1. Convection & plate tectonics Section 2

2. Vocabulary for week 5 Convection currents Convection currents Continental drift Continental drift Fossil Fossil Alfred Wegener Alfred Wegener Mesosaurus Mesosaurus

3. Review Types of heat transfer Types of heat transfer –Radiation –Conduction –Convection define all of these.

4. Convection The one the most important to us is convection. The one the most important to us is convection. –Convection currents: the movement of a fluid caused by the differences in temperature that transfers heat from one part of the fluid to another.  Why is this important? – these convection currents are part of what cause the earths magnetic field and are a part of the driving force in plate tectonics.

5. Continental drift The world hasn't always looked the same. The world hasn't always looked the same. –Once only Europe existed – and the world was flat –The Americas were not connected –Only the east cost was discover –Then in the 1700 geologist were sure that the contents never moved

6. Continental drift continued In 1910 a young German scientist suggested something amazing, he figured out that the continents all fit together like a jigsaw puzzle. In 1910 a young German scientist suggested something amazing, he figured out that the continents all fit together like a jigsaw puzzle. –Alfred Wegener was the first to hypothesize that earth continents moved.  He was also the first to suggest that all of the continents drifted together to form Pangaea. –Pangaea: single landmass that broke apart 200 million years ago, and gave rise to today's continents

7. Evidence Evidence from land features Evidence from land features –Mountains  Wegener found that when he pieced north and south America together that the mountain ranges lined up. –Coal deposits  He also noticed that the coal deposits in Europe matched up with the coal fields in North America

8. More evidence Evidence from fossils Evidence from fossils –He found a fossilized fern (Glossopteris) that grew in a very specific time, on 5 different continents Africa, South America, Australia, India, and Antarctica. This is very strong evidence that all of the land where the ferns grew was at a different place than now. The ferns need a warm moist climate to grow and Antarctica isn't either of those.

9. And even more Evidence Evidence from climate Evidence from climate – in South Africa there are places where glaciers have been proven to have existed in the past. But the climate now in South Africa the climate is much to warm and mild.

10. And even more evidence than before The geological community believed that mountains were formed because the earth was cooling, and the crust acted like an apple skin and it would wrinkle. Wegener said that if that’s the case we should mountains all over the place, but they are only found at the edges of continents. He suggested that the continents collided causing a lifting or crunching The geological community believed that mountains were formed because the earth was cooling, and the crust acted like an apple skin and it would wrinkle. Wegener said that if that’s the case we should mountains all over the place, but they are only found at the edges of continents. He suggested that the continents collided causing a lifting or crunching

11. Rejected Not so fast Not so fast –Even with all of his other evidence Wegener couldn't prove HOW the continent moved he didn’t have the technologies to prove it. So the geological community wouldn’t accept his theory.

12. Today With today's info we know how they move and that Wegener’s explanation and hypotheses were correct. With today's info we know how they move and that Wegener’s explanation and hypotheses were correct.

13. Convection Currents Quiz Convection Currents Quiz 1. how do convection currents work? 1. how do convection currents work? 2. refer to the drawing on the board correctly name what it is asking for. 2. refer to the drawing on the board correctly name what it is asking for. 3. who was the first person to come up with the idea that the continents moved? 3. who was the first person to come up with the idea that the continents moved?

14. Convection Current Quiz cont. 4.What year did he come up with the idea? 4.What year did he come up with the idea? 5. what was fossilized and how many different continents was it found on, 5. what was fossilized and how many different continents was it found on, Bonus: Bonus: 6.list all of the continents the fossil was found on. 6.list all of the continents the fossil was found on.

15. Sea floor spreading What is sea floor spreading? What is sea floor spreading? –The process by which molten material adds new oceanic crust to the sea floor. –What effect does it have on us?  It moves the plates and spreads out the continents.  Where does this happen? –At the mid-oceanic ridges  Mid-oceanic ridge: an undersea mountain chain where new ocean floor is produced; a divergent plate boundary

16. Sea floor spreading In sea floor spreading the sea floor spreads apart along both sides of the mid- oceanic ridge as new crust is added. As a result, the ocean floor moves like conveyor belts, carrying the continents along with them. In sea floor spreading the sea floor spreads apart along both sides of the mid- oceanic ridge as new crust is added. As a result, the ocean floor moves like conveyor belts, carrying the continents along with them. –Who came up with the idea of sea floor spreading?  Harry Hess. In 1960

17. Evidence for seafloor spreading There are three main types of evidence for Hess theory. There are three main types of evidence for Hess theory. –Molten material –Magnetic stripes –Drilling samples

18. Evidence from molten material In the 1960’s scientist were able to dive to the ocean floor in Alvin a small submarine designed to take the enormous amount of pressures at the bottom of the ocean. In the 1960’s scientist were able to dive to the ocean floor in Alvin a small submarine designed to take the enormous amount of pressures at the bottom of the ocean. –When they got down there they saw pillow shaped or they look like they just got squeezed from a tube of tooth past shaped rock formations.  These can only be formed when molten material come in contact with seawater immediately after reaching the surface.

19. Evidence from magnetic stripes Magnetic stripes are when patterns in the seafloor made when the Earth Magnetic poles switch. Magnetic stripes are when patterns in the seafloor made when the Earth Magnetic poles switch. –When the poles switch the magnetic metals in the molten material will line up to the north, then when it switches they line up to the new north or current south.  This leaves a time line for two things 1 st we know how old the sea floor is at different places 2 nd we know when the last time the poles switched was –780,000 years ago.

20. Evidence from drilling. Drilling Drilling A ship called the Glomar Challenger was designed to drill into the ocean floor, through 6 km of water. These samples were examined by scientist and dated every time the youngest rocks came from the ridges and the oldest rocks were the farthest away. Proving that seafloor spreading was taking place. A ship called the Glomar Challenger was designed to drill into the ocean floor, through 6 km of water. These samples were examined by scientist and dated every time the youngest rocks came from the ridges and the oldest rocks were the farthest away. Proving that seafloor spreading was taking place.

21. Subduction What is subduction? What is subduction? –Subduction: is the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.  Think of a conveyer belt, new crust is made at the mid-oceanic crust and as it gets farther away from the ridge it gets cooler and denser. This causes it to sink at the trench where is goes down into the mantle.

22. How it works.

23. What effect does this have? When old crust is taken faster then new crust can be made the ocean start to get smaller and when new crust is made faster then the old crust is taken the ocean is getting bigger. When old crust is taken faster then new crust can be made the ocean start to get smaller and when new crust is made faster then the old crust is taken the ocean is getting bigger. –Is this happening today?  Yes the Pacific ocean is getting smaller and the Atlantic ocean is getting bigger.

24. The end