Plate Tectonics Theories

Maddy St. Clair

Continental Drift


  1. Continental Drift Powerpoint
  2. Page 141 Worksheet
  3. Voicethread on Continental Drift (first slide)

Voicethread Response: Wegner's theory is right. I believe this because if you look at a map, the continents all fit together like a puzzle piece. Also, there were many details that suppported this theory. These were freshwater fossils, plant fossils, similar rocks, and climate similarities in different continents that couldn't get there without the continents touching before.

Summary: I do not believe in the continental drift theory, that Alfred Wegener came up with. I do not believe this because all the proof he had was that the continents looked like they could be fit together like a puzzle-piece. Also, the rest of the proof came after he died. Also, most of the proof could be looked as an accident or coincidence. There are also proof that disproves continental drift. One is that there are fresh-water currents through the ocean, and that is how the fresh-water animals got to continents across the ocean.

Seafloor Spreading


  1. Seafloor Spreading Powerpoint
  2. Seafloor Spreading Worksheet
  3. Voicethread on Seafloor Spreading (second slide)

Voicethread Response: Magentic Reversal-

As the magma cools, the minerals in the oceanic crust will either be north or south. As you continue out farther, they will switch between north and south.

Summary: I am in between believing and not believing in seafloor spreading. I don't believe in seafloor spreading because we do not know if there is such a thing like magma in the upper mantle or subduction zones. No one has been down in that area to say for sure that there are those things there. Also, how do we know the poles reversed magnetically? We don't. I do not believe that this would affect or relate to seafloor spreading. But I do believe in seafloor spreading because there is no other way that scientists could explain how there are old and new rocks in the ocean.

Plate Tectonics


  1. Plate Tectonics Powerpoint
  2. Plate Boundary Characteristics
  3. Plate Tectonics Video Worksheet

Voicethread Response: I think that heat can move the plates because when we lit the candle and the top blew off and this proves that the heat had nowhere to go, so it popped off the lid. This also means that the heat from the magma has nowhere to go, so the heat will move the plates. The plates are heavier, and that it why the plates only move two centimeters each year.

Summary: I actually believe in the plate tectonics theory because it makes the most sense to me. All the plate boundaries also explain the earthquakes, volcanoes, mountains, etc. I think that the convention currents make sense, and could actually be true. I think this because of the experiments we did in class. When we lit the candle, and caused the dust in the metal can to move fast, the lid flew off the top. So when the heat from the magma has nowhere to go, the heat will move the plates. The plates are heavier, and that it why the plates only move two centimeters each year.

Thank you!