Download Chapter 13 Section 2 Directed Reading

Chapter 13-2 Directed Reading
Name: _________________________ Period: ____
Chapter 13 Section 2: Volcanic Eruptions
Pages
325-330
_____1. Lava provides an opportunity for scientists to study
a. the nature of Earth’s inner core.
b. the nature of Earth’s tectonic plates.
c. temperatures within Earth.
d. the nature of Earth’s crust and mantle.
______ 2. By analyzing the composition of volcanic rocks, geologists have concluded that there
a. is only one general type of magma. b. are two general types of magma.
c. are three general types of magma. d. are two minerals in magma.
______ 3. Mafic rock commonly makes up
a. oceanic crust.
b. continental crust. c. Earth’s inner core. d. tectonic plates.
______ 4. Felsic rock commonly makes up
a. oceanic crust.
b. continental crust. c. Earth’s inner core. d. tectonic plates.
TYPES OF ERUPTIONS
(page 325)
_____ 5. The force of a volcanic eruption is affected by
a. magma temperature.
b. the distance from the top of the volcano to its base.
c. the viscosity of magma
d. the geologic age of the volcano.
______ 6. Felsic magmas, with high viscosity and sticky lava, cause
a. quiet eruptions. b. explosive eruptions. c. continuous eruptions. d. most volcanic eruptions.
______ 7. Explosive eruptions are most likely to be caused by magma with
a. small amounts of dissolved gases. b. large amounts of trapped, dissolved gases.
c. any amount of dissolved gases.
d. small amounts of dissolved rock.
______ 8. Oceanic volcanoes commonly form from
a. mafic magma. b. felsic magma. c. mafic or felsic magma. d. solid magma
In the space provided, write the letter of the description that best matches the term or phrase.
______ 9. pahoehoe
a. forms jagged, sharp chunks when it cools
______ 10. aa lava
b. forms a smooth, ropy texture as it cools
______ 11. blocky lava
c. breaks into large chunks at the surface while hot lava continues to flow underneath
12. Pyroclastic particles less than 2 mm in diameter that mostly fall on the land that immediately
surrounds the volcano are called ____________________________.
13. Pyroclastic particles less than 0.25 mm in diameter that are so small they might travel around Earth
in the upper atmosphere are called ________________________________.
14. The largest pyroclastic particles, which form from solid rock blasted from the volcano’s vent, are
called _________________________________.
TYPES OF VOLCANOES (page 328)
______ 15. volcanic cone
a. a volcanic cone that is broad at the base and has gently sloping sides
______ 16. crater
b. structure formed by lava and pyroclastic material ejected during volcanic eruptions
______ 17. shield volcano
c. volcano with very steep slopes that are rarely more than a few hundred meters
high and have angles close to 40°
______ 18. cinder cone
d. volcano made of alternating layers of hardened lava flows and pyroclastic material
______ 19. composite volcano
e. the funnel-shaped pit at the top of a volcanic
20. What is a caldera?
PREDICTING VOLCANIC ERUPTIONS (page 329)
21. One of the most important warning signals of volcanic eruptions is
a. a change in earthquake activity around the volcano.
c. a change in animal behavior around the volcano.
b. a change in air pressure around the volcano.
d. increased steepness of the volcanic cone.
22. What are three causes of small earthquakes that could signal a volcanic eruption?