1 00:00:02,000 --> 00:00:05,000 KIRK JOHNSON: North America, the land that we love. 2 00:00:05,000 --> 00:00:08,000 It looks pretty familiar, don't you think? 3 00:00:13,000 --> 00:00:14,000 Well, think again! 4 00:00:20,000 --> 00:00:24,000 The ground we walk on is full of surprises 5 00:00:24,000 --> 00:00:25,000 if you know where to look. 6 00:00:25,000 --> 00:00:27,000 As a geologist, 7 00:00:27,000 --> 00:00:30,000 the Grand Canyon is perhaps the best place in the world. 8 00:00:30,000 --> 00:00:32,000 Every single one of these layers tells its own story 9 00:00:32,000 --> 00:00:34,000 about what North America was like 10 00:00:34,000 --> 00:00:37,000 when that layer was deposited. 11 00:00:37,000 --> 00:00:38,000 Are you ready for a little time travelling? 12 00:00:39,000 --> 00:00:41,000 I'm Kirk Johnson, 13 00:00:41,000 --> 00:00:43,000 the director of the Smithsonian 14 00:00:43,000 --> 00:00:45,000 National Museum of Natural History, 15 00:00:46,000 --> 00:00:50,000 and I'm taking off on the field trip of a lifetime. 16 00:00:50,000 --> 00:00:52,000 Wow, look at that rock right there. 17 00:00:52,000 --> 00:00:54,000 That is crazy! 18 00:00:54,000 --> 00:00:56,000 To find out how did our amazing continent 19 00:00:56,000 --> 00:00:58,000 get to be the way it is? 20 00:00:58,000 --> 00:01:00,000 EMILY WOLIN: Underneath Lake Superior, 21 00:01:00,000 --> 00:01:01,000 that's about 30 miles of volcanic rock. 22 00:01:01,000 --> 00:01:04,000 30 miles of volcanic rock? 23 00:01:06,000 --> 00:01:09,000 How did the landscape shape the creatures 24 00:01:09,000 --> 00:01:10,000 who lived and died here? 25 00:01:10,000 --> 00:01:12,000 14-foot-long fish in Kansas? 26 00:01:12,000 --> 00:01:13,000 MAN: That's what I'm telling you! 27 00:01:15,000 --> 00:01:18,000 JOHNSON: And how did we turn the rocks of our homeland... 28 00:01:18,000 --> 00:01:19,000 Oh, man! 29 00:01:19,000 --> 00:01:20,000 ...into riches? 30 00:01:20,000 --> 00:01:21,000 This thing is phenomenal. 31 00:01:22,000 --> 00:01:26,000 In this episode, we hunt down the clues 32 00:01:26,000 --> 00:01:27,000 to our continent's epic past. 33 00:01:27,000 --> 00:01:30,000 You can see new land being formed 34 00:01:30,000 --> 00:01:31,000 right in front of your eyes. 35 00:01:31,000 --> 00:01:34,000 Why does this golf course hold the secret 36 00:01:34,000 --> 00:01:36,000 to the rise and fall of the Rockies? 37 00:01:38,000 --> 00:01:41,000 What forces nearly cracked North America in half? 38 00:01:41,000 --> 00:01:45,000 And is it possible that the New York City skyline... 39 00:01:45,000 --> 00:01:46,000 I've always wanted to do this. 40 00:01:46,000 --> 00:01:50,000 ...was once dominated not by skyscrapers, 41 00:01:50,000 --> 00:01:51,000 but by towering mountains? 42 00:01:56,000 --> 00:02:00,000 We're uncovering secrets hiding in our own backyard. 43 00:02:00,000 --> 00:02:01,000 Peel it back. 44 00:02:01,000 --> 00:02:04,000 Whoa, that is unbelievable! 45 00:02:04,000 --> 00:02:10,000 "Making North America: Origins," right now on NOVA. 46 00:02:27,000 --> 00:02:29,000 Major funding for NOVA is provided by the following: 47 00:02:36,000 --> 00:02:39,000 KIRK JOHNSON: North America, our continent. c 48 00:02:42,000 --> 00:02:44,000 Filled with all these spectacular landscapes. 49 00:02:50,000 --> 00:02:54,000 They look like they've been here forever, 50 00:02:54,000 --> 00:02:56,000 but they are anything but permanent. 51 00:03:00,000 --> 00:03:05,000 The truth is, our continent has had its ups and downs-- 52 00:03:05,000 --> 00:03:06,000 literally! 53 00:03:09,000 --> 00:03:15,000 It's an epic tale of creation and destruction 54 00:03:15,000 --> 00:03:18,000 playing out over thousands, millions, 55 00:03:18,000 --> 00:03:21,000 even billions of years. 56 00:03:23,000 --> 00:03:24,000 Wow. 57 00:03:24,000 --> 00:03:25,000 We're going to trace this story 58 00:03:25,000 --> 00:03:29,000 back to the very beginning, 59 00:03:29,000 --> 00:03:31,000 to the origins of North America. 60 00:03:39,000 --> 00:03:41,000 (tail rattling) 61 00:03:49,000 --> 00:03:53,000 Our journey starts here in the American Southwest. 62 00:04:02,000 --> 00:04:05,000 This place is a paradise for geologists 63 00:04:05,000 --> 00:04:07,000 and one of our national treasures. 64 00:04:09,000 --> 00:04:13,000 It is, of course, the Grand Canyon. 65 00:04:16,000 --> 00:04:20,000 That is a big hole! 66 00:04:20,000 --> 00:04:21,000 And it gets me every time. 67 00:04:26,000 --> 00:04:29,000 Wow, this is absolutely awesome! 68 00:04:31,000 --> 00:04:34,000 The landscape is breathtaking, and so much more. 69 00:04:34,000 --> 00:04:37,000 As a geologist, the Grand Canyon 70 00:04:37,000 --> 00:04:39,000 is perhaps the best place in the world. 71 00:04:39,000 --> 00:04:41,000 It's this incredible 300-mile-long slice 72 00:04:41,000 --> 00:04:43,000 through the earth, 73 00:04:43,000 --> 00:04:46,000 and you can see layer after layer after layer 74 00:04:46,000 --> 00:04:48,000 after layer of sedimentary rock. 75 00:04:53,000 --> 00:04:55,000 Each layer is a time capsule 76 00:04:55,000 --> 00:04:59,000 with a slice of our continent's epic history locked inside, 77 00:04:59,000 --> 00:05:04,000 stretching hundreds of millions of years into the past. 78 00:05:04,000 --> 00:05:06,000 Every single one of these layers tells its own story 79 00:05:06,000 --> 00:05:08,000 about what North America was like 80 00:05:08,000 --> 00:05:10,000 when that layer was deposited. 81 00:05:10,000 --> 00:05:12,000 So here in one place, 82 00:05:12,000 --> 00:05:14,000 you have this incredible story of our continent 83 00:05:14,000 --> 00:05:16,000 laid out for your viewing pleasure. 84 00:05:22,000 --> 00:05:25,000 But to really tell that story, 85 00:05:25,000 --> 00:05:28,000 I've got to step out of my comfort zone. 86 00:05:28,000 --> 00:05:30,000 Are you ready for a little time travelling? 87 00:05:32,000 --> 00:05:34,000 I'm going to rappel down the cliff 88 00:05:34,000 --> 00:05:38,000 to get up close and personal with these rocks. 89 00:05:40,000 --> 00:05:44,000 Looks like I'm good to step off the edge of the Grand Canyon. 90 00:05:44,000 --> 00:05:46,000 I can't believe I'm doing this. 91 00:05:46,000 --> 00:05:49,000 I really don't like the fact you've put a cactus right here. 92 00:05:52,000 --> 00:05:54,000 This is the moment of truth. 93 00:06:03,000 --> 00:06:05,000 Oh, baby! 94 00:06:05,000 --> 00:06:08,000 This is not the easiest thing to do, 95 00:06:08,000 --> 00:06:12,000 especially in 100-degree heat, but it's worth it. 96 00:06:14,000 --> 00:06:17,000 Every foot I descend takes me further back in time. 97 00:06:24,000 --> 00:06:26,000 The first layer you come to in this part of the canyon 98 00:06:26,000 --> 00:06:29,000 is this pinkish rock I'm hanging next to right now. 99 00:06:29,000 --> 00:06:32,000 It's called the Esplanade Layer, 100 00:06:32,000 --> 00:06:34,000 and like all the rocks in the Grand Canyon, 101 00:06:34,000 --> 00:06:37,000 it's an ancient landscape frozen in time. 102 00:06:43,000 --> 00:06:45,000 300 million years ago, 103 00:06:45,000 --> 00:06:48,000 this place, and all of the American Southwest, 104 00:06:48,000 --> 00:06:52,000 was a vast sea of sand. 105 00:06:54,000 --> 00:06:58,000 Hot, dry winds sculpted an immense desert landscape 106 00:06:58,000 --> 00:06:59,000 of endless dunes. 107 00:07:02,000 --> 00:07:04,000 Over time, the sand compressed 108 00:07:04,000 --> 00:07:07,000 and transformed into the sandstone 109 00:07:07,000 --> 00:07:11,000 that forms the top ledge of the Grand Canyon here today. 110 00:07:13,000 --> 00:07:18,000 Further down, there's evidence of a very different landscape. 111 00:07:21,000 --> 00:07:23,000 About 1,000 feet below the rim of the canyon, 112 00:07:23,000 --> 00:07:27,000 the rock changes to limestone loaded with fossils. 113 00:07:27,000 --> 00:07:29,000 I've got a little fossil coral in my hand. 114 00:07:29,000 --> 00:07:31,000 It's fossils like this that tell us 115 00:07:31,000 --> 00:07:34,000 that this whole landscape was once underwater. 116 00:07:44,000 --> 00:07:48,000 340 million years ago, 117 00:07:48,000 --> 00:07:52,000 a warm, shallow sea covered all of the American Southwest. 118 00:07:55,000 --> 00:07:57,000 Its waters were teeming 119 00:07:57,000 --> 00:08:00,000 with trillions of microscopic marine organisms. 120 00:08:00,000 --> 00:08:06,000 When they died, their skeletons piled up on the seafloor 121 00:08:06,000 --> 00:08:08,000 and compressed into limestone, 122 00:08:08,000 --> 00:08:13,000 forming layers that are hundreds of feet thick. 123 00:08:17,000 --> 00:08:21,000 And so it goes, layer after layer of rock 124 00:08:21,000 --> 00:08:25,000 telling us the story of long-lost landscapes, 125 00:08:25,000 --> 00:08:29,000 each one once the surface of our continent. 126 00:08:36,000 --> 00:08:38,000 And right at the bottom, 127 00:08:38,000 --> 00:08:42,000 you find the granddaddy of Grand Canyon rocks: 128 00:08:42,000 --> 00:08:44,000 Granodiorite. 129 00:08:44,000 --> 00:08:46,000 This rock is more than 4,000 feet 130 00:08:46,000 --> 00:08:49,000 below the rim of the canyon, 131 00:08:49,000 --> 00:08:51,000 and it's one of the oldest rocks of them all. 132 00:08:51,000 --> 00:08:56,000 By measuring the radioactive elements in this granodiorite, 133 00:08:56,000 --> 00:08:58,000 the rock here at the bottom, 134 00:08:58,000 --> 00:09:04,000 geologists have figured out that it formed 1.7 billion years ago. 135 00:09:04,000 --> 00:09:08,000 Old for sure, but not the oldest rock on our continent. 136 00:09:08,000 --> 00:09:11,000 In fact, not even close. 137 00:09:17,000 --> 00:09:19,000 The first rocks on our planet formed 138 00:09:19,000 --> 00:09:22,000 over four billion years ago. 139 00:09:22,000 --> 00:09:26,000 Back then, the whole thing was a lump of molten rock 140 00:09:26,000 --> 00:09:29,000 under constant fire from asteroids. 141 00:09:34,000 --> 00:09:39,000 Eventually, the bombardment slowed and the earth cooled. 142 00:09:43,000 --> 00:09:46,000 It formed a hard, rocky crust, 143 00:09:46,000 --> 00:09:51,000 and as water seeped from the rocks, 144 00:09:51,000 --> 00:09:54,000 oceans soon covered almost the entire planet. 145 00:09:56,000 --> 00:09:58,000 Under an orange methane atmosphere, 146 00:09:58,000 --> 00:10:01,000 there was hardly any land in sight. 147 00:10:05,000 --> 00:10:08,000 So, how did North America and its fellow continents 148 00:10:08,000 --> 00:10:10,000 get started? 149 00:10:18,000 --> 00:10:21,000 To see what the very first land might have looked like, 150 00:10:21,000 --> 00:10:24,000 I'm heading to a place far from our continent, 151 00:10:24,000 --> 00:10:26,000 right in the middle of the Pacific ocean: 152 00:10:26,000 --> 00:10:31,000 Hawaii. 153 00:10:31,000 --> 00:10:34,000 Here, you can witness a force of nature 154 00:10:34,000 --> 00:10:36,000 that creates land from scratch. 155 00:10:44,000 --> 00:10:47,000 From up here, it looks like paradise, 156 00:10:47,000 --> 00:10:51,000 but there's an inferno bubbling under the surface. 157 00:10:56,000 --> 00:11:00,000 Just below us, lava is pouring right out of the mountainside. 158 00:11:20,000 --> 00:11:23,000 I'm flying over Mount Kilauea, 159 00:11:23,000 --> 00:11:28,000 one of the most active volcanoes on earth. 160 00:11:38,000 --> 00:11:41,000 Erupting since 1983, 161 00:11:41,000 --> 00:11:46,000 Mount Kilauea has spewed out ten billion tons of lava 162 00:11:46,000 --> 00:11:50,000 and resurfaced 50 square miles of land. 163 00:12:10,000 --> 00:12:13,000 All land on our planet started out like this, 164 00:12:13,000 --> 00:12:19,000 as lava cooling and turning into dark, heavy volcanic rock. 165 00:12:19,000 --> 00:12:22,000 It would take a dramatic transformation 166 00:12:22,000 --> 00:12:25,000 to turn volcanic islands like this 167 00:12:25,000 --> 00:12:26,000 into the first continents. 168 00:12:26,000 --> 00:12:29,000 I've got two kinds of rocks here. 169 00:12:29,000 --> 00:12:33,000 The first one is this dark, heavy stuff called basalt. 170 00:12:33,000 --> 00:12:35,000 This is the kind of rock you find on ocean floors 171 00:12:35,000 --> 00:12:38,000 and ocean crust and ocean islands like Hawaii. 172 00:12:38,000 --> 00:12:41,000 The second kind of rock is lighter in color 173 00:12:41,000 --> 00:12:43,000 and it's lighter in weight. 174 00:12:43,000 --> 00:12:44,000 It's called granite, 175 00:12:44,000 --> 00:12:47,000 and rocks like this form the stuff of our continents. 176 00:12:52,000 --> 00:12:55,000 You can find granite all over the place in North America, 177 00:12:55,000 --> 00:12:58,000 from the Appalachians on the East Coast 178 00:12:58,000 --> 00:13:02,000 to the sheer rock faces of Yosemite 179 00:13:02,000 --> 00:13:05,000 and the towering peaks of the Rockies. 180 00:13:07,000 --> 00:13:11,000 Without granite and other light rocks, 181 00:13:11,000 --> 00:13:13,000 there might not even be any continents. 182 00:13:13,000 --> 00:13:15,000 Because at one time, 183 00:13:15,000 --> 00:13:17,000 the only rock on the face of the Earth 184 00:13:17,000 --> 00:13:20,000 was volcanic rock like basalt. 185 00:13:22,000 --> 00:13:24,000 The trick is, how do you get the granite in the first place 186 00:13:24,000 --> 00:13:26,000 if you start out with only basalt? 187 00:13:32,000 --> 00:13:34,000 Under the ancient oceans, 188 00:13:34,000 --> 00:13:37,000 our whole planet was covered in basalt, 189 00:13:37,000 --> 00:13:41,000 broken into large chunks called plates. 190 00:13:43,000 --> 00:13:45,000 Deep beneath them, 191 00:13:45,000 --> 00:13:48,000 the heat of the earth softens the rocks 192 00:13:48,000 --> 00:13:52,000 and moves them like a giant conveyor belt. 193 00:13:52,000 --> 00:13:58,000 This pushes and pulls the plates of basalt along the surface 194 00:13:58,000 --> 00:14:02,000 and sometimes even drags them down, 195 00:14:02,000 --> 00:14:06,000 triggering a reaction in the red hot rocks below. 196 00:14:11,000 --> 00:14:15,000 The lighter stuff melts, floats upwards, 197 00:14:15,000 --> 00:14:19,000 and cools into granite, gradually building up 198 00:14:19,000 --> 00:14:24,000 a thick layer of light, buoyant rock. 199 00:14:26,000 --> 00:14:30,000 And this is how you turn heavy volcanic rocks 200 00:14:30,000 --> 00:14:35,000 into the rocks that make continents, including our own. 201 00:14:38,000 --> 00:14:41,000 In southern Canada, just north of Lake Superior, 202 00:14:41,000 --> 00:14:43,000 I'm on the hunt 203 00:14:43,000 --> 00:14:45,000 for some of the oldest rocks on our continent. 204 00:14:48,000 --> 00:14:50,000 I'm Kirk Johnson, here to see Cameron McLean. 205 00:14:50,000 --> 00:14:51,000 Okay, on you go. 206 00:14:51,000 --> 00:14:52,000 Thanks very much. 207 00:14:54,000 --> 00:14:59,000 This is Lac des Iles, a mine in Thunder Bay, Ontario. 208 00:14:59,000 --> 00:15:02,000 This huge open pit is just the tip of the iceberg. 209 00:15:04,000 --> 00:15:06,000 I'll be going way deeper. 210 00:15:15,000 --> 00:15:16,000 How deep are we going right now? 211 00:15:16,000 --> 00:15:18,000 We're going to get off at the 740 level. 212 00:15:18,000 --> 00:15:20,000 That's 740 meters below the surface. 213 00:15:20,000 --> 00:15:22,000 So over 2,000 feet, something like that. 214 00:15:24,000 --> 00:15:25,000 We're going down! 215 00:15:25,000 --> 00:15:26,000 Way down. 216 00:15:26,000 --> 00:15:27,000 Way down! 217 00:15:31,000 --> 00:15:34,000 At the bottom, nearly half a mile down, 218 00:15:34,000 --> 00:15:37,000 I realize the full scale of the mining operation. 219 00:15:43,000 --> 00:15:45,000 (explosion) 220 00:15:48,000 --> 00:15:53,000 Every day, they blast out 3,000 tons of rocks 221 00:15:53,000 --> 00:15:57,000 to find a treasure that formed a long time ago. 222 00:15:57,000 --> 00:15:59,000 McLEAN: Here, we've got a pile of ore 223 00:15:59,000 --> 00:16:01,000 that was just blasted this morning. 224 00:16:01,000 --> 00:16:02,000 We're in the ore now? Yup. 225 00:16:02,000 --> 00:16:05,000 JOHNSON: You basically shovel it out, 226 00:16:05,000 --> 00:16:09,000 grind it up, process it, and what do you get? 227 00:16:09,000 --> 00:16:11,000 We get this. 228 00:16:11,000 --> 00:16:13,000 Palladium. 229 00:16:19,000 --> 00:16:22,000 JOHNSON: Every day, miners extract nearly $400,000 worth of pall 230 00:16:22,000 --> 00:16:24,000 from these rocks. 231 00:16:27,000 --> 00:16:28,000 This silvery metal 232 00:16:28,000 --> 00:16:33,000 makes our cars' catalytic converters function. 233 00:16:33,000 --> 00:16:37,000 Palladium is 35 times more rare than gold. 234 00:16:40,000 --> 00:16:42,000 But to me, the most valuable thing down here 235 00:16:42,000 --> 00:16:44,000 is the rock the miners throw away. 236 00:16:47,000 --> 00:16:53,000 Geologists have dated the rock here in Lac des Iles 237 00:16:53,000 --> 00:16:56,000 and figured out that it formed nearly three billion years ago, 238 00:16:56,000 --> 00:16:59,000 which is just mind-blowing. 239 00:16:59,000 --> 00:17:01,000 That's almost a billion years older 240 00:17:01,000 --> 00:17:04,000 than the oldest rock at the bottom of the Grand Canyon. 241 00:17:10,000 --> 00:17:15,000 Lac des Iles sits in an ancient chunk of continental crust, 242 00:17:15,000 --> 00:17:19,000 one of the oldest building blocks of North America. 243 00:17:22,000 --> 00:17:25,000 Cooked up nearly three billion years ago, 244 00:17:25,000 --> 00:17:29,000 it merged with other chunks about 1.7 billion years ago 245 00:17:29,000 --> 00:17:33,000 to build the very first version of our continent: 246 00:17:33,000 --> 00:17:34,000 Laurentia. 247 00:17:39,000 --> 00:17:42,000 To this day, the ancient rocks of Laurentia 248 00:17:42,000 --> 00:17:44,000 form a solid foundation 249 00:17:44,000 --> 00:17:47,000 reaching about 100 miles deeper into the Earth 250 00:17:47,000 --> 00:17:50,000 than the rest of North America. 251 00:17:50,000 --> 00:17:53,000 Building Laurentia was a huge step forward 252 00:17:53,000 --> 00:17:56,000 in the making of North America. 253 00:17:58,000 --> 00:17:59,000 But there was some trouble ahead. 254 00:18:10,000 --> 00:18:13,000 150 miles farther south, 255 00:18:13,000 --> 00:18:16,000 the peaceful shores of Lake Superior 256 00:18:16,000 --> 00:18:19,000 hold traces of a cataclysmic event 257 00:18:19,000 --> 00:18:23,000 that very nearly ripped Laurentia apart. 258 00:18:27,000 --> 00:18:29,000 I've always loved beachcombing. 259 00:18:29,000 --> 00:18:32,000 You find amazing things on beaches. 260 00:18:32,000 --> 00:18:35,000 And one thing as a geologist you learn very quickly 261 00:18:35,000 --> 00:18:38,000 is that every single pebble tells a story. 262 00:18:38,000 --> 00:18:39,000 And on this beach, 263 00:18:39,000 --> 00:18:42,000 I'm looking for a very particular kind of pebble. 264 00:18:49,000 --> 00:18:52,000 Oh, here's one, that's excellent. 265 00:18:52,000 --> 00:18:55,000 It doesn't look like much on the backside of it, 266 00:18:55,000 --> 00:18:58,000 but if you turn it over, you can actually see 267 00:18:58,000 --> 00:18:59,000 this incredible banded structure. 268 00:18:59,000 --> 00:19:02,000 This is a classic beautiful Lake Superior agate. 269 00:19:02,000 --> 00:19:07,000 Agates form in cavities in rocks made by gas bubbles, 270 00:19:07,000 --> 00:19:10,000 and the result is this incredible banded 271 00:19:10,000 --> 00:19:12,000 semi-precious gemstone. 272 00:19:12,000 --> 00:19:15,000 Where you find agates, 273 00:19:15,000 --> 00:19:18,000 volcanoes, the source of the gas bubbles, 274 00:19:18,000 --> 00:19:20,000 are usually not far away. 275 00:19:23,000 --> 00:19:26,000 And just a stone's throw from the beach at Gooseberry Falls, 276 00:19:26,000 --> 00:19:32,000 I find a landscape made of nothing but volcanic rock. 277 00:19:32,000 --> 00:19:34,000 That tells me that this place 278 00:19:34,000 --> 00:19:38,000 was not always as serene as it looks today. 279 00:19:43,000 --> 00:19:46,000 A billion years ago, it was a hellish scene. 280 00:19:48,000 --> 00:19:54,000 And geophysicist Emily Wolin has the evidence. 281 00:19:54,000 --> 00:19:56,000 These falls are the record of a series 282 00:19:56,000 --> 00:19:58,000 of volcanic eruptions that happened in this area. 283 00:19:58,000 --> 00:20:00,000 So we have five steps in these falls, 284 00:20:00,000 --> 00:20:02,000 and you can think of each of those steps, 285 00:20:02,000 --> 00:20:04,000 each of these layers as another volcanic eruption. 286 00:20:07,000 --> 00:20:10,000 We have flow after flow of lava coming out, 287 00:20:10,000 --> 00:20:11,000 and believe it or not, what we're seeing here-- 288 00:20:11,000 --> 00:20:14,000 this huge stack of basalt-- is really only the tip. 289 00:20:14,000 --> 00:20:17,000 So it goes deep into the ground below us. 290 00:20:17,000 --> 00:20:19,000 It goes much deeper into the ground. 291 00:20:20,000 --> 00:20:24,000 So just how deep does this volcanic rock go? 292 00:20:28,000 --> 00:20:30,000 Emily has brought a piece of equipment 293 00:20:30,000 --> 00:20:33,000 that can help us see below the surface. 294 00:20:33,000 --> 00:20:37,000 It's an array of seismic sensors 295 00:20:37,000 --> 00:20:39,000 that you simply pin into the ground. 296 00:20:41,000 --> 00:20:43,000 Emily is part of a team 297 00:20:43,000 --> 00:20:45,000 that has deployed similar sensors 298 00:20:45,000 --> 00:20:48,000 all around Lake Superior. 299 00:20:48,000 --> 00:20:49,000 Should we test this now? 300 00:20:49,000 --> 00:20:51,000 WOLIN: Absolutely, go for it. 301 00:20:51,000 --> 00:20:52,000 JOHNSON: All right. 302 00:20:56,000 --> 00:20:58,000 I'm setting off little earthquakes! 303 00:20:58,000 --> 00:20:59,000 This is great! 304 00:21:00,000 --> 00:21:02,000 Did that work? 305 00:21:02,000 --> 00:21:04,000 WOLIN: Looks good. 306 00:21:04,000 --> 00:21:06,000 The key to this is that seismic waves 307 00:21:06,000 --> 00:21:10,000 travel at different speeds through different kinds of rock. 308 00:21:10,000 --> 00:21:11,000 The waves travel at different speeds 309 00:21:11,000 --> 00:21:13,000 through soil and granite and basalt? 310 00:21:13,000 --> 00:21:14,000 Exactly, yeah. 311 00:21:14,000 --> 00:21:17,000 We've put seismometers all around Lake Superior, 312 00:21:17,000 --> 00:21:19,000 and that tells us the kind of material 313 00:21:19,000 --> 00:21:20,000 that's far, far below our feet 314 00:21:20,000 --> 00:21:22,000 without actually having to drill down. 315 00:21:22,000 --> 00:21:24,000 How much basalt is actually down there? 316 00:21:24,000 --> 00:21:25,000 Underneath Lake Superior, 317 00:21:25,000 --> 00:21:29,000 this basalt and other volcanic rocks associated with it 318 00:21:29,000 --> 00:21:32,000 stretch 55 kilometers into the crust. 319 00:21:32,000 --> 00:21:34,000 That's about 30 miles of volcanic rock. 320 00:21:34,000 --> 00:21:37,000 30 miles of volcanic rock straight down. 321 00:21:37,000 --> 00:21:40,000 That's a lot of volcanic rock. 322 00:21:40,000 --> 00:21:42,000 That is a huge pile of volcanic rock. 323 00:21:42,000 --> 00:21:45,000 This rock is what remains 324 00:21:45,000 --> 00:21:48,000 from one of the biggest volcanic eruptions 325 00:21:48,000 --> 00:21:52,000 in the history of our planet. 326 00:21:52,000 --> 00:21:58,000 Where the water runs today, there once flowed a sea of fire. 327 00:22:01,000 --> 00:22:04,000 A little more than a billion years ago, 328 00:22:04,000 --> 00:22:06,000 Gooseberry Falls was the scene 329 00:22:06,000 --> 00:22:07,000 of one of the most violent events 330 00:22:07,000 --> 00:22:11,000 in North America's history. 331 00:22:11,000 --> 00:22:15,000 Huge torrents of lava poured from the earth off and on 332 00:22:15,000 --> 00:22:17,000 for about 20 million years. 333 00:22:21,000 --> 00:22:25,000 And it wasn't just burning up what's now Minnesota; 334 00:22:25,000 --> 00:22:29,000 the devastation spread much farther. 335 00:22:31,000 --> 00:22:35,000 Evidence of the immense scale comes from surveys 336 00:22:35,000 --> 00:22:37,000 like the ambitious project called the USArray. 337 00:22:39,000 --> 00:22:44,000 It's a huge network of 400 movable seismic sensors. 338 00:22:44,000 --> 00:22:46,000 In the last eight years, 339 00:22:46,000 --> 00:22:51,000 scientists have deployed these across the United States. 340 00:22:51,000 --> 00:22:54,000 It's providing the first complete picture 341 00:22:54,000 --> 00:22:56,000 of the rocks that make up our continent, 342 00:22:56,000 --> 00:23:01,000 almost like a 3-D MRI scan of North America, 343 00:23:01,000 --> 00:23:06,000 revealing an ancient geological wound. 344 00:23:06,000 --> 00:23:09,000 I'm looking at a map of the midwest United States. 345 00:23:09,000 --> 00:23:11,000 What I'm seeing is the distribution 346 00:23:11,000 --> 00:23:13,000 of these basalt flows. 347 00:23:13,000 --> 00:23:14,000 They stretch all the way through Iowa 348 00:23:14,000 --> 00:23:16,000 up into Minnesota, to Lake Superior, 349 00:23:16,000 --> 00:23:17,000 and then back down to Lake Michigan. 350 00:23:17,000 --> 00:23:21,000 It's a huge area about 1,000 miles long. 351 00:23:21,000 --> 00:23:22,000 And this map is really revealing 352 00:23:22,000 --> 00:23:24,000 because it shows a tremendous scar 353 00:23:24,000 --> 00:23:26,000 across the North American continent. 354 00:23:26,000 --> 00:23:31,000 The scar is the result of a huge rift that opened up 355 00:23:31,000 --> 00:23:34,000 in the heart of Laurentia over one billion years ago. 356 00:23:34,000 --> 00:23:40,000 Torrents of lava poured from the Earth. 357 00:23:40,000 --> 00:23:43,000 It was a gash more than 1,000 miles long 358 00:23:43,000 --> 00:23:48,000 that threatened to split our budding continent apart. 359 00:23:50,000 --> 00:23:52,000 But the rift mysteriously stopped. 360 00:23:56,000 --> 00:23:58,000 Today, all that's left of this gaping wound 361 00:23:58,000 --> 00:24:00,000 is the scar tissue, 362 00:24:00,000 --> 00:24:04,000 the basalt we find under Gooseberry Falls 363 00:24:04,000 --> 00:24:06,000 and right through the Midwest. 364 00:24:09,000 --> 00:24:13,000 What happened that kept our young continent whole? 365 00:24:13,000 --> 00:24:16,000 What was it that stopped the rift? 366 00:24:20,000 --> 00:24:22,000 No one knows for sure, 367 00:24:22,000 --> 00:24:26,000 but it could have been our neighbors. 368 00:24:26,000 --> 00:24:28,000 A billion years ago, 369 00:24:28,000 --> 00:24:31,000 some of the other continents on Earth 370 00:24:31,000 --> 00:24:33,000 converged on North America 371 00:24:33,000 --> 00:24:36,000 to form a supercontinent called Rodinia. 372 00:24:40,000 --> 00:24:43,000 It was a titanic group hug, 373 00:24:43,000 --> 00:24:49,000 and when it broke up, the rift had healed. 374 00:24:49,000 --> 00:24:53,000 North America was safe, but far from finished. 375 00:24:57,000 --> 00:25:00,000 Our continent now had a stable core. 376 00:25:02,000 --> 00:25:06,000 But to build its coastlines east and west, 377 00:25:06,000 --> 00:25:07,000 it would take a beating 378 00:25:07,000 --> 00:25:11,000 that went on for hundreds of millions of years. 379 00:25:19,000 --> 00:25:21,000 Making the East Coast we know today 380 00:25:21,000 --> 00:25:24,000 is an epic story of heat and collisions. 381 00:25:31,000 --> 00:25:34,000 Today, I'm hunting for relics 382 00:25:34,000 --> 00:25:38,000 of this continental makeover in Manhattan. 383 00:25:38,000 --> 00:25:40,000 Apartment block. 384 00:25:40,000 --> 00:25:42,000 Apartment block... 385 00:25:42,000 --> 00:25:44,000 Apartment block. 386 00:25:45,000 --> 00:25:47,000 Wow. 387 00:25:47,000 --> 00:25:49,000 No apartment block here. 388 00:25:49,000 --> 00:25:50,000 Rock! 389 00:25:54,000 --> 00:25:58,000 All over the city, you can see outcrops of bedrock. 390 00:25:58,000 --> 00:26:04,000 It's called Manhattan schist, and it's a clue to how the city 391 00:26:04,000 --> 00:26:08,000 and the whole East Coast was made. 392 00:26:08,000 --> 00:26:10,000 These rocky outcrops in Central Park 393 00:26:10,000 --> 00:26:13,000 don't really show up in too many guidebooks, 394 00:26:13,000 --> 00:26:15,000 but they're as important to New York's history 395 00:26:15,000 --> 00:26:16,000 as the Statue of Liberty or the Empire State Building. 396 00:26:22,000 --> 00:26:25,000 Here in the heart of midtown, a brand new apartment complex 397 00:26:25,000 --> 00:26:27,000 will soon rise up from the rocks. 398 00:26:30,000 --> 00:26:32,000 To build the foundation, 399 00:26:32,000 --> 00:26:37,000 the crew has to dig a pit deep into the Manhattan schist. 400 00:26:37,000 --> 00:26:39,000 So what's the toughest thing about drilling into this rock? 401 00:26:39,000 --> 00:26:41,000 A.B. OLEVIC: This rock is very solid. 402 00:26:41,000 --> 00:26:42,000 We've been here for ten weeks, 403 00:26:42,000 --> 00:26:44,000 and so far we went down about three feet. 404 00:26:44,000 --> 00:26:46,000 Wow, and you're just pounding away 405 00:26:46,000 --> 00:26:47,000 with those rock hammers? 406 00:26:47,000 --> 00:26:49,000 OLEVIC: Drilling and hammering away, yeah. 407 00:26:53,000 --> 00:26:54,000 Can I have a try? 408 00:26:54,000 --> 00:26:56,000 Absolutely, here's your chance. 409 00:26:56,000 --> 00:26:57,000 JOHNSON: All right, let's go do it. 410 00:27:01,000 --> 00:27:04,000 This is great, I've always wanted to do this. 411 00:27:04,000 --> 00:27:07,000 Takes a little concentration, but it's pretty straightforward. 412 00:27:07,000 --> 00:27:11,000 Up, down, backwards and then down, and then, hammer! 413 00:27:16,000 --> 00:27:18,000 This is incredibly hard rock. 414 00:27:18,000 --> 00:27:21,000 I mean, I could sit in this cab for hours pounding away, 415 00:27:21,000 --> 00:27:22,000 and it would take a long time 416 00:27:22,000 --> 00:27:25,000 to make even a couple of inches of progress. 417 00:27:25,000 --> 00:27:28,000 It's the tough Manhattan schist 418 00:27:28,000 --> 00:27:32,000 that's allowed the city's skyscrapers to soar. 419 00:27:32,000 --> 00:27:35,000 And the thing about schist is that it started its life as mud. 420 00:27:35,000 --> 00:27:40,000 What could have turned mud into this beast of a rock? 421 00:27:40,000 --> 00:27:45,000 I've found some evidence at the bottom of this construction pit. 422 00:27:45,000 --> 00:27:48,000 You can see the rock has a particular shine to it. 423 00:27:49,000 --> 00:27:51,000 This is a mineral called muscovite. 424 00:27:51,000 --> 00:27:55,000 And muscovite forms in big, platy crystals. 425 00:27:55,000 --> 00:27:57,000 Here's one that's almost an inch in diameter, 426 00:27:57,000 --> 00:27:59,000 and what's cool about this stuff 427 00:27:59,000 --> 00:28:01,000 is that it forms in even larger sheets, 428 00:28:01,000 --> 00:28:04,000 and in Moscow, where the word muscovite comes from, 429 00:28:04,000 --> 00:28:07,000 they used to use sheets of muscovite as window glass. 430 00:28:07,000 --> 00:28:11,000 Muscovite forms at over 500 degrees, 431 00:28:11,000 --> 00:28:14,000 and some of the surrounding schist formed 432 00:28:14,000 --> 00:28:16,000 at even higher temperatures. 433 00:28:16,000 --> 00:28:20,000 That gives me an idea about what happened 434 00:28:20,000 --> 00:28:22,000 that turned soft mud into hard rock. 435 00:28:25,000 --> 00:28:27,000 About a half a billion years ago, 436 00:28:27,000 --> 00:28:30,000 a chain of volcanic islands headed towards North America. 437 00:28:34,000 --> 00:28:36,000 Riding the Earth's conveyor belt, 438 00:28:36,000 --> 00:28:39,000 these islands bulldozed mud from the seafloor, 439 00:28:39,000 --> 00:28:43,000 dumped it onto the East Coast, and buried it. 440 00:28:54,000 --> 00:28:58,000 Over time, the mud compressed and baked into the hard bedrock, 441 00:28:58,000 --> 00:29:01,000 or schist, that's shaped the face of New York City. 442 00:29:03,000 --> 00:29:05,000 The skyline of New York City is so familiar. 443 00:29:05,000 --> 00:29:07,000 It's got this incredible group of tall buildings 444 00:29:07,000 --> 00:29:10,000 in the midtown, and then far to the south, 445 00:29:10,000 --> 00:29:11,000 down in downtown Manhattan, 446 00:29:11,000 --> 00:29:14,000 there's a second clump of skyscrapers. 447 00:29:14,000 --> 00:29:16,000 And in between there's much smaller buildings. 448 00:29:16,000 --> 00:29:20,000 And what's going on here is that in midtown, 449 00:29:20,000 --> 00:29:22,000 the Manhattan schist comes near the surface, 450 00:29:22,000 --> 00:29:25,000 and that allows the builders of the skyscrapers 451 00:29:25,000 --> 00:29:28,000 to attach their foundations firmly to bedrock. 452 00:29:28,000 --> 00:29:32,000 The same thing happens to the far south in downtown. 453 00:29:32,000 --> 00:29:34,000 And in between the bedrock dips deep below the surface 454 00:29:34,000 --> 00:29:36,000 where it's covered by gravels and sands. 455 00:29:36,000 --> 00:29:38,000 And there's not so many skyscrapers there-- 456 00:29:38,000 --> 00:29:40,000 it's much smaller buildings. 457 00:29:40,000 --> 00:29:43,000 So it's actually the geology that gives 458 00:29:43,000 --> 00:29:46,000 this very American city its very particular look. 459 00:29:55,000 --> 00:29:57,000 While other factors are involved, 460 00:29:57,000 --> 00:29:59,000 today these steel and concrete giants 461 00:29:59,000 --> 00:30:01,000 dominate New York's skyline. 462 00:30:01,000 --> 00:30:05,000 But 440 million years ago, they would have been dwarfed 463 00:30:05,000 --> 00:30:07,000 by something else. 464 00:30:12,000 --> 00:30:16,000 The same collision that created the Manhattan schist 465 00:30:16,000 --> 00:30:19,000 turned a flat coastal plain into something 466 00:30:19,000 --> 00:30:23,000 that's hard to believe-- a mountain range. 467 00:30:23,000 --> 00:30:27,000 Standing almost ten times taller than any skyscraper 468 00:30:27,000 --> 00:30:32,000 in New York today: the Taconic Mountains. 469 00:30:37,000 --> 00:30:39,000 The ancient Taconic Mountains were really big. 470 00:30:39,000 --> 00:30:42,000 They were the size of the Alps, maybe 13,000 feet tall. 471 00:30:42,000 --> 00:30:44,000 Today, very little remains. 472 00:30:48,000 --> 00:30:50,000 So where did they go? 473 00:30:55,000 --> 00:30:58,000 In Manhattan, they eroded away, leaving only bedrock. 474 00:31:01,000 --> 00:31:04,000 And this reveals one of the great geologic truths: 475 00:31:04,000 --> 00:31:06,000 no landscape is permanent. 476 00:31:10,000 --> 00:31:13,000 The formation of New York and the East Coast 477 00:31:13,000 --> 00:31:15,000 was just the first in a series 478 00:31:15,000 --> 00:31:17,000 of gigantic continental collisions 479 00:31:17,000 --> 00:31:20,000 that would transform not just North America, 480 00:31:20,000 --> 00:31:22,000 but the entire planet. 481 00:31:26,000 --> 00:31:27,000 (beeping) 482 00:31:29,000 --> 00:31:32,000 Evidence of this great clash of continents is hidden 483 00:31:32,000 --> 00:31:35,000 in one of the most spectacular vistas of North America. 484 00:31:39,000 --> 00:31:43,000 Over here, Kirk, this is one of the best spots up here. 485 00:31:45,000 --> 00:31:46,000 Wow, what a spot this is. 486 00:31:46,000 --> 00:31:48,000 This is incredible. 487 00:31:55,000 --> 00:31:59,000 JOHNSON: This is Zion Canyon. 488 00:31:59,000 --> 00:32:02,000 Its 2,000-foot sandstone cliffs 489 00:32:02,000 --> 00:32:05,000 are among the tallest of their kind on the planet. 490 00:32:11,000 --> 00:32:16,000 Locked inside them are the remnants of a lost world. 491 00:32:16,000 --> 00:32:19,000 DAVID LOOPE: Put yourself back in the Jurassic. 492 00:32:19,000 --> 00:32:24,000 JOHNSON: 200 million years ago, these rocks were endless dunes 00:32:29,000 in a vast desert covering much of the West. 494 00:32:31,000 --> 00:32:34,000 LOOPE: So this sandstone means we had nothing but sand 495 00:32:34,000 --> 00:32:39,000 being blown over an almost lifeless desert. 496 00:32:39,000 --> 00:32:43,000 And you piled up more and more and more, dune after dune. 497 00:32:43,000 --> 00:32:44,000 JOHNSON: So these great cliffs of Zion, 498 00:32:44,000 --> 00:32:46,000 these great sandstone cliffs 499 00:32:46,000 --> 00:32:50,000 are actually the stacked fossilized ancient sand dunes. 500 00:32:50,000 --> 00:32:51,000 LOOPE: That's it. 501 00:32:57,000 --> 00:32:59,000 JOHNSON: The rocks here in Zion bear witness 502 00:32:59,000 --> 00:33:02,000 to a traumatic phase in our continent's history. 503 00:33:08,000 --> 00:33:13,000 More than 300 million years ago, all the continents on Earth 504 00:33:13,000 --> 00:33:17,000 came together into the biggest landmass ever: 505 00:33:17,000 --> 00:33:26,000 the mega-continent Pangaea. 506 00:33:26,000 --> 00:33:30,000 A towering mountain range rose in its center, 507 00:33:30,000 --> 00:33:32,000 disrupting the climate 508 00:33:32,000 --> 00:33:35,000 and turning great swaths of North America parched and dry. 509 00:33:39,000 --> 00:33:42,000 It was a huge desert. 510 00:33:42,000 --> 00:33:44,000 Everything was so far from a source of moisture 511 00:33:44,000 --> 00:33:46,000 that you couldn't get rainfall. 512 00:33:46,000 --> 00:33:48,000 No moisture in the air. 513 00:33:48,000 --> 00:33:51,000 JOHNSON: So what happened to this giant desert? 514 00:33:51,000 --> 00:33:53,000 Why did it disappear? 515 00:33:55,000 --> 00:33:59,000 David has brought me here to look for clues 516 00:33:59,000 --> 00:34:04,000 in the rocks beneath our feet. 517 00:34:04,000 --> 00:34:07,000 But they're not easy to spot. 518 00:34:07,000 --> 00:34:09,000 LOOPE: We're getting close here. 519 00:34:09,000 --> 00:34:10,000 JOHNSON: And they'll be round? 520 00:34:10,000 --> 00:34:12,000 Or are they irregular? 521 00:34:12,000 --> 00:34:15,000 They'll look like circles on the rock surface. 522 00:34:15,000 --> 00:34:18,000 Always takes me a little while to get tuned in. 523 00:34:25,000 --> 00:34:26,000 JOHNSON: Is this one over here? 524 00:34:26,000 --> 00:34:28,000 Like this thing? 525 00:34:28,000 --> 00:34:31,000 LOOPE: Yup, you got it. 526 00:34:31,000 --> 00:34:32,000 There's that one. 527 00:34:32,000 --> 00:34:33,000 So they're in a row? 528 00:34:33,000 --> 00:34:35,000 You got a scale? 529 00:34:35,000 --> 00:34:38,000 LOOPE: That's about as good as it gets, yeah. 530 00:34:38,000 --> 00:34:41,000 JOHNSON: What we've found are strangely regular circles 531 00:34:41,000 --> 00:34:42,000 in the sandstone. 532 00:34:47,000 --> 00:34:52,000 Some of them lined up like a string of pearls. 533 00:34:52,000 --> 00:34:54,000 What could have made them? 534 00:34:57,000 --> 00:35:01,000 LOOPE: I ruled out tracks, I ruled out burrows, 535 00:35:01,000 --> 00:35:04,000 and then when I saw the near perfect alignment 536 00:35:04,000 --> 00:35:06,000 of these in lines and how they cross cut 537 00:35:06,000 --> 00:35:11,000 several different dune deposits, the light finally came on 538 00:35:11,000 --> 00:35:13,000 and I realized it's gotta be earthquakes. 539 00:35:13,000 --> 00:35:15,000 JOHNSON: Earthquakes? 540 00:35:15,000 --> 00:35:17,000 How could these little circles 541 00:35:17,000 --> 00:35:20,000 have anything to do with earthquakes? 542 00:35:20,000 --> 00:35:23,000 Turns out the mega-continent Pangaea was too big 543 00:35:23,000 --> 00:35:25,000 for its own good. 544 00:35:27,000 --> 00:35:32,000 Trapped heat rising from the earth caused enormous stress 545 00:35:32,000 --> 00:35:34,000 under the gigantic landmass, 546 00:35:34,000 --> 00:35:37,000 sending earthquakes shuddering across the land. 547 00:35:39,000 --> 00:35:41,000 When they hit the deserts of Zion, 548 00:35:41,000 --> 00:35:45,000 streams of groundwater shot up through the dunes 549 00:35:45,000 --> 00:35:48,000 and erupted in mini volcanoes of quicksand. 550 00:35:52,000 --> 00:35:55,000 So you're telling me that there'd be geysers of sand 551 00:35:55,000 --> 00:35:57,000 shooting out of these holes? 552 00:35:57,000 --> 00:36:00,000 (chuckling): That's what I'm telling you. 553 00:36:02,000 --> 00:36:06,000 JOHNSON: Pangaea ruled the Earth for 100 million years, 554 00:36:06,000 --> 00:36:08,000 but, finally, this monster of a continent 555 00:36:08,000 --> 00:36:11,000 couldn't hold it together, and it cracked apart. 556 00:36:14,000 --> 00:36:17,000 The sea flowed into a rift between the continents 557 00:36:17,000 --> 00:36:20,000 to form the Atlantic Ocean. 558 00:36:20,000 --> 00:36:23,000 North America drifted northward and as the climate changed, 559 00:36:23,000 --> 00:36:25,000 it became green again. 560 00:36:33,000 --> 00:36:35,000 Finally, our continent was free. 561 00:36:38,000 --> 00:36:41,000 The break-up of Pangaea more or less marks the moment 562 00:36:41,000 --> 00:36:44,000 that North America became a continent in its own right 563 00:36:44,000 --> 00:36:47,000 with the newly formed Atlantic on one side, 564 00:36:47,000 --> 00:36:49,000 what would become the Pacific on the other side, 565 00:36:49,000 --> 00:36:52,000 and a shape we'd recognize today. 566 00:36:52,000 --> 00:36:57,000 Still, one very important thing was missing: 567 00:36:57,000 --> 00:37:00,000 the Rocky Mountains. 568 00:37:05,000 --> 00:37:10,000 Miles high, stretching all the way from New Mexico to Canada, 569 00:37:10,000 --> 00:37:13,000 you'd think they've been here forever. 570 00:37:13,000 --> 00:37:16,000 But you would be wrong. 571 00:37:20,000 --> 00:37:25,000 These majestic mountains have come and gone several times. 572 00:37:28,000 --> 00:37:30,000 (beeping) 573 00:37:35,000 --> 00:37:38,000 Just outside the Mile High City of Denver, Colorado, 574 00:37:38,000 --> 00:37:41,000 you can see that for the Rocky Mountains, 575 00:37:41,000 --> 00:37:44,000 ups and downs were par for the course. 576 00:37:50,000 --> 00:37:53,000 This is an embarrassingly manicured landscape 577 00:37:53,000 --> 00:37:55,000 for a geologist, 578 00:37:55,000 --> 00:37:57,000 but I'm heading to the 14th hole, 579 00:37:57,000 --> 00:37:59,000 where there's some pretty amazing evidence 580 00:37:59,000 --> 00:38:03,000 for the forces involved in the uplift of the Rocky Mountains. 581 00:38:06,000 --> 00:38:08,000 Hey Kirk, how are you? 582 00:38:08,000 --> 00:38:10,000 Good to see you. 583 00:38:10,000 --> 00:38:15,000 Drone expert Jon Fredericks and I are gonna take 584 00:38:15,000 --> 00:38:19,000 his state of the art eye in the sky for a little spin. 585 00:38:19,000 --> 00:38:21,000 RICHIE: All right, let's take off. 586 00:38:34,000 --> 00:38:37,000 JOHNSON: The drone camera reveals a bizarre landscape. 587 00:38:40,000 --> 00:38:43,000 Jagged slabs of sandstone jutting out of the ground. 588 00:38:44,000 --> 00:38:45,000 Oh, look at that. 589 00:38:45,000 --> 00:38:47,000 Incredible. 590 00:38:47,000 --> 00:38:50,000 Just a beautiful landscape there. 591 00:38:55,000 --> 00:38:56,000 This is like being a bird 592 00:38:56,000 --> 00:38:58,000 and that's what geologists want to do, 593 00:38:58,000 --> 00:39:00,000 they want to get up in the air and look down on these rocks. 594 00:39:00,000 --> 00:39:05,000 And I can see just a beautiful perspective. 595 00:39:05,000 --> 00:39:07,000 These are layers of sandstone, they started off as sand, 596 00:39:07,000 --> 00:39:09,000 which means they were originally horizontal. 597 00:39:09,000 --> 00:39:11,000 Now they're tilted up. 598 00:39:11,000 --> 00:39:13,000 It's the kind of landscape you look at and wonder, 599 00:39:13,000 --> 00:39:14,000 what happened here? 600 00:39:20,000 --> 00:39:23,000 If you take a closer look at the sandstone slabs, 601 00:39:23,000 --> 00:39:26,000 you'll find some clues to how they got here. 602 00:39:28,000 --> 00:39:31,000 Mixed in with the finer sand grains are big pebbles 603 00:39:31,000 --> 00:39:33,000 with sharp edges. 604 00:39:33,000 --> 00:39:35,000 These are way too big to have been blown by wind. 605 00:39:35,000 --> 00:39:37,000 And given the size of these particles 606 00:39:37,000 --> 00:39:40,000 and how angular they are, there's probably only one way 607 00:39:40,000 --> 00:39:42,000 to get this kind of sediment moved along 608 00:39:42,000 --> 00:39:43,000 and that's by a river. 609 00:39:43,000 --> 00:39:46,000 And fast-flowing rivers begin in big mountains. 610 00:39:50,000 --> 00:39:52,000 So I'm thinking I'm looking at a sandstone that was formed 611 00:39:52,000 --> 00:39:53,000 near a mountain range. 612 00:39:53,000 --> 00:39:57,000 But what mountains? 613 00:39:57,000 --> 00:39:59,000 It can't be the Rockies. 614 00:39:59,000 --> 00:40:02,000 This sandstone formed way before they even existed. 615 00:40:03,000 --> 00:40:05,000 So what's the story? 616 00:40:11,000 --> 00:40:15,000 Standing here 300 million years ago, 617 00:40:15,000 --> 00:40:20,000 I'd be witnessing the birth of a long-lost mountain range. 618 00:40:22,000 --> 00:40:25,000 Called the Ancestral Rockies, 619 00:40:25,000 --> 00:40:27,000 they were nearly as high as the Rockies we see today. 620 00:40:36,000 --> 00:40:39,000 But over millions of years, 621 00:40:39,000 --> 00:40:42,000 rivers and rain ground down these ancient mountains 622 00:40:42,000 --> 00:40:45,000 and reduced them to sand and gravel, 623 00:40:45,000 --> 00:40:49,000 which compressed into sandstone. 624 00:40:49,000 --> 00:40:52,000 So the slabs we see on the golf course 625 00:40:52,000 --> 00:40:56,000 are all that's left of this long-forgotten mountain range. 626 00:40:58,000 --> 00:41:01,000 But how come these layers that were once horizontal 627 00:41:01,000 --> 00:41:05,000 are now standing on their heads? 628 00:41:05,000 --> 00:41:08,000 What was the force that was strong enough 629 00:41:08,000 --> 00:41:11,000 to push up hundreds of feet of layered rock up into the sky? 630 00:41:17,000 --> 00:41:20,000 70 million years ago, the rock that makes our modern Rockies 631 00:41:20,000 --> 00:41:25,000 was deep underground and covered by 10,000 feet of layered rock. 632 00:41:29,000 --> 00:41:33,000 But then something happened hundreds of miles away, 633 00:41:33,000 --> 00:41:35,000 on the western edge of North America: 634 00:41:35,000 --> 00:41:38,000 a slab of ocean floor diving deep into the earth 635 00:41:38,000 --> 00:41:41,000 suddenly starts attacking our continent, 636 00:41:41,000 --> 00:41:45,000 bulldozing right through its foundations. 637 00:41:47,000 --> 00:41:51,000 Far inland, this forced up a massive mountain range-- 638 00:41:51,000 --> 00:41:53,000 the Rockies 2.0. 639 00:42:01,000 --> 00:42:07,000 They lifted up the 10,000 feet of layered rock above them, 640 00:42:07,000 --> 00:42:10,000 tilting that ancient layer of sandstone, 641 00:42:10,000 --> 00:42:15,000 which erosion then sculpted into sharp, angled slabs: 642 00:42:15,000 --> 00:42:17,000 the jagged red monoliths 643 00:42:17,000 --> 00:42:19,000 that make this golf course so special. 644 00:42:22,000 --> 00:42:24,000 The colossal mountains that created them 645 00:42:24,000 --> 00:42:28,000 eventually eroded down. 646 00:42:28,000 --> 00:42:31,000 But then, about ten million years ago, 647 00:42:31,000 --> 00:42:36,000 the entire region was lifted a mile above sea level, 648 00:42:36,000 --> 00:42:43,000 giving us the spectacular Colorado Rockies we see today, 649 00:42:43,000 --> 00:42:45,000 a true signature landscape of the American West. 650 00:42:48,000 --> 00:42:49,000 They're still under construction, 651 00:42:49,000 --> 00:42:53,000 pushing up from below even as erosion 652 00:42:53,000 --> 00:42:56,000 keeps carving away at their majestic peaks. 653 00:43:03,000 --> 00:43:06,000 Now there's just one more big piece to add 654 00:43:06,000 --> 00:43:08,000 to our continental puzzle. 655 00:43:10,000 --> 00:43:13,000 The magnificent landscapes of the West Coast. 656 00:43:18,000 --> 00:43:20,000 Like Big Sur, 657 00:43:20,000 --> 00:43:25,000 the snow-capped volcanoes of the Pacific Northwest, 658 00:43:25,000 --> 00:43:30,000 and the fjords and islands of British Columbia and Alaska. 659 00:43:45,000 --> 00:43:47,000 To find out what made these landscapes, 660 00:43:47,000 --> 00:43:50,000 I'm gonna have to crack open a few rocks. 661 00:43:54,000 --> 00:43:56,000 of fossil hunters Tow 662 00:43:56,000 --> 00:43:59,000 to this remote beach. 663 00:43:59,000 --> 00:44:01,000 So what time is it? 664 00:44:01,000 --> 00:44:03,000 MAN: I think the tide has probably turned. 665 00:44:03,000 --> 00:44:05,000 MAN: 7:41. 666 00:44:05,000 --> 00:44:06,000 MAN: So we have about three hours right? 667 00:44:06,000 --> 00:44:08,000 JOHNSON: So I'm gonna turn you guys loose on this outcrop 00:44:11,000 and just scream if you find something good, all right? 669 00:44:11,000 --> 00:44:15,000 I've been here before and I really wanted to come back. 670 00:44:21,000 --> 00:44:25,000 (grunting) 671 00:44:25,000 --> 00:44:26,000 Nothing. 672 00:44:26,000 --> 00:44:28,000 It's just rock. 673 00:44:28,000 --> 00:44:31,000 You gotta break a lot of rock though to find fossils. 674 00:44:33,000 --> 00:44:37,000 There's nothing quite like splitting open slabs of rock-- 675 00:44:37,000 --> 00:44:40,000 you never know what you will find hidden inside. 676 00:44:40,000 --> 00:44:43,000 The bigger the slab you can lift up the better, 677 00:44:43,000 --> 00:44:45,000 because you just can't-- I can't emphasize it enough. 678 00:44:45,000 --> 00:44:47,000 MAN: I think you've been emphasizing it quite a bit. 679 00:44:47,000 --> 00:44:51,000 (grunting) 680 00:44:51,000 --> 00:44:52,000 JOHNSON: We've been cracking rocks for hours 681 00:44:52,000 --> 00:44:55,000 and we're running out of time. 682 00:44:58,000 --> 00:45:01,000 The tide is coming in, guys-- it's about 20 feet behind us. 683 00:45:02,000 --> 00:45:03,000 MAN: There it goes. 684 00:45:03,000 --> 00:45:05,000 JOHNSON: I have the rock, you take that rock. 685 00:45:05,000 --> 00:45:07,000 MAN: Peel this one back. 686 00:45:07,000 --> 00:45:08,000 And no fossil. 687 00:45:12,000 --> 00:45:14,000 Big split. 688 00:45:14,000 --> 00:45:15,000 No fossil. 689 00:45:15,000 --> 00:45:16,000 MAN: Big nothing! 690 00:45:16,000 --> 00:45:18,000 JOHNSON: With the tide on our heels, 691 00:45:18,000 --> 00:45:20,000 we get one last shot. 692 00:45:22,000 --> 00:45:24,000 You're on it. 693 00:45:24,000 --> 00:45:26,000 My fingers. 694 00:45:26,000 --> 00:45:28,000 Okay, we're... whoa. 695 00:45:28,000 --> 00:45:29,000 Oh, yes! 696 00:45:29,000 --> 00:45:34,000 Okay now, get this edge right here and just peel it back. 697 00:45:34,000 --> 00:45:36,000 Real slow-- one, two, three. 698 00:45:36,000 --> 00:45:41,000 (cheering) 699 00:45:41,000 --> 00:45:42,000 Look, there it is. 700 00:45:42,000 --> 00:45:44,000 Oh, my God. 701 00:45:44,000 --> 00:45:48,000 We've hit the jackpot: a fossilized palm frond. 702 00:45:49,000 --> 00:45:51,000 That is unbelievable! 703 00:45:53,000 --> 00:45:57,000 That, my friends, is a palm frond. 704 00:45:57,000 --> 00:46:02,000 The reason I'm so excited is we're not on 705 00:46:02,000 --> 00:46:03,000 the sunny shores of California... 706 00:46:06,000 --> 00:46:10,000 We're in Alaska! 707 00:46:10,000 --> 00:46:15,000 What's a palm leaf doing so far north? 708 00:46:15,000 --> 00:46:16,000 I'll tell you what. 709 00:46:16,000 --> 00:46:20,000 If you have a palm tree, the ground doesn't freeze. 710 00:46:20,000 --> 00:46:24,000 This palm grew here when the climate in Alaska 711 00:46:24,000 --> 00:46:28,000 and the rest of the world was much warmer. 712 00:46:28,000 --> 00:46:33,000 But there's something else going on here, 713 00:46:33,000 --> 00:46:36,000 because we've also found fossilized corals 714 00:46:36,000 --> 00:46:38,000 on a neighboring island. 715 00:46:38,000 --> 00:46:41,000 And they're much older than the palm frond. 716 00:46:43,000 --> 00:46:45,000 We know these corals lived near the equator, 717 00:46:45,000 --> 00:46:49,000 so how did their fossils wind up here in Alaska? 718 00:46:53,000 --> 00:47:00,000 Turns out the corals hitched a ride on strings of islands 719 00:47:00,000 --> 00:47:04,000 moving up from the Pacific, smacking into North America 720 00:47:04,000 --> 00:47:07,000 over millions of years. 721 00:47:10,000 --> 00:47:13,000 These travelling landmasses radically re-shaped 722 00:47:13,000 --> 00:47:16,000 our Pacific coastline. 723 00:47:19,000 --> 00:47:22,000 Imagine an island the size of Japan and imagine that island 724 00:47:22,000 --> 00:47:24,000 off the coast of North America drifting towards the coast 725 00:47:24,000 --> 00:47:26,000 at about three inches a year. 726 00:47:26,000 --> 00:47:30,000 Then imagine this field of logs is like lots of little Japans, 727 00:47:30,000 --> 00:47:32,000 log after log smacking in and sliding north, 728 00:47:32,000 --> 00:47:34,000 smacking in and sliding north. 729 00:47:34,000 --> 00:47:36,000 And you start to see a model 730 00:47:36,000 --> 00:47:39,000 for how the west coast of North America grew. 731 00:47:41,000 --> 00:47:46,000 It was a titanic geological logjam 732 00:47:46,000 --> 00:47:49,000 that grafted thousands of miles of new coastline 733 00:47:49,000 --> 00:47:53,000 onto our continent and still had enough power 734 00:47:53,000 --> 00:47:56,000 to push up the spectacular coastal mountain ranges 735 00:47:56,000 --> 00:47:58,000 of Alaska and British Columbia. 736 00:48:00,000 --> 00:48:03,000 The West coast is the most recent addition 737 00:48:03,000 --> 00:48:07,000 in the great continental construction project 738 00:48:07,000 --> 00:48:11,000 that built North America, but it's far from complete. 739 00:48:17,000 --> 00:48:20,000 On the coast of California, 740 00:48:20,000 --> 00:48:24,000 it's easy to find the signs of ongoing work. 741 00:48:24,000 --> 00:48:28,000 Just 30 miles north of San Francisco, 742 00:48:28,000 --> 00:48:32,000 Tomales Bay is one of the most enigmatic places 743 00:48:32,000 --> 00:48:33,000 on the West Coast, 744 00:48:33,000 --> 00:48:38,000 and a favorite spot for geologist Lisa White. 745 00:48:38,000 --> 00:48:39,000 Growing up in San Francisco, 746 00:48:39,000 --> 00:48:40,000 I always loved this area so much. 747 00:48:44,000 --> 00:48:46,000 It's really a curious situation here because the rocks 748 00:48:46,000 --> 00:48:50,000 on that side of the bay, that whole peninsula has been 749 00:48:50,000 --> 00:48:53,000 moving for millions of years from an area further south. 750 00:48:53,000 --> 00:48:55,000 And part of the puzzle 751 00:48:55,000 --> 00:48:57,000 is we're standing on the San Andreas fault. 752 00:49:03,000 --> 00:49:05,000 JOHNSON: Hidden deep under this bay 753 00:49:05,000 --> 00:49:08,000 is an enormous crack in the earth. 754 00:49:11,000 --> 00:49:13,000 This is the San Andreas fault. 755 00:49:17,000 --> 00:49:20,000 It cuts right through Tomales Bay 756 00:49:20,000 --> 00:49:22,000 and runs 800 miles through California, 757 00:49:22,000 --> 00:49:27,000 separating two huge chunks of the earth's crust-- 758 00:49:27,000 --> 00:49:35,000 the Pacific plate and the North American plate-- 759 00:49:35,000 --> 00:49:37,000 which are sliding in opposite directions. 760 00:49:41,000 --> 00:49:44,000 WHITE: We're sitting on the North American plate 761 00:49:44,000 --> 00:49:45,000 and the Pacific plate over there 762 00:49:45,000 --> 00:49:50,000 relative to where we're sitting is moving to the northwest. 763 00:49:50,000 --> 00:49:52,000 So that whole peninsula is moving along. 764 00:49:52,000 --> 00:49:53,000 How fast is it going? 765 00:49:53,000 --> 00:49:55,000 That whole peninsula is moving 766 00:49:55,000 --> 00:49:57,000 about the speed that our fingernails grow, 767 00:49:57,000 --> 00:49:59,000 so couple of inches every year. 768 00:50:04,000 --> 00:50:06,000 JOHNSON: Tension in the San Andreas 769 00:50:06,000 --> 00:50:10,000 can trigger violent earthquakes, like the one that devastated 770 00:50:10,000 --> 00:50:15,000 San Francisco in 1906 and many others since. 771 00:50:19,000 --> 00:50:22,000 WHITE: 1906, 1989, 1993-- 772 00:50:22,000 --> 00:50:23,000 you name them. 773 00:50:23,000 --> 00:50:25,000 Pretty much most decades we can think of 774 00:50:25,000 --> 00:50:28,000 significant earthquakes that happened. 775 00:50:28,000 --> 00:50:31,000 JOHNSON: The power of the moving plates 776 00:50:31,000 --> 00:50:35,000 constantly changes the face of California, 777 00:50:35,000 --> 00:50:38,000 with surprising long-term results. 778 00:50:38,000 --> 00:50:41,000 So what this is means is that sooner or later Los Angeles 779 00:50:41,000 --> 00:50:45,000 is going to pull up right next to San Francisco. 780 00:50:45,000 --> 00:50:49,000 The view from the Hollywood hills will be very different. 781 00:50:52,000 --> 00:50:54,000 WHITE: Imagine that. 782 00:50:54,000 --> 00:50:56,000 So two towns that don't even like each other very much 783 00:50:56,000 --> 00:50:58,000 will be neighbors. 784 00:50:58,000 --> 00:51:02,000 But what understanding the geology of California 785 00:51:02,000 --> 00:51:04,000 really illustrates is just how dynamic the state is. 786 00:51:06,000 --> 00:51:08,000 JOHNSON: California is one of those places 787 00:51:08,000 --> 00:51:11,000 where the forces under our feet really make themselves known. 788 00:51:16,000 --> 00:51:21,000 Our wild ride across North America and back in time 789 00:51:21,000 --> 00:51:24,000 reveals these forces are relentlessly at work. 790 00:51:26,000 --> 00:51:29,000 Continent building never ends 791 00:51:29,000 --> 00:51:31,000 because we know one thing for sure in geology-- 792 00:51:31,000 --> 00:51:34,000 nothing ever stays the same for very long. 793 00:51:35,000 --> 00:51:39,000 North America has seen some amazing transformations. 794 00:51:42,000 --> 00:51:46,000 It took billions of years to take the shape it is today. 795 00:51:49,000 --> 00:51:52,000 But far from reaching the end of our story, 796 00:51:52,000 --> 00:51:56,000 we're really just embarking on the next chapter: 797 00:51:56,000 --> 00:52:00,000 how geology shaped life on our continent. 798 00:52:03,000 --> 00:52:04,000 (hissing) 799 00:52:22,000 --> 00:52:24,000 The three-part NOVA series "Making North America" The investig 800 00:52:24,000 --> 00:52:26,000 is available on DVD. 801 00:52:26,000 --> 00:52:32,000 To order, visit shoppbs.org or call 1-800-PLAY-PBS. 802 00:52:32,000 --> 00:52:34,000 NOVA is also available for download from iTunes.