Exercises

Topography and Tectonics > Step Two

Other types of tectonic activity can be inferred by looking at topography. For example, around the Pacific rim it is common to see deep sea trenches adjacent to chains of volcanoes--either as strings of islands as in Japan and the Phillipines, or along the edges of continents, as in Central and South America. These features mark subduction zones, a second type of convergent plate boundary. Here thin and dense oceanic plates descend into the Earth's mantle. Where the plate bends down there is a topographic low, or trench. In the mantle the plates melt and rise to the surface again, forming the chains of volcanoes.

For this exercise we'll make another topography map using QUEST.

• If you don't have a QUEST window open, mouse over the Tools button along the top banner of this page. Scroll down to Web Tools and click on the Launch QUEST button.

• Next, click on the Menu button in the bottom left corner of the QUEST window.

• Click on Map Area and the map area window will appear. Select World in the Region pull down menu and select Hill Shaded Topography from the Base Map pull down menu. Click OK to close the window.

• Next, clear old map selections by checking Earthquakes, Volcanoes and Topography all have Show None selected.
  

• Lastly, click on the GET MAP button and in a few moments your map will appear in the main maparea.
  

QUESTIONS:

1. Where is the deepest part of the ocean?

2. Where are the ocean's mountain ranges?

 

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