problem about geology, EES 1. Go to Iceland (type Iceland into the search box).

Question

problem about geology, EES

1. Go to Iceland (type Iceland into the search box). Using observations of the available Google Earth layers, what are two explanations for why Iceland currently has so much volcanic activity? Select the two that apply.

1. subduction zone. 2. mantle plume. 3.mid-ocean ridge. 4.continental rifting

Question 2 1.5 pts How many active volcanoes are shown in Iceland? Make sure "Global Volcanism Program-Holocene Volcanoes" layer is turned on. You should see volcanoes as red triangles.

A. 5-10 B. 15-20 C. 25-34 D. 35-40

Question 3 1.5 pts What pattern do you notice in the distribution of Iceland's volcanoes?

They are all found along the coastline. Many but not all are lined up along the mid-ocean ridge. They are randomly distributed. They are all in the western-most part of Iceland.

Question 4 1.5 pts Much of the volcanic actvity in Iceland involves basalt flows. Why is this expected?

Because basalt forms at subduction zones. Because basalt is associated with composite/stratovolcanoes. Because basalt forms at mid-ocean ridges. Because basalt forms from completely melting the mantle.

Question 5 1.5 pts The volcanoes Hekla, Katla, Eyjafjallaj?kull, Grimsv?tn, and Vestmannaeyjar are not basaltic, but rhyolitic instead. They also are distinct, steep-sided, cone-shaped volcanoes, except for Grimsv?tn and Eyjafjallaj?kull, which are beneath glaciers and not visible. What do you think explains the difference in lava type and structure of these volcanoes?

They are basaltic shield volcanoes. They are small cinder cones from basaltic eruptions. They are stratovolcanoes that formed from mantle plume activity. They are stratovolcanoes that formed at subduction zones.

Question 6 1.5 pts Under the Hot Spot Data file, turn on the "hotspot-data.kml" subfile, if it is not already on. Yellow placemarks give data about the ages of volcanic rocks in millions of years. What is the age of the volcanic rock sampled in Iceland?

10 million years 1000 years 1 million years 0.01 million years

Question 7 1.5 pts Evidence for volcanic activity on the seafloor associated with Iceland extends both to the east and to the west of Iceland. This is called the "trail" of the mantle plume. How does the bathymetry (shape of the seafloor) east (between Iceland and Ireland) and west (between Iceland and Greenland) differ compared to the seafloor to the north and south of these areas? GE-Iceland.png

There are deep ocean trenches, indicating the presence of subduction zones. There are abundant mid-ocean ridges. The area is smoother and flatter from the abundant lava flows. There is no noticable difference.

Question 8 1.5 pts The North Atlantic opened up as the supercontinent of Pangaea broke apart. Evidence of this event in the form of volcanic rocks stretches from Greenland to Europe. How long ago did Greenland separate from Europe, based on the ages of volcanic rocks associated with the Iceland mantle plume "trail", from Greenland to the British Isles? Hint: Remembering that the British Isles and Greenland were connected before the Atlantic Ocean opened up, where would you find the oldest volcanic rocks associated with the formation of this ocean basin?

5 million years ago 30-40 million years ago 40-50 million years ago 50-60 million years ago

Question 9 1.5 pts Next, fly to Hawaii (type Hawaii into the search box, or 19.502042, -155.609674). Be sure to leave the "hotspot-data.kml" subfile turned on. Looking at the radiometric dates for lava flows on the main island of Hawaii, approximately how long ago did this part of the Pacific Plate drift over the mantle plume?

0.1 million years ago 0.22 million years ago. 0.46 million years ago. 0. 75 million years ago

Question 10 1.5 pts Loihi will become the next island in the chain. How long ago did Loihi start to form?

0.01 million years 82.7 million years. 0.38 million years. 0. 46 million years

Explanation / Answer

Q.1 Answer

2.Mantle plume.

3.Mid-oceanicridge

Q-2 1.5 Answer

C-25_34.

Q3 1.5 Answer

Many but not all are lined up along the MOR.

Q4 1.5 Answer

Because basalt is associated with composite/stratovolcanoes.

Q5 1.5 Answer

They are basaltic shield volcanoes.

Q6 1.5 Answe

10 millions

Q7 1.5 Answer

There are abundent MOR.

Q8 1.5 Answer

50-60million years ago.

Q1 0.5 Answer

0.46 millions year ago.

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