Continental Drift [Updated, 2018] — Transcript

Full transcript

1. 0:02[Music]
2. 0:07[Laughter]
3. 0:14take a look at this satellite image of
4. 0:16Earth's surface if you look carefully at
5. 0:19the continents you might notice
6. 0:21something which many have noticed in the
7. 0:23past and that is that the continents
8. 0:25almost look like they fit together kind
9. 0:28of like the pieces of some sort of giant
10. 0:31massive puzzle of course you probably
11. 0:34notice this the very first time you saw
12. 0:37a map of the earth or a globe while a
13. 0:39child in school the place on the earth
14. 0:42where this is most obvious is along the
15. 0:45eastern coast of South America and the
16. 0:48western coast of Africa here it really
17. 0:51appears like the continents fit together
18. 0:55now of course people have known this for
19. 0:57hundreds of years ever since the first
20. 1:00accurate maps were created but most
21. 1:03people just chalked it up to mere
22. 1:05coincidence one person who had trouble
23. 1:08with that though was German
24. 1:10meteorologist Alfred Wegener you see
25. 1:13Vagner couldn't just accept that this
26. 1:16was a coincidence and that these land
27. 1:18masses had such similar shaped
28. 1:20coastlines and so he began to think
29. 1:24about this and try and come up with some
30. 1:26sort of explanation and what he
31. 1:29concluded was something radical that the
32. 1:32continents are moving an inventor's head
33. 1:36if the continents are in fact moving and
34. 1:39you run time backwards there must have
35. 1:42been a time when all of those continents
36. 1:44work together in some sort of
37. 1:46supercontinent something he named
38. 1:49Pangaea coming from the greek term for
39. 1:53all earth this became known as vague
40. 1:58neurs theory of continental drift
41. 2:02now vague nur being a man of science
42. 2:04knew that if his theory was going to
43. 2:06gain any traction he needed to provide
44. 2:09evidence and so he set to his life's
45. 2:12work of researching every corner of the
46. 2:15planet to better understand this strange
47. 2:18observation and to explain it to the
48. 2:21scientific community
49. 2:23by the end of his life he had collected
50. 2:26four main pieces of evidence and we're
51. 2:30going to look at those today we'll begin
52. 2:34where we've already begun and that is
53. 2:37with this shape of the continents if we
54. 2:40look carefully all over the earth
55. 2:42coastlines appear to fit together like
56. 2:44this part of South America and this part
57. 2:48of Africa and so that becomes evidence
58. 2:51number one the apparent fit of the
59. 2:54continents that the coastlines appear to
60. 2:57fit together like the pieces of some
61. 2:59sort of giant puzzle but of course this
62. 3:02was just a starting point and so Vagner
63. 3:05continued his research the next thing he
64. 3:08dove into involved life fagner began to
65. 3:13study fossils of ancient creatures and
66. 3:15more importantly where those fossils
67. 3:18were located take for instance this
68. 3:21creature an ancient freshwater reptile
69. 3:24called a mezzo Saurus interestingly if
70. 3:28you look on all of the continents and
71. 3:31land masses of Earth fossils of the meso
72. 3:34source are only found in two places
73. 3:37these include the very southern tip of
74. 3:41South America and the southern tip of
75. 3:44Africa now let's think about this how
76. 3:47could this be possible
77. 3:49we know the meso source could not have
78. 3:52evolved in one location and then
79. 3:54traveled to the other it was a
80. 3:57freshwater reptile and therefore could
81. 3:59never make the journey through the salty
82. 4:01atlantic ocean and so that idea is out
83. 4:04the window another idea is that perhaps
84. 4:08the same exact creature evolved in the
85. 4:11same exact way at the same exact time in
86. 4:13two locations that are separated by
87. 4:17thousands of miles but too vague no that
88. 4:21was unlikely if not impossible and so
89. 4:24what he concluded was that during the
90. 4:27days when the Meza source thrived Africa
91. 4:31and South America were not separated by
92. 4:33an ocean but rather they were connected
93. 4:35as one land
94. 4:37where the Mesozoic and roam free and
95. 4:39then at some point later on those land
96. 4:42masses with the remains of the Mesozoic
97. 4:45were ripped apart and separated by the
98. 4:48ocean as we see today
99. 4:51now this seemed like a radical idea to
100. 4:53Vagner until he began to look at other
101. 4:56species of living organisms from the
102. 4:59time and what he found was much the same
103. 5:02there were all sorts of creatures beyond
104. 5:05the meso source like the sign onethis
105. 5:08and glassy Terrace and Lystra Soros who
106. 5:10all showed very similar unique fossil
107. 5:14distributions as seen here and strangely
108. 5:19enough if you reassemble the continents
109. 5:21according to their shapes the
110. 5:24distribution of the fossils makes
111. 5:26perfect sense and so this becomes piece
112. 5:28of evidence number two fossil
113. 5:31correlation or the matching up of
114. 5:34similar fossils found in distant
115. 5:36locations at this point vague nor is
116. 5:39excited because his theory is coming
117. 5:42together and his ideas seem to have a
118. 5:44lot of support and so he's set off to
119. 5:47find even more evidence and he did so by
120. 5:50studying geology or rock structures very
121. 5:55similar to what he saw with fossil
122. 5:58distribution he saw with rock
123. 6:00distribution in fact if you look at the
124. 6:02mountains of the modern day northeastern
125. 6:05United States they are the exact type
126. 6:08and age of rock found in the mountains
127. 6:11of the UK and northern Scandinavia and
128. 6:15so Vagner said to himself could it be
129. 6:18that the same exact rocks formed at the
130. 6:20same exact time but in very different
131. 6:23locations well it is possible but it
132. 6:26seems unlikely
133. 6:27and so what Vagner concluded was that
134. 6:29those rocks formed at the same time in
135. 6:32the same location and then that area was
136. 6:35torn apart by the motion of the
137. 6:37continents carrying those rocks
138. 6:40to the distant locations they are in
139. 6:42today and so this becomes evidence
140. 6:45number three Rock and mountain
141. 6:48correlation or the matching
142. 6:50of similar rocks from distant locations
143. 6:53proving that they were once together and
144. 6:56finally his fourth piece of evidence is
145. 6:59probably the most compelling of all and
146. 7:01this involves a look at the past climate
147. 7:04of the earth so vague nurse studied
148. 7:07things like glaciers and what he knew
149. 7:11was that when glaciers move over the
150. 7:14surface of the earth they leave behind
151. 7:16evidence in the form of these glacial
152. 7:19striations or deep scratches in the rock
153. 7:21that show the direction the ice moved as
154. 7:24it dragged over the surface now
155. 7:27interestingly if you look at where on
156. 7:30earth we find glacial striations today
157. 7:32they're located in areas like the Amazon
158. 7:35rainforest on the equatorial South
159. 7:39American continent and the hot sticky
160. 7:42jungles of Central Africa now of course
161. 7:45these are places where you could not
162. 7:47find glaciers today simply because
163. 7:50they're too close to the equator and
164. 7:52getting sunlight that is too intense and
165. 7:55hot preventing glaciers from forming and
166. 7:58so what Vagner concluded was that these
167. 8:00areas were not always near the equator
168. 8:03but rather in the past they were located
169. 8:06closer to the poles where a colder
170. 8:09climate could exist and support glaciers
171. 8:13similarly Wagner looked at rocks like
172. 8:17bituminous coal which is a sedimentary
173. 8:20rock that can be found on the new york
174. 8:22state earth science reference tables you
175. 8:25can find this table at this link
176. 8:30bituminous coal is a sedimentary rock
177. 8:34that is made from compacted and cemented
178. 8:36plant remains but not just any plant
179. 8:39remains tropical plant remains from hot
180. 8:42sticky humid jungles interestingly if
181. 8:47you look at the major coal deposits on
182. 8:49earth today they don't fall in hot humid
183. 8:52areas but rather they fall in frigid
184. 8:55areas like northern Asia and Antarctica
185. 8:59so Vagner knew that if this was the
186. 9:02observation he was
187. 9:04making this tropical cold being found in
188. 9:07frigid places that those places must not
189. 9:10always have been frigid and maybe in
190. 9:13fact they were once located closer to
191. 9:16the equator and so this becomes piece of
192. 9:19evidence number four Paleo climate data
193. 9:22or past climate data like finding
194. 9:25evidence of coal in currently cold areas
195. 9:29and evidence of glaciers and currently
196. 9:31warm areas and so these four pieces of
197. 9:35evidence put together became the theory
198. 9:37of continental drift as published by
199. 9:39Vecna in his book the origin of
200. 9:42continents and oceans unfortunately
201. 9:48there was one thing that Vagner could
202. 9:50never wrap his mind around and that was
203. 9:52what force could be driving the motion
204. 9:55of the continents he couldn't understand
205. 9:58how it would be possible for huge land
206. 10:01masses to actually move considering the
207. 10:04amount of force and energy required to
208. 10:07do so and without this explanation his
209. 10:10theory of continental drift remains
210. 10:13largely rejected in the scientific
211. 10:16community
212. 10:18in November of 1930 while on a research
213. 10:23expedition on the ice sheets of
214. 10:24Greenland Vagner froze to death his body
215. 10:29was found in the ice months later you
216. 10:34can still visit a cross that marks the
217. 10:38site of his death frozen on the ice
218. 10:41sheets of Greenland the story of Alfred
219. 10:47Wegener is a tragic one it's the story
220. 10:49of a great scientific mind who was ahead
221. 10:52of his time but died before he reached
222. 10:55his true potential modern geologists owe
223. 10:59to him their understanding of how the
224. 11:02earth actually works
225. 11:10you
226. 11:11[Music]