1 00:00:04,440 --> 00:00:08,920 This is the story of the island of Ireland. 2 00:00:08,920 --> 00:00:11,760 Originating south of the equator, 3 00:00:11,760 --> 00:00:14,720 it's been on a long and dramatic journey. 4 00:00:19,000 --> 00:00:22,040 Travelling northwards through colliding continents 5 00:00:22,040 --> 00:00:23,840 and disappearing oceans, 6 00:00:23,840 --> 00:00:29,000 it has been formed and reformed over 1.8 billion years. 7 00:00:36,560 --> 00:00:40,960 The evidence for this remarkable journey is woven into the fabric 8 00:00:40,960 --> 00:00:45,160 of our mountains, lakes and deepest ocean beds. 9 00:00:48,600 --> 00:00:52,720 Its imprint visible in the stunning ravages of the Ice Age, 10 00:00:52,720 --> 00:00:56,960 in its plants, its animals and its people. 11 00:00:59,600 --> 00:01:03,680 This is a story, 1.8 billion years in the making, 12 00:01:03,680 --> 00:01:06,240 the story of The Island. 13 00:01:15,520 --> 00:01:18,000 Over 1.8 billion years, 14 00:01:18,000 --> 00:01:22,040 the rocks that make up the island were forged together, 15 00:01:22,040 --> 00:01:25,640 making their way north to where Ireland is now located, 16 00:01:25,640 --> 00:01:28,080 on the edge of the North Atlantic. 17 00:01:30,880 --> 00:01:34,080 With all the rocks now in place, Ireland's story moved into 18 00:01:34,080 --> 00:01:37,000 what geologists call the quaternary. 19 00:01:39,280 --> 00:01:43,080 This is the period when our unique landscape, with its valleys, 20 00:01:43,080 --> 00:01:47,200 caves and coastlines, were sculpted by the dominant forces 21 00:01:47,200 --> 00:01:49,160 of water and ice. 22 00:01:55,720 --> 00:02:00,440 At this time, temperatures dropped, causing massive ice sheets to spread 23 00:02:00,440 --> 00:02:05,240 from the poles and cover much of North America and Europe. 24 00:02:05,240 --> 00:02:09,040 At times, Ireland was completely shrouded in thick ice 25 00:02:09,040 --> 00:02:11,800 that extended far out to the sea. 26 00:02:15,040 --> 00:02:17,840 These ice sheets have long since retreated. 27 00:02:17,840 --> 00:02:21,960 But you don't have to travel too far to witness their power. 28 00:02:36,000 --> 00:02:38,800 1,000 kilometres or so to the north-east, 29 00:02:38,800 --> 00:02:43,200 the tremendous force of a glacier still carves the spectacular valley 30 00:02:43,200 --> 00:02:45,520 of Briksdalsbreen in Norway. 31 00:02:52,440 --> 00:02:56,160 The whole area here is like a classroom without a roof 32 00:02:56,160 --> 00:03:00,400 for a geologist. You can see so many glacier features here. 33 00:03:00,400 --> 00:03:03,520 The whole landscape here was formed during the Ice Ages, 34 00:03:03,520 --> 00:03:06,880 when a 2km thick ice cap was covering this area 35 00:03:06,880 --> 00:03:10,920 and the ice was slowly sliding down the valleys here. 36 00:03:12,480 --> 00:03:17,800 The landscapes of Norway and Ireland are very much the same. 37 00:03:17,800 --> 00:03:20,000 They are formed by the same processes. 38 00:03:20,000 --> 00:03:22,680 The only difference is that here, we still have glaciers 39 00:03:22,680 --> 00:03:26,000 that are active and still form the landscape. 40 00:03:26,000 --> 00:03:31,040 But we have to go back in geological time, back to 2.7 million years ago. 41 00:03:31,040 --> 00:03:33,800 After that, we had more than 40 ice ages, 42 00:03:33,800 --> 00:03:36,520 lasting for 100,000 years with ice, 43 00:03:36,520 --> 00:03:41,480 20,000 years without ice and repeating it over and over again. 44 00:03:41,480 --> 00:03:45,080 And that was time periods where we built up huge ice sheets, 45 00:03:45,080 --> 00:03:49,400 one over Scandinavia and one over Ireland and British islands. 46 00:03:49,400 --> 00:03:52,920 And at some points, they also connected with each other. 47 00:03:52,920 --> 00:03:56,640 So also in Ireland, you had this massive glacier erosion. 48 00:03:56,640 --> 00:04:00,600 You had valleys that was carved out by the glacier that was entering 49 00:04:00,600 --> 00:04:04,400 into the fjords and into the deep ocean around. 50 00:04:06,120 --> 00:04:09,880 Once ice accumulates to a depth of about 50 metres, 51 00:04:09,880 --> 00:04:13,840 it begins to move, spreading outwards and downwards 52 00:04:13,840 --> 00:04:17,120 under the pressure of its own weight. 53 00:04:17,120 --> 00:04:20,160 The base of the glacier is in contact with the earth 54 00:04:20,160 --> 00:04:23,760 and is therefore slightly warmer than the rest of the ice, 55 00:04:23,760 --> 00:04:26,280 so a thin layer of water forms, 56 00:04:26,280 --> 00:04:29,240 allowing the glacier to slide over it. 57 00:04:30,240 --> 00:04:32,520 Ice is amazing material. 58 00:04:32,520 --> 00:04:35,280 It behaves like a plastic mass. 59 00:04:35,280 --> 00:04:38,760 At the same time, it can be fragile and crack up. 60 00:04:38,760 --> 00:04:40,440 Like the ice behind me here, 61 00:04:40,440 --> 00:04:42,600 it was formed at the summit of the glacier, 62 00:04:42,600 --> 00:04:45,400 about 2,000 metres above sea level. 63 00:04:45,400 --> 00:04:50,320 Snow is accumulating and then there is a movement down and the ice, 64 00:04:50,320 --> 00:04:53,280 when it get pressurised, 65 00:04:53,280 --> 00:04:56,400 it moves like a plastic material. 66 00:04:56,400 --> 00:04:58,120 You can imagine like a toothpaste 67 00:04:58,120 --> 00:04:59,720 where you squeeze out the toothpaste. 68 00:04:59,720 --> 00:05:02,680 It's the same with the ice and it moves by the force 69 00:05:02,680 --> 00:05:05,640 of the gravity and comes down into the frontal part 70 00:05:05,640 --> 00:05:08,240 of the outer glacier, where it melts. 71 00:05:10,880 --> 00:05:16,000 During the last 2.6 million years, ice has repeatedly advanced 72 00:05:16,000 --> 00:05:18,480 from the poles and then retreated, 73 00:05:18,480 --> 00:05:23,600 carving and moulding the land with every ebb and flow. 74 00:05:23,600 --> 00:05:27,320 It's thought that these vast sheets of ice reached Ireland on at least 75 00:05:27,320 --> 00:05:29,960 four occasions during this time. 76 00:05:29,960 --> 00:05:33,920 But the sheer power of glaciers can erode away all traces 77 00:05:33,920 --> 00:05:35,840 of previous glaciations. 78 00:05:35,840 --> 00:05:39,280 So places like this provide fascinating insights 79 00:05:39,280 --> 00:05:41,680 into what Ireland would have looked like for much 80 00:05:41,680 --> 00:05:44,240 of the past 2.6 million years. 81 00:05:46,160 --> 00:05:50,440 Even though the ice sheets have long since retreated, our most recent 82 00:05:50,440 --> 00:05:53,360 Ice Age has certainly left its mark on Ireland. 83 00:05:53,360 --> 00:05:56,080 In fact, in the last half a million years or so, 84 00:05:56,080 --> 00:05:59,360 ice has been the dominant shaping force on our landscape. 85 00:05:59,360 --> 00:06:03,040 And nowhere is all that carving and sculpting more apparent 86 00:06:03,040 --> 00:06:05,200 than here in Connemara. 87 00:06:09,840 --> 00:06:13,840 These drowned U-shaped valleys are known as fjords. 88 00:06:13,840 --> 00:06:18,240 And in Killary Harbour, in the heart of Connemara, a natural border 89 00:06:18,240 --> 00:06:22,480 between the counties of Galway and Mayo was carved by ice. 90 00:06:24,320 --> 00:06:28,360 The whole mountain landscape here has been directly and greatly 91 00:06:28,360 --> 00:06:31,240 impacted by those glaciations. 92 00:06:31,240 --> 00:06:34,800 Those depressions that we see as we drive through Connemara 93 00:06:34,800 --> 00:06:37,480 on most hillsides and in some areas, 94 00:06:37,480 --> 00:06:40,160 they're backing onto each other almost. 95 00:06:40,160 --> 00:06:43,200 So, they're facing north and south. They're facing all directions. 96 00:06:43,200 --> 00:06:47,120 It gives us an idea of the birth of that ice sheet. 97 00:06:47,120 --> 00:06:51,360 It helps you visualise this sense of massive creaking, 98 00:06:51,360 --> 00:06:54,520 groaning rivers, almost, of ice there, 99 00:06:54,520 --> 00:06:57,720 often compared to rivers much slower in their action. 100 00:06:57,720 --> 00:07:03,000 But accumulation of ice making its way down on its own journey 101 00:07:03,000 --> 00:07:07,640 down into the lower reaches, down into places like the fjord here, 102 00:07:07,640 --> 00:07:11,280 heading out to sea and ending up possibly as icebergs 103 00:07:11,280 --> 00:07:13,160 and floating off into the Atlantic. 104 00:07:13,160 --> 00:07:16,920 So, really, a beautiful journey for something which, 105 00:07:16,920 --> 00:07:22,600 once it solidifies into ice, becomes almost a different entity. 106 00:07:22,600 --> 00:07:25,880 You know, it becomes a living thing, a glacier. 107 00:07:25,880 --> 00:07:30,080 So let's talk about this iconic fjord, Killary Fjord. 108 00:07:30,080 --> 00:07:33,720 How was it created during the last Ice Age? 109 00:07:33,720 --> 00:07:39,200 The fjord here is that accumulation of just the sheer weight of ice, 110 00:07:39,200 --> 00:07:42,120 probably helped by, we think, a fault, 111 00:07:42,120 --> 00:07:47,480 so a deeper geological structure which created a line of weakness 112 00:07:47,480 --> 00:07:51,680 maybe along a pre-existing river valley, but that allowed just a bit 113 00:07:51,680 --> 00:07:54,400 more erosion to occur along a certain line. 114 00:07:54,400 --> 00:07:58,960 And then over time, as the ice came and went repeatedly, 115 00:07:58,960 --> 00:08:03,760 that same slight lowering due to the previous glaciation 116 00:08:03,760 --> 00:08:08,040 would have eroded it deeper and deeper and deeper 117 00:08:08,040 --> 00:08:11,360 until it became then what's known as linear erosion, 118 00:08:11,360 --> 00:08:14,120 where the ice gets focused again and again 119 00:08:14,120 --> 00:08:19,520 along the same avenue, creating these much over deepened valleys. 120 00:08:19,520 --> 00:08:21,800 What are the defining features of a fjord? 121 00:08:21,800 --> 00:08:24,800 They're characterised by this over deepening that I talked about 122 00:08:24,800 --> 00:08:27,880 where you have this concentration of erosion. 123 00:08:27,880 --> 00:08:31,240 They tend to be quite straight because that river of ice 124 00:08:31,240 --> 00:08:33,240 is quite strong in its effect. 125 00:08:33,240 --> 00:08:35,600 So it can bulldoze away the hillside. 126 00:08:35,600 --> 00:08:37,840 So, over time, it straightens and it deepens. 127 00:08:37,840 --> 00:08:40,720 But then when it gets to its outer reaches, and this is characteristic 128 00:08:40,720 --> 00:08:43,960 of fjords in Norway or Iceland, it shallows. 129 00:08:43,960 --> 00:08:47,680 So we think this is an effect of the buoyancy of water 130 00:08:47,680 --> 00:08:52,240 at the outer edge, so it loses that downward erosive power. 131 00:08:52,240 --> 00:08:55,560 And so you tend to get this, what's called a sill 132 00:08:55,560 --> 00:08:57,200 on the outer margins. 133 00:08:57,200 --> 00:09:00,680 And so we have three locations in Ireland where we have deep linear 134 00:09:00,680 --> 00:09:04,160 erosion in a straight line, just like Killary here. 135 00:09:04,160 --> 00:09:08,640 There's also deep erosion at the Swilly and there's also Carlingford. 136 00:09:08,640 --> 00:09:13,120 What kind of rocks are we talking about here and what power 137 00:09:13,120 --> 00:09:16,560 would that glacial ice sheet have to have to literally 138 00:09:16,560 --> 00:09:18,200 slice through it? 139 00:09:18,200 --> 00:09:22,440 Connemara is characterised by very old, very strong rocks. 140 00:09:23,440 --> 00:09:27,360 These are metamorphosed, so they've been baked and pressurised 141 00:09:27,360 --> 00:09:30,400 over multiple mountain building periods. 142 00:09:30,400 --> 00:09:33,280 So this is a very erosive force. 143 00:09:33,280 --> 00:09:34,560 It's the same in Norway. 144 00:09:34,560 --> 00:09:37,040 Some of the hardest rocks in the world are there 145 00:09:37,040 --> 00:09:41,120 and they've been eroded into these very over deepened valleys, 146 00:09:41,120 --> 00:09:45,200 much deeper even than Killary Harbour. 147 00:09:45,200 --> 00:09:47,320 It's not just the ice, it's the rocks themselves 148 00:09:47,320 --> 00:09:52,320 that get taken away from the higher areas of glaciation, 149 00:09:52,320 --> 00:09:54,280 brought down at the base of the ice. 150 00:09:54,280 --> 00:09:56,520 They will scour like sandpaper. 151 00:10:02,840 --> 00:10:06,200 So is this why you chose this particular day 152 00:10:06,200 --> 00:10:07,680 to bring me out here? 153 00:10:07,680 --> 00:10:12,160 This sheet of white in the back that almost obliterates the fjord, 154 00:10:12,160 --> 00:10:14,760 to allow me to experience what an ice sheet 155 00:10:14,760 --> 00:10:16,920 might have looked like. Is that why? 156 00:10:16,920 --> 00:10:19,520 Ice has always been evocative to me, 157 00:10:19,520 --> 00:10:23,840 ever since I started studying it, doing my A-levels, 158 00:10:23,840 --> 00:10:29,280 seeing pictures of Arctic Canada on the wall in my geography class. 159 00:10:29,280 --> 00:10:32,960 And just that visualisation of something that has been before, 160 00:10:32,960 --> 00:10:36,160 has left its signature, its imprint, and is gone now. 161 00:10:36,160 --> 00:10:39,240 So it's been compared in the past to living with the ghosts 162 00:10:39,240 --> 00:10:40,600 of past ice sheets. 163 00:10:42,040 --> 00:10:46,240 It's that idea of a magnificent landscape-changing entity 164 00:10:46,240 --> 00:10:47,280 that is no longer. 165 00:10:47,280 --> 00:10:50,760 But it leaves these tantalising clues all over the landscape 166 00:10:50,760 --> 00:10:53,000 if you know how to look for them, to tell them, 167 00:10:53,000 --> 00:10:56,480 "I was here and this is what I did, and it's up to you now to try 168 00:10:56,480 --> 00:10:59,520 "and piece together that story, if you wish." 169 00:11:00,680 --> 00:11:02,200 That's what keeps me coming back, 170 00:11:02,200 --> 00:11:04,800 so every place I go now in Ireland is almost a curse. 171 00:11:04,800 --> 00:11:09,200 I'm constantly looking for evidence of those past ice sheets. 172 00:11:15,760 --> 00:11:18,280 With each successive Ice Age, 173 00:11:18,280 --> 00:11:21,920 the island was sculpted by the force of advancing glaciers 174 00:11:21,920 --> 00:11:24,320 and the awe-inspiring results are evident 175 00:11:24,320 --> 00:11:27,360 all across the Irish landscape. 176 00:11:27,360 --> 00:11:31,320 But there are other remnants of their erosive power. 177 00:11:31,320 --> 00:11:34,000 As well as what the glaciers carved out 178 00:11:34,000 --> 00:11:36,640 are the deposits they left behind. 179 00:11:39,960 --> 00:11:43,920 Croagh Patrick stands at a mighty 764 metres 180 00:11:43,920 --> 00:11:47,440 and is one of the few peaks that was left sticking above the glaciers 181 00:11:47,440 --> 00:11:49,800 during Ireland's last Ice Age. 182 00:11:49,800 --> 00:11:52,320 I'm not here to climb it, though, but to find out about some of 183 00:11:52,320 --> 00:11:56,200 the most iconic glacial deposits around Ireland's coastlines, 184 00:11:56,200 --> 00:11:58,320 the drumlins of Clew Bay. 185 00:12:10,800 --> 00:12:15,200 So, Robbie, is this one of the few peaks that was left above 186 00:12:15,200 --> 00:12:17,520 the ice sheet during our ice ages? 187 00:12:17,520 --> 00:12:21,640 Yeah, it was, Liz. Croagh Patrick was what's called a nunatak. 188 00:12:21,640 --> 00:12:22,840 A nunatak? 189 00:12:22,840 --> 00:12:25,440 Nunatak is an Inuit word. 190 00:12:25,440 --> 00:12:27,680 When you think about it, like, now up in Canada, 191 00:12:27,680 --> 00:12:30,720 in Arctic Canada, we've got lots of ice. 192 00:12:30,720 --> 00:12:33,560 We've got the odd peak that pokes up above the ice. 193 00:12:33,560 --> 00:12:37,600 So nunatak is the name that they bestow upon those features. 194 00:12:37,600 --> 00:12:42,840 And in Ireland, we know that we had 76 nunataks. 195 00:12:42,840 --> 00:12:45,640 We had 76 little islands like Croagh Patrick 196 00:12:45,640 --> 00:12:47,560 that poked up above the ice. 197 00:12:47,560 --> 00:12:50,520 So how much of it was sticking above the ice sheet? 198 00:12:50,520 --> 00:12:53,920 Yeah, about the top 200, maybe 250 metres. 199 00:12:53,920 --> 00:12:55,560 So effectively the cone. 200 00:12:55,560 --> 00:12:57,720 And the rest would have been ice? 201 00:12:57,720 --> 00:13:00,320 So we would have been deep, deep in the ice here? 202 00:13:00,320 --> 00:13:03,440 When you think about that, you look over there, 203 00:13:03,440 --> 00:13:05,360 you see Nephin Mountain in the distance, 204 00:13:05,360 --> 00:13:07,160 you see Knockanaffrin Mountain over here. 205 00:13:07,160 --> 00:13:10,080 They were the next nearest nunataks. 206 00:13:10,080 --> 00:13:14,400 If you were wrapped up warm enough and if you had the energy, 207 00:13:14,400 --> 00:13:18,160 you could have come down off Croagh Patrick 20,000 years ago, 208 00:13:18,160 --> 00:13:20,760 walked across the ice to Nephin. 209 00:13:20,760 --> 00:13:22,040 You could have kept going. 210 00:13:22,040 --> 00:13:24,360 You could have walked to Ben Nevis and Scotland. 211 00:13:24,360 --> 00:13:28,040 You could have walked across that same ice sheet to Siberia. 212 00:13:28,040 --> 00:13:30,880 And if you really wanted, and you had your Weetabix, 213 00:13:30,880 --> 00:13:33,280 you could have walked to the North Pole. 214 00:13:33,280 --> 00:13:34,440 It's kind of mind boggling. 215 00:13:34,440 --> 00:13:35,880 It is mind boggling. 216 00:13:35,880 --> 00:13:38,560 And let's talk about another feature of our Ice Ages, 217 00:13:38,560 --> 00:13:41,400 the famous drumlins of Clew Bay. 218 00:13:41,400 --> 00:13:44,880 Tell me how these beautiful formations came about. 219 00:13:44,880 --> 00:13:48,400 The drumlins themselves, they are about 20 or 30 metres high. 220 00:13:48,400 --> 00:13:49,960 They're ridges. 221 00:13:49,960 --> 00:13:52,720 And when we're down among them, they look huge. 222 00:13:52,720 --> 00:13:56,240 But when you're at the ice sheet scale, like we are now, looking out 223 00:13:56,240 --> 00:14:02,680 over Clew Bay itself, we can imagine how the bay was swamped with ice. 224 00:14:02,680 --> 00:14:07,920 What that ice did was, it smeared these ridges at its base 225 00:14:07,920 --> 00:14:10,560 and those are the actual drumlins that we see, 226 00:14:10,560 --> 00:14:12,480 those ridges that we see. 227 00:14:12,480 --> 00:14:14,240 There tended to be a rippling effect 228 00:14:14,240 --> 00:14:17,560 and we can see that in their form in the bay itself. 229 00:14:17,560 --> 00:14:20,760 They take the form of really large scale ripples. 230 00:14:20,760 --> 00:14:25,600 And because ice is a fluid medium, just as the sea is, when it causes 231 00:14:25,600 --> 00:14:29,240 ripples to form along a beach, the ice itself started to ripple 232 00:14:29,240 --> 00:14:34,320 at the base and allowed these ribbed forms to actually generate. 233 00:14:34,320 --> 00:14:38,600 Now, legend has it that there are 365 drumlins in the bay, 234 00:14:38,600 --> 00:14:41,440 but I'm not seeing 365. That's not true, is it? 235 00:14:41,440 --> 00:14:47,000 No, and the 365 number, that's very common in Irish folklore. 236 00:14:47,000 --> 00:14:50,960 Is it? There's supposed to be 365 lakes in Cavan 237 00:14:50,960 --> 00:14:54,200 as well as 365 drumlins in Clew Bay. 238 00:14:54,200 --> 00:14:56,840 And there's an ancient Irish warrior, Miach, 239 00:14:56,840 --> 00:14:58,840 who was part of the Tuatha De Danann, 240 00:14:58,840 --> 00:15:02,480 and he had 365 herbs growing on his grave. 241 00:15:02,480 --> 00:15:04,720 But when we actually count the drumlins, 242 00:15:04,720 --> 00:15:07,520 count the ridges within Clew Bay itself, 243 00:15:07,520 --> 00:15:09,320 there's only about 70 or 80 of them, 244 00:15:09,320 --> 00:15:13,440 depending on how high and how low the tide is within the bay itself. 245 00:15:15,960 --> 00:15:17,400 Drumlins are common in Russia. 246 00:15:17,400 --> 00:15:20,840 They're common moving across Scandinavia. 247 00:15:20,840 --> 00:15:23,240 Parts of northern Britain have them. 248 00:15:23,240 --> 00:15:25,280 We have lots of them in Ireland. 249 00:15:25,280 --> 00:15:28,440 And the biggest drumlin fields in the world are in places 250 00:15:28,440 --> 00:15:31,000 like Nunavut and Labrador in Canada, 251 00:15:31,000 --> 00:15:34,120 where we've got hundreds and hundreds of kilometres. 252 00:15:35,280 --> 00:15:39,680 The drumlins of Clew Bay are amongst the greatest and best loved sites 253 00:15:39,680 --> 00:15:41,560 in the west of Ireland. 254 00:15:41,560 --> 00:15:44,680 But the truth is, they are not drumlins at all. 255 00:15:45,960 --> 00:15:48,840 We have 20,000 drumlins in this country, 256 00:15:48,840 --> 00:15:50,120 huge amounts of them. 257 00:15:50,120 --> 00:15:52,360 About a fifth of the country is covered in drumlins. Really? 258 00:15:52,360 --> 00:15:55,480 But the drumlins themselves are parts of much, 259 00:15:55,480 --> 00:15:57,320 much bigger features. 260 00:15:57,320 --> 00:16:00,640 So in essence, they're chains of drumlins 261 00:16:00,640 --> 00:16:03,640 that form even bigger ridge features. 262 00:16:03,640 --> 00:16:07,080 And those features are called ribbed moraines. Ribbed moraines? 263 00:16:07,080 --> 00:16:11,480 Ribbed moraines. And they look like a stack of ribs, effectively. 264 00:16:11,480 --> 00:16:13,120 They're an echelon. 265 00:16:13,120 --> 00:16:16,200 And if we look at the drumlins in the bay, we can see that. 266 00:16:16,200 --> 00:16:20,040 They're long linear ridges, one after the other 267 00:16:20,040 --> 00:16:22,840 in a sort of a ripple or ribbed pattern. 268 00:16:24,960 --> 00:16:28,640 The biggest ribbed moraine field in the world is actually in Ireland. 269 00:16:28,640 --> 00:16:32,200 Is it? Where? It's up in the north central parts of the country, 270 00:16:32,200 --> 00:16:35,520 stretching across from County Leitrim into County Monaghan, 271 00:16:35,520 --> 00:16:37,480 County Armagh, Counties Fermanagh. 272 00:16:37,480 --> 00:16:41,600 And it covers about 100 by 120km, 273 00:16:41,600 --> 00:16:45,520 so that's 12,000 square kilometres of ribbed moraine. 274 00:16:45,520 --> 00:16:47,400 It's the biggest field anywhere in the world 275 00:16:47,400 --> 00:16:50,280 and the biggest ribbed moraine, the biggest feature itself, 276 00:16:50,280 --> 00:16:53,040 is just outside Monaghan town. 277 00:16:56,960 --> 00:17:00,200 We continue to learn more about our geological features, don't we? 278 00:17:00,200 --> 00:17:03,560 But who initially named our drumlins? 279 00:17:03,560 --> 00:17:07,880 The first naming of a drumlin was back in the 1840s 280 00:17:07,880 --> 00:17:12,000 by quite a famous Irish geologist, the Reverend Maxwell Close, 281 00:17:12,000 --> 00:17:16,480 who began studying these ridges and realised that they were actually 282 00:17:16,480 --> 00:17:19,240 illustrating the direction of ice floe. 283 00:17:19,240 --> 00:17:23,480 And he came up with that term, drumlin, from the Irish, droimnin, 284 00:17:23,480 --> 00:17:25,200 which means little hill. 285 00:17:37,040 --> 00:17:40,520 Ice is the dominant, eroding force on Earth, 286 00:17:40,520 --> 00:17:45,480 capable of destroying landscapes and of creating new ones. 287 00:17:45,480 --> 00:17:49,280 The masses of ice that covered the island during the last Ice Age 288 00:17:49,280 --> 00:17:53,560 were up to a kilometre deep, exerting an enormous weight 289 00:17:53,560 --> 00:17:55,720 and pressure on the land. 290 00:17:55,720 --> 00:17:59,760 But then the ice retreated and the island rebounded. 291 00:18:01,240 --> 00:18:04,360 That weight removal from the land 292 00:18:04,360 --> 00:18:09,040 meant that the land was no longer compressed, no longer depressed. 293 00:18:09,040 --> 00:18:14,680 So with the release of that weight then, the land begins to uplift, 294 00:18:14,680 --> 00:18:16,040 like a trampoline. 295 00:18:16,040 --> 00:18:18,080 When you take the weight off a trampoline, 296 00:18:18,080 --> 00:18:21,120 it comes back up again. 297 00:18:21,120 --> 00:18:24,640 All along our coastline is the spectacular evidence 298 00:18:24,640 --> 00:18:28,480 for the island's slow emergence from under the ice. 299 00:18:28,480 --> 00:18:31,320 These are the raised beaches of Malin Head 300 00:18:31,320 --> 00:18:35,200 on the Inishowen Peninsula in County Donegal, 301 00:18:35,200 --> 00:18:38,560 clearly displaying where the sea level was when the land 302 00:18:38,560 --> 00:18:40,640 was under pressure from the glaciers 303 00:18:40,640 --> 00:18:43,720 and where it is now, since the land recovered. 304 00:18:45,240 --> 00:18:49,000 We have an ancient raised beach, or shingle bar, 305 00:18:49,000 --> 00:18:51,200 where Ballyhillan village is, 306 00:18:51,200 --> 00:18:55,320 but below it is the most spectacular evidence 307 00:18:55,320 --> 00:19:01,200 of a raised beach, clearly seen incised or cut into the landscape. 308 00:19:01,200 --> 00:19:06,800 A landscape that has now blanketed the former raised beach, 309 00:19:06,800 --> 00:19:08,160 has become stabilised. 310 00:19:08,160 --> 00:19:10,360 It's become covered in soil. 311 00:19:10,360 --> 00:19:14,160 That is our paleoshoreline, our old shoreline. 312 00:19:16,600 --> 00:19:19,520 But as you make your way around the island, 313 00:19:19,520 --> 00:19:21,680 this ancient shoreline gets lower 314 00:19:21,680 --> 00:19:23,480 the further south you go. 315 00:19:26,880 --> 00:19:32,120 It appears that the ice was not uniform across the landscape. 316 00:19:32,120 --> 00:19:36,920 When colleagues looked at shoreline levels, they found that shoreline 317 00:19:36,920 --> 00:19:40,400 heights was six metres in Antrim and only two metres in Dublin. 318 00:19:40,400 --> 00:19:42,240 So there was a tilt. 319 00:19:42,240 --> 00:19:46,000 There's a tilt evident in the landscape and that appears 320 00:19:46,000 --> 00:19:50,360 to have come from the fact that there was a much greater volume 321 00:19:50,360 --> 00:19:55,240 and weight of ice over north-east Ireland. 322 00:19:55,240 --> 00:19:59,360 Some 300km south of Malin Head is Bottle Quay 323 00:19:59,360 --> 00:20:01,880 on the northern edge of Dublin Bay. 324 00:20:03,000 --> 00:20:06,240 The raised beach here stands just a few metres above 325 00:20:06,240 --> 00:20:08,200 what the sea level is today. 326 00:20:10,200 --> 00:20:14,200 So while the ice was retreating, sea levels were still low enough 327 00:20:14,200 --> 00:20:18,360 to make it possible to walk across the Irish Sea to Britain. 328 00:20:19,760 --> 00:20:24,720 In essence, the land itself underneath the ice was conjoined. 329 00:20:24,720 --> 00:20:26,440 It was part of the same mass. 330 00:20:26,440 --> 00:20:30,040 There was no sea between us at that time. 331 00:20:30,040 --> 00:20:33,760 Once the ice starts melting, huge amounts of meltwater are released 332 00:20:33,760 --> 00:20:35,560 and they end up in the sea. 333 00:20:35,560 --> 00:20:38,880 The sea levels rise gradually and you've got this kind of... 334 00:20:38,880 --> 00:20:41,680 ..this catch up happening where the ice margin is retreating 335 00:20:41,680 --> 00:20:44,520 back up the Irish Sea, back up through Ireland, 336 00:20:44,520 --> 00:20:45,840 back up through Britain. 337 00:20:45,840 --> 00:20:48,200 And it's probably around this point here, 338 00:20:48,200 --> 00:20:50,240 somewhere in the vicinity of Dublin. 339 00:20:50,240 --> 00:20:52,440 If you draw a line here between Dublin and Wales, 340 00:20:52,440 --> 00:20:55,600 it's probably around that point that the sea actually catches up 341 00:20:55,600 --> 00:21:00,840 with the ice and you actually get ice being, not being pushed up 342 00:21:00,840 --> 00:21:04,000 by the sea, but being followed by the sea as it moved 343 00:21:04,000 --> 00:21:05,440 back up the channel. 344 00:21:10,080 --> 00:21:13,720 The rocks that make up the island of Ireland have been buried 345 00:21:13,720 --> 00:21:16,800 beneath each other, lifted, folded, 346 00:21:16,800 --> 00:21:20,120 and then carved into the landscape we see today. 347 00:21:20,120 --> 00:21:23,440 And it's these relatively more recent events that have shaped 348 00:21:23,440 --> 00:21:25,120 the island we now know. 349 00:21:27,040 --> 00:21:30,120 The Irish landscape has been etched by ice, the mountains 350 00:21:30,120 --> 00:21:34,280 of Kerry, Cork, Donegal, Mayo, all this spectacular scenery 351 00:21:34,280 --> 00:21:37,000 with cliffs and quarries and U-shaped valleys, 352 00:21:37,000 --> 00:21:40,440 that's all a direct result of the ice. 353 00:21:40,440 --> 00:21:44,720 Our peat bogs, they again are as a result of the ice itself. 354 00:21:47,600 --> 00:21:49,720 The beach is made up of gravels. 355 00:21:49,720 --> 00:21:51,280 It's made up of sand. 356 00:21:51,280 --> 00:21:53,560 There is no fine material in there because, again, 357 00:21:53,560 --> 00:21:57,040 the water washes that out and there are lots of shells. 358 00:21:57,040 --> 00:22:00,200 We've got limpets, we've got periwinkles, we've got cockles, 359 00:22:00,200 --> 00:22:02,920 we've got oysters, we've got sea snails, 360 00:22:02,920 --> 00:22:04,840 all of the various kind of species 361 00:22:04,840 --> 00:22:07,240 that you would see on a modern beach. 362 00:22:07,240 --> 00:22:09,880 The only difference is, first off, this is five metres 363 00:22:09,880 --> 00:22:11,080 above that level. 364 00:22:11,080 --> 00:22:14,360 And secondly, this is about 14,000 years old. 365 00:22:14,360 --> 00:22:17,880 These materials that lie above the bedrock, also, 366 00:22:17,880 --> 00:22:21,240 they protect our ground water, like, because we're a wet country, 367 00:22:21,240 --> 00:22:25,160 we have vast reserves of ground water hidden beneath the surface 368 00:22:25,160 --> 00:22:27,080 that can be exploited for drinking water. 369 00:22:27,080 --> 00:22:30,280 And again, that water is filtered through all of these materials 370 00:22:30,280 --> 00:22:32,280 as the rain comes down through it 371 00:22:32,280 --> 00:22:35,480 and attenuates through this material. 372 00:22:35,480 --> 00:22:37,920 It recharges the ground water and it means 373 00:22:37,920 --> 00:22:40,560 that it's quite clear, it's quite purified. 374 00:22:40,560 --> 00:22:42,920 We've got a huge resource there. 375 00:22:42,920 --> 00:22:45,920 Farming-wise, we've a huge resource because we're at 376 00:22:45,920 --> 00:22:47,640 the Western seaboard of Europe. 377 00:22:47,640 --> 00:22:50,720 We've got lots of rain. That interacts with these materials 378 00:22:50,720 --> 00:22:52,760 and it gives you very rich and fertile soils. 379 00:22:52,760 --> 00:22:57,080 So we have a very rich agricultural legacy because, almost effectively, 380 00:22:57,080 --> 00:22:59,400 directly related to the Ice Age. 381 00:23:09,560 --> 00:23:13,680 Ireland emerged from the destruction wreaked by ice, but the power 382 00:23:13,680 --> 00:23:16,560 of water continued to shape it. 383 00:23:16,560 --> 00:23:20,920 When the ice retreated, rivers and lakes formed in a new 384 00:23:20,920 --> 00:23:24,720 post-glacial landscape, leaving an indelible mark, 385 00:23:24,720 --> 00:23:27,040 from fast-flowing mountain streams 386 00:23:27,040 --> 00:23:30,320 to lowland waterways meandering into the sea. 387 00:23:34,000 --> 00:23:36,520 And this is just on the surface. 388 00:23:36,520 --> 00:23:40,320 Beneath it lies an entirely different world. 389 00:23:40,320 --> 00:23:44,280 At any one time, far more water is stored underground 390 00:23:44,280 --> 00:23:47,200 than in the rivers and lakes above. 391 00:23:47,200 --> 00:23:51,240 This is because Ireland's rocks and sediments are particularly good 392 00:23:51,240 --> 00:23:55,360 at holding water - what geologists call "aquifers". 393 00:23:57,440 --> 00:24:00,360 In Ireland, all rocks are defined as an aquifer, 394 00:24:00,360 --> 00:24:02,080 but some are better than others. 395 00:24:02,080 --> 00:24:04,280 The best types are the ones that have, erm, 396 00:24:04,280 --> 00:24:06,920 layers in, like we can see behind us here, 397 00:24:06,920 --> 00:24:09,360 and also that are quite brittle, 398 00:24:09,360 --> 00:24:12,200 so that when they are subjected to, kind of, earth movements 399 00:24:12,200 --> 00:24:15,400 or tectonic forces, then they fracture. 400 00:24:15,400 --> 00:24:19,320 Even what might appear as solid rock will still contain many 401 00:24:19,320 --> 00:24:21,240 small gaps and fractures. 402 00:24:21,240 --> 00:24:23,920 As such, all rocks are porous. 403 00:24:23,920 --> 00:24:25,320 The more porous the rock, 404 00:24:25,320 --> 00:24:27,800 the more effective aquifers they make. 405 00:24:29,960 --> 00:24:32,640 Because these grains are irregularly shaped, 406 00:24:32,640 --> 00:24:34,600 we've got a lot of space in between of those grains. 407 00:24:34,600 --> 00:24:37,360 So I've got here, I've got five litres of water and I've got five 408 00:24:37,360 --> 00:24:40,040 litres of gravel, and we'll do an experiment to see how much water 409 00:24:40,040 --> 00:24:42,320 we can actually get in. 410 00:24:42,320 --> 00:24:44,040 You can see it seeping down there. 411 00:24:48,880 --> 00:24:52,280 And that's showing we've got an awful lot of space. I'm still going! 412 00:24:53,320 --> 00:24:56,120 So here we are. The water level is just coming up to the surface. 413 00:24:56,120 --> 00:24:58,000 There we go. We've got a ground water flood 414 00:24:58,000 --> 00:25:00,360 and I've got almost half 415 00:25:00,360 --> 00:25:05,200 of that five litre tub of water into my jar here. 416 00:25:06,880 --> 00:25:10,400 Between a quarter and three quarters of a river's flow 417 00:25:10,400 --> 00:25:14,360 comes from ground water that's seeping up into the waterway 418 00:25:14,360 --> 00:25:19,440 all along its base, as is evident with Ireland's longest river. 419 00:25:19,440 --> 00:25:23,280 The Shannon runs for about 360 kilometres 420 00:25:23,280 --> 00:25:25,520 from a pure ground water spring. 421 00:25:35,280 --> 00:25:38,680 The Shannon Pot and the slopes of the Cuilcagh Mountains 422 00:25:38,680 --> 00:25:42,440 in County Cavan was long thought to be the river's source. 423 00:25:42,440 --> 00:25:46,720 But in the last few years, cavers have explored an underground network 424 00:25:46,720 --> 00:25:48,800 that feeds into the Shannon Pot, 425 00:25:48,800 --> 00:25:51,120 and water has been traced all the way 426 00:25:51,120 --> 00:25:55,240 from caves in County Fermanagh, over ten kilometres away. 427 00:25:58,600 --> 00:26:01,800 A good aquifer is one in which we've got plenty of space 428 00:26:01,800 --> 00:26:03,400 and all the space is connected. 429 00:26:03,400 --> 00:26:06,320 So really, that is the key, is number of fractures 430 00:26:06,320 --> 00:26:08,400 and then also their interconnectivity, 431 00:26:08,400 --> 00:26:10,600 and also, to a certain extent, the size of the fracture. 432 00:26:10,600 --> 00:26:13,160 So we can have really big fault zones which can have 433 00:26:13,160 --> 00:26:16,640 quite large gaps between each face of the fault. 434 00:26:16,640 --> 00:26:18,760 So if you think of it like a motorway, 435 00:26:18,760 --> 00:26:21,000 that's the big fracture zone, the big fault zone. 436 00:26:21,000 --> 00:26:23,760 But then you also need the kind of the national roads and the local 437 00:26:23,760 --> 00:26:28,440 roads and even the boreens feeding the water in to that motorway. 438 00:26:30,080 --> 00:26:34,920 The Marble Arch Caves in County Fermanagh are a spectacular example 439 00:26:34,920 --> 00:26:37,520 of this complex underground network. 440 00:26:44,560 --> 00:26:47,040 It's absolutely breathtaking 441 00:26:47,040 --> 00:26:48,800 and such a massive cave. 442 00:26:48,800 --> 00:26:52,240 I mean, do we even know when this was formed, Caoimhe? 443 00:26:52,240 --> 00:26:54,760 It's very hard to date a cave, but what we can do 444 00:26:54,760 --> 00:26:57,400 is we can look at stuff like the stalactites, the sediment 445 00:26:57,400 --> 00:27:00,880 in the cave, and we can carbon date them and see how old they are. 446 00:27:00,880 --> 00:27:03,440 And then we know the cave must be at least older than them. 447 00:27:03,440 --> 00:27:07,800 So for example, there's bits of speleothem, so the calcite 448 00:27:07,800 --> 00:27:10,840 in some of the cave sediments, and we can date that and it indicates 449 00:27:10,840 --> 00:27:14,040 that the cave is at least half a million years old. 450 00:27:14,040 --> 00:27:17,080 It probably would have been formed by glacial meltwater. 451 00:27:17,080 --> 00:27:20,120 So as the glaciers were melting, huge volumes of water 452 00:27:20,120 --> 00:27:22,320 would have been rushing through here, which would 453 00:27:22,320 --> 00:27:24,920 have created, carved out, these big spaces. 454 00:27:24,920 --> 00:27:28,120 We know this is limestone and there's a lot of it in Ireland. 455 00:27:28,120 --> 00:27:31,520 Does all the limestone in Ireland have the capacity to be dissolved 456 00:27:31,520 --> 00:27:33,520 and to form caves like this? 457 00:27:33,520 --> 00:27:35,360 Not really. Some more than others. 458 00:27:35,360 --> 00:27:38,800 It depends on different things, like the purity of the limestone, 459 00:27:38,800 --> 00:27:42,400 so the amount of calcium carbonate in the limestone, how pure it is, 460 00:27:42,400 --> 00:27:43,680 what other things are there. 461 00:27:43,680 --> 00:27:46,960 If there's a lot of mud sediments or shaly limestone, 462 00:27:46,960 --> 00:27:50,200 it can't dissolve the rain, the water can't dissolve it as much. 463 00:27:50,200 --> 00:27:52,720 Also, you need to have some sort of bedding planes 464 00:27:52,720 --> 00:27:54,360 or lines of weaknesses. 465 00:27:54,360 --> 00:27:56,880 So the water doesn't get in through the rock mass. 466 00:27:56,880 --> 00:28:00,640 It flows in through the cracks in the rocks. 467 00:28:00,640 --> 00:28:05,320 Beneath the surface of the island is an enormous, interconnected system 468 00:28:05,320 --> 00:28:10,000 with water seeping into the ground and making its way through cracks, 469 00:28:10,000 --> 00:28:13,800 gaps, sinkholes and disappearing streams. 470 00:28:17,560 --> 00:28:20,640 Usually, in karst environments is the only time you can really get 471 00:28:20,640 --> 00:28:22,240 into...inside the aquifer. 472 00:28:22,240 --> 00:28:26,120 And that's because karst means the rock is soluble, 473 00:28:26,120 --> 00:28:28,040 so it can be dissolved, and we can actually... 474 00:28:28,040 --> 00:28:30,840 It's big enough for humans to go in and see it. 475 00:28:30,840 --> 00:28:33,640 So not all aquifers are karst? No. 476 00:28:33,640 --> 00:28:36,720 Not all aquifers are dissolvable. So this is very special. Yes. 477 00:28:36,720 --> 00:28:40,240 What are the most iconic features that are formed in a cave like this? 478 00:28:40,240 --> 00:28:44,440 The stream is constantly evolving and eroding and dissolving out 479 00:28:44,440 --> 00:28:46,240 new pathways for itself. 480 00:28:46,240 --> 00:28:49,680 There's also deposition in the cave so we can see some of the features 481 00:28:49,680 --> 00:28:50,920 in the ceiling here. 482 00:28:50,920 --> 00:28:53,200 Basically, as the water moves through the rock, you know, 483 00:28:53,200 --> 00:28:54,880 it's acidic, it picks up the lime, 484 00:28:54,880 --> 00:28:56,960 and then when it hits the cave roof, 485 00:28:56,960 --> 00:28:59,560 the carbon dioxide kind of evaporates out. 486 00:28:59,560 --> 00:29:02,040 And then it can't hold that lime as much because it doesn't 487 00:29:02,040 --> 00:29:03,480 have the CO2 to hold the lime. 488 00:29:03,480 --> 00:29:06,560 So a little ring of limestone is left behind. 489 00:29:06,560 --> 00:29:10,120 And as that happens, over time, little stalactites grow. 490 00:29:10,120 --> 00:29:12,120 And as more water comes in again, 491 00:29:12,120 --> 00:29:14,320 they just get bigger and bigger. And then the opposite. 492 00:29:14,320 --> 00:29:16,120 So where that splashes, 493 00:29:16,120 --> 00:29:18,840 again, it degasses, it loses a bit of carbon dioxide. 494 00:29:18,840 --> 00:29:21,960 So you'd always see a stalagmite which grows up 495 00:29:21,960 --> 00:29:23,560 sort of underneath the stalactite. 496 00:29:23,560 --> 00:29:26,920 And if they grow together, over time, they can grow together 497 00:29:26,920 --> 00:29:28,400 and form a pillar. 498 00:29:28,400 --> 00:29:30,720 And there's also other features like curtain, the kind 499 00:29:30,720 --> 00:29:33,000 of curtain drapery almost. Yeah. Beautiful! 500 00:29:33,000 --> 00:29:35,600 And that's where you've got, like, flowing water and it's degassing 501 00:29:35,600 --> 00:29:38,040 and depositing calcite all the way along. 502 00:29:38,040 --> 00:29:40,720 So it's the same principle. Yes, yeah. Stunning features. 503 00:29:40,720 --> 00:29:43,600 I'm curious about the dimpling on these walls, though. 504 00:29:43,600 --> 00:29:44,800 On the rock themselves. 505 00:29:44,800 --> 00:29:46,120 What causes that? 506 00:29:46,120 --> 00:29:49,320 That's called scalloping, and that's formed by, 507 00:29:49,320 --> 00:29:51,400 basically by the water moving through it. 508 00:29:51,400 --> 00:29:53,640 As it's moving so fast, it's turbulent flow. 509 00:29:53,640 --> 00:29:57,560 So in a non-karst aquifer, the flow is considered laminar. 510 00:29:57,560 --> 00:29:59,920 It doesn't kind of have that turbulent. 511 00:29:59,920 --> 00:30:02,360 So as it's twirling around so fast, 512 00:30:02,360 --> 00:30:05,200 it kind of dissolves out these little pockmarks. 513 00:30:08,040 --> 00:30:10,280 Do you know everything there is to know about caves now? 514 00:30:10,280 --> 00:30:13,240 Like, this particular cave? Are you constantly discovering new things? 515 00:30:13,240 --> 00:30:14,760 Yeah. And it is constantly evolving. 516 00:30:14,760 --> 00:30:17,160 Like, the cave itself is evolving, but there's new discoveries 517 00:30:17,160 --> 00:30:20,360 all the time. Even the Marble Arch Caves, the length of it changes 518 00:30:20,360 --> 00:30:23,080 because we've got another passageway that somebody joins 519 00:30:23,080 --> 00:30:25,560 to this passageway, and then suddenly your cave is bigger again. 520 00:30:25,560 --> 00:30:28,000 You're looking at the world's deepest caves, longest caves. 521 00:30:28,000 --> 00:30:30,160 The list just changes all the time. 522 00:30:34,840 --> 00:30:39,040 The karst aquifers have also given rise to one of the most intriguing 523 00:30:39,040 --> 00:30:42,840 water features on the Irish landscape - turloughs. 524 00:30:44,680 --> 00:30:46,320 Pretty much unique to Ireland, 525 00:30:46,320 --> 00:30:49,720 these bodies of water seem to appear on the surface 526 00:30:49,720 --> 00:30:52,800 and then disappear just as quickly. 527 00:30:53,880 --> 00:30:56,480 One of these mysterious vanishing lakes 528 00:30:56,480 --> 00:31:00,960 is the Caherglassaun Turlough outside Kinvara in County Galway. 529 00:31:04,800 --> 00:31:06,800 This is a beautiful turlough. 530 00:31:06,800 --> 00:31:09,040 It's not a particularly dramatic-looking turlough. 531 00:31:09,040 --> 00:31:12,560 But there's so much going on here that's of real interest to us 532 00:31:12,560 --> 00:31:16,040 as geologists, as hydrogeologists, but also in terms of understanding 533 00:31:16,040 --> 00:31:17,960 how water moves in and on the landscape. 534 00:31:17,960 --> 00:31:20,720 And one of the things about this is when we walk around it, 535 00:31:20,720 --> 00:31:22,960 what you won't see is you won't see any rivers coming in 536 00:31:22,960 --> 00:31:24,800 or rivers coming out. 537 00:31:24,800 --> 00:31:26,000 So when you look at it, 538 00:31:26,000 --> 00:31:28,520 it just looks like an isolated body of water. 539 00:31:28,520 --> 00:31:32,840 But we know that it's connected to the sea in one direction. 540 00:31:32,840 --> 00:31:35,120 And we know heading back in this direction, 541 00:31:35,120 --> 00:31:37,120 it's connected to another turlough system, 542 00:31:37,120 --> 00:31:40,360 which is just over the hill behind us, about a kilometre away. 543 00:31:40,360 --> 00:31:43,400 And that system is connected to another turlough system 544 00:31:43,400 --> 00:31:45,120 and another one and another one, 545 00:31:45,120 --> 00:31:47,440 which gets us back up to the Slieve Aughty hills 546 00:31:47,440 --> 00:31:49,520 about 30 kilometres from here. 547 00:31:51,440 --> 00:31:54,200 Turloughs appear on the Irish landscape 548 00:31:54,200 --> 00:31:57,480 because of our island's position in the North Atlantic, 549 00:31:57,480 --> 00:31:59,360 our high levels of rainfall 550 00:31:59,360 --> 00:32:04,200 and the abundance of low lying, relatively undisturbed limestone. 551 00:32:07,320 --> 00:32:09,680 One of the things about limestone is that 552 00:32:09,680 --> 00:32:11,640 if you have the right conditions - 553 00:32:11,640 --> 00:32:14,680 and the right conditions essentially mean getting water onto 554 00:32:14,680 --> 00:32:17,840 the limestone that's chemically aggressive to the limestone - 555 00:32:17,840 --> 00:32:21,400 what it will do is it'll dissolve the limestone and remove it, 556 00:32:21,400 --> 00:32:23,480 and it'll carve a landscape. 557 00:32:23,480 --> 00:32:25,840 And the landscape will have features like turloughs 558 00:32:25,840 --> 00:32:29,040 and like these extended bits of the bedding that we see here 559 00:32:29,040 --> 00:32:30,800 and swallow holes and sinkholes. 560 00:32:30,800 --> 00:32:34,120 Exactly the kind of things we expect to see in karst areas. 561 00:32:34,120 --> 00:32:37,680 And the burren, essentially, that's probably the best known example. 562 00:32:37,680 --> 00:32:41,600 All of that is carved by water interacting with the rock. 563 00:32:41,600 --> 00:32:45,160 And as you can see here, you can track the bed with your eye. 564 00:32:45,160 --> 00:32:48,400 So that's also suggesting that if we were to continue tracking it 565 00:32:48,400 --> 00:32:50,760 in the landscape, we'd see that bed running. 566 00:32:50,760 --> 00:32:53,480 And if we were to continue tracking in that direction, we'd see it. 567 00:32:53,480 --> 00:32:55,080 So once the water gets in there, 568 00:32:55,080 --> 00:32:57,840 there's potential for it to cover huge areas. 569 00:32:59,000 --> 00:33:02,160 Although Caherglassaun is a freshwater turlough 570 00:33:02,160 --> 00:33:05,960 located five kilometres from the sea, it's still influenced 571 00:33:05,960 --> 00:33:09,800 by the ocean and rises and falls with the tide. 572 00:33:11,280 --> 00:33:13,200 This can fill up in a number of days, 573 00:33:13,200 --> 00:33:15,480 but it can take weeks for it to drain. 574 00:33:15,480 --> 00:33:18,640 So what we see is, generally speaking, because we're towards 575 00:33:18,640 --> 00:33:21,320 the end of this system, we're relatively close to the sea, 576 00:33:21,320 --> 00:33:25,080 it's accumulating all the water from roughly 500 square kilometres, 577 00:33:25,080 --> 00:33:28,920 that all of that water essentially has to come through here. 578 00:33:28,920 --> 00:33:32,440 If you put water into a system and it can leave at the same rate, 579 00:33:32,440 --> 00:33:34,360 there's no flood. 580 00:33:34,360 --> 00:33:37,320 But if you put so much water in that it can't leave at the same rate 581 00:33:37,320 --> 00:33:39,120 during the same period of time, 582 00:33:39,120 --> 00:33:41,200 the water in the middle has to go somewhere, 583 00:33:41,200 --> 00:33:44,240 and if it's on the surface, it's in the flood plain. 584 00:33:44,240 --> 00:33:47,040 And if it's on the ground, what happens is those pipes 585 00:33:47,040 --> 00:33:50,040 start filling up and then we get the turloughs rising. 586 00:33:50,040 --> 00:33:53,520 And if there's still so much water, the turloughs will start backing up. 587 00:33:53,520 --> 00:33:57,480 So this turlough will back up the one behind it because it can't drain 588 00:33:57,480 --> 00:34:00,720 and it drains it backs up the turlough behind it and so on. 589 00:34:00,720 --> 00:34:05,240 So the whole way up the system can backfill as well as front fill. 590 00:34:07,920 --> 00:34:11,720 Virtually none of these vanishing lakes can be found anywhere else 591 00:34:11,720 --> 00:34:16,200 in the world, but there are over 400 turloughs in Ireland... 592 00:34:17,600 --> 00:34:21,480 ..the result of the role water has played in the island's unique 593 00:34:21,480 --> 00:34:23,960 and remarkable geological journey. 594 00:34:26,680 --> 00:34:30,000 And we look at the place names on old maps that will give us clues. 595 00:34:30,000 --> 00:34:31,920 So anything with turlough in the name, 596 00:34:31,920 --> 00:34:34,440 it probably means we're going to see water on the ground. 597 00:34:34,440 --> 00:34:37,000 Anything with "Powell" in the name is useful as well, because 598 00:34:37,000 --> 00:34:40,040 it probably means there's a hole in the ground where water comes down 599 00:34:40,040 --> 00:34:42,600 or water comes up, and there's lots of other things. 600 00:34:42,600 --> 00:34:46,520 One of my favourite is Owenbristy, which is a "broken river", 601 00:34:46,520 --> 00:34:48,360 which means you have a river on the surface, 602 00:34:48,360 --> 00:34:50,480 then going underground, and then rising, as well. 603 00:34:50,480 --> 00:34:53,040 So, yeah, I think one of the things that's really interesting 604 00:34:53,040 --> 00:34:56,000 about Ireland is that our cultural history 605 00:34:56,000 --> 00:34:59,120 is tied in to our geological history as well, 606 00:34:59,120 --> 00:35:02,120 and that the place names reflect, largely speaking, 607 00:35:02,120 --> 00:35:05,000 the geology and the landscape around us. 608 00:35:15,360 --> 00:35:18,160 I've travelled around Ireland in search of clues 609 00:35:18,160 --> 00:35:21,160 about how and where this island was formed, 610 00:35:21,160 --> 00:35:24,360 following in the footsteps of the geologists who have mapped 611 00:35:24,360 --> 00:35:26,920 this island since the 19th century. 612 00:35:31,400 --> 00:35:35,960 Now I'm heading offshore to explore the island's marine environment 613 00:35:35,960 --> 00:35:39,080 with 21st-century technology. 614 00:35:45,600 --> 00:35:49,000 So Eoin, how does seabed mapping work? 615 00:35:49,000 --> 00:35:51,320 What's the process and how has it changed over the years? 616 00:35:51,320 --> 00:35:54,000 Some of the areas that we're mapping now, the last time they were mapped 617 00:35:54,000 --> 00:35:57,280 could have been in the mid to late 1800s. Wow! 618 00:35:57,280 --> 00:35:59,920 And the technology in use at the time would literally 619 00:35:59,920 --> 00:36:03,320 have been a length of rope with a weight on the end made of lead. 620 00:36:03,320 --> 00:36:05,640 And they would have lowered that over the side of the vessel 621 00:36:05,640 --> 00:36:09,320 and measured out how much rope they paid out until it hit the seabed 622 00:36:09,320 --> 00:36:10,480 and that was their depth. 623 00:36:10,480 --> 00:36:13,640 Whereas now, with a vessel like this, the RV KIRI, 624 00:36:13,640 --> 00:36:16,760 we can actually map the whole seabed in 3D. 625 00:36:16,760 --> 00:36:20,440 The sonar below the vessel sends out a big pulse of sound. 626 00:36:20,440 --> 00:36:22,600 It could be up to 50 times a second, 627 00:36:22,600 --> 00:36:24,440 depending on how shallow the water is. OK. 628 00:36:24,440 --> 00:36:27,600 And that pulse is split into hundreds of beams. 629 00:36:27,600 --> 00:36:31,000 And at the end of each of those beams, we get a depth reading 630 00:36:31,000 --> 00:36:33,920 and the computers can put all of those depth readings together 631 00:36:33,920 --> 00:36:37,040 very quickly and actually make a full 3D map of the seafloor. 632 00:36:37,040 --> 00:36:41,480 We can get down to imaging an object 25 centimetres across. Amazing! 633 00:36:41,480 --> 00:36:45,160 As the sonar is scanning, the data is actually appearing in real time 634 00:36:45,160 --> 00:36:47,960 on the screen, almost like a computer game where we're painting 635 00:36:47,960 --> 00:36:49,120 in the seabed. 636 00:36:49,120 --> 00:36:52,560 Quite a serious game, because if we stray off our course at all, 637 00:36:52,560 --> 00:36:55,400 if we lose focus, there are very dangerous rocks 638 00:36:55,400 --> 00:36:56,840 just off to the side. 639 00:36:56,840 --> 00:37:00,200 But because the sonar, as you can see there, is able to look sideways 640 00:37:00,200 --> 00:37:03,480 as we come back on the next track, even closer to the land, 641 00:37:03,480 --> 00:37:05,520 we can see what hazards might be awaiting us. 642 00:37:05,520 --> 00:37:09,400 So you can see there from the deeper blue colours into the greens 643 00:37:09,400 --> 00:37:12,000 and the yellows, you can actually see the shape of the seabed 644 00:37:12,000 --> 00:37:14,160 and the rocks as it's getting shallower. Beautiful! 645 00:37:14,160 --> 00:37:15,680 So every little bump and lump... 646 00:37:15,680 --> 00:37:17,640 That's a boulder or a rock on the seafloor. 647 00:37:17,640 --> 00:37:21,080 They're just beautiful, aren't they? It's really nice imagery. 648 00:37:21,080 --> 00:37:24,840 And also, we're seeing it in high detail for the first time ever. 649 00:37:24,840 --> 00:37:28,280 How much of a game changer is this tech, then? 650 00:37:28,280 --> 00:37:31,200 It is a huge game changer in terms of seafloor exploration. 651 00:37:31,200 --> 00:37:33,840 It's been around now for a couple of decades, but in recent years, 652 00:37:33,840 --> 00:37:38,320 it's really come into its own and become far more accurate and able 653 00:37:38,320 --> 00:37:41,360 to produce really crisp and more detailed images. 654 00:37:41,360 --> 00:37:44,240 Every year, we resurvey some of the famous shipwrecks 655 00:37:44,240 --> 00:37:46,600 around the Irish coast to test the equipment, 656 00:37:46,600 --> 00:37:48,880 and we're getting more and more detailed imagery 657 00:37:48,880 --> 00:37:50,120 with the passage of time. 658 00:37:50,120 --> 00:37:52,600 So what's gained above the waterline? 659 00:37:52,600 --> 00:37:55,400 What's gained below it? Both complement each other? 660 00:37:55,400 --> 00:37:58,840 The thing about geology on land is it is obscured most of the time 661 00:37:58,840 --> 00:38:01,400 by forests, grass, farmland. 662 00:38:01,400 --> 00:38:04,080 So the great thing about the geology and the sea is, 663 00:38:04,080 --> 00:38:06,360 while we can't easily get down and touch it, 664 00:38:06,360 --> 00:38:10,120 it's far more exposed than on land because of wave and current action 665 00:38:10,120 --> 00:38:12,000 that's stripping away the top cover. 666 00:38:12,000 --> 00:38:14,920 The ultimate goal is if we can join the two together. 667 00:38:14,920 --> 00:38:18,000 I'll give you a really good example is in Galway Bay, 668 00:38:18,000 --> 00:38:21,080 you've got the limestone of the Burren on the Aran Islands 669 00:38:21,080 --> 00:38:24,120 and on the Clare Coast, and on the north coast of Galway Bay, 670 00:38:24,120 --> 00:38:26,520 you've got the granite of Connemara. 671 00:38:26,520 --> 00:38:29,400 And for decades, people were trying to find the connection 672 00:38:29,400 --> 00:38:33,000 between the two. But once we came along and mapped this, 673 00:38:33,000 --> 00:38:35,160 we were actually able to see in clear detail, 674 00:38:35,160 --> 00:38:37,160 just by looking at the texture, 675 00:38:37,160 --> 00:38:40,840 the change from the limestone, which is very well layered, 676 00:38:40,840 --> 00:38:43,760 to the granite, which is much more of a mass of rock. 677 00:38:43,760 --> 00:38:47,480 And you can see it clear as day now on the imagery. 678 00:38:47,480 --> 00:38:51,080 These cutting edge maps have many more practical uses, 679 00:38:51,080 --> 00:38:54,320 including providing important information 680 00:38:54,320 --> 00:38:57,920 about the location of some of Ireland's precious marine life. 681 00:38:57,920 --> 00:39:02,400 Different species of fish and shellfish need specific habitats 682 00:39:02,400 --> 00:39:06,440 for spawning, and this mapping helps to identify these crucial 683 00:39:06,440 --> 00:39:08,480 areas for conservation. 684 00:39:11,880 --> 00:39:15,000 How thrilling is it for you as a geologist to see this 685 00:39:15,000 --> 00:39:18,360 for the very first time in this amount of detail? 686 00:39:18,360 --> 00:39:21,000 Probably a little too excited, according to most of my friends! 687 00:39:21,000 --> 00:39:24,320 But very excited! Are you geeking out, Eoin?! Sure. 688 00:39:24,320 --> 00:39:28,000 This is a super geek out moment for me because it is true discovery 689 00:39:28,000 --> 00:39:29,320 in the best sense of the word. 690 00:39:29,320 --> 00:39:31,240 You're seeing something for the first time. 691 00:39:31,240 --> 00:39:33,440 Some of these might have been seen by divers 692 00:39:33,440 --> 00:39:35,960 or fishermen would have picked up some of the detail 693 00:39:35,960 --> 00:39:38,040 on their own fish finders. 694 00:39:38,040 --> 00:39:41,520 But this kind of blanket mapping where we're imaging 695 00:39:41,520 --> 00:39:44,520 the entire seabed and giving it to the public for free, 696 00:39:44,520 --> 00:39:46,280 it feels really good to be doing it. 697 00:39:49,320 --> 00:39:52,680 Hidden in the dark, cold depths of Ireland's seas 698 00:39:52,680 --> 00:39:56,280 lie the secrets of a rich seafaring past. 699 00:40:01,800 --> 00:40:06,120 Over 18,000 shipwrecks have been documented in Irish waters, 700 00:40:06,120 --> 00:40:09,120 and these relics can offer fascinating insights 701 00:40:09,120 --> 00:40:12,160 into the processes at play in our oceans. 702 00:40:19,080 --> 00:40:22,840 So, Charise, how long have you been mapping shipwrecks? 703 00:40:22,840 --> 00:40:26,840 Well, I started working with the project in 2007, Liz, 704 00:40:26,840 --> 00:40:30,080 but prior to that, the project had been mapping shipwrecks 705 00:40:30,080 --> 00:40:32,880 since about 2000, 2001 and 2. OK. 706 00:40:32,880 --> 00:40:36,200 So what we've done is, today, we've just mapped this particular 707 00:40:36,200 --> 00:40:38,840 shipwreck here, which is the Manchester Merchant in Dingle Bay. 708 00:40:38,840 --> 00:40:41,400 What are you discovering about this particular wreck? 709 00:40:41,400 --> 00:40:44,320 So this particular wreck, the image here you'll see 710 00:40:44,320 --> 00:40:47,880 on the right-hand side here, this is from about ten years ago. Right. 711 00:40:47,880 --> 00:40:50,640 And what we did then in 2019 was 712 00:40:50,640 --> 00:40:53,760 we surveyed the wreck in this extreme detail. 713 00:40:53,760 --> 00:40:55,440 Look at the difference! 714 00:40:55,440 --> 00:40:58,840 And then what we've discovered in the image ten years later 715 00:40:58,840 --> 00:41:01,840 is actually there's been a change in this shipwreck on the seabed. 716 00:41:01,840 --> 00:41:05,160 You'll see that one of the boilers has been displaced in the centre 717 00:41:05,160 --> 00:41:06,400 of the shipwreck. Yeah. 718 00:41:06,400 --> 00:41:10,400 And also, you can actually see now that it's become more exposed 719 00:41:10,400 --> 00:41:13,320 and you can see all of the structures from the shipwreck 720 00:41:13,320 --> 00:41:15,800 are now visible to us here. Absolutely. 721 00:41:15,800 --> 00:41:18,960 So it's not just because of the accuracy of the technology now, 722 00:41:18,960 --> 00:41:22,240 it's also due to wave action, currents, etc. For sure. 723 00:41:22,240 --> 00:41:24,040 Everything changes down there. Exactly. 724 00:41:24,040 --> 00:41:25,680 And why is that important to know? 725 00:41:25,680 --> 00:41:27,240 It's like a time capsule. 726 00:41:27,240 --> 00:41:30,400 Shipwrecks which are over 100 years old are protected. 727 00:41:30,400 --> 00:41:33,880 So they're a really important part of our marine heritage. 728 00:41:33,880 --> 00:41:39,160 And also, they can give indication, then, of the intensity of storms. 729 00:41:39,160 --> 00:41:42,920 And we can use shipwrecks to look at scours on the seabed, 730 00:41:42,920 --> 00:41:45,800 to look at the currents and how those currents are changing. 731 00:41:45,800 --> 00:41:49,120 So it links to, you know, issues like climate change 732 00:41:49,120 --> 00:41:52,840 and also oceanography and various other things. 733 00:41:52,840 --> 00:41:56,040 What fascinates you the most about this kind of work? 734 00:41:56,040 --> 00:41:58,600 I think for me, with the shipwreck side, 735 00:41:58,600 --> 00:42:01,240 it's the human connection to a shipwreck. 736 00:42:01,240 --> 00:42:05,320 You can see what that ship was about, why it was built, 737 00:42:05,320 --> 00:42:08,120 what it was doing at the time of its sinking. 738 00:42:08,120 --> 00:42:10,600 There's a number of shipwrecks around the coast of Ireland 739 00:42:10,600 --> 00:42:14,160 that are graves. You know, that souls were lost on them. 740 00:42:14,160 --> 00:42:16,440 And then there's a lot of communities around the coast 741 00:42:16,440 --> 00:42:19,760 of Ireland that have a very close link to a particular ship 742 00:42:19,760 --> 00:42:22,320 that may have sank off their coast. 743 00:42:23,600 --> 00:42:26,640 There's a kind of a romance attached to shipwrecks, isn't there, really? 744 00:42:26,640 --> 00:42:27,840 Oh, absolutely. 745 00:42:27,840 --> 00:42:34,080 It's something that this story of the time that this ship went to sea. 746 00:42:34,080 --> 00:42:37,520 So this particular ship had just been...come out of being used 747 00:42:37,520 --> 00:42:41,160 in the Boer War, and it was then going back into a transit 748 00:42:41,160 --> 00:42:42,600 across the Atlantic. 749 00:42:42,600 --> 00:42:46,800 Unfortunately, it was carrying a cargo of cotton and turpentine. 750 00:42:46,800 --> 00:42:49,600 And this spontaneous combustion 751 00:42:49,600 --> 00:42:52,400 with kind of an inexplicable fire occurred. 752 00:42:52,400 --> 00:42:55,000 So obviously the crew had to go into a panic. 753 00:42:55,000 --> 00:42:57,720 You know, what would we do? We would try and put this fire out. 754 00:42:57,720 --> 00:43:00,720 They tried to put the fire out. Unfortunately, they weren't able to. 755 00:43:00,720 --> 00:43:03,360 And they obviously all made it to lifeboats. 756 00:43:03,360 --> 00:43:05,680 And then, unfortunately, it met its fate and sank. 757 00:43:05,680 --> 00:43:08,400 But there's a story from the other side of that, then, 758 00:43:08,400 --> 00:43:10,400 where the captain of this particular ship 759 00:43:10,400 --> 00:43:13,120 was so grateful to the local people around here, 760 00:43:13,120 --> 00:43:17,240 they donated the bell from the ship to the church in Annascaul, 761 00:43:17,240 --> 00:43:18,680 which is the home of Tom Crean. 762 00:43:18,680 --> 00:43:23,040 So you've got that whole maritime link and the community link. 763 00:43:23,040 --> 00:43:24,960 Fantastic stuff. 764 00:43:24,960 --> 00:43:26,600 And we're right over it here, are we? 765 00:43:26,600 --> 00:43:30,320 Yeah, we're just right over it here. 11 metres below us. 11 metres below? 766 00:43:30,320 --> 00:43:33,480 It's not even that deep. It's not, no, not at all. Yeah. 767 00:43:36,920 --> 00:43:39,560 Ireland may seem relatively small, 768 00:43:39,560 --> 00:43:44,440 but when its seabed territory of 880,000 square kilometres 769 00:43:44,440 --> 00:43:46,520 is taken into account, 770 00:43:46,520 --> 00:43:49,720 it's actually one of the largest countries in Europe. 771 00:43:53,840 --> 00:43:57,360 It's been said that more is known about the surface of the Moon 772 00:43:57,360 --> 00:43:59,000 than of our ocean floors. 773 00:43:59,000 --> 00:44:02,680 But this claim doesn't hold true for Ireland, which is on track 774 00:44:02,680 --> 00:44:05,040 to become the first country in the world 775 00:44:05,040 --> 00:44:07,720 to map its entire ocean territory. 776 00:44:13,360 --> 00:44:16,840 This is the real map of Ireland, 777 00:44:16,840 --> 00:44:20,160 with the red line marking the marine territory boundary - 778 00:44:20,160 --> 00:44:23,720 an area more than ten times that of the land. 779 00:44:26,280 --> 00:44:28,880 Ireland has embarked on 780 00:44:28,880 --> 00:44:31,400 what is probably the largest contiguous 781 00:44:31,400 --> 00:44:34,320 mapping exercise done by any state. 782 00:44:34,320 --> 00:44:38,200 There are other countries that have built up data which will be 783 00:44:38,200 --> 00:44:40,200 of similar size and that. 784 00:44:40,200 --> 00:44:45,120 But because we've systematically done it in one full area, 785 00:44:45,120 --> 00:44:49,200 it means that we have been able to use the most modern technology 786 00:44:49,200 --> 00:44:53,720 and do it in a systematic way, which means that putting it all together 787 00:44:53,720 --> 00:44:57,160 afterwards gives you a much better overall picture. 788 00:44:58,400 --> 00:45:03,080 It was an Irishman, Piers Gardner, who developed the accepted formula 789 00:45:03,080 --> 00:45:06,880 for establishing the outer limits of a state's continental shelf 790 00:45:06,880 --> 00:45:09,400 until it tapers off into the abyss. 791 00:45:11,000 --> 00:45:15,960 The mapping is all done by vessels such as the Celtic Voyager here, 792 00:45:15,960 --> 00:45:21,640 and the Celtic Explorer, which spent almost two years going out to sea 793 00:45:21,640 --> 00:45:26,800 and mapping in depths up to 4,000 metres of depth. 794 00:45:33,040 --> 00:45:34,960 There's no visual images. 795 00:45:34,960 --> 00:45:38,640 However, the interpretation of the sonar gives you... 796 00:45:38,640 --> 00:45:42,120 It's very much like an ultrasound that you see in the hospital. 797 00:45:42,120 --> 00:45:45,560 And it's that sort of imagery that's indicative of what's there. 798 00:45:45,560 --> 00:45:49,000 It's not a real image, but it's a sonar return. 799 00:45:51,400 --> 00:45:55,720 Stretching 200 nautical miles from the coastline is Ireland's 800 00:45:55,720 --> 00:45:59,480 continental shelf, where the land extends under the sea 801 00:45:59,480 --> 00:46:03,840 to the outer edge of the continental margin beyond. 802 00:46:03,840 --> 00:46:06,480 It's a very different world down there. 803 00:46:24,200 --> 00:46:26,480 What's really fascinating about going to the ocean 804 00:46:26,480 --> 00:46:29,520 is the amount of discoveries that you can make there. 805 00:46:29,520 --> 00:46:32,520 But it is hard, it is rough. You get seasick. 806 00:46:32,520 --> 00:46:35,120 You're often kilometres away from your study area. 807 00:46:35,120 --> 00:46:36,600 So there are challenges. 808 00:46:36,600 --> 00:46:40,760 But I think the rewards are just obvious in terms 809 00:46:40,760 --> 00:46:44,200 of this wonderful environment that we have on the seabed, 810 00:46:44,200 --> 00:46:47,120 that's just a wonder to observe and to understand. 811 00:46:50,080 --> 00:46:54,720 Ireland's deep ocean is home to massive cold water coral reefs 812 00:46:54,720 --> 00:46:59,240 hundreds of metres tall, living in complete darkness and feeding 813 00:46:59,240 --> 00:47:03,760 on organic matter that rains down from the surface. 814 00:47:03,760 --> 00:47:05,760 And then there are canyons 815 00:47:05,760 --> 00:47:09,200 that dwarf any geological features on the land. 816 00:47:12,400 --> 00:47:14,320 Submarine canyons are big. 817 00:47:14,320 --> 00:47:16,360 That's probably the best way to describe them. 818 00:47:16,360 --> 00:47:20,920 And they start from the shelf break with about 200 metres' water depth 819 00:47:20,920 --> 00:47:25,800 and go all the way down to the deep ocean, maybe five kilometres down. 820 00:47:25,800 --> 00:47:27,840 And they're vast systems, 821 00:47:27,840 --> 00:47:31,240 Grand Canyon-esque kind of scales. 822 00:47:31,240 --> 00:47:34,080 And rather than just draining a river 823 00:47:34,080 --> 00:47:36,800 that a terrestrial canyon would drain, 824 00:47:36,800 --> 00:47:42,000 these also transport water and sediment and carbon and nutrients 825 00:47:42,000 --> 00:47:44,480 down from the surface waters into the deep ocean. 826 00:47:44,480 --> 00:47:47,880 So a real connection between the deep ocean, 827 00:47:47,880 --> 00:47:51,880 the deep reservoirs of ocean, and what's happening on the surface. 828 00:47:51,880 --> 00:47:55,320 They're very important in understanding how oceans 829 00:47:55,320 --> 00:47:57,760 overturn and interact. 830 00:48:00,800 --> 00:48:05,320 In 2011, just beyond Ireland's territorial waters, 831 00:48:05,320 --> 00:48:07,560 an Irish-led research team 832 00:48:07,560 --> 00:48:12,320 discovered huge hydrothermal vents rising out of the ocean floor. 833 00:48:15,880 --> 00:48:18,120 Up to 60 metres in height, 834 00:48:18,120 --> 00:48:22,880 they emit plumes of scalding hot water, harking back to the processes 835 00:48:22,880 --> 00:48:27,440 that helped to form the island over the past 1.8 billion years. 836 00:48:29,960 --> 00:48:32,680 So these are places where we've got volcanic activity, 837 00:48:32,680 --> 00:48:34,720 where the plates are pulling apart. 838 00:48:34,720 --> 00:48:38,280 And this volcanic activity is heating sea water. 839 00:48:38,280 --> 00:48:40,120 It's pumping through the crust, 840 00:48:40,120 --> 00:48:44,080 becoming mineralised and forming these black smoker chimneys. 841 00:48:45,280 --> 00:48:48,160 So this is a sample here 842 00:48:48,160 --> 00:48:53,080 of a piece of one of the black smoker vents. 843 00:48:53,080 --> 00:48:56,360 And hot fluid, several hundred degrees C, 844 00:48:56,360 --> 00:48:59,000 would have flowed up from the subsurface. 845 00:48:59,000 --> 00:49:03,320 And when it hit the sea water, it becomes quenched and cools down. 846 00:49:03,320 --> 00:49:06,160 And all the minerals, all the elements that have been solution 847 00:49:06,160 --> 00:49:10,720 mineralise to form these black sulphide deposits. 848 00:49:10,720 --> 00:49:15,560 You can see where one of the vents was, but there's various minerals 849 00:49:15,560 --> 00:49:18,520 in here and on the back, you can see it's rusting. 850 00:49:18,520 --> 00:49:20,280 So there's iron. 851 00:49:20,280 --> 00:49:22,840 The white area is anhydrite 852 00:49:22,840 --> 00:49:25,280 because this was very, very hot sea salt. 853 00:49:25,280 --> 00:49:30,680 And in the greyish, greenish-greyish areas, these are metal sulphides. 854 00:49:30,680 --> 00:49:34,880 And there's various metals of zinc and copper and lead. 855 00:49:37,200 --> 00:49:42,520 Since they were first discovered in 1977, deep sea hydrothermal vents 856 00:49:42,520 --> 00:49:44,600 have sparked great debate. 857 00:49:44,600 --> 00:49:48,440 One school of thought is that black smokers might be the birthplace 858 00:49:48,440 --> 00:49:49,960 of all life on Earth. 859 00:49:52,480 --> 00:49:58,240 They support bacterial communities, called chemosynthetic bacteria, 860 00:49:58,240 --> 00:50:01,800 and they get their energy from chemical reactions 861 00:50:01,800 --> 00:50:04,000 going on in these black smokers. 862 00:50:04,000 --> 00:50:08,320 So they have an energy source completely independent of sunlight. 863 00:50:08,320 --> 00:50:11,000 So all other life on the planet 864 00:50:11,000 --> 00:50:13,280 is, in some way, dependent on the Sun. 865 00:50:13,280 --> 00:50:15,360 The Sun creates the plants, we eat the plants, 866 00:50:15,360 --> 00:50:17,360 we eat the animals that eat the plants. 867 00:50:17,360 --> 00:50:19,960 If the Sun went out tomorrow, 868 00:50:19,960 --> 00:50:22,360 the whole life on the planet would die, 869 00:50:22,360 --> 00:50:24,880 apart from at these black smokers. 870 00:50:24,880 --> 00:50:27,160 And that's very intriguing, because that means 871 00:50:27,160 --> 00:50:31,120 that if we have hydrothermal systems on other moons, 872 00:50:31,120 --> 00:50:35,080 perhaps under thick ice caps on Europa or somewhere like that, 873 00:50:35,080 --> 00:50:39,680 we may have a system of life similar to those black smokers. 874 00:50:39,680 --> 00:50:41,520 So there's a lot of interest in that. 875 00:50:44,960 --> 00:50:47,760 From Ireland's intimate connection to water 876 00:50:47,760 --> 00:50:51,760 to the point in its history when life began to flourish, 877 00:50:51,760 --> 00:50:55,120 the next chapter will trace the story of life, 878 00:50:55,120 --> 00:50:59,880 from the remains of its first residents preserved in the rocks 879 00:50:59,880 --> 00:51:03,760 to the arrival of humans and beyond, 880 00:51:03,760 --> 00:51:07,520 and will explore the geological changes that lie ahead 881 00:51:07,520 --> 00:51:08,840 for the island.