is the largest area of continuous high ground 301 00:19:43,682 --> 00:19:48,320 in Ireland: nearly 200 square miles 302 00:19:48,320 --> 00:19:53,225 with an unbroken elevation of more than one thousand feet. 303 00:19:56,328 --> 00:19:59,165 The entire region is the result of what's known as 304 00:19:59,165 --> 00:20:03,235 an igneous intrusion: a massive geological event 305 00:20:03,235 --> 00:20:07,006 that occurred about 400 million years ago. 306 00:20:10,509 --> 00:20:14,480 The continental plates of North America and Europe collided, 307 00:20:14,480 --> 00:20:18,317 generating tremendous heat that melted the rock, 308 00:20:18,317 --> 00:20:22,621 which then rose as magma. 309 00:20:22,621 --> 00:20:27,693 But without the fiery force of a volcano, the magma slowly cooled 310 00:20:27,693 --> 00:20:32,198 without breaching the surface, creating a form of igneous rock 311 00:20:32,198 --> 00:20:35,601 familiar to us all: granite. 312 00:20:40,106 --> 00:20:44,343 This mass of granite forms the Leinster mountain chain, 313 00:20:44,343 --> 00:20:48,747 the largest continuous area of granite in Ireland and Britain. 314 00:20:52,284 --> 00:20:54,720 For centuries, man has quarried granite 315 00:20:54,720 --> 00:20:58,824 from the Wicklow Mountains, but it's not the only product 316 00:20:58,824 --> 00:21:02,428 of these beautiful hills and valleys. 317 00:21:02,428 --> 00:21:06,265 As the rocks were subjected to intense heat and pressure, 318 00:21:06,265 --> 00:21:08,300 they were effectively cooked, 319 00:21:08,300 --> 00:21:13,072 changing form into what's known as metamorphic rock. 320 00:21:13,072 --> 00:21:14,673 These rocks contain elements 321 00:21:14,673 --> 00:21:18,377 such as lead and zinc, copper and silver. 322 00:21:18,377 --> 00:21:22,848 They were concentrated into thin narrow veins of mineral ore. 323 00:21:22,848 --> 00:21:26,652 They filled those cracks in the rock and concentrated 324 00:21:26,652 --> 00:21:32,124 in specific kind of fractures so they then became a target 325 00:21:32,124 --> 00:21:34,460 for miners in the 1800s. 326 00:21:34,460 --> 00:21:36,595 They were a place where you could go in and you could 327 00:21:36,595 --> 00:21:41,333 dig in a narrow tunnel to extract the lead ore. 328 00:21:41,333 --> 00:21:46,272 It was a mining center of great importance in the 1800s. 329 00:21:50,442 --> 00:21:53,145 For more than 150 years, 330 00:21:53,145 --> 00:21:58,184 the Wicklow mountains were mined for their treasures. 331 00:21:58,184 --> 00:22:01,754 There was even a brief gold rush in the 18th century 332 00:22:01,754 --> 00:22:05,524 after nearly 200 pounds of gold were discovered here. 333 00:22:10,229 --> 00:22:15,467 Today, the lead mines, closed for good in the mid-1950s, 334 00:22:15,467 --> 00:22:19,638 sit abandoned in the Glendalough and Glendasan Valleys. 335 00:22:27,079 --> 00:22:30,583 But long before miners began their excavations, 336 00:22:30,583 --> 00:22:37,122 glaciers left their mark on the Wicklow Mountains. 337 00:22:37,122 --> 00:22:41,393 During the Ice Age, layers of snow and ice accumulated, 338 00:22:41,393 --> 00:22:45,531 growing heavier with each year. 339 00:22:45,531 --> 00:22:49,335 Over time, the glacier slid down the mountainside, 340 00:22:49,335 --> 00:22:55,174 carving out massive hollows and valleys between the peaks. 341 00:22:55,174 --> 00:22:57,876 The glacier came down and scooped the rock 342 00:22:57,876 --> 00:23:00,179 out of this valley and deepened it, 343 00:23:00,179 --> 00:23:02,348 and then after all the ice melted away 344 00:23:02,348 --> 00:23:05,618 the over-deepened valley was filled with water 345 00:23:05,618 --> 00:23:11,490 and that's what's here now. 346 00:23:11,490 --> 00:23:15,761 At the heart of the Wicklow Mountains is Glendalough: 347 00:23:15,761 --> 00:23:19,632 the valley of two lakes. 348 00:23:19,632 --> 00:23:23,135 Glendalough stretches for nearly two miles and is 349 00:23:23,135 --> 00:23:28,173 one of Ireland's most popular tourist destinations. 350 00:23:28,173 --> 00:23:32,344 It is an area of sublime natural beauty 351 00:23:32,344 --> 00:23:37,583 and fascinating history: from miners and monks, to monsters. 352 00:23:39,485 --> 00:23:42,621 The sixth-century monk St. Kevin is said to have 353 00:23:42,621 --> 00:23:46,592 banished a monster from one of the lakes at Glendalough 354 00:23:46,592 --> 00:23:50,329 after it harassed the locals and their livestock. 355 00:23:55,334 --> 00:23:58,103 Upper Glendalough is a magnificent example 356 00:23:58,103 --> 00:24:02,741 of a glacial ribbon lake, a long and narrow body of water 357 00:24:02,741 --> 00:24:08,580 usually found in a trough formed by a glacier. 358 00:24:08,580 --> 00:24:11,083 A normal river valley is a kind of a V-shape 359 00:24:11,083 --> 00:24:15,387 but a glacial U-shaped valley is sculpted by ice 360 00:24:15,387 --> 00:24:19,191 in a glacier going down and, as you can see behind us, 361 00:24:19,191 --> 00:24:21,727 it's got steep sides, steep cliffs there, 362 00:24:21,727 --> 00:24:28,667 and the valley floor is relatively flat. 363 00:24:28,667 --> 00:24:31,437 To maintain water levels at Glendalough, 364 00:24:31,437 --> 00:24:35,507 these glacial basins need to be fed, 365 00:24:35,507 --> 00:24:38,477 and no glaciers remain today. 366 00:24:45,250 --> 00:24:48,787 Mountain streams and rivers now feed these lakes 367 00:24:48,787 --> 00:24:53,258 and provide drinking water for nearby towns. 368 00:24:57,262 --> 00:25:00,599 The River Liffey, which runs through the center of Dublin 369 00:25:00,599 --> 00:25:07,206 more than 50 miles away, begins its journey here 370 00:25:07,206 --> 00:25:13,045 at the Liffey Head Bog. 371 00:25:13,045 --> 00:25:17,182 Lots of rain, combined with poor soil drainage 372 00:25:17,182 --> 00:25:20,219 provides the ideal environment for Wicklow's 373 00:25:20,219 --> 00:25:24,823 signature ecosystem: the Blanket Bog. 374 00:25:24,823 --> 00:25:29,228 A blanket bog is what coats the mountain plateau here. 375 00:25:29,228 --> 00:25:32,131 It's a kind of plant structure 376 00:25:32,131 --> 00:25:38,637 that's growing in a waterlogged soil on top of the rock. 377 00:25:38,637 --> 00:25:44,143 Moss grows in that and it forms this layer a meter or two thick 378 00:25:44,143 --> 00:25:46,545 over the upland areas and it's a very 379 00:25:46,545 --> 00:25:52,284 specific kind of plant community. 380 00:25:52,284 --> 00:25:55,521 The blanket bog, and the moss that dominates it, 381 00:25:55,521 --> 00:25:59,591 draw nutrients from rainfall to create an environment 382 00:25:59,591 --> 00:26:05,130 that's highly acidic, poor in nutrients and low in oxygen. 383 00:26:06,732 --> 00:26:11,403 Only certain plants can tolerate such a hostile setting, 384 00:26:11,403 --> 00:26:18,343 making the blanket bog a highly specialized ecosystem. 385 00:26:18,343 --> 00:26:21,513 As as the sort of living layer keeps growing up, 386 00:26:21,513 --> 00:26:23,182 the bottom bits die away. 387 00:26:23,182 --> 00:26:25,684 But because they're waterlogged, they form this layer of peat 388 00:26:25,684 --> 00:26:29,688 which is a low-energy carbon fuel. 389 00:26:29,688 --> 00:26:34,526 And people used to dig that in the past. 390 00:26:34,526 --> 00:26:38,363 If you're on those upland areas, you see these sort of trenches 391 00:26:38,363 --> 00:26:43,235 where people have extracted peat. 392 00:26:43,235 --> 00:26:47,573 For centuries, people in the mountains cut peat for fuel 393 00:26:47,573 --> 00:26:51,243 to warm their houses. 394 00:26:51,243 --> 00:26:55,414 Today, just 28 percent of Ireland's original blanket bog 395 00:26:55,414 --> 00:27:01,153 remains intact. 396 00:27:01,153 --> 00:27:04,590 But now it's protected because it's an ecological community 397 00:27:04,590 --> 00:27:08,660 that's very well represented in Ireland. 398 00:27:08,660 --> 00:27:10,596 It's important to maintain because it's plant 399 00:27:10,596 --> 00:27:15,601 and ecological diversity that you don't see in other, say, 400 00:27:15,601 --> 00:27:18,370 upland areas in Europe. 401 00:27:18,370 --> 00:27:21,373 Peat grows just a fraction of an inch per year 402 00:27:21,373 --> 00:27:25,577 and can reach down for several yards. 403 00:27:25,577 --> 00:27:29,481 The partially decomposed plant matter that forms a peat bog 404 00:27:29,481 --> 00:27:33,519 can take thousands of years to accumulate. 405 00:27:33,519 --> 00:27:38,824 It's a slow process, like the movement of tectonic plates, 406 00:27:38,824 --> 00:27:41,793 the crush of glaciers, 407 00:27:41,793 --> 00:27:48,534 and the building of a bridge to Scotland. 408 00:27:48,534 --> 00:27:53,272 According to Irish legend, the amazing rock formations at the 409 00:27:53,272 --> 00:27:57,809 Giant's Causeway on Northern Ireland's Antrim coast 410 00:27:57,809 --> 00:28:02,981 are the remains of a bridge built by the giant Finn McCool. 411 00:28:07,019 --> 00:28:09,755 He built it for a showdown with his rival, 412 00:28:09,755 --> 00:28:14,660 an oversized Scottish rogue named Benandonner 413 00:28:14,660 --> 00:28:19,031 who lived across the North Channel in Scotland. 414 00:28:19,031 --> 00:28:22,200 Or so some would have you believe. 415 00:28:22,200 --> 00:28:25,437 The Giant's Causeway is more than rocks. 416 00:28:25,437 --> 00:28:28,106 I have listened to stories about a giant called Finn McCool 417 00:28:28,106 --> 00:28:29,041 all my life. 418 00:28:29,041 --> 00:28:31,777 And I've been working here for 30 years. 419 00:28:31,777 --> 00:28:34,079 I've been sharing them stories with visitors 420 00:28:34,079 --> 00:28:37,049 virtually all my life. 421 00:28:37,049 --> 00:28:41,119 It's easy to imagine why early inhabitants would credit 422 00:28:41,119 --> 00:28:47,793 a mythic giant with the creation of this extraordinary setting. 423 00:28:47,793 --> 00:28:51,163 But the 40,000 interlocking basalt columns 424 00:28:51,163 --> 00:28:54,232 of the Giant's Causeway were actually formed 425 00:28:54,232 --> 00:28:59,204 by a volcanic event more than 50 million years ago. 426 00:29:01,406 --> 00:29:05,544 Deep below the surface, shifting tectonic plates 427 00:29:05,544 --> 00:29:09,348 forced massive volumes of molten rock through fissures 428 00:29:09,348 --> 00:29:15,053 in the surface to create layers of basalt rock. 429 00:29:15,053 --> 00:29:21,059 Wind, rain and waves carved a valley. 430 00:29:21,059 --> 00:29:24,029 More volcanic eruptions followed. 431 00:29:24,029 --> 00:29:27,232 Lava flowed quickly in thick streams. 432 00:29:27,232 --> 00:29:30,068 The valley filled up with lava until it was 100 meters deep. 433 00:29:30,068 --> 00:29:31,770 It was 1,200 degrees Celsius. 434 00:29:31,770 --> 00:29:33,438 And it's like everything. 435 00:29:33,438 --> 00:29:36,041 If you boil a kettle it will cool down. 436 00:29:36,041 --> 00:29:38,377 The pool of lava had to cool down. 437 00:29:39,778 --> 00:29:44,249 Lava at the bottom of the valley cooled slowly. 438 00:29:44,249 --> 00:29:48,253 Then, like mud in a shallow pond on a hot day, 439 00:29:48,253 --> 00:29:54,493 as the lava cooled it contracted and cracked in even patterns. 440 00:29:57,429 --> 00:29:58,463 During the Ice Age, 441 00:29:58,463 --> 00:30:04,436 glaciers scraped away at the top layers of rock. 442 00:30:04,436 --> 00:30:07,806 When the ice retreated, sea levels rose, 443 00:30:07,806 --> 00:30:13,812 and pounding waves wore away at more rock. 444 00:30:13,812 --> 00:30:16,148 Variations in the rate of cooling 445 00:30:16,148 --> 00:30:22,821 produced the honeycomb-like monument that stands today. 446 00:30:22,821 --> 00:30:26,358 Columns can reach 39 feet tall. 447 00:30:26,358 --> 00:30:29,227 While the solid lava deposits in the cliffs 448 00:30:29,227 --> 00:30:32,197 measure more than 90 feet thick. 449 00:30:39,805 --> 00:30:45,477 High seas pound the rocks of the Giant's Causeway. 450 00:30:45,477 --> 00:30:49,648 Ireland is known for its volatile weather, 451 00:30:49,648 --> 00:30:51,883 and here on the north-east coast, 452 00:30:51,883 --> 00:30:56,421 sea mist can roll in quickly. 453 00:30:56,421 --> 00:30:59,324 Navigation can be treacherous, 454 00:30:59,324 --> 00:31:03,395 and ships need to steer clear of the rocks. 455 00:31:08,467 --> 00:31:11,369 The coastline that surrounds Giant's Causeway 456 00:31:11,369 --> 00:31:14,706 has caused many wrecks. 457 00:31:14,706 --> 00:31:19,444 In 1588, more than 1,000 seamen died when a 458 00:31:19,444 --> 00:31:25,417 Spanish military ship loaded with treasures sank here. 459 00:31:25,417 --> 00:31:27,219 Today, these formations 460 00:31:27,219 --> 00:31:30,689 also go by the name Spaniard Rock. 461 00:31:35,694 --> 00:31:40,198 There are many versions of the legend of the Giant's Causeway. 462 00:31:43,702 --> 00:31:47,539 Some say Finn destroyed the bridge he built. 463 00:31:47,539 --> 00:31:51,276 Others say the Scottish giant destroyed it. 464 00:31:51,276 --> 00:31:56,782 But no one disputes why the legend arose in the first place. 465 00:31:56,782 --> 00:31:59,851 Eighty miles across the North Channel, 466 00:31:59,851 --> 00:32:02,521 on the Scottish island of Staffa, 467 00:32:02,521 --> 00:32:04,222 there are basalt columns 468 00:32:04,222 --> 00:32:08,660 identical to those found on the Giant's Causeway. 469 00:32:08,660 --> 00:32:12,063 The columns at Staffa are part of the same lava field 470 00:32:12,063 --> 00:32:14,599 that built the Giant's Causeway, 471 00:32:14,599 --> 00:32:19,337 and have fueled its long-standing legend. 472 00:32:19,337 --> 00:32:24,209 The Giant's Causeway has been a tourist draw for 300 years. 473 00:32:24,209 --> 00:32:28,547 More than half a million people visit each year. 474 00:32:28,547 --> 00:32:32,284 It is the by far the most popular tourist attraction 475 00:32:32,284 --> 00:32:36,488 in Northern Ireland. 476 00:32:36,488 --> 00:32:40,158 Geological studies here have contributed greatly 477 00:32:40,158 --> 00:32:45,197 to our understanding of basaltic volcanism. 478 00:32:45,197 --> 00:32:47,833 In 1986, the Causeway was declared 479 00:32:47,833 --> 00:32:51,336 a UNESCO World Heritage site. 480 00:32:55,507 --> 00:33:00,245 Today it's owned and managed by the National Trust in the UK, 481 00:33:00,245 --> 00:33:03,548 to protect this iconic segment of Irish heritage 482 00:33:03,548 --> 00:33:06,418 for future generations. 483 00:33:06,418 --> 00:33:08,553 When this site was actually privately owned, 484 00:33:08,553 --> 00:33:10,155 the site was quarried. 485 00:33:10,155 --> 00:33:11,623 There was a serious lot of stones took off it. 486 00:33:11,623 --> 00:33:13,558 The National Trust bought the site. 487 00:33:13,558 --> 00:33:17,362 When they bought the site all that stopped. 488 00:33:17,362 --> 00:33:21,733 You know, no more stones left the site. 489 00:33:21,733 --> 00:33:24,502 A good thing, too. 490 00:33:24,502 --> 00:33:26,838 No one wants a giant at their door 491 00:33:26,838 --> 00:33:30,175 looking for his stolen rocks. 492 00:33:36,281 --> 00:33:40,352 Some rocks near the Causeway, carved by millions of years 493 00:33:40,352 --> 00:33:47,058 of erosion, resemble elements of Finn McCool's world: 494 00:33:50,795 --> 00:33:53,798 the Chimney Stacks, 495 00:34:02,574 --> 00:34:05,310 the Organ, 496 00:34:13,418 --> 00:34:18,757 and the Giant's Boot. 497 00:34:18,757 --> 00:34:21,326 The Boot is one of the most popular features 498 00:34:21,326 --> 00:34:25,530 on the Causeway. 499 00:34:25,530 --> 00:34:28,767 Based on the size of the boot, it's estimated that Finn 500 00:34:28,767 --> 00:34:32,570 would have been more than 50 feet tall. 501 00:34:32,570 --> 00:34:33,638 It's a boot. 502 00:34:33,638 --> 00:34:36,274 You know, it's the shape of a boot. 503 00:34:36,274 --> 00:34:37,609 I believe it's a boot. 504 00:34:37,609 --> 00:34:40,145 I believe the giant Finn McCool left it there 505 00:34:40,145 --> 00:34:41,646 for us to have a look at. 506 00:34:41,646 --> 00:34:43,415 It's a size 93 and a half. 507 00:34:43,415 --> 00:34:45,283 A geologist would totally disagree with you. 508 00:34:57,529 --> 00:35:00,532 The same period of extreme volcanic activity 509 00:35:00,532 --> 00:35:04,402 that created the Giant's Causeway also gave rise 510 00:35:04,402 --> 00:35:08,506 to Slieve Gullion 100 miles to the south. 511 00:35:16,648 --> 00:35:18,783 Slieve Gullion is known as the most mysterious mountain 512 00:35:18,783 --> 00:35:19,985 in Ireland. 513 00:35:19,985 --> 00:35:23,355 And it's got lots of myths and legends associated with it. 514 00:35:23,355 --> 00:35:25,623 And it's the eroded heart of a volcano. 515 00:35:25,623 --> 00:35:30,628 More than 60 million years ago, volcanic turmoil far beneath 516 00:35:30,628 --> 00:35:34,632 the surface caused the original Slieve Gullion volcano 517 00:35:34,632 --> 00:35:39,404 to collapse into a great chamber far below. 518 00:35:39,404 --> 00:35:41,272 The magma in this chamber 519 00:35:41,272 --> 00:35:46,344 slowly cooled to form the solid granite seen today. 520 00:35:46,344 --> 00:35:50,248 Surrounding the volcano was a circular fracture in the rocks, 521 00:35:50,248 --> 00:35:52,817 seven miles in diameter. 522 00:35:52,817 --> 00:35:56,187 Magma rose through this crack and cooled, 523 00:35:56,187 --> 00:35:58,556 forming what's known as a ring dyke, 524 00:35:58,556 --> 00:36:02,460 leaving a circle of hills around Slieve Gullion, 525 00:36:02,460 --> 00:36:07,632 known today as the Ring of Gullion. 526 00:36:07,632 --> 00:36:10,068 The landscape here has been designated 527 00:36:10,068 --> 00:36:13,471 as an Area of Outstanding Natural Beauty, 528 00:36:13,471 --> 00:36:19,044 and is home to a vibrant floral community. 529 00:36:19,044 --> 00:36:22,280 Slieve Gullion is designated as a special area of conservation. 530 00:36:22,280 --> 00:36:24,516 This heather is very, very special. 531 00:36:24,516 --> 00:36:27,318 We've got ling heather and bell heather. 532 00:36:27,318 --> 00:36:30,055 You can still see the lovely purple shades up the mountain. 533 00:36:42,167 --> 00:36:44,636 Tales of the Irish giant Finn McCool 534 00:36:44,636 --> 00:36:47,605 dwell in Slieve Gullion as well. 535 00:36:55,213 --> 00:36:57,615 The landscape has ignited the imaginations 536 00:36:57,615 --> 00:37:02,320 of settlers old and new. 537 00:37:02,320 --> 00:37:04,656 People here living nowadays, they draw inspiration 538 00:37:04,656 --> 00:37:06,758 from the mountain and those myths and legends 539 00:37:06,758 --> 00:37:09,127 and those characters in their past. 540 00:37:09,127 --> 00:37:11,596 On a day like today whenever we do have that low-lying mist, 541 00:37:11,596 --> 00:37:14,599 it's fantastic because we can see the peaks of the ring dyke 542 00:37:14,599 --> 00:37:16,668 peeking through all that mist. 543 00:37:16,668 --> 00:37:19,170 You can just imagine whenever those myths and legends 544 00:37:19,170 --> 00:37:22,073 and those characters in the past were roaming around here 545 00:37:22,073 --> 00:37:23,775 and it's very easy to see why this is one of the most 546 00:37:23,775 --> 00:37:26,311 mystical mountains in Ireland. 547 00:37:26,311 --> 00:37:29,547 The legend of Finn McCool extends from Slieve Gullion 548 00:37:29,547 --> 00:37:34,419 in the east, all the way west to the Slieve League Cliffs. 549 00:37:38,189 --> 00:37:39,457 At the base of the cliffs, 550 00:37:39,457 --> 00:37:43,128 in the Grey Mountains of County Donegal, 551 00:37:43,128 --> 00:37:47,532 two sea stacks - the Giant's Desk and Chair - 552 00:37:47,532 --> 00:37:50,201 are said to be where Finn McCool 553 00:37:50,201 --> 00:37:56,641 drew up his plans for the Giant's Causeway. 554 00:37:56,641 --> 00:37:59,244 But there's more here than the office furniture 555 00:37:59,244 --> 00:38:04,749 of an angry giant. 556 00:38:04,749 --> 00:38:06,184 The big significance here I suppose 557 00:38:06,184 --> 00:38:08,219 is the sheer size in the landscape. 558 00:38:08,219 --> 00:38:11,256 So it's notable from the sea, so early mariners, 559 00:38:11,256 --> 00:38:15,126 people coming to Ireland over the times, would've seen it. 560 00:38:15,126 --> 00:38:19,130 It would've been a landmark for them. 561 00:38:19,130 --> 00:38:21,533 The majestic cliffs of Slieve League 562 00:38:21,533 --> 00:38:27,172 rise nearly 2,000 feet above the ocean. 563 00:38:27,172 --> 00:38:30,475 They are the highest sea cliffs in Ireland, 564 00:38:30,475 --> 00:38:35,213 twice as tall as the more famous Cliffs of Moher. 565 00:38:37,715 --> 00:38:41,686 Their origins are just as remarkable. 566 00:38:41,686 --> 00:38:44,822 About 200 million years ago, ourselves and the Appalachians 567 00:38:44,822 --> 00:38:48,593 were all the one mountain system way down south of the equator 568 00:38:48,593 --> 00:38:51,162 and over time the whole system moved up north 569 00:38:51,162 --> 00:38:53,464 and divided apart. 570 00:38:59,370 --> 00:39:02,106 Slieve League has been recognized as the official 571 00:39:02,106 --> 00:39:06,611 landfall for the International Appalachian Trail. 572 00:39:06,611 --> 00:39:08,780 These mountains are the trans-Atlantic, 573 00:39:08,780 --> 00:39:11,616 geologic extension of North America's 574 00:39:11,616 --> 00:39:16,020 Appalachian Mountains. 575 00:39:16,020 --> 00:39:18,356 The rock here has been directly linked 576 00:39:18,356 --> 00:39:22,360 to that on the east coast of Canada. 577 00:39:24,796 --> 00:39:26,764 Our nearest neighbor in those times 578 00:39:26,764 --> 00:39:28,366 would've been Newfoundland. 579 00:39:28,366 --> 00:39:30,034 So you can see where the Irish connection 580 00:39:30,034 --> 00:39:33,304 was in Newfoundland even way before the people were there. 581 00:39:37,542 --> 00:39:43,314 The crashing waves below seem quiet from so high above. 582 00:39:45,116 --> 00:39:48,820 And although Slieve League's steep face plunges straight into 583 00:39:48,820 --> 00:39:53,124 the powerful Atlantic, erosion by waves has played 584 00:39:53,124 --> 00:39:57,695 only a minor role in shaping this part of the coast. 585 00:40:03,635 --> 00:40:10,141 Slieve League was carved not by water, but by glaciers. 586 00:40:10,141 --> 00:40:12,410 This whole area here would've been under ice 587 00:40:12,410 --> 00:40:18,116 maybe 70 to 100 meters deep and the ice has ground out 588 00:40:18,116 --> 00:40:21,653 and very much shaped the cliffs. 589 00:40:21,653 --> 00:40:25,356 We had thousands of years of ice here up until about 590 00:40:25,356 --> 00:40:28,159 10,000 years ago at the end of the last ice age. 591 00:40:28,159 --> 00:40:30,194 But right behind me here down in the cove there 592 00:40:30,194 --> 00:40:31,796 with the Giant's Desk and Chair, 593 00:40:31,796 --> 00:40:34,565 was a glacier there for thousands of years. 594 00:40:47,178 --> 00:40:51,516 Research suggests that the ice sheet that covered Slieve League 595 00:40:51,516 --> 00:40:55,553 may have been nearly half a mile thick. 596 00:40:55,553 --> 00:41:01,292 Deep enough to encase the summit. 597 00:41:01,292 --> 00:41:04,362 The enormous weight of that volume of ice would have 598 00:41:04,362 --> 00:41:09,133 depressed the Earth's surface by as much as 650 feet. 599 00:41:13,571 --> 00:41:18,576 Slieve League's dizzying slopes rise to the ridges and trails 600 00:41:18,576 --> 00:41:24,315 used by hikers to traverse this natural wonder. 601 00:41:27,719 --> 00:41:33,358 Leading to the summit is a trail known as One Man's Pass. 602 00:41:33,358 --> 00:41:36,461 It is an arete, a knife-like ridge of rock 603 00:41:36,461 --> 00:41:41,199 formed when two glaciers erode parallel, opposing valleys. 604 00:41:46,704 --> 00:41:51,209 It offers breathtaking views for hikers with good balance 605 00:41:51,209 --> 00:41:55,179 and nerves of steel. 606 00:41:55,179 --> 00:41:57,415 Most people can cross the One Man's Pass. 607 00:41:57,415 --> 00:42:00,418 But it's a section of the trail that's about a half mile long 608 00:42:00,418 --> 00:42:02,653 that's only two foot wide. 609 00:42:02,653 --> 00:42:06,557 You've a drop down to the ocean of over 1800 feet. 610 00:42:06,557 --> 00:42:07,759 I always lean the other way, 611 00:42:07,759 --> 00:42:12,663 it's only 1400 feet down to a wee lake. 612 00:42:12,663 --> 00:42:15,333 Some people will crawl it, some people will walk it, 613 00:42:15,333 --> 00:42:17,335 some people will pray on it. 614 00:42:23,141 --> 00:42:26,544 The otherworldly majesty of Slieve League 615 00:42:26,544 --> 00:42:30,581 has drawn and inspired giants and mere mortals alike 616 00:42:30,581 --> 00:42:34,652 over hundreds if not thousands of years. 617 00:42:38,623 --> 00:42:44,328 Some seek to connect with a higher power. 618 00:42:44,328 --> 00:42:45,863 There's a Christian pilgrimage going on here 619 00:42:45,863 --> 00:42:48,232 for almost 2000 years, 620 00:42:48,232 --> 00:42:50,401 since the early Christian monks settled up here. 621 00:42:50,401 --> 00:42:53,171 And these pilgrimages we know go back pre-Christian 622 00:42:53,171 --> 00:42:55,606 and archaeological evidence will show us 623 00:42:55,606 --> 00:42:57,475 that there was people living, or doing things 624 00:42:57,475 --> 00:43:00,144 on these mountains way before Christianity. 625 00:43:13,524 --> 00:43:17,628 The cliffs are also home to military installations built 626 00:43:17,628 --> 00:43:21,666 to watch over the possible trespasses of a French Emperor. 627 00:43:24,769 --> 00:43:26,838 These signal towers, the British built them here 628 00:43:26,838 --> 00:43:30,675 from 1803 until about 1806 or 1807. 629 00:43:30,675 --> 00:43:32,176 And they built a whole series of these 630 00:43:32,176 --> 00:43:34,812 right around the coast of Ireland. 631 00:43:34,812 --> 00:43:37,281 They were watching out for Napoleon. 632 00:43:37,281 --> 00:43:40,084 The British were afraid he would invade Ireland, arm the Irish, 633 00:43:40,084 --> 00:43:42,653 and then maybe chase them out and invade Britain. 634 00:43:42,653 --> 00:43:45,089 So this system was set up - 635 00:43:45,089 --> 00:43:47,558 an early watch system basically is what they are. 636 00:43:47,558 --> 00:43:50,127 And they're still standing today. 637 00:44:16,120 --> 00:44:20,157 Shaped by glaciers, the cliffs of Slieve League 638 00:44:20,157 --> 00:44:24,695 are a breathtaking example of Ireland's natural beauty. 639 00:44:28,165 --> 00:44:30,535 You couldn't be closer to nature than here. 640 00:44:30,535 --> 00:44:34,705 You have the ocean, the sky, the light, 641 00:44:34,705 --> 00:44:36,807 the wind even in your hair. 642 00:44:36,807 --> 00:44:39,443 You can just get lost in nature. 643 00:44:39,443 --> 00:44:45,783 You couldn't be in a better place. 644 00:44:45,783 --> 00:44:51,656 Ireland: small in size, but epic in wonder. 645 00:44:55,226 --> 00:45:02,733 Its vistas and wild spaces are fit for ancient, mythical heroes 646 00:45:02,733 --> 00:45:09,607 and 21st-century explorers. 647 00:45:09,607 --> 00:45:12,610 It is surrounded by the sea, 648 00:45:12,610 --> 00:45:17,648 yet tied to other lands far across the ocean. 649 00:45:17,648 --> 00:45:24,488 Here, rock and water are locked in constant struggle, 650 00:45:24,488 --> 00:45:28,159 keeping the Earth in a state of flux, 651 00:45:28,159 --> 00:45:33,464 ensuring that nothing is set in stone forever. 652 00:45:33,464 --> 00:45:40,338 Ireland's mountains and cliffs, its valleys and lakes, 653 00:45:40,338 --> 00:45:46,377 will continue to rise and fall with the passage of time 654 00:45:46,377 --> 00:45:51,182 on a scale far beyond the realm of mere mortals. 655 00:45:56,320 --> 00:46:06,297 ♪♪ 656 00:46:06,297 --> 00:46:11,769 ♪♪ 657 00:46:11,769 --> 00:46:19,977 ♪♪