Chapter 3 Test


Cones, Eruptions, and Pyroclasts

Complete each section of the test. DO NOT HIT ENTER when you have completed one of the sections. Wait until you have completed all of the sections and then go to the bottom of the test and click on the GRADE TEST button. If at any time you would like to erase all of the answers and start over just click on the START OVER button.

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Questions 1-7, Click and hold on the boxes and, select the correct answer out of the ones in the boxes, each answer is used only once.

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1. Lava A. Rough and fragmented lava flows
2. Pahoehoe B. The most explosive eruption type. Ash plumes may reach 50,000 feet.
3. Plinian C. Molten rock on the surface of the Earth
4. Hawaiian D. Large pyroclasts-over 2 inches long with a rounded shape
5. Aa E. Smooth and ropy lava flows
6. Low Viscosity F. Thin and runny magma that usually erupts quietly with large amounts of lava.
7. Bombs G. Eruption type in which thin and runny magma reaches the surface of the Earth through the main vent and fissures.

Questions 8-10, Click on the button in front of each of the correct answers.

8. Name two reasons that volcanic eruptions occur.

Earthquakes make cracks in the Earth's Surface. Magma rises up and spills out of those cracks, because it is lighter than the surrounding rocks.

Convection currents carry magma to the surface. The force of the added magma building up there cause the magma to erupt onto the surface.

Magma will rise to the surface of the Earth when it is less dense than the surrounding rock in the mantle. When the magma reaches the surface of the Earth the pressure difference between the gases in the magma and the surface pressures allows the magma to boil out.

9. Name the three kinds of volcanic cones.
Shield, Cinder, Stratovolcano or Composite cone.

Ash, Lava, Pyroclatic Cones.

Active, Dormant, Extinct Cones.

< /dl> 10. What is a hot spot?

A hot spot is the area within the volcano where the magma is stored.

A hot spot occurs near the crust where very hot solid rock rises through the mantle (a mantle plume) and forms magma near the surface of the Earth. Hot spots form volcanoes in both oceanic plates and continental plates.

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Fill in the blank with the correct answer.
Click and hold on the boxes and, select the correct answer out of the boxes


11. A large rough edged, angular pyroclast that is ejected during a volcanic eruption is called a .

12. A is a bowl-shaped depression caused by a volcanic eruption in which the top of the volcano collapses.

13. The smallest of the pyroclasts are called . They may stay in the atmosphere for years.

14. A forms when the surface of the lava cools and hardens, while the molten interior flows through and drains away.

15. is the second smallest pyroclast. This material along with lava builds stratovolcanoes larger with repeated eruptions.

16. A is very hot, solid rock that rises through the mantle and will become magma as it reaches the surface of the Earth. They form hot spots.

17. A is a very hot, twirling mixture of ash, small pieces of pumice and other pyroclasts that are heavier than air and move down a volcano at high rates of speed.


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