Question

1. look at the picture on the left. about how long ago did the continents appear this way? ~ 250 million years
2. what two pieces of evidence did wegener discover that supported the idea of pangaea?
3. what does “pangaea” mean in greek? “all earth”/“all lands”
4. what two major landmasses broke apart from pangaea?
5. what does the modern theory of plate tectonics state?
6. write one observation you made as you completed this activity.
7. compare the thickness of continental crust and oceanic crust.
8. which type of crust is usually the oldest?
9. what is the border between two tectonic plates called?

in the table below, describe each type of boundary and draw a picture of the boundary.

1. convergent
2. divergent
3. transform

Explanation:

1. The continents have appeared in their current - like form about 250 million years ago due to the process of continental drift.
2. Wegener's evidence for Pangaea included the fit of the continents (like puzzle pieces) and the distribution of similar fossils across different continents.
3. In Greek, "Pangaea" means "all Earth" or "all land".
4. The two major landmasses that broke apart from Pangaea were Laurasia and Gondwana.
5. The modern theory of plate tectonics states that the lithosphere is broken into tectonic plates that move constantly, which explains earthquakes, volcanic activity, and the formation of mountains.
6. An observation could be that the shapes of the continents can be fitted together to form a super - continent, similar to a jigsaw puzzle.
7. Continental crust is thicker (about 30 - 70 km) than oceanic crust (about 5 - 10 km).
8. Continental crust is usually the oldest because oceanic crust is constantly being recycled at subduction zones.
9. The border between two tectonic plates is called a plate boundary.
10. Convergent boundary: Plates move towards each other. Can cause subduction (oceanic - continental or oceanic - oceanic) or mountain building (continental - continental). [A simple drawing could show two plates colliding, with one plate going under the other in the case of subduction or mountains forming in the case of continental - continental collision].
11. Divergent boundary: Plates move away from each other. Magma rises to fill the gap, creating new crust. [A simple drawing could show two plates moving apart with magma welling up].
12. Transform boundary: Plates slide past each other horizontally. Can cause earthquakes. [A simple drawing could show two plates sliding side - by - side].

Answer:

1. About 250 million years ago.
2. Fit of continents and fossil distribution.
3. "All Earth"/"All land".
4. Laurasia and Gondwana.
5. The lithosphere is broken into moving tectonic plates.
6. Continents can be fitted like a jigsaw puzzle.
7. Continental crust is thicker than oceanic crust.
8. Continental crust.
9. Plate boundary.
10. Plates move towards each other; [Drawing description as above].
11. Plates move away from each other; [Drawing description as above].
12. Plates slide past each other horizontally; [Drawing description as above].