1 00:00:00,000 --> 00:00:28,680 Wow! 2 00:00:28,680 --> 00:00:29,680 This is amazing! 3 00:00:29,680 --> 00:00:31,160 This is so cool! 4 00:00:31,160 --> 00:00:34,040 I can't believe I'm touching a dinosaur bone! 5 00:00:34,040 --> 00:00:35,040 Is this real? 6 00:00:35,040 --> 00:00:36,040 Yes it is! 7 00:00:36,040 --> 00:00:41,680 Hi, I'm David Wittman, I'm a park ranger here, and these bones are 150 million years 8 00:00:41,680 --> 00:00:42,680 old. 9 00:00:42,680 --> 00:00:43,680 Wow! 10 00:00:43,680 --> 00:00:44,680 Want to see something really neat? 11 00:00:44,680 --> 00:00:45,680 Yes! 12 00:00:45,680 --> 00:00:46,680 Follow me. 13 00:00:46,680 --> 00:00:47,680 Amazing! 14 00:00:47,680 --> 00:00:52,600 I've never seen anything like this! 15 00:00:52,600 --> 00:00:54,440 Did you just put these bones in the wall? 16 00:00:54,440 --> 00:00:55,840 No, we didn't. 17 00:00:55,840 --> 00:00:59,600 The excavation started here in 1909 and ended in 1990. 18 00:00:59,600 --> 00:01:05,080 We're doing excavations elsewhere, but during that period of time, we uncovered over a thousand 19 00:01:05,080 --> 00:01:06,080 dinosaur bones. 20 00:01:06,080 --> 00:01:07,520 How did they all get here? 21 00:01:07,520 --> 00:01:12,560 A lot of them died of natural causes, and some of them died when the river dried up 22 00:01:12,560 --> 00:01:13,560 and they didn't have enough water. 23 00:01:13,560 --> 00:01:15,200 Oh, I almost forgot. 24 00:01:15,200 --> 00:01:18,680 My friends wanted to find out for sure if fossils are clues towards plate tectonics 25 00:01:18,680 --> 00:01:19,680 and earthquakes. 26 00:01:19,680 --> 00:01:20,680 Oh, I can help you with that. 27 00:01:20,680 --> 00:01:21,680 I have lots of questions. 28 00:01:21,680 --> 00:01:23,520 What was the environment like? 29 00:01:23,760 --> 00:01:29,520 Well, this was the bottom of a river, and the area was flat, arid, there were a lot 30 00:01:29,520 --> 00:01:33,760 of plants growing along the rivers, and of course that's where the dinosaurs congregated. 31 00:01:33,760 --> 00:01:34,760 Another question. 32 00:01:34,760 --> 00:01:35,760 How warm was the climate? 33 00:01:35,760 --> 00:01:43,000 It was hot year-round, and the reason for that was that this area was a lot closer to 34 00:01:43,000 --> 00:01:46,960 the equator 150 million years ago. 35 00:01:46,960 --> 00:01:53,160 So over the last 150 million years, because of plate tectonics or continental drift, this 36 00:01:53,160 --> 00:01:56,000 area has moved northward 400 miles. 37 00:01:56,000 --> 00:01:58,480 It's hard to believe that land can actually move that far. 38 00:01:58,480 --> 00:02:03,360 I read in a book once that no one believed Alfred Wagner in the early 1900s when he proposed 39 00:02:03,360 --> 00:02:05,960 the idea known as continental drift. 40 00:02:05,960 --> 00:02:07,600 What is continental drift? 41 00:02:07,600 --> 00:02:14,360 It was a theory that stated that the continents were once one large land mass called Pangaea. 42 00:02:14,360 --> 00:02:18,880 Clues indicate that in the last 200 million years, the continents have moved or drifted 43 00:02:18,880 --> 00:02:21,160 horizontally to their current locations. 44 00:02:21,160 --> 00:02:26,600 A revised theory called plate tectonics explains why continents drift. 45 00:02:26,600 --> 00:02:31,480 Continents are a part of large plates that move across the Earth's surface and bang into 46 00:02:31,480 --> 00:02:34,760 one another, causing earthquakes and pushing up mountain ranges. 47 00:02:34,760 --> 00:02:36,560 You mean fossil clues? 48 00:02:36,560 --> 00:02:39,720 Yes, fossils can be clues to continental drift. 49 00:02:39,720 --> 00:02:45,640 For example, fossils of the reptile Messosaurus have been found in South America and Africa. 50 00:02:45,640 --> 00:02:50,160 These reptiles live in freshwater and on land, so how could they be found on different continents 51 00:02:50,160 --> 00:02:52,960 unless the continents had at one time been together? 52 00:02:52,960 --> 00:02:55,160 Well, another clue could be found in rocks. 53 00:02:55,160 --> 00:02:56,160 Strange. 54 00:02:56,160 --> 00:02:59,560 How do you know that a rock found here is the same as another rock found in the Colorado 55 00:02:59,560 --> 00:03:00,560 Plateau? 56 00:03:00,560 --> 00:03:01,560 Well, why don't you come with me? 57 00:03:01,560 --> 00:03:02,960 We'll take a walk and find out. 58 00:03:02,960 --> 00:03:03,960 Great. 59 00:03:06,960 --> 00:03:08,760 Well, Jacob, this is the Green River. 60 00:03:08,760 --> 00:03:09,760 Wow. 61 00:03:09,760 --> 00:03:11,760 I know I'd never seen anything like this before. 62 00:03:11,760 --> 00:03:15,360 As you can see, there's lots of different kinds of rocks here. 63 00:03:15,360 --> 00:03:18,360 Rocks can be clues to continental drift, but that's not the case here. 64 00:03:18,360 --> 00:03:19,920 They all look the same to me. 65 00:03:19,920 --> 00:03:21,920 How can you tell the difference between rock structures? 66 00:03:21,920 --> 00:03:23,920 Well, it's like a detective story. 67 00:03:23,920 --> 00:03:25,920 We look over at this sandstone over here. 68 00:03:25,920 --> 00:03:30,820 It looks like six other types of sandstone that we have in the monument. 69 00:03:30,820 --> 00:03:32,640 So how do we tell the difference? 70 00:03:32,640 --> 00:03:35,720 We have to look at the rocks that are associated with it. 71 00:03:35,720 --> 00:03:40,520 We look at the rock that's just below that sandstone, we can tell it's the Chinle Formation. 72 00:03:40,520 --> 00:03:43,840 Chinle looks the same all across the Colorado Plateau. 73 00:03:43,840 --> 00:03:47,920 So now we know the rock above it, this sandstone, is the Glen Canyon Sandstone. 74 00:03:47,920 --> 00:03:49,720 Do you have earthquakes here? 75 00:03:49,720 --> 00:03:52,720 Earthquakes are caused by mountain building forces. 76 00:03:52,720 --> 00:04:00,720 So 65 million years ago, as these flat rocks were being pushed up into an arch, earthquakes occurred. 77 00:04:00,720 --> 00:04:07,720 If you've ever seen a cake in an oven, it'll rise and rise and rise, but at some point, what happens to the cake? 78 00:04:07,720 --> 00:04:08,720 It rises too much. 79 00:04:08,720 --> 00:04:10,720 It has to sink back down eventually. 80 00:04:10,720 --> 00:04:11,720 It'll collapse. 81 00:04:11,720 --> 00:04:13,720 Well, the same thing happens with rocks. 82 00:04:13,720 --> 00:04:19,720 They'll be bent, but they can only bend so far, and at some point, they'll eventually break. 83 00:04:19,720 --> 00:04:21,720 And when the rocks break, is that what causes an earthquake? 84 00:04:21,720 --> 00:04:22,720 That's correct. 85 00:04:22,720 --> 00:04:27,720 That break is the fault line, and when the rocks move along the fault line, it creates an earthquake. 86 00:04:27,720 --> 00:04:29,720 Well, have I answered all your questions? 87 00:04:29,720 --> 00:04:31,720 Yeah, I can't wait to go email the treehouse detectives. 88 00:04:31,720 --> 00:04:34,720 Well, do you have some time to go look for some fossils? 89 00:04:34,720 --> 00:04:35,720 Sure. 90 00:04:35,720 --> 00:04:36,720 All right, let's go.