1 00:00:04,160 --> 00:00:06,960 This is Geology Bites with Oliver Strimple. 2 00:00:08,760 --> 00:00:11,840 With the help of plate tectonics, we have a relatively 3 00:00:11,840 --> 00:00:15,440 straightforward picture of how major mountain chains formed. 4 00:00:16,280 --> 00:00:20,320 For example, at a very high level, the Himalaya resulted 5 00:00:20,360 --> 00:00:23,560 from the collision of two continental plates, India and 6 00:00:23,560 --> 00:00:26,920 Eurasia. And the Andes are a volcanic 7 00:00:26,920 --> 00:00:29,520 chain that formed where the oceanic Nasca. 8 00:00:29,520 --> 00:00:32,439 Plate subducts beneath the South American plate. 9 00:00:33,480 --> 00:00:36,320 But what about the Alps? They are the most. 10 00:00:36,320 --> 00:00:39,560 Intensively studied of all mountain chains being readily 11 00:00:39,560 --> 00:00:42,360 accessed from the geological research centers of Europe. 12 00:00:43,160 --> 00:00:46,520 But despite this, there remains considerable uncertainty as to 13 00:00:46,520 --> 00:00:50,520 how the Alps were formed. One of the major challenges in 14 00:00:50,520 --> 00:00:54,080 Alpine research is to understand how rocks deform on various 15 00:00:54,080 --> 00:00:56,800 scales. From individual mineral grains 16 00:00:56,840 --> 00:00:58,480 up to the scale. Of mountains. 17 00:00:59,480 --> 00:01:02,080 But the picture is complicated by the presence of several 18 00:01:02,080 --> 00:01:05,560 sedimentary basins and tectonic fragments along the southern 19 00:01:05,560 --> 00:01:09,320 margin of Europe in the Eocene epoch, about 40 million years 20 00:01:09,320 --> 00:01:11,360 ago, when the Alps started to form. 21 00:01:13,040 --> 00:01:16,480 Rob Butler has devoted much of his research career to the Alps, 22 00:01:16,840 --> 00:01:20,080 and particularly to discovering how defamation within Alpine 23 00:01:20,080 --> 00:01:23,760 rocks has been concentrated over the past 40 million years. 24 00:01:24,810 --> 00:01:28,610 It turns out that while recent defamation is clearly visible as 25 00:01:28,610 --> 00:01:32,370 folds and faults in the rocks today, it was the structure of 26 00:01:32,370 --> 00:01:35,690 the southern margin of Europe before the Alps started to form 27 00:01:36,090 --> 00:01:38,610 that played a critical role in the early evolution. 28 00:01:38,610 --> 00:01:43,010 Of the Alps, Rob Butler is Professor of Tectonics at the 29 00:01:43,010 --> 00:01:47,090 University of Aberdeen. Rob Butler, welcome to Geology 30 00:01:47,090 --> 00:01:48,170 Bites. Thank you. 31 00:01:48,170 --> 00:01:50,680 It's great to be here. Since I just mentioned the 32 00:01:50,680 --> 00:01:53,440 importance of the situation on the southern margin of Europe 33 00:01:53,440 --> 00:01:56,440 before the Alps started to form, let's start with that. 34 00:01:57,040 --> 00:01:59,680 What did the geography of the region look like in the EAR 35 00:01:59,680 --> 00:02:01,640 scene about 40 million years ago? 36 00:02:01,960 --> 00:02:03,480 Yeah, it was a great starting point. 37 00:02:03,520 --> 00:02:05,680 I mean, first of all, we have to be quite clear what we mean by 38 00:02:05,680 --> 00:02:08,720 Europe at that stage. And the Italians won't like 39 00:02:08,720 --> 00:02:10,880 this, but we're not going to include them in Europe at this 40 00:02:10,880 --> 00:02:12,480 stage. They're going to be part of a 41 00:02:12,720 --> 00:02:15,800 small continental block that geologists generally referred to 42 00:02:15,840 --> 00:02:22,190 as Adria or Apulia. And that was a distinct fragment 43 00:02:22,670 --> 00:02:26,670 of similar continental blocks that decorated or got caught up 44 00:02:26,670 --> 00:02:29,990 between the two major continental masses of Africa and 45 00:02:29,990 --> 00:02:31,870 Europe. So when we're talking about 46 00:02:31,870 --> 00:02:35,270 Europe at that stage about 40 million years ago, in terms of 47 00:02:35,270 --> 00:02:38,470 land masses, the bits, I'm interested in Western Europe. 48 00:02:38,470 --> 00:02:42,390 So that's very much SE France if you like running around into 49 00:02:42,390 --> 00:02:45,070 Western Switzerland or at least the northern part of Western 50 00:02:45,070 --> 00:02:49,400 Switzerland. So we have that being an area of 51 00:02:49,640 --> 00:02:52,360 low lying ground, some of it above, some of it below sea 52 00:02:52,360 --> 00:02:57,480 level, some very simple bits of proto mountain range beginning 53 00:02:57,480 --> 00:03:01,800 to develop in there, nothing very substantial either side of 54 00:03:01,800 --> 00:03:04,200 that. You've got mountain ranges 55 00:03:04,200 --> 00:03:07,720 beginning to develop in the sense of topography and ranges. 56 00:03:07,720 --> 00:03:10,240 So in the east and outs running into Austria and so forth, 57 00:03:10,240 --> 00:03:14,080 modern day Austria and beyond, there would be more conventional 58 00:03:14,080 --> 00:03:18,650 types of mountain range, perhaps like the modern day Caucasus or 59 00:03:18,650 --> 00:03:20,890 somewhere like that. Not a big white belt, but narrow 60 00:03:20,890 --> 00:03:22,610 strips. Similarly a sort of proto 61 00:03:22,610 --> 00:03:26,490 Pyrenees between Spain and Liberia and southern France. 62 00:03:27,290 --> 00:03:31,010 So we have a complicated surroundings of proto mountain 63 00:03:31,010 --> 00:03:34,050 ranges, but in the western Alps we've got essentially a very low 64 00:03:34,050 --> 00:03:36,290 lying area, most of it underwater. 65 00:03:36,730 --> 00:03:40,170 So what events set? The mountain building process in 66 00:03:40,170 --> 00:03:44,280 motion, so probably the preceding 50 + 1,000,000 years. 67 00:03:44,280 --> 00:03:49,000 There's been convergence between Africa and Europe and the bits 68 00:03:49,000 --> 00:03:51,480 of these small content blocks are getting shuffled and pushed 69 00:03:51,480 --> 00:03:53,600 together. So there's an area of general 70 00:03:53,600 --> 00:03:58,680 convergence and reshaping the geological Europe, not the land 71 00:03:58,680 --> 00:04:01,040 that we would call it. So if you were potching around 72 00:04:01,040 --> 00:04:04,920 in the ESC you'd see the seaway. But actually the geology of 73 00:04:04,920 --> 00:04:08,080 Europe continued and begun to subduct or get carried beneath 74 00:04:08,080 --> 00:04:10,400 this northern margin of Puli or Adria. 75 00:04:11,060 --> 00:04:14,620 So that's the preceding part. As with any mountain range, 76 00:04:14,620 --> 00:04:17,940 pretty much there's a period of seduction of the ocean areas and 77 00:04:17,940 --> 00:04:21,380 thin bits of continent being taken down into the upper 78 00:04:21,380 --> 00:04:24,380 mantle. So that's the preceding game and 79 00:04:24,460 --> 00:04:27,780 you just let the tape run so that the convergence continues 80 00:04:27,780 --> 00:04:29,860 and eventually you collide mountains. 81 00:04:29,860 --> 00:04:31,420 And that's a Himalayan situation. 82 00:04:31,420 --> 00:04:33,420 That's the same in any collision mountain belt. 83 00:04:33,900 --> 00:04:36,460 But in the ESSE, we're not quite at that stage yet in the out. 84 00:04:36,460 --> 00:04:38,940 So 40 million years ago it's all set to go. 85 00:04:39,240 --> 00:04:41,160 So wait a minute. So you have this shallow sea 86 00:04:41,160 --> 00:04:43,920 that you talked about, this low lying area, part above sea 87 00:04:43,920 --> 00:04:47,200 level, part below and that is subducting in which direction? 88 00:04:47,320 --> 00:04:51,840 Broadly southwards or South and E underneath this continental 89 00:04:51,840 --> 00:04:55,280 fragment that you can think of as Italy, modern day Italy or 90 00:04:55,320 --> 00:04:57,040 Adria as you called it. Quite so. 91 00:04:57,120 --> 00:04:59,520 OK. So that then swallowed up that 92 00:04:59,520 --> 00:05:02,600 low lying area. So during this period there was 93 00:05:02,600 --> 00:05:06,840 no actual topography created and then it was only when that area 94 00:05:06,840 --> 00:05:10,480 got fully consumed that you then started a more conventional 95 00:05:10,720 --> 00:05:12,520 mountain building process. Yeah. 96 00:05:12,520 --> 00:05:15,000 So we need to think a little bit about what this area that's 97 00:05:15,000 --> 00:05:18,120 already going down the plug hole if you like what that actually 98 00:05:18,120 --> 00:05:20,480 consists of and that's thin crust. 99 00:05:20,480 --> 00:05:24,160 The old continental margin people think rather like the 100 00:05:24,160 --> 00:05:28,600 modern day Atlantic margin of Iberia or of Western France. 101 00:05:28,960 --> 00:05:32,920 So you have a an area of thin tapering wedge of content 102 00:05:32,920 --> 00:05:37,000 lacrosse sedimentary basins that have been gradually taken down 103 00:05:37,320 --> 00:05:42,200 into the system. So you've got thin crust and a 104 00:05:42,200 --> 00:05:46,520 big root of mantle underneath it, and that's the driver that 105 00:05:46,560 --> 00:05:50,120 allows the content with crust, the thin crust to be taken down 106 00:05:50,160 --> 00:05:55,950 and seducted in contrast, as you go further out into what you 107 00:05:55,950 --> 00:05:59,390 might think is stable Europe, the normal Europe, which if you 108 00:05:59,390 --> 00:06:02,630 like would be the sort of massive central of France in 109 00:06:02,630 --> 00:06:07,270 terms of what you see in the outcrop today, that's normal 110 00:06:07,270 --> 00:06:11,670 thickness continental crust. And the change will happen when 111 00:06:11,670 --> 00:06:17,550 that enters the seduction zone and chokes it so that thicker 112 00:06:17,550 --> 00:06:22,310 crust is too buoyant, too thick to be carried down by its mantle 113 00:06:22,310 --> 00:06:27,230 root into the mantle. And it's then that you'll start 114 00:06:27,230 --> 00:06:31,110 thickening that up and making mountain ranges okay. 115 00:06:31,110 --> 00:06:33,110 So now we've wound the clock forward to. 116 00:06:33,190 --> 00:06:37,750 About 25,000,000 years ago. Would that be in the early Mayo 117 00:06:37,750 --> 00:06:39,270 scene? Roughly yes. 118 00:06:39,310 --> 00:06:43,150 And deligacy in early Mayo scene is when there's evidence in the 119 00:06:43,150 --> 00:06:48,510 geological record for a change in the surrounding basin areas 120 00:06:48,510 --> 00:06:51,790 that are going to collect the detritus that erodes off the 121 00:06:52,410 --> 00:06:54,650 proto Alpine chain. So as you begin to the 122 00:06:54,650 --> 00:06:58,130 mountains, they poke up in the air, they erode and the signal 123 00:06:58,130 --> 00:07:02,250 of that is detritus being washed into the surrounding areas and 124 00:07:02,250 --> 00:07:05,490 that really gets going into the early Miocene, virtually nothing 125 00:07:05,530 --> 00:07:08,770 before that. Is the initiation of the 126 00:07:08,770 --> 00:07:13,930 topography in this region still driven by what's happening with 127 00:07:13,930 --> 00:07:15,850 the subduction zone and how it gets. 128 00:07:15,850 --> 00:07:17,330 Clogged up with this thick crust? 129 00:07:17,330 --> 00:07:21,540 Or are we talking about the more regional convergence of Africa 130 00:07:21,740 --> 00:07:24,740 up north towards Europe? Well, it's both really, because 131 00:07:24,740 --> 00:07:27,540 that convergence happens because you're able to have the 132 00:07:27,540 --> 00:07:32,100 seduction going on and the likelihood is that the motor for 133 00:07:32,100 --> 00:07:36,700 the convergence as it continues is the pull of that seducted 134 00:07:36,700 --> 00:07:42,280 slab of mantle lithosphere that lay under the grifted margin and 135 00:07:42,280 --> 00:07:44,440 beyond. So that that's an extra pull 136 00:07:44,440 --> 00:07:46,040 that pulls the material in together. 137 00:07:46,400 --> 00:07:50,160 So that's so-called slab pull process, which is one of the 138 00:07:50,160 --> 00:07:53,040 main drivers of plate tectonics. Anyway, It's much easier to 139 00:07:53,040 --> 00:07:57,640 think of processes in terms of slab pull rather than if you 140 00:07:57,640 --> 00:08:00,530 like a car crash of continents okay. 141 00:08:00,530 --> 00:08:03,130 So you have this slab pool operating which consumes these 142 00:08:03,130 --> 00:08:06,330 low lying areas and then you say get choked up by the massive 143 00:08:06,330 --> 00:08:09,770 santral type thick crust. So what happens next? 144 00:08:09,850 --> 00:08:12,170 That thick crust is not completely thick. 145 00:08:12,170 --> 00:08:15,290 It actually consists of slightly weaker rifted basins, perhaps 146 00:08:15,290 --> 00:08:17,690 like the margins of intercontinental rifts like the 147 00:08:17,690 --> 00:08:21,850 North Sea for example, so that it's got some scope to deform 148 00:08:22,090 --> 00:08:27,030 and squash and to thicken up process we call inversion 149 00:08:27,030 --> 00:08:29,870 tectonics because what was basins have now become 150 00:08:29,870 --> 00:08:33,190 mountains. And in bygone days people really 151 00:08:33,190 --> 00:08:37,630 didn't recognize the presence of these old basin sections in the 152 00:08:37,630 --> 00:08:39,750 Alps. And the reason we now know this 153 00:08:40,110 --> 00:08:42,390 is because of a lot of detail work done by Alpine 154 00:08:42,390 --> 00:08:44,470 strategraphers and paleontologists, actually not by 155 00:08:44,470 --> 00:08:48,310 structural geologists who recognized earlier rift basins, 156 00:08:48,310 --> 00:08:51,230 The sort of things we now know exist because of seismic and so 157 00:08:51,230 --> 00:08:52,870 forth, places like the North Sea. 158 00:08:53,350 --> 00:08:57,430 And we recognize those in the stratigraphy now squashed up in 159 00:08:57,430 --> 00:09:01,350 the car crash of the Alps. So you've thickened the crust by 160 00:09:01,350 --> 00:09:03,190 squashing together those old basins. 161 00:09:03,550 --> 00:09:05,310 Okay. I'm still a little confused 162 00:09:05,310 --> 00:09:10,910 about the mechanism by which the basins get squashed together 163 00:09:10,990 --> 00:09:13,310 and. Form the topography. 164 00:09:13,310 --> 00:09:18,590 If the subduction process is essentially ground to a halt, 165 00:09:19,190 --> 00:09:23,540 the subduction is continuing in terms of what's happening for 166 00:09:23,540 --> 00:09:25,700 the upper mantle, rather like pulling a rug. 167 00:09:26,260 --> 00:09:29,340 And the material on the rug, which is the crust, gets rammed 168 00:09:29,340 --> 00:09:32,140 together. So you can imagine having a rug 169 00:09:32,140 --> 00:09:35,500 on the floor and you're pulling, Let's imagine you pull a rug 170 00:09:35,540 --> 00:09:38,180 under a bed. The furniture that's on that rug 171 00:09:38,500 --> 00:09:42,020 gets bashed into the bed frame. That's the concept of crust 172 00:09:42,020 --> 00:09:45,220 being bashed together. But the pull the rug, the slab 173 00:09:45,220 --> 00:09:50,540 pull continues until, of course, the amount of furniture has 174 00:09:50,540 --> 00:09:53,140 rammed up against the bed and you can't pull the rug anymore. 175 00:09:53,460 --> 00:09:55,660 And that's essentially what's happening in a collision 176 00:09:55,660 --> 00:09:59,260 process, that the crust that's coming in clogs the system up. 177 00:09:59,700 --> 00:10:02,580 But the process continues to the extent that it then creates 178 00:10:02,580 --> 00:10:05,340 topography and the squashing as you refer to it. 179 00:10:05,340 --> 00:10:08,890 Yeah, because the crust is thick, it doesn't take much 180 00:10:09,090 --> 00:10:11,570 extra squash to generate mountain ranges. 181 00:10:11,890 --> 00:10:15,570 The interesting feature of the thin crust that preceded it in 182 00:10:15,570 --> 00:10:19,250 the system is that it looks like that can be just carried down 183 00:10:19,250 --> 00:10:23,570 into the mantle and doesn't really do much topographically. 184 00:10:23,690 --> 00:10:26,410 It doesn't thicken much, it just gets in Trained in and we see 185 00:10:26,410 --> 00:10:30,130 that recorded by high pressure metamorphism in it, the record 186 00:10:30,210 --> 00:10:33,210 mineralogically of the material being taken down to great depth 187 00:10:33,330 --> 00:10:35,450 and changing character mineralogy. 188 00:10:36,220 --> 00:10:40,940 It then returns in that seduction zone by its residual 189 00:10:40,940 --> 00:10:43,980 buoyancy and it sort of squirts back up rather like toothpaste 190 00:10:43,980 --> 00:10:47,780 if you like being squirted out of the toothpaste tube, but 191 00:10:47,780 --> 00:10:50,860 that's a seduction process and isn't doing very much to 192 00:10:50,860 --> 00:10:53,420 generate topography. It's certainly making some neat 193 00:10:53,420 --> 00:10:56,060 structures in the rocks, but isn't really manifest in 194 00:10:56,060 --> 00:10:59,740 landscape processes. So let's wind the clock forward 195 00:10:59,740 --> 00:11:02,310 a bit. Well, that process we can date 196 00:11:02,310 --> 00:11:05,310 it radiometrically from cooling gauges and crystallization of 197 00:11:05,310 --> 00:11:09,270 minerals so that return flow, most of it seems to have 198 00:11:09,270 --> 00:11:13,790 happened by about thirtyish million years, so towards the 199 00:11:13,790 --> 00:11:16,670 end of the league of scene and that represents the change when 200 00:11:16,670 --> 00:11:19,470 that thicker concept of crust is arriving on the scene. 201 00:11:20,190 --> 00:11:22,990 So you get this return flow. You pack stuff up in the upper 202 00:11:22,990 --> 00:11:27,490 crust as it crushes in, and at the same time the thick content 203 00:11:27,530 --> 00:11:30,450 crust arrives and begins to thicken up as well. 204 00:11:30,570 --> 00:11:32,770 And that process is clogging the whole system up. 205 00:11:32,770 --> 00:11:36,010 Content crust is having a hard time getting down the subduction 206 00:11:36,010 --> 00:11:37,610 zone. Now you've got too much of it. 207 00:11:37,610 --> 00:11:40,290 It's too buoyant. And so that thickens. 208 00:11:40,610 --> 00:11:44,450 And now you start creating a range topographic mountain 209 00:11:44,450 --> 00:11:46,770 range. So you elevate the rocks that 210 00:11:46,770 --> 00:11:49,610 have come up this channel. You start seeing metamorphic 211 00:11:49,610 --> 00:11:53,090 rocks at the surface. They generate detritus that 212 00:11:53,090 --> 00:11:55,330 appears in the surrounding sedimentary records. 213 00:11:55,920 --> 00:11:59,080 And so you can chart not only that but also the bits of 214 00:11:59,200 --> 00:12:01,920 detritus coming off the thickening continental crust as 215 00:12:01,920 --> 00:12:03,400 well. And you see them all coming out 216 00:12:03,400 --> 00:12:05,640 together into the surrounding areas. 217 00:12:05,840 --> 00:12:08,560 And where do we see that detritus today? 218 00:12:08,920 --> 00:12:12,640 One of the really great records of it's actually is in a package 219 00:12:12,640 --> 00:12:15,720 of ROTS called the Manos Aranessa which is a Miacene 220 00:12:15,720 --> 00:12:18,160 succession in Northern Italy as you could probably guess from 221 00:12:18,160 --> 00:12:21,680 the name of notwithstanding my bad pronunciation and it's 222 00:12:21,680 --> 00:12:24,900 caught up in what is now the Northern Appanines and that 223 00:12:24,900 --> 00:12:28,740 package is a sequence of circle turbotites which are relatively 224 00:12:28,740 --> 00:12:32,540 deep water rocks. That area was low lying and is 225 00:12:32,580 --> 00:12:36,300 essentially submarine fans building out into what is to 226 00:12:36,300 --> 00:12:39,300 become Northern Italy. That's the smoking gun for these 227 00:12:39,300 --> 00:12:44,100 processes is that part of the Poe Basin today it went 228 00:12:44,100 --> 00:12:47,180 underneath the Poe Basin. The Poe Basin is yet younger 229 00:12:47,180 --> 00:12:50,740 still to try to that's come off the Alps and N Napanines and is 230 00:12:50,740 --> 00:12:53,970 still accumulating today. I said earlier that the 231 00:12:53,970 --> 00:12:57,130 preexisting structure along the southern margin of Europe played 232 00:12:57,130 --> 00:12:59,130 a critical role in the early evolution. 233 00:12:59,930 --> 00:13:02,930 Are you referring there to the transition from the thin crust 234 00:13:02,930 --> 00:13:06,050 to the thick crust or is there more fine grained detail that we 235 00:13:06,050 --> 00:13:08,810 see reflected in the deformation of the Alps today? 236 00:13:08,810 --> 00:13:12,370 That is a testament to that situation 40 million years ago. 237 00:13:12,650 --> 00:13:15,210 You're right first time. The general distribution of 238 00:13:15,210 --> 00:13:17,410 crustal thickness is fundamentally related to a 239 00:13:17,410 --> 00:13:21,010 rifting process in the Mesozoic which was forming tethers, the 240 00:13:21,010 --> 00:13:23,490 precursor ocean to the Alps and other chains. 241 00:13:24,090 --> 00:13:27,770 But in detail you can see that quite a lot of the contractual 242 00:13:27,770 --> 00:13:29,650 structures, the folds and so forth. 243 00:13:29,650 --> 00:13:33,610 You see it certainly in parts of the Alps like the Ekram National 244 00:13:33,610 --> 00:13:36,530 Park area to the east of the city of Gronog. 245 00:13:37,050 --> 00:13:38,850 The folds there, lots of the folds there. 246 00:13:38,850 --> 00:13:41,810 You can relate to rocks being squashed up against fault 247 00:13:41,810 --> 00:13:44,450 blocks, pre Jurassic age fault blocks. 248 00:13:44,810 --> 00:13:47,850 So the structures you see when you wander around in the Alps, 249 00:13:47,850 --> 00:13:51,990 many of them have the spatial distribution control by these 250 00:13:51,990 --> 00:13:56,750 preexisting basin structures. And the areas that didn't have 251 00:13:56,750 --> 00:14:00,670 very many preexisting normal faults have a much simpler 252 00:14:00,670 --> 00:14:03,910 stratigraphy, much more like a continuous layer cake. 253 00:14:04,110 --> 00:14:09,430 And those areas permitted thrust slip to go out rather like 254 00:14:09,430 --> 00:14:13,270 having a tablecloth moving out across a table top. 255 00:14:13,580 --> 00:14:16,380 If that table is broken up and has lots of different steps on 256 00:14:16,380 --> 00:14:17,740 it, that's much harder of course. 257 00:14:17,740 --> 00:14:22,180 So the areas that have those big so-called de Como are unsticking 258 00:14:22,180 --> 00:14:25,980 tectonics are places where there were very weak developments of 259 00:14:25,980 --> 00:14:29,620 these preexisting rift basins. And what regions would those 260 00:14:29,620 --> 00:14:32,740 correspond to today? The classic example of the Jura 261 00:14:32,740 --> 00:14:35,780 Hills in northern Switzer running around to that corner of 262 00:14:35,780 --> 00:14:38,820 France, that's the continuation, so outboard from Geneva, if you 263 00:14:38,820 --> 00:14:41,620 like, going right round towards outboard of Zurich. 264 00:14:42,310 --> 00:14:45,190 So that's the classic example. But you can see hints of it 265 00:14:45,190 --> 00:14:48,870 elsewhere in the geology of the Alps, where strata that 266 00:14:48,870 --> 00:14:52,710 deposited at a large scale across the top of blocks have 267 00:14:52,710 --> 00:14:55,070 been peeled off and carried out as thrust sheets. 268 00:14:55,270 --> 00:14:58,270 The term that people use all the time to describe these sheets 269 00:14:58,270 --> 00:15:00,750 are naps. That's what you're referring to, 270 00:15:00,750 --> 00:15:02,350 is it? Yeah, nappy sheet. 271 00:15:02,350 --> 00:15:05,150 So that's basically a tablecloth slipping around the place. 272 00:15:05,550 --> 00:15:08,750 Now, of course, if you squash any rocks enough, they can sort 273 00:15:08,750 --> 00:15:10,990 of squirt out. So that's not the exclusive 274 00:15:10,990 --> 00:15:13,990 reason why you get thrush sheets, some of the sedimentary 275 00:15:13,990 --> 00:15:15,510 basins when they're squashed a lot. 276 00:15:15,550 --> 00:15:18,830 Essentially, you're squirting the contents like a jam 277 00:15:18,830 --> 00:15:20,510 sandwich. You sort of squirt the contents 278 00:15:20,510 --> 00:15:23,470 out, and those can become far trouble thrush sheets as well. 279 00:15:23,550 --> 00:15:26,490 It's like an inelegant sort. Let's talk a bit about the 280 00:15:26,490 --> 00:15:29,170 different deformation styles then SO you already mentioned. 281 00:15:29,450 --> 00:15:32,130 How the juror are this tablecloth? 282 00:15:32,130 --> 00:15:34,610 Or I don't know if there's a more technical term for it, 283 00:15:34,810 --> 00:15:37,130 tectonics. Could you just describe the 284 00:15:37,130 --> 00:15:39,370 different parts of the Alps a little bit in terms of how 285 00:15:39,370 --> 00:15:42,490 they've deformed and how that manifests in what we see there 286 00:15:42,490 --> 00:15:44,450 today? Yes, take Cornwell. 287 00:15:44,450 --> 00:15:47,250 Tectonics would be the fanciest way you'd save for tablecloth. 288 00:15:47,250 --> 00:15:49,890 Takes on ungluing detachment tectonics. 289 00:15:50,290 --> 00:15:53,880 And that means just like a tablecloth, if you make that 290 00:15:53,880 --> 00:15:57,080 slip surface slightly sticky, it can rock up and make folds, and 291 00:15:57,080 --> 00:16:00,760 the folds have a very simple type of form, kilometer wide 292 00:16:01,040 --> 00:16:03,400 structures, they make the hills of quite a lot the juror. 293 00:16:03,400 --> 00:16:08,080 The landscape actually mimics the bedrock geology as you go 294 00:16:08,640 --> 00:16:12,080 deeper into the outs. Those rocks have had material 295 00:16:12,080 --> 00:16:13,520 taken off the top, they were hotter. 296 00:16:13,520 --> 00:16:15,800 Therefore, when they deformed, they were once deeper 297 00:16:16,280 --> 00:16:21,160 underground. And in those situations you get 298 00:16:21,320 --> 00:16:24,120 different types of folds. Shorter wavelengths for much 299 00:16:24,120 --> 00:16:25,400 shorter wavelengths. Folds. 300 00:16:25,880 --> 00:16:28,520 I've already touched on the idea that if they're preexisting 301 00:16:28,520 --> 00:16:33,160 normal faults, that the sedimentary strata in the little 302 00:16:33,160 --> 00:16:36,440 basins get squashed up against normal faults, and that will 303 00:16:36,440 --> 00:16:39,960 generate much shorter wavelength upright faults, much more 304 00:16:39,960 --> 00:16:44,680 intense folding than you see in the decor, more systems of the 305 00:16:44,680 --> 00:16:49,560 juror. So there's a fold scale and fold 306 00:16:49,680 --> 00:16:54,440 shape variation that relates to these different settings, in 307 00:16:54,440 --> 00:16:58,160 part related to where they lay on the old wifted concept of 308 00:16:58,160 --> 00:17:00,280 margin, whether they were normal faults or not. 309 00:17:00,360 --> 00:17:04,119 And in part where they lay in the crust or in the roots of the 310 00:17:04,119 --> 00:17:07,440 mountain range, what level they lay, which controls some of the 311 00:17:07,440 --> 00:17:09,560 ductility of the rocks when they were deforming. 312 00:17:10,400 --> 00:17:13,440 So these jewel controls, it is quite difficult to tease these 313 00:17:13,440 --> 00:17:16,160 out actually. What are the relative importance 314 00:17:16,160 --> 00:17:19,260 of of each Part of the issue is that structural geologists 315 00:17:19,260 --> 00:17:21,339 traditionally have only been really that bothered about the 316 00:17:21,339 --> 00:17:24,339 structure and haven't thought very much about the basins, the 317 00:17:24,339 --> 00:17:27,140 preexisting basin stratigraphy. These days, of course they do, 318 00:17:27,140 --> 00:17:30,820 but you go back 50 years when a lot of the ideas of folds 319 00:17:30,820 --> 00:17:34,380 relating to ductility were developed, the idea there were 320 00:17:34,380 --> 00:17:36,860 riff basins in the Alps was barely thought about. 321 00:17:37,620 --> 00:17:42,300 Is that partly because the structural features are so much 322 00:17:42,620 --> 00:17:44,780 easier to see? I mean, even the untrained eye 323 00:17:44,820 --> 00:17:48,030 like mine, you can see the glorious thrust, for example, 324 00:17:48,030 --> 00:17:50,070 It's just a great big line across the mountain. 325 00:17:50,110 --> 00:17:54,030 Is that because there's a selection effect based upon what 326 00:17:54,270 --> 00:17:57,230 it's easy to see when you go hiking in the mountains? 327 00:17:57,510 --> 00:18:00,070 I'm sure that's true. And there's a tendency also for 328 00:18:00,070 --> 00:18:03,350 people to work on things that they can recognize, things you 329 00:18:03,350 --> 00:18:05,670 can't necessarily make your mind up about straight away. 330 00:18:05,670 --> 00:18:08,510 I think there's a tendency for all of us to to put to one side, 331 00:18:08,870 --> 00:18:12,800 and often the stratigraphic relationships make for slightly 332 00:18:12,800 --> 00:18:15,680 more complicated structures because the layering wasn't nice 333 00:18:15,680 --> 00:18:19,680 and continuous to start with, so people have tended to overlook 334 00:18:19,680 --> 00:18:21,520 them. Nowadays people are going after 335 00:18:21,520 --> 00:18:24,880 them all over the place because those are the key and it's an 336 00:18:24,880 --> 00:18:28,560 interesting challenge in an investigation of any region. 337 00:18:28,880 --> 00:18:31,520 Something we have in the sciences, of course, is that the 338 00:18:31,640 --> 00:18:35,160 the world is our oyster, but it's a big world and a lot of 339 00:18:35,160 --> 00:18:37,290 oysters. And so the question is which 340 00:18:37,290 --> 00:18:39,930 bits do you concentrate on, which you think are important? 341 00:18:40,050 --> 00:18:42,090 For me, I think the important stuff is always the stuff you 342 00:18:42,090 --> 00:18:44,330 can't understand. It's the stuff that doesn't leap 343 00:18:44,330 --> 00:18:46,770 out at you, because that's almost certainly where you're 344 00:18:46,770 --> 00:18:49,450 going to find the solution. The things that are most obvious 345 00:18:49,450 --> 00:18:52,690 are usually not the most important, and in this case, the 346 00:18:52,690 --> 00:18:55,730 less obvious stuff is the preexisting stratigraphy. 347 00:18:56,050 --> 00:18:58,330 It's the areas where there's preexisting stratographic 348 00:18:58,330 --> 00:19:01,290 variation, those in Rift systems, those will happen most 349 00:19:01,290 --> 00:19:04,210 dramatically from one side of a normal fork to another, from a 350 00:19:04,210 --> 00:19:06,910 fork block to a basin. So you want to find those. 351 00:19:07,110 --> 00:19:09,110 It's a holistic approach. You want to try and put that 352 00:19:09,110 --> 00:19:12,430 strategically together at the same time as you are trying to 353 00:19:12,470 --> 00:19:15,510 unravel the structure one of the ways in which people. 354 00:19:15,790 --> 00:19:20,790 Try to disentangle the various contributions to this 355 00:19:20,790 --> 00:19:24,910 accommodation, if you like, Of the one continent moving next to 356 00:19:24,910 --> 00:19:27,190 another one is really the overall amount of crustal 357 00:19:27,190 --> 00:19:30,190 shortening that's taken place. And at least in the case of 358 00:19:30,190 --> 00:19:32,950 Himalayas, there's often a debate about to what extent 359 00:19:32,950 --> 00:19:37,810 that's accommodated by huge boundary faults, or by integral 360 00:19:38,250 --> 00:19:41,730 shortening through faults and maybe smaller faults on many 361 00:19:41,730 --> 00:19:44,810 different scales. Is that a similar debate in the 362 00:19:44,810 --> 00:19:48,090 Alps with respect to the fact that these early major faults 363 00:19:48,090 --> 00:19:50,690 were detected first and now we're finding out much more 364 00:19:50,690 --> 00:19:54,530 about the finer scale structure, understanding distributed 365 00:19:54,530 --> 00:19:58,090 deformation. An individual hand block won't 366 00:19:58,090 --> 00:20:01,570 have that much convergence between Italy and France 367 00:20:01,570 --> 00:20:04,130 recorded in it, but you put a lot of blocks together. 368 00:20:04,500 --> 00:20:08,580 That's a lot of convergence. And the catch is to capture that 369 00:20:08,580 --> 00:20:10,940 as an insight, it's quite difficult. 370 00:20:10,940 --> 00:20:12,300 You can't take a photograph of it. 371 00:20:12,820 --> 00:20:15,220 You can take a photograph of a little bit of it, but you can't 372 00:20:15,220 --> 00:20:17,620 capture the essence in the same way as you can by taking a 373 00:20:17,620 --> 00:20:20,700 photograph of the Glarus thrust. So I think in structural 374 00:20:20,700 --> 00:20:24,220 geology, I think this goes for many other scaledependent parts 375 00:20:24,220 --> 00:20:26,580 of the science. There's a tendency to deal with 376 00:20:26,580 --> 00:20:29,140 the things that you can capture the photograph or capture with 377 00:20:29,140 --> 00:20:32,620 the view, not necessarily capture the distributed nature 378 00:20:32,620 --> 00:20:35,090 of defamation. That's .1. 379 00:20:35,770 --> 00:20:39,530 However, the question really is whether you can evaluate the 380 00:20:39,530 --> 00:20:42,810 amount of shortening in mounting belts to actually get the 381 00:20:42,810 --> 00:20:44,650 convergence. It's something I tried a long 382 00:20:44,650 --> 00:20:46,890 time ago. In fact, my first post doc was 383 00:20:46,890 --> 00:20:49,770 to try and do exactly that in the outs, and I came up with a 384 00:20:49,770 --> 00:20:51,970 number of hundreds of kilometers shortening because if you 385 00:20:51,970 --> 00:20:54,250 unravel all these structures, that's the sort of number you 386 00:20:54,250 --> 00:20:55,530 get. The people have had similar 387 00:20:55,530 --> 00:21:00,010 numbers for centuries, but how much of that is because of the 388 00:21:00,010 --> 00:21:01,890 return flow in our subduction channel. 389 00:21:02,530 --> 00:21:05,010 So you since you're double accounting, you've got the 390 00:21:05,010 --> 00:21:06,890 material that's gone down off seduction zone. 391 00:21:06,890 --> 00:21:08,970 So that's recording true plate conversions. 392 00:21:09,810 --> 00:21:12,650 But if you also add in the return flow coming back up, 393 00:21:12,850 --> 00:21:15,210 you're counting it twice because it's come back up. 394 00:21:15,610 --> 00:21:18,530 So I think there's been an awful lot of double accounting going 395 00:21:18,530 --> 00:21:22,370 on and the challenge is to recognize it because there's 396 00:21:22,370 --> 00:21:23,890 obviously real convergence as well. 397 00:21:23,890 --> 00:21:27,130 So separating those two components, well, I don't think 398 00:21:27,130 --> 00:21:31,040 you can and maybe you try and find other explanations or other 399 00:21:31,040 --> 00:21:34,840 tools to establish the far field tectonic convergence in the 400 00:21:34,840 --> 00:21:37,280 system. What kind of tools might those 401 00:21:37,280 --> 00:21:39,120 be? For example, the Himalayan 402 00:21:39,120 --> 00:21:41,360 collision with Tibet and the rest of Asia. 403 00:21:41,360 --> 00:21:43,800 We understand how that works because we can reconstruct the 404 00:21:43,800 --> 00:21:47,360 plate motion on a global scale and reconstruct India's relative 405 00:21:47,360 --> 00:21:50,160 motion through the opening of the Indian Ocean basin for 406 00:21:50,160 --> 00:21:52,920 example and tied into a whole of plate tectonic model. 407 00:21:53,640 --> 00:21:56,480 And we can do a similar thing between the whole of Africa and, 408 00:21:56,480 --> 00:22:00,560 if you like, stable Europe. But what you can't do is then 409 00:22:00,560 --> 00:22:03,320 define the movements of the individual little blocks caught 410 00:22:03,320 --> 00:22:06,640 up in the car crash between which is the Alps, the other 411 00:22:06,640 --> 00:22:09,720 Mediterranean chains. You need to sort all those out. 412 00:22:10,240 --> 00:22:12,920 And that's tough anymore. That would be to if you have a 413 00:22:12,920 --> 00:22:15,720 car crash and to work out where a particular piece has come out 414 00:22:15,720 --> 00:22:16,840 of the car and where it's gone to. 415 00:22:16,880 --> 00:22:20,720 You couldn't forecast where that wing mirror went when you had a 416 00:22:20,720 --> 00:22:22,640 car crash. Not easily. 417 00:22:23,000 --> 00:22:26,080 So that's the challenge we have is having a marker we can work 418 00:22:26,080 --> 00:22:27,760 at. It's a scale that's appropriate 419 00:22:27,920 --> 00:22:31,890 to the scale of Alpine system. So then what you're suggesting 420 00:22:31,890 --> 00:22:35,810 is that there were many more fragments that came into play in 421 00:22:35,810 --> 00:22:39,130 determining what happened in this crash than there were in, 422 00:22:39,130 --> 00:22:42,130 for example, the Himalayan case. Let's take that in two parts. 423 00:22:42,250 --> 00:22:46,410 Certainly in an Alpine Mediterranean context, there is 424 00:22:46,410 --> 00:22:49,690 great debates about what the distribution of the various 425 00:22:49,690 --> 00:22:52,330 pieces of older concept of fragments. 426 00:22:52,330 --> 00:22:55,930 By all do I mean pretethis. So that's Triassic and older 427 00:22:55,930 --> 00:22:58,580 fragments, what their distribution was. 428 00:22:58,580 --> 00:23:01,420 You can identify where they are. There's a huge controversy about 429 00:23:01,420 --> 00:23:06,540 where, for example, the Calabria that the foot of Italy exactly 430 00:23:06,540 --> 00:23:09,220 sat nowhere near where it is now. 431 00:23:09,820 --> 00:23:12,580 Some of the other fragments that make up the Italian peninsula, 432 00:23:12,580 --> 00:23:17,580 where do those sit, let alone the southern margin of the Alps 433 00:23:17,580 --> 00:23:20,140 going into northern Italy? Where precisely was that 434 00:23:20,660 --> 00:23:24,540 precisely in this case is ±100 kilometers. 435 00:23:24,540 --> 00:23:26,780 Well, 100 kilometers is quite a lot of shortening in Alpine 436 00:23:26,780 --> 00:23:28,460 context. So that uncertainty of where 437 00:23:28,460 --> 00:23:31,660 you're going to put it feeds into the far field 438 00:23:31,660 --> 00:23:35,820 determinations of strain in the mountain belt and the price is 439 00:23:35,820 --> 00:23:39,660 in that value, not it's all about the 10s of kilometers, not 440 00:23:39,660 --> 00:23:42,260 the hundreds of kilometers when it comes to understanding the 441 00:23:42,260 --> 00:23:44,980 structure at the scale of those mountain ranges. 442 00:23:44,980 --> 00:23:48,060 Now the question is how much of that is also true of the 443 00:23:48,060 --> 00:23:49,660 Himalayas, and we just don't know it yet. 444 00:23:50,140 --> 00:23:53,140 People talk about the presence of volcanic arcs that were 445 00:23:53,140 --> 00:23:58,220 between India and Eurasia and whether those collided with 446 00:23:58,220 --> 00:24:00,260 Eurasia first or collided with India first. 447 00:24:00,420 --> 00:24:02,700 But we're not really talking about volcanic arcs. 448 00:24:02,700 --> 00:24:05,260 Yeah, we're just talking about where all these little terrains 449 00:24:05,900 --> 00:24:08,340 came to be after the previous phase of rifting. 450 00:24:08,460 --> 00:24:10,100 That's right. But the question is then what do 451 00:24:10,100 --> 00:24:12,020 you mean by terrain? So you could think of an 452 00:24:12,020 --> 00:24:15,980 individual fault block which has had a bit of stretch away from 453 00:24:15,980 --> 00:24:19,050 another bit of fault block on a rifted margin as being a 454 00:24:19,050 --> 00:24:21,890 microcontinental block. It was all joined together by 455 00:24:21,890 --> 00:24:24,210 bits of continent. But understanding where all 456 00:24:24,210 --> 00:24:29,010 those fragments exactly sit is the prize, and so you need to be 457 00:24:29,010 --> 00:24:31,610 able to unravel that. So it okay in a Himalayan case. 458 00:24:31,810 --> 00:24:34,530 What did that rifted margin look like that's been caught up? 459 00:24:35,330 --> 00:24:38,650 The amount of geological investigation of that problem in 460 00:24:38,650 --> 00:24:43,010 the Himalayas is miniscule compared to the understanding of 461 00:24:43,010 --> 00:24:46,370 what's been built in the Alps, where there's been two centuries 462 00:24:46,370 --> 00:24:49,900 of stratigraphic studies rather than a handful of expeditions 463 00:24:49,900 --> 00:24:52,460 into rather remote parts of the northern Himalayas. 464 00:24:52,820 --> 00:24:56,140 Coming back to the Alps, then, what are the most pressing 465 00:24:56,140 --> 00:24:59,020 research themes that people are engaged in today? 466 00:24:59,580 --> 00:25:02,380 There's a lot of effort trying to add geochronological 467 00:25:02,380 --> 00:25:05,420 precision to the timing of things, trying to get better 468 00:25:05,420 --> 00:25:09,940 estimates of the conditions in the subduction zone, partly 469 00:25:09,940 --> 00:25:13,900 because subduction zones are continuing to be a major topic 470 00:25:13,900 --> 00:25:16,500 in a science research. Understanding how continental 471 00:25:17,180 --> 00:25:21,060 fragments get entrained into subduction zones is a global 472 00:25:21,060 --> 00:25:23,780 issue, and the opposite is a place that you can try and look 473 00:25:23,780 --> 00:25:26,820 at that. Part of the challenge though is 474 00:25:26,820 --> 00:25:32,540 that many of these works rely on quite historical reconstructions 475 00:25:32,780 --> 00:25:36,620 of the large scale structure. So the question is, it's all 476 00:25:36,620 --> 00:25:40,500 very well having a very precise number on the defamation, but if 477 00:25:40,500 --> 00:25:43,620 you're imprecise about where it is in space, it doesn't 478 00:25:43,980 --> 00:25:48,530 necessarily help you that there remains this problem of how you 479 00:25:48,530 --> 00:25:53,370 deal with the diversity of data you need to solve these sorts of 480 00:25:53,370 --> 00:25:56,250 problems. And you've alluded to the idea 481 00:25:56,250 --> 00:26:00,330 that one of the app's great assets is the sheer amount of 482 00:26:00,330 --> 00:26:03,490 data. How do you handle it? 483 00:26:04,210 --> 00:26:06,530 Most of it's not real data. Most of it's first order 484 00:26:06,530 --> 00:26:10,490 interpretation derived from observations and caught up by 485 00:26:10,490 --> 00:26:13,490 all those issues we've been touching on such as selection 486 00:26:13,490 --> 00:26:16,440 bias. And so how do you see through 487 00:26:16,440 --> 00:26:17,960 all that? It's a challenge. 488 00:26:18,160 --> 00:26:20,760 I mean it's a challenge I have in trying to teach Alpine 489 00:26:20,760 --> 00:26:22,840 geology. How do you really get into what 490 00:26:22,840 --> 00:26:27,400 is knowledge, what is inference, what is known, what is unknown, 491 00:26:27,640 --> 00:26:30,480 what do we think we know? But actually we just assume and 492 00:26:30,480 --> 00:26:33,520 I think there's a real challenge with knowing too much or not 493 00:26:33,520 --> 00:26:37,560 being able to filter. Are the apps still growing today 494 00:26:38,000 --> 00:26:40,120 going up? Yes, they are. 495 00:26:40,450 --> 00:26:43,770 They're also wearing away and sending detritus down the River 496 00:26:43,770 --> 00:26:46,130 Poe whenever it rains, which this year it did a lot. 497 00:26:46,810 --> 00:26:50,290 So there's still Africa convergence going on that is, 498 00:26:50,890 --> 00:26:54,170 that is squeezing the crust a little bit, although hardly at 499 00:26:54,170 --> 00:26:55,770 all. And most of those earthquakes 500 00:26:55,770 --> 00:26:58,450 are not in the Alps there in places like Sicily and elsewhere 501 00:26:58,450 --> 00:27:00,930 in the Mediterranean area. But there's still a weak 502 00:27:00,930 --> 00:27:03,290 convergence going on. There's still earthquakes 503 00:27:03,290 --> 00:27:06,890 because of rebound rebounding crust is coming up and that 504 00:27:06,890 --> 00:27:08,970 that's not a steady process. It's creaky. 505 00:27:08,970 --> 00:27:11,730 So you get earthquakes, you get mountains that are growing. 506 00:27:12,330 --> 00:27:15,330 We know that not only because of geological research, it's also 507 00:27:15,330 --> 00:27:19,250 had a loss of topographic surveys for centuries, but also 508 00:27:19,530 --> 00:27:21,730 over the last 30 years from G PS:. 509 00:27:21,730 --> 00:27:23,810 Records. But you can also see the uplift 510 00:27:23,890 --> 00:27:26,530 in some of the long railway tunnels in Switzerland, which 511 00:27:26,530 --> 00:27:29,570 starts off horizontal and now bowed, so that there's 512 00:27:29,730 --> 00:27:33,010 relatively short kilometers wavelength differential uplift 513 00:27:33,010 --> 00:27:34,530 happening across the Alps as well. 514 00:27:35,120 --> 00:27:36,800 And that uplift has a tectonic origin. 515 00:27:36,920 --> 00:27:40,960 The principal driver is actually erosion, so that as you erode 516 00:27:41,080 --> 00:27:44,640 material and take it away from the Alps, you're taking a load 517 00:27:44,640 --> 00:27:47,400 off the Alps, which means the bits that haven't eroded, which 518 00:27:47,400 --> 00:27:50,800 are the mountain peaks rather than the mountain valleys, rise. 519 00:27:51,120 --> 00:27:56,240 So it's an isostatic response to erosion that's fascinating. 520 00:27:56,240 --> 00:28:00,560 So actually, by wearing down the mountains, we're just really 521 00:28:00,560 --> 00:28:04,300 creating more relief. We're not actually wearing down 522 00:28:04,300 --> 00:28:06,100 the peaks. Yeah, we're not wearing down the 523 00:28:06,100 --> 00:28:07,620 mountains. We're eroding the valleys, the 524 00:28:07,620 --> 00:28:10,660 valley sides, particularly in a glaciated time. 525 00:28:11,100 --> 00:28:13,740 Then you're wearing out to the bottoms and the sides of the 526 00:28:13,740 --> 00:28:16,140 valleys and the spiky bits go higher. 527 00:28:16,420 --> 00:28:18,380 Obviously, they fall down catastrophically every now and 528 00:28:18,380 --> 00:28:19,900 then. But actually, overall you 529 00:28:19,900 --> 00:28:23,420 generate exactly more relief. But that's really because 530 00:28:23,700 --> 00:28:25,500 overall, the Alps are still fairly young. 531 00:28:25,500 --> 00:28:27,700 I mean, eventually they'll be flattened like the Urals or 532 00:28:27,700 --> 00:28:30,490 something, won't they? Presumably once you've taken all 533 00:28:30,490 --> 00:28:33,370 the load off your ship, it just goes back to where it was. 534 00:28:33,410 --> 00:28:37,890 So yeah, are you currently engaged yourself in any Alpine 535 00:28:37,890 --> 00:28:39,810 research? One of the things I've been 536 00:28:39,810 --> 00:28:43,730 playing with is trying to use the sedimentary rocks and the 537 00:28:43,730 --> 00:28:48,010 strata that deposited around the time, particularly of the Eocene 538 00:28:48,210 --> 00:28:53,210 Oligocene to reconstruct relief. But it's submarine relief 539 00:28:53,490 --> 00:28:56,530 because these were submarine deposits, the turbulites, and 540 00:28:56,530 --> 00:29:00,600 they were fed into kilometer deep Seaways that surround the 541 00:29:00,600 --> 00:29:02,360 Alps. The things I mentioned before, 542 00:29:02,760 --> 00:29:04,920 the earliest ones weren't derived from the Alpine chain 543 00:29:04,920 --> 00:29:07,080 because the Alps wasn't generating topography, they were 544 00:29:07,080 --> 00:29:09,880 derived from other places and it came into this seaway. 545 00:29:09,880 --> 00:29:13,400 And so if you can reuse this record, you can potentially get 546 00:29:13,400 --> 00:29:18,600 a very detailed and quite subtle story of how bathymetry 547 00:29:18,760 --> 00:29:22,080 submarine topography varied around the edge of the Alps. 548 00:29:22,440 --> 00:29:25,800 I think it will provide information about the slab 549 00:29:25,800 --> 00:29:29,540 processes, the seduction zone processes that were just coming 550 00:29:29,540 --> 00:29:32,580 to an end at this sort of time, and it will tell us potentially 551 00:29:32,940 --> 00:29:37,180 how those slabs coupled with the adjacent, not so rifted margin 552 00:29:37,180 --> 00:29:39,940 of Europe. I'm a believer in serendipity 553 00:29:40,300 --> 00:29:43,820 and the importance of doing curiosity research. 554 00:29:43,860 --> 00:29:47,220 I don't know if it'll have any tectonic value at all, but if 555 00:29:47,220 --> 00:29:48,700 you don't do it, you'll never find out. 556 00:29:48,900 --> 00:29:51,300 Whereabouts are you actually looking at these sedimentary 557 00:29:51,340 --> 00:29:54,350 structures? I'm looking at it in a system 558 00:29:54,350 --> 00:29:56,950 that's Germany, known as the Great Dano, which is quite a 559 00:29:56,950 --> 00:29:59,430 famous set of turbodites in southeast France. 560 00:29:59,430 --> 00:30:03,270 And you can find its continuation around that rim 561 00:30:03,270 --> 00:30:06,390 through the Dauphin and maybe even up to that corner of 562 00:30:06,390 --> 00:30:08,990 western Switzerland, right around the western Alpine Ark. 563 00:30:09,230 --> 00:30:11,350 It's a nice place to go as well. So it's always good to have a 564 00:30:11,350 --> 00:30:16,350 hobby that provides good wine. Rob Butler, thank you very much. 565 00:30:16,350 --> 00:30:19,710 Thank you. It's been fun to see pictures 566 00:30:19,710 --> 00:30:22,430 and illustrations that support this podcast. 567 00:30:22,890 --> 00:30:28,330 Go to geologybytes.com, where you'll also find transcripts and 568 00:30:28,330 --> 00:30:30,690 a subject matter index of all the episodes. 569 00:30:31,610 --> 00:30:34,970 There you can also give me feedback, which I welcome, as 570 00:30:34,970 --> 00:30:37,930 well as sign up to get my emails about new episodes.