1 00:00:04,800 --> 00:00:07,600 This is John G B with all of us crumple. 2 00:00:08,400 --> 00:00:11,700 This episode is the second of two of my conversation with 3 00:00:11,700 --> 00:00:15,000 Martin giggling. In the first episode, we 4 00:00:15,000 --> 00:00:18,700 discussed fluvial deposits in the geological record and we 5 00:00:18,700 --> 00:00:22,100 trace the effect that the breakup of Pangaea around, 200 6 00:00:22,100 --> 00:00:27,000 million years ago had on river systems In this episode, we 7 00:00:27,000 --> 00:00:30,800 address the history of rivers of Europe and the Americas as well 8 00:00:30,800 --> 00:00:32,800 as the impact of recent ice ages. 9 00:00:32,800 --> 00:00:36,700 On today's Rivers, we end by considering how humans have 10 00:00:36,700 --> 00:00:39,600 changed with us and their deposits throughout the history 11 00:00:39,600 --> 00:00:42,900 of mankind. Martin gambling has spent a 12 00:00:42,900 --> 00:00:45,400 lifetime studying rivers and river sediments around the 13 00:00:45,400 --> 00:00:47,800 world. He's Emeritus professor in the 14 00:00:47,800 --> 00:00:50,500 department of Earth and environmental Sciences at 15 00:00:50,500 --> 00:00:54,600 Dalhousie University in Halifax, Nova Scotia in Canada. 16 00:00:56,300 --> 00:00:59,200 What about the rivers of Europe? You've already touched on a few. 17 00:00:59,300 --> 00:01:03,400 What is their history? The European story is dominated 18 00:01:03,400 --> 00:01:07,200 by the Collision of Africa, along with micro continents 19 00:01:07,400 --> 00:01:11,000 against southern Europe. And of course, this generates 20 00:01:11,000 --> 00:01:14,800 the Alps in particular 30 million years ago, the 21 00:01:14,800 --> 00:01:18,300 carpathians is a great bulge of the Alpine system. 22 00:01:18,400 --> 00:01:22,900 Something like 15 million years ago and complications with the 23 00:01:22,900 --> 00:01:27,600 Pyrenees as well in Iberia. The Alps in particular has 24 00:01:27,600 --> 00:01:30,700 really dominated the scene. The would have been Rivers 25 00:01:30,700 --> 00:01:35,800 flowing down across northern Europe into tethers, but once 26 00:01:35,800 --> 00:01:39,600 the Alps began to rise, those were all effectively destroyed 27 00:01:39,600 --> 00:01:42,300 or turned into tributaries of other systems. 28 00:01:42,700 --> 00:01:47,200 So Europe, at least Western Europe is largely a story of 29 00:01:47,200 --> 00:01:51,900 Three Rivers, the Rhone the Rhine and the Danube, the Rhone 30 00:01:51,900 --> 00:01:55,500 may have been the original major river running around the 31 00:01:55,500 --> 00:01:57,700 Western. Side of the Alps, which would 32 00:01:57,700 --> 00:02:00,500 initially have just been an island in the toughest for 33 00:02:00,500 --> 00:02:04,800 gradually became a dominating mountain chain and progressively 34 00:02:04,800 --> 00:02:08,100 through time. After about say 10 15 million 35 00:02:08,100 --> 00:02:12,000 years ago, it was the Danube that was dominating flowing 36 00:02:12,000 --> 00:02:15,600 around Eastwood's, right? Brand The Fringe of the Alps as 37 00:02:15,600 --> 00:02:20,000 they extended and then running down into the pannonian, Basin 38 00:02:20,000 --> 00:02:24,400 in Hungary, through Vienna, and out into the Hungarian Plains 39 00:02:24,400 --> 00:02:28,200 for quite a long time. Time is flowed into a very large 40 00:02:28,200 --> 00:02:32,800 lake in the pannonian Basin but had Advanced with a major Delta 41 00:02:33,100 --> 00:02:37,800 filled in the lake with alpine sediment, cut through ranges and 42 00:02:37,800 --> 00:02:40,700 got down to the Black Sea about 4 million years ago. 43 00:02:40,900 --> 00:02:44,900 What is the pannonian Basin? Yes, the pannonian Basin is the 44 00:02:44,900 --> 00:02:50,200 very big horse Plains of Hungary where the Maggie has raised, 45 00:02:50,200 --> 00:02:53,900 their horses, famous Horseman, and those are still present as 46 00:02:53,900 --> 00:02:57,800 very big flat Plains but Underneath a lake deposits. 47 00:02:58,100 --> 00:03:02,400 And this is part of what sometimes called the lag Amare 48 00:03:02,400 --> 00:03:07,100 in European terms, very large lakes connected to tethers, 49 00:03:07,300 --> 00:03:11,700 partly, brackish partly, fresh that ran all across this tract 50 00:03:11,700 --> 00:03:15,000 of country. But what's been happening lately 51 00:03:15,100 --> 00:03:19,000 is that the Rhine has started to come into its own, it occupies a 52 00:03:19,000 --> 00:03:22,400 rift valley where there have been volcanics, quite recent 53 00:03:22,400 --> 00:03:26,500 volcanic, sand places and for quite a long time the Mine was a 54 00:03:26,500 --> 00:03:29,900 series of disconnected, drainages most, particularly the 55 00:03:29,900 --> 00:03:32,900 Moselle coming in from Eastern France. 56 00:03:33,300 --> 00:03:37,200 But by about 3 million years ago, these drainages are 57 00:03:37,208 --> 00:03:41,000 connected up and Alpine sediment was now making its way right 58 00:03:41,000 --> 00:03:44,800 through to the North Sea and because the Rhine is occupying a 59 00:03:44,800 --> 00:03:47,700 rift valley at a lower elevation, it's beginning to 60 00:03:47,700 --> 00:03:51,700 suck out the headwaters of the Danube and in places in the 61 00:03:51,700 --> 00:03:55,900 swabian Alps, there are cave systems where water is draining. 62 00:03:56,000 --> 00:03:59,800 Underground out of the Danube and into the headwaters of the 63 00:03:59,800 --> 00:04:01,900 Rhine through a series of Springs. 64 00:04:01,900 --> 00:04:04,300 It's a river capture in progress. 65 00:04:04,400 --> 00:04:06,400 Moving, more or less underground. 66 00:04:06,400 --> 00:04:09,400 It's incredible stuff. Can you talk about the history 67 00:04:09,400 --> 00:04:12,800 of South American rivers and especially that of today's 68 00:04:12,800 --> 00:04:15,500 largest river? The Amazon that is one of the 69 00:04:15,500 --> 00:04:17,700 most fantastic River stories of all. 70 00:04:17,800 --> 00:04:20,500 There's the Amazon, it's the world's largest river. 71 00:04:20,600 --> 00:04:24,100 By a very large margin. It's bigger than something like 72 00:04:24,100 --> 00:04:25,900 the eighth. Next Rivers all. 73 00:04:26,100 --> 00:04:30,400 Lined and it is only about nine million years old in its present 74 00:04:30,400 --> 00:04:32,500 position. What happened? 75 00:04:32,500 --> 00:04:36,000 Was that South America began to drift away from Africa? 76 00:04:36,300 --> 00:04:40,400 And were Rivers flowing into the Pacific on the far side. 77 00:04:40,400 --> 00:04:44,600 One of which would have been a Proto Amazon it is sometimes 78 00:04:44,600 --> 00:04:49,100 referred to as the sano-sama which is amazonas spelt 79 00:04:49,100 --> 00:04:53,000 backwards if you wanted a name for River now flowing in the 80 00:04:53,000 --> 00:04:57,300 opposite direction, that it now occupies But in the bias seen 81 00:04:57,300 --> 00:05:01,300 about 25 million years ago, the and he's started to rise and 82 00:05:01,300 --> 00:05:03,600 drainage began to flow eastwards. 83 00:05:03,800 --> 00:05:08,600 And so, the Amazon went through a reversion and initially it 84 00:05:08,600 --> 00:05:13,000 terminated as a series of major Wetlands on the South American 85 00:05:13,000 --> 00:05:16,100 continent blocked off by a rock Arch. 86 00:05:16,100 --> 00:05:19,800 So it didn't get to the Atlantic eventually, it broke through the 87 00:05:19,800 --> 00:05:24,300 arch and then ran into a rift that runs along the lower line 88 00:05:24,300 --> 00:05:28,600 of the Amazon and reach The Atlantic Ocean that was about 9 89 00:05:28,600 --> 00:05:32,400 million years ago. And that's when Andean sediment 90 00:05:32,400 --> 00:05:36,100 first begins to appear in the deep sea fan of the Amazon off, 91 00:05:36,100 --> 00:05:40,400 the South American Coast. Meanwhile, the Amazon has picked 92 00:05:40,400 --> 00:05:44,600 up a lot of the drainage from The Orinoco in the northern part 93 00:05:44,600 --> 00:05:47,200 of the continent. And there's a very bizarre 94 00:05:47,200 --> 00:05:51,700 circumstance called the Cassie Ciara Channel which is a place 95 00:05:52,100 --> 00:05:56,100 which actually connects the two rivers and where the Amazon In 96 00:05:56,100 --> 00:05:59,200 is draining off flow from the Orinoco, but they've not 97 00:05:59,200 --> 00:06:02,000 separated into separate catchments as yet. 98 00:06:02,100 --> 00:06:05,600 It's a river capture that actually in progress and 99 00:06:05,600 --> 00:06:08,500 Alexander Von Humboldt took a canoe through it. 100 00:06:08,600 --> 00:06:12,200 And showed in the early 1800s that these were actually 101 00:06:12,200 --> 00:06:15,500 connected armchair observers in Europe, have claimed that it 102 00:06:15,508 --> 00:06:18,300 couldn't possibly be true. Can you pick out a couple of 103 00:06:18,308 --> 00:06:22,000 examples that represent the diverse histories of the rivers 104 00:06:22,000 --> 00:06:25,100 of North America? Yes, I could talk forever about 105 00:06:25,100 --> 00:06:26,500 this. There are so many The rivers. 106 00:06:26,500 --> 00:06:28,500 They history is a so interesting. 107 00:06:28,700 --> 00:06:31,900 We've talked a bit about the Mississippi and that goes back 108 00:06:31,900 --> 00:06:36,200 to about 300 million years following the line of the Fallen 109 00:06:36,200 --> 00:06:40,200 Basin along the western side of the Appalachians that was a 110 00:06:40,207 --> 00:06:44,700 mountain chain of Andean scale. But once Pangea was assembled, 111 00:06:44,700 --> 00:06:48,800 along that line then very big Rivers would have run out across 112 00:06:48,800 --> 00:06:53,300 the continent and some of them ran out into the Boreal see in 113 00:06:53,300 --> 00:06:57,500 north western Canada so you have It'll scale rivers that no 114 00:06:57,500 --> 00:06:59,700 longer exist. Running out from the 115 00:06:59,700 --> 00:07:04,900 Appalachians. The Mississippi continued to run 116 00:07:04,900 --> 00:07:10,000 south and in the Cretaceous in particular, the Cordillera began 117 00:07:10,000 --> 00:07:12,300 to rise in Western North America. 118 00:07:12,500 --> 00:07:15,600 And then the entire drainage system of North, America was 119 00:07:15,600 --> 00:07:18,800 altered the Gulf of Mexico had come into existence in the 120 00:07:18,800 --> 00:07:22,400 Jurassic and you had Rivers running down off the chordal 121 00:07:22,400 --> 00:07:27,300 error rivers, that we know today like the plat, the I saw the red 122 00:07:27,300 --> 00:07:31,700 Canadian P cos rivers and so on and these all ran down to the 123 00:07:31,700 --> 00:07:35,700 gulf where they competed, if you like with the Mississippi for 124 00:07:35,700 --> 00:07:39,900 access to the Gulf Waters. So the Mississippi at times was 125 00:07:39,900 --> 00:07:44,100 reduced to quite a small River But as time passed the Missouri 126 00:07:44,100 --> 00:07:46,500 fed into it. And so the Mississippi has 127 00:07:46,500 --> 00:07:50,700 regrown into a very major drainage that captures a lot of 128 00:07:50,700 --> 00:07:52,900 what comes off the Western Plains. 129 00:07:53,100 --> 00:07:55,300 So it's managed to maintain its place. 130 00:07:56,000 --> 00:07:59,500 The river that you have to talk about though with North America 131 00:07:59,500 --> 00:08:02,900 as the Colorado River. And I couldn't possibly talk to 132 00:08:02,900 --> 00:08:05,700 you about this without getting into the issues of the Grand 133 00:08:05,700 --> 00:08:11,300 Canyon and in the Cretaceous the Colorado headed eastwards into 134 00:08:11,300 --> 00:08:15,300 the Western interior Seaway across the Midwest. 135 00:08:15,500 --> 00:08:20,900 But then Dynamic topography came in as the continent drifted over 136 00:08:20,900 --> 00:08:25,800 the Pacific, the Colorado Plateau Rose and the basement 137 00:08:26,000 --> 00:08:30,700 Range Systems of rift. Valleys lowered the topography 138 00:08:30,900 --> 00:08:34,400 in the very western part of the continent and all of this 139 00:08:34,400 --> 00:08:38,900 resulted initially in rather disconnected drainage systems. 140 00:08:39,200 --> 00:08:43,600 But eventually, a through flowing river system of the 141 00:08:43,608 --> 00:08:48,200 Colorado that connected drainages ran into a series of 142 00:08:48,200 --> 00:08:52,700 Lake basins and then about 4 million years ago or so in the 143 00:08:52,700 --> 00:08:57,500 pliocene made its way down to the Pacific and cut right 144 00:08:57,500 --> 00:09:02,600 through and the Grand Canyon. Most of it was cut apparently 145 00:09:02,600 --> 00:09:04,500 within the past six million years. 146 00:09:04,700 --> 00:09:06,900 It's incredibly big. Have you been there? 147 00:09:06,900 --> 00:09:08,500 Yeah, I have. Yeah, absolutely. 148 00:09:08,500 --> 00:09:12,800 An impressive thing to see and it's very young the lowered base 149 00:09:12,800 --> 00:09:15,000 level when it got through to the ocean. 150 00:09:15,300 --> 00:09:19,000 Meant that the river just cut a massive Gorge as other rivers 151 00:09:19,000 --> 00:09:21,000 have done. The vulgar has done that. 152 00:09:21,100 --> 00:09:24,200 The Nile has done that, and these will eventually fill up 153 00:09:24,200 --> 00:09:27,600 with sediment probably as The other ones have done but at the 154 00:09:27,600 --> 00:09:30,300 moment, it's standing. There is the most famous Canyon 155 00:09:30,300 --> 00:09:33,200 on Earth. What about the ice ages? 156 00:09:33,200 --> 00:09:36,200 Particularly the more recent ones, how they had a significant 157 00:09:36,200 --> 00:09:39,000 impact on Rivers? They certainly have and I have 158 00:09:39,000 --> 00:09:42,400 had an impact at a far more rapid rate than the plate 159 00:09:42,400 --> 00:09:46,200 tectonic effects which are in the millions tens of millions of 160 00:09:46,200 --> 00:09:48,600 years. The ice age has been operating 161 00:09:48,600 --> 00:09:52,500 on scales really of thousands or hundreds of thousands of years 162 00:09:52,700 --> 00:09:55,800 and the changes are absolutely radical, the ice. 163 00:09:55,900 --> 00:10:00,700 Ice across North America and Eurasia came a long way down 164 00:10:00,700 --> 00:10:05,900 down into as far as Nebraska in North America and this is ice 3 165 00:10:05,900 --> 00:10:08,800 kilometers thick. It does extraordinary things it 166 00:10:08,800 --> 00:10:12,500 erodes river, valleys it spreads, huge volumes of 167 00:10:12,500 --> 00:10:16,100 glacial, debris everywhere it depresses the crust. 168 00:10:16,400 --> 00:10:18,900 It does everything. And rivers, of course, cease to 169 00:10:18,900 --> 00:10:22,300 exist when the ice that magnitude covers them. 170 00:10:22,700 --> 00:10:24,900 So let me give you a few examples. 171 00:10:25,100 --> 00:10:28,100 The Yukon. It was initially a relatively 172 00:10:28,100 --> 00:10:32,700 small drainage that Rose NIV Pacific Ocean and ran down into 173 00:10:32,700 --> 00:10:38,000 the Pacific but it's exit got blocked by a nice lobe and It 174 00:10:38,000 --> 00:10:43,300 reversed and so at the present day it rises within 50 175 00:10:43,300 --> 00:10:48,500 kilometers of the Pacific and then runs 3000 km round to the 176 00:10:48,500 --> 00:10:53,400 Bering Strait quite incredible. And the McKenzie one of the big 177 00:10:53,400 --> 00:10:57,700 rivers of North America occupied Is a glacially eroded trough 178 00:10:57,700 --> 00:11:01,400 that didn't previously exist. There was no drainage along its 179 00:11:01,400 --> 00:11:06,200 present course and the Mackenzie has originated only since the 180 00:11:06,200 --> 00:11:10,100 Ice Age something like 12,000 years ago and it must be among 181 00:11:10,100 --> 00:11:13,800 the youngest of all the big rivers of Earth entirely as a 182 00:11:13,800 --> 00:11:18,700 result of glacial effects. Other things that happened in 183 00:11:18,700 --> 00:11:22,300 particular in North America, the weight of the ice depressed, the 184 00:11:22,308 --> 00:11:25,700 land and once the ice sheets melted back which they did, 185 00:11:26,000 --> 00:11:30,900 Quickly enormous glacial lakes formed, including glacial Lake 186 00:11:30,900 --> 00:11:35,800 Agassiz in North America as well as very big lakes and Siberia. 187 00:11:36,300 --> 00:11:39,000 And these were held in place by lobes of ice. 188 00:11:39,000 --> 00:11:43,400 That was belting as well as glacial debris natural dams 189 00:11:43,500 --> 00:11:48,100 which failed and released a number of catastrophic Outburst 190 00:11:48,100 --> 00:11:52,800 floods and meltwater that rahl down, rivers to the ocean down 191 00:11:52,800 --> 00:11:57,000 the Mississippi system as far as the Gulf of Echo out through the 192 00:11:57,000 --> 00:11:58,800 st. Lawrence and Hudson to the 193 00:11:58,800 --> 00:12:02,800 Atlantic and out along the Columbia River to the Pacific. 194 00:12:03,500 --> 00:12:06,700 And it's the Columbia river floods that really brought all 195 00:12:06,700 --> 00:12:10,000 of this to light through the work of J Harlen Bretz. 196 00:12:10,000 --> 00:12:15,000 In the 1920s who interpreted the landscape of the channeled 197 00:12:15,000 --> 00:12:19,300 scablands in Washington state has due to catastrophic floods 198 00:12:19,800 --> 00:12:23,600 geomorphologist didn't like this, this was catastrophism 199 00:12:23,800 --> 00:12:27,800 this smacked of old creation. I thought and they laid into 200 00:12:27,800 --> 00:12:30,200 him, it couldn't be right. There must be other 201 00:12:30,200 --> 00:12:33,800 explanations, but in the course of time Brett's was proved to be 202 00:12:33,800 --> 00:12:36,800 correct. And the estimates now are the 203 00:12:36,800 --> 00:12:40,300 for short periods of time, the outbursts that ran down the 204 00:12:40,300 --> 00:12:44,400 Columbia. Rated at 20 million cubic meters 205 00:12:44,400 --> 00:12:48,400 per second, and that's equivalent of 50 River. 206 00:12:48,400 --> 00:12:52,100 Amazon's at Peak flow. Absolutely stunning. 207 00:12:52,100 --> 00:12:56,400 They generated water falls on the scale of Niagara Era which 208 00:12:56,400 --> 00:12:59,300 are now completely Drive. You've ever been across that 209 00:12:59,300 --> 00:13:02,500 extraordinary landscape. And They Carried sediment out 210 00:13:02,500 --> 00:13:05,700 for 1,000 kilometers down into the Pacific and something like 211 00:13:05,700 --> 00:13:09,400 200 meters of sand it. Deep water off the Pacific. 212 00:13:09,400 --> 00:13:13,700 That resulted from all of this, did the ice ages also affect the 213 00:13:13,700 --> 00:13:16,500 courses of European rivers. Yes. 214 00:13:16,600 --> 00:13:20,500 This the channel river which initially connected the Rhine, 215 00:13:20,700 --> 00:13:26,000 the Thames, the saying of the psalm into one large river, The 216 00:13:26,000 --> 00:13:29,400 drained, most of Western Europe ran right down to the Bay of 217 00:13:29,400 --> 00:13:32,400 Biscay. And when the ice sheets melted 218 00:13:32,400 --> 00:13:36,400 the sea level rise, simply drowned out the lowest 800 219 00:13:36,400 --> 00:13:40,600 kilometres of the channel river system, and the rivers were all 220 00:13:40,600 --> 00:13:43,900 left, is disconnected. Remnants, the Rhine, the Thames, 221 00:13:43,900 --> 00:13:47,700 the psalm, and of course, in terms of human geography, this 222 00:13:47,700 --> 00:13:51,600 is affected everything running right through from the Stone Age 223 00:13:51,700 --> 00:13:53,600 right through to modern-day brexit. 224 00:13:53,700 --> 00:13:58,800 It's an ongoing story of how River and glacial Dynamics have 225 00:13:58,800 --> 00:14:00,900 affected human political history. 226 00:14:01,300 --> 00:14:05,900 Speaking of recent effects, humans are now having a massive 227 00:14:05,900 --> 00:14:09,200 impact on Rivers. What with all the dams we've 228 00:14:09,200 --> 00:14:13,300 constructed and the confines we've placed on Rivers for 229 00:14:13,300 --> 00:14:16,900 agricultural purposes and to protect cities from flooding, 230 00:14:17,600 --> 00:14:21,300 how far back can the impact of humans be seen in the record of 231 00:14:21,300 --> 00:14:25,600 fluvial deposits. that's a really very fundamental question 232 00:14:25,600 --> 00:14:29,700 with a lot of importance that the present-day hominins arise 233 00:14:29,700 --> 00:14:34,600 something like 7 million years ago in Africa and I asked Gail 234 00:14:34,600 --> 00:14:38,700 Ashley who'd worked at Olduvai Gorge whether she could document 235 00:14:38,700 --> 00:14:42,800 any trace of what early humans did we're talking perhaps two or 236 00:14:42,800 --> 00:14:46,300 three million years ago and her response which I've always 237 00:14:46,300 --> 00:14:50,400 remembered is that the early hominins trod likely on the 238 00:14:50,400 --> 00:14:54,000 earth leaving only stone tools and Footprints. 239 00:14:54,400 --> 00:14:58,000 And so there's nothing that she could see where you could make a 240 00:14:58,000 --> 00:15:03,800 link between River Dynamics. And humans once fire was used, 241 00:15:03,800 --> 00:15:07,200 which goes back about a million and a half years in Africa, the 242 00:15:07,200 --> 00:15:10,700 must have been some effect on alluvial Landscapes with the 243 00:15:10,700 --> 00:15:15,500 burning of forests release of sediments and so on, but so far 244 00:15:15,600 --> 00:15:19,400 I haven't come across anything that really links early fire 245 00:15:19,400 --> 00:15:21,000 records. Two Rivers. 246 00:15:21,000 --> 00:15:22,900 At least not as far back as that. 247 00:15:23,900 --> 00:15:28,000 When humans really began to have an effect is once they start to 248 00:15:28,000 --> 00:15:31,600 domesticate plants and animals. And that is, as recently as 249 00:15:31,600 --> 00:15:36,600 about, 11,000 years ago, prior to that the Fisher is along 250 00:15:36,600 --> 00:15:38,800 rivers. There was food processing by 251 00:15:38,800 --> 00:15:42,600 Rivers, but settlements were only transient and people were 252 00:15:42,600 --> 00:15:46,700 hunter-gatherers moving through the landscape and as people say, 253 00:15:46,700 --> 00:15:50,300 in Northern Canada, following the wealth of the land, their 254 00:15:50,300 --> 00:15:54,800 livelihood, depended on their Mobility, But once plants were 255 00:15:54,800 --> 00:15:59,200 domesticated, wheat. Barley, beans onions, Etc. 256 00:15:59,200 --> 00:16:04,800 In the near East and animals cattle sheep goats Pigs by about 257 00:16:04,800 --> 00:16:08,500 10,000 years ago. Then things began to change 258 00:16:08,800 --> 00:16:13,100 something like nearly 10,000 years ago, people recognize 259 00:16:13,100 --> 00:16:16,000 agriculture as an organized system. 260 00:16:16,300 --> 00:16:19,900 And within a few thousand years of that, it's reckoned that 261 00:16:19,900 --> 00:16:23,400 virtually everyone in the near East was a farmer probably 262 00:16:23,400 --> 00:16:26,800 within little more than three thousand years at around the 263 00:16:26,800 --> 00:16:30,900 same time, you're getting rice. Domesticated in China just 264 00:16:30,900 --> 00:16:36,200 Inland from Hong, Kong something like 9,000 years ago and all 265 00:16:36,200 --> 00:16:39,400 sorts of Water. Systems, irrigation goes along 266 00:16:39,400 --> 00:16:44,000 with that you get Staples like Maize and squash in Central 267 00:16:44,000 --> 00:16:48,400 America domesticated nine to ten thousand years ago and oddly 268 00:16:48,400 --> 00:16:51,000 bananas in New Guinea going back. 269 00:16:51,000 --> 00:16:54,900 Something like I think seven Thousand years or thereabouts, 270 00:16:55,300 --> 00:16:59,100 the Amazon basin, long thought to have been a kind of human 271 00:16:59,100 --> 00:17:04,200 Backwater by people who probably never went there as emerged as 272 00:17:04,200 --> 00:17:07,500 being a major Centre for plant, domestication of all kinds. 273 00:17:07,700 --> 00:17:11,000 As a lot of research going on into what happened there. 274 00:17:11,400 --> 00:17:15,000 And we know about these things because you can document the 275 00:17:15,000 --> 00:17:20,700 changes in animal bone structure size and so on, and in plant 276 00:17:20,700 --> 00:17:23,000 genetics that go along with humans, too. 277 00:17:23,099 --> 00:17:26,500 Deliberately engineering plants and animals for their own 278 00:17:26,500 --> 00:17:30,200 purposes and over the next few thousand years. 279 00:17:30,500 --> 00:17:35,000 You have donkeys domesticated in Egypt horses on the Russian 280 00:17:35,000 --> 00:17:40,500 steppe Yaks, in eastern, Asia water, buffalo, probably in 281 00:17:40,500 --> 00:17:43,800 India, or China, and then camels in Arabia. 282 00:17:44,100 --> 00:17:47,000 And all of these were domesticated over a period of 283 00:17:47,000 --> 00:17:50,600 three or four thousand years. And why was this important for 284 00:17:50,600 --> 00:17:52,600 Rivers? Well, if you're going to have 285 00:17:52,600 --> 00:17:55,500 cropped, Ends. You have to Deforest the land. 286 00:17:55,500 --> 00:17:59,300 Make way, for the arable products you need pasture for 287 00:17:59,300 --> 00:18:02,900 grazing animals, and these all affect the stability of river 288 00:18:02,900 --> 00:18:07,700 systems and the sediment Supply coming down to the river's but 289 00:18:07,700 --> 00:18:11,400 very importantly in places like Mesopotamia. 290 00:18:11,900 --> 00:18:15,600 You have got to have irrigation if you're going to have crops 291 00:18:16,000 --> 00:18:19,500 and this goes along with the rise of permanent settlements in 292 00:18:19,500 --> 00:18:25,100 places particularly like Jericho some and years ago in the rift 293 00:18:25,100 --> 00:18:29,900 valley of the Jordan and then the cities of Mesopotamia along 294 00:18:29,900 --> 00:18:34,500 the Euphrates and the Tigris in Egypt, along the Nile and with 295 00:18:34,500 --> 00:18:38,000 the Indus Valley Civilization along the Indus and its 296 00:18:38,000 --> 00:18:40,500 tributaries. And if you've got cities with 297 00:18:40,500 --> 00:18:44,400 big numbers of people, you need water supply, you need sewage 298 00:18:44,400 --> 00:18:47,400 systems. You need infrastructure along 299 00:18:47,400 --> 00:18:51,400 the rivers wharfs Bridges Pathways. 300 00:18:51,700 --> 00:18:55,800 You generate large Depressions. Which have been documented by 301 00:18:55,800 --> 00:18:58,400 archaeology on floodplains to make bricks. 302 00:18:58,600 --> 00:19:02,500 These cities were brick mud brick manufacture and all that 303 00:19:02,500 --> 00:19:04,300 came out of the floodplain plays. 304 00:19:04,700 --> 00:19:09,000 And so, I 6,500 years ago, you had the rise of irrigation 305 00:19:09,000 --> 00:19:14,100 systems in Mesopotamia and the first Big Dam in Egypt, the 306 00:19:14,100 --> 00:19:17,600 damn, of the pagans nearly 5,000 years ago. 307 00:19:18,000 --> 00:19:21,700 We're 14 meters high with a facing of stone blocks. 308 00:19:21,900 --> 00:19:25,200 And so, people are really Really beginning to modify the river 309 00:19:25,200 --> 00:19:29,700 systems and I have to mention the Yellow River in China, where 310 00:19:29,700 --> 00:19:32,200 Emperor's going back. Several thousand years, 311 00:19:32,400 --> 00:19:36,600 constructed enormous embankments relief channels and kept the 312 00:19:36,600 --> 00:19:40,700 river in its place for the benefits of Agriculture and of 313 00:19:40,700 --> 00:19:44,400 navigation. And finally, the Romans masters 314 00:19:44,400 --> 00:19:47,600 of water management as they were a pretty much anything else in 315 00:19:47,600 --> 00:19:54,500 the engineering line aqueducts, 100 km long and Large dams built 316 00:19:54,500 --> 00:19:58,500 in the near East to supply. The Roman Legions with water and 317 00:19:58,500 --> 00:20:01,600 food. So humans over the past 10,000 318 00:20:01,600 --> 00:20:05,700 years have really been affecting river systems in an earlier 319 00:20:05,700 --> 00:20:08,500 podcast. I talked with Phil gabbard about 320 00:20:08,500 --> 00:20:11,600 whether and how we might establish a new geological 321 00:20:11,600 --> 00:20:15,200 period called the anthropocene defined by human impact on the 322 00:20:15,200 --> 00:20:18,200 planet. If we do, establish such a 323 00:20:18,200 --> 00:20:21,200 period, we would need to Mark the start of it. 324 00:20:21,200 --> 00:20:24,200 With something laid down in the occurred that happened, more or 325 00:20:24,208 --> 00:20:26,300 less simultaneously around the globe. 326 00:20:26,800 --> 00:20:29,400 Can our impact on Rivers? Help us out here. 327 00:20:29,800 --> 00:20:31,800 I think you can help us out quite a lot. 328 00:20:32,100 --> 00:20:36,400 I've liked the approach of Phil gabbard, and his colleagues that 329 00:20:36,400 --> 00:20:38,800 you need to consider the anthropocene to be a very 330 00:20:38,800 --> 00:20:42,900 broad-based event. Going back a very long way in 331 00:20:42,900 --> 00:20:45,400 human history. And I've moved away from 332 00:20:45,400 --> 00:20:49,700 thinking of a narrowly defined Global spike in what we've been 333 00:20:49,700 --> 00:20:52,900 talking about with human effects on Rivers means. 334 00:20:53,100 --> 00:20:57,100 They go back about ten thousand years with domestication of 335 00:20:57,100 --> 00:21:00,100 animals and plants. And you can pick that up with 336 00:21:00,100 --> 00:21:02,300 what people call Legacy sediments. 337 00:21:02,500 --> 00:21:06,500 The enormous runoffs of sediments into rivers, along 338 00:21:06,500 --> 00:21:11,400 with serial pollen, the bones of domesticated animals, techno 339 00:21:11,400 --> 00:21:15,700 fossils, such as pottery and bits of masonry, and you can 340 00:21:15,700 --> 00:21:20,100 show that humans were affecting the Landscapes very prominently 341 00:21:20,200 --> 00:21:23,600 far back in time. And once you get Ting, say, 342 00:21:23,600 --> 00:21:27,200 5,000 years ago, you begin to get written records of 343 00:21:27,200 --> 00:21:30,300 irrigation development Mesopotamia. 344 00:21:30,500 --> 00:21:34,100 And the documentation is in China in particular associated 345 00:21:34,100 --> 00:21:36,800 with the attempts of The Emperor's to control the Yellow 346 00:21:36,800 --> 00:21:39,000 River. So there's no question at all 347 00:21:39,200 --> 00:21:42,300 that human effects. Go back a long way. 348 00:21:42,700 --> 00:21:46,500 The attempt to put a golden spike in to Mark the base of the 349 00:21:46,500 --> 00:21:51,400 anthropocene is focusing on about 1950 linked to nuclear 350 00:21:51,400 --> 00:21:57,200 fallout from Bombs and bomb tests, I'm uncomfortable with 351 00:21:57,200 --> 00:22:00,100 using nuclear fallout in this way. 352 00:22:00,400 --> 00:22:04,700 These are destructive systems. They caused huge deaths of All 353 00:22:04,700 --> 00:22:07,200 Sorts. But really my line of thought is 354 00:22:07,200 --> 00:22:11,000 more that we need a broad all-encompassing term that takes 355 00:22:11,000 --> 00:22:15,100 us a long way back in Earth history to understand what we've 356 00:22:15,100 --> 00:22:19,300 done and our widespread impact on Rivers. 357 00:22:19,700 --> 00:22:21,800 Where would you put that then? Would it be the rise of the 358 00:22:21,800 --> 00:22:24,300 modern engineer? Damn, we're pretty much every 359 00:22:24,300 --> 00:22:26,800 major river on the planet has been significantly. 360 00:22:26,800 --> 00:22:28,500 Damn door. Would you put it further back in 361 00:22:28,500 --> 00:22:30,300 Antiquity? There's no question that the 362 00:22:30,300 --> 00:22:34,100 rise of the big dams has hugely affected virtually, all modern 363 00:22:34,100 --> 00:22:38,900 Rivers, but it doesn't just begin there, for example, by the 364 00:22:38,900 --> 00:22:44,200 time of the domesday book in 1087 or thereabouts when William 365 00:22:44,200 --> 00:22:48,300 the Conqueror invaded Britain, he recorded a water mill for 366 00:22:48,300 --> 00:22:50,900 every 250 inhabitants of Britain. 367 00:22:51,400 --> 00:22:55,000 And those water Mills Had small Weir's. 368 00:22:55,000 --> 00:22:58,600 They had little dams. They had Mill, ponds and 369 00:22:58,600 --> 00:23:00,600 Records. Particularly out of monasteries 370 00:23:00,600 --> 00:23:03,400 show that the stocks of salmon and other. 371 00:23:03,400 --> 00:23:06,600 Migrating fish were cut back through the medieval period. 372 00:23:06,600 --> 00:23:10,100 We've been doing this for hundreds of years, even in that 373 00:23:10,100 --> 00:23:14,400 kind of setting. And by the 1840s in the 374 00:23:14,400 --> 00:23:18,200 northeastern us alone, there were sixty five thousand small, 375 00:23:18,200 --> 00:23:22,400 dams and Mill, ponds, all the rivers have been retooled long 376 00:23:22,400 --> 00:23:25,200 long. For the era of the big dance, we 377 00:23:25,200 --> 00:23:28,500 have to understand the human impact on the land as being very 378 00:23:28,500 --> 00:23:32,700 long ranging, you've studied just about every major river on 379 00:23:32,700 --> 00:23:35,200 the planet. Do you have a favorite River? 380 00:23:35,500 --> 00:23:37,500 I wish I had studied every major river. 381 00:23:37,500 --> 00:23:40,700 All the black that has. I've got a long way to go, but 382 00:23:40,700 --> 00:23:43,600 of all the rivers that I think about, I would have to place the 383 00:23:43,600 --> 00:23:46,800 channel country of Australia at the top of my list. 384 00:23:46,900 --> 00:23:50,100 I spent a long time with an Australian colleagues out there 385 00:23:50,300 --> 00:23:53,000 in the red Centre of Australia. We drove along. 386 00:23:53,100 --> 00:23:56,500 On the old, droving roads through Queensland, rivers of 387 00:23:56,500 --> 00:24:00,200 the channel country, like the diamantina Cooper Creek, the 388 00:24:00,200 --> 00:24:02,700 Georgina. And these run down through the 389 00:24:02,700 --> 00:24:06,800 sand dunes down to Lake are with the salt flats and they are 390 00:24:06,800 --> 00:24:10,000 absolutely fascinating. It's very hot work often into 391 00:24:10,000 --> 00:24:13,500 the 40 Celsius range. But you find that life has found 392 00:24:13,500 --> 00:24:18,100 a way to quote Jurassic Park and there are kangaroos and emus, 393 00:24:18,100 --> 00:24:22,200 crayfish Burrows, eucalyptus trees growing along the side 394 00:24:22,400 --> 00:24:24,600 phlox. Of herod's budgies. 395 00:24:24,900 --> 00:24:29,000 And these are multi Channel and anastomose in rivers, dry for 396 00:24:29,000 --> 00:24:32,000 many months of the year, and then, flooding down to Lake 397 00:24:32,000 --> 00:24:34,800 Eyre, and it's absolutely fascinating walking through the 398 00:24:34,800 --> 00:24:38,400 Creeks, these are about as near to a pristine Rivers. 399 00:24:38,400 --> 00:24:42,000 You're likely to get there just wonderful places, Martin 400 00:24:42,000 --> 00:24:43,600 giggling. Thank you very much. 401 00:24:43,700 --> 00:24:45,300 Oliver. Thank you very much for talking 402 00:24:45,300 --> 00:24:46,700 with me. I'm delighted to talk about 403 00:24:46,700 --> 00:24:59,800 rivers anytime. For more about geology b, as 404 00:24:59,800 --> 00:25:02,900 well as pictures and illustrations, that support this 405 00:25:02,900 --> 00:25:05,500 podcast, go to geology B.com.