1. It’s most likely that this feature is the result of processes.

2. Which of the following is NOT one of the Earth's spheres?

• atmosphere
• hydrosphere
• troposphere
• geosphere

3. The water that feeds into Silfra originates in glaciers and as groundwater. It is therefore most likely that the water in Silfra is

• Fresh water
• Saltwater

4. Which of the following geoscience processes happen on a timescale similar to the formation of Silfra?

• Mountain uplift
• Earthquake
• Landslide
• Volcanic eruption

5. Silfra is most likely located at which type of tectonic plate boundary?

• Transform
• Convergent
• Divergent

6. Silfra is a relatively new fissure; it did not exist before 1789. Using what you know about plate tectonics, as well as the given information, which of the following statements best explains how Silfra was likely formed?

• Two tectonic plates suddenly moved away from one another, creating a fissure between them.
• A volcano suddenly formed and melted a hole in Earth’s surface, creating the fissure.
• Silfra had slowly been forming over millions of years, but no one noticed it until the fissure was quite large.
• Slowly-building tension between plates caused an earthquake that rapidly created a fissure in Earth’s surface.

7. What effect would you most expect the plants to have on the rocks in the image?

• The plant roots will help to holds the rocks more closely together and prevent weathering and erosion.
• The plant roots will slowly break apart the rocks to cause further weathering and erosion.
• The plants will generate heat to melt snow that falls into the cracks and prevent ice from pushing apart the rock.
• The plants will slow down the wind and prevent it from further eroding the rocks they’re growing into.

8. Which of the following changes to the features of the landforms pictured gives evidence of plate tectonics?

• An increase in the amount of water and plant matter inside the Silfra fissure.
• The width of Silfra increasing by a few centimeters every year.
• The sides of the mountain eroding over time.
• The deposition of rocks and sediment from the sides of the mountain into the water below.

9. Iceland experiences quite a bit of volcanic activity. Describe how plate tectonics lead to the formation of volcanoes.

10. Using the given information, identify and describe the geologic processes that shape the features in Iceland. Include in your answer an explanation of the time scales over which these processes occur.

11. Describe the role of water in shaping the background mountains over time.

12. How do volcanic eruptions change the features on Earth’s surface over time?

13. Over the next 100 years, what are two geologic processes that you’d expect to change this feature?

14. In the back left of the image is a small mountain. How does the phenomenon that we observe here help to explain the existence of that mountain?