Earth Science - Volcanoes - Quiz Questions A10: When a column of exploding material collapses, it races down

the side of a mountain as a pyroclastic flow. A lahar is a mud flow

Magma is underground melted rock. Lava is magma that has Q11: How do igneous rocks form?
reached Earth’s surface and cooled.
A11: From cooling of magma or lava
Q2: Imagine a volcano with only one vent. What change might
cause a second vent to appear on the side of the volcano? Q12: What about the appearance of an igneous rock gives you a
clue about whether it cooled slowly or quickly?
A second vent could appear on the side of the volcano if a still or
dike broke through to the surface. A12: slow cooling = large crystals; fast cooling = small crystals

Q3: About 7,000 years ago, Mount Mazama erupted and the Q13: Math Problem: The speed of a pyroclastic flow is 100 km/hr.
summit (top) of the volcano collapsed forming a depression that How far would this flow travel in 10 minutes? (Show your work –
was filled with rain and melted snow. The depression is now called not just the answer! Hint: Begin by converting 100 km/hr to ?
Crater Lake. Mount Mazama is an extinct volcano. What is the best km/min first.)
term to describe the depression that holds Crater Lake?
A-3: The depression is called a caldera. A13: 100 km/hr divided by 60 = 1.67 km/min (x) 10 min. = 16.67
km distance
Q4: Which kind of volcano is being described below? Use one of
these terms: active, dormant, or extinct. Q14: What is volcano?
a. No longer erupting;
b. Could be described as “sleeping”; A14: An erupting vent through which molten rock reaches Earth’s
c. May erupt in the future but is not erupting at present or recently; surface or a mountain built from the products of an eruption.
d. Erupting on a regular basis;
e. The volcano is eroding and a volcanic rock is exposed. Q15: magma?
A-4: A. extinct B. Dormant C. dormant
D. Active E. extinct A15: Underground melted rock

Q5: What is the difference between a dormant volcano and an Q16: magma chamber?
active volcano?
A16: A location where magma collects inside Earth
A-5: A dormant volcano is not currently active, but may become
active in the future. An active volcano is erupting or has erupted Q17: conduit?
recently and is expected to erupt again in the near future.
A17: Central internal vertical shaft that carries magma up inside a
Q6: Based on your reading in this section, answer these questions: volcano

a. Under what conditions of temperature and pressure does a solid Q18: vent?
rock begin to melt?
A18: An opening to the surface where magma leaves the volcano
b. Under what conditions of temperature and water content does a conduit
solid rock begin to melt?
Q19: dike?
A-6: A rock begins to melt at low temperature and high water
content –or- a rock begins to melt at high temperature and low A19: An upward-slanting sheet of magma within a volcano
water content.
Q20: sill?
Q7: What did early map makers notice about the locations of
volcanoes? A20: The sideways movement of magma underground inside a
volcano
A7: Volcanoes were located along coastlines.
Q21: lava ?
Q8: What causes the region called the Ring of Fire?
A21: Magma that has reached and cooled on Earth’s surface
A8: The Ring of Fire is caused by subduction of the Pacific Plate
under other plates. Q22: caldera ?

Q9: If you could melt a piece of quartz in some lava, would the lava A22: A bowl-shaped vent of a volcano after it has erupted
get more sticky or less sticky? Explain your answer.
Q23: resurgent dome? A23: A mound in the vent of an
A9: Adding this mineral to lava makes it stickier. erupted volcano

Q10: What is the difference between a pyroclastic flow and a lahar? Q24: lava lake ?
A24: A lake that contains lava that has formed in a caldera boundary

Q25: active volcano? Q40: subduction zone?

A26: A volcano that is erupting or has erupted recently A40: An area where denser basaltic oceanic plates dive under less
dense continental plates
Q27: dormant volcano?
Q41: shield volcano?
A27: A volcano that is not erupting now, but that may erupt in the
future A41: Low silica magma producing a wide, flat volcano

Q28: extinct volcano? Q42: cinder cone?

A28: A volcano that no longer erupts and is in the process of A42: A pile of rock bits that forms on the sides or in the caldera of
eroding a volcano

Q29: volcano neck? Q43: fire fountain?

A29: Solid remains of magma that filled the conduit of an extinct A43: A high gas magma eruption
volcano. The neck is exposed as the volcano erodes.
Q44: composite volcano?A44: A tall, explosive, cone- shaped
Q30: Ring of Fire? volcano formed by layers of silica-rich lava and ash

A30: A region of Earth’s plate boundaries where oceanic crust is Q45: pyroclastic flow?A45: A destructive cloud of volcanic material
subducting under other plates that moves quickly down the side of a volcano after an explosive
eruption
Q31: basalt?
Q46: lava bombs?A46: Blobs of glowing lava thrown from an
A31: A dense, oceanic, dark-colored rock that is NOT silica rich explosive eruption

Q32: silica? Q47: lahar?A47: A mudflow that results from a volcanic eruption

A32: Like the mineral quartz, it makes magma thick and sticky Q48: water cycle?A48: A set of processes energized by the Sun that
keeps water moving from place to place on Earth
Q33: pillow lava?
Q49: geologic cycle?A49: A set of processes that keeps rocky
A33: Runny basaltic lava that oozes out at a mid-ocean ridge and material moving from place to place on Earth
cools quickly in water
Q50: geysers?A50: An explosive eruption of water from volcanic-
Q34: volcanic island? heated underground chambers

A34: A volcano that forms away from a plate boundary on an Q51: hot springs?A51: Volcanic-heated water that rises to the
oceanic plate surface in pools

Q35: hot spot? Q52: igneous rocks?A52: Rocks that are formed from magma or
lava
A35: The top of an established mantle plume
Q53: granite?A53: Light-colored igneous rock with large, visible
Q36: volcanic island chain? quartz and feldspar crystals made from silica-rich magma

A36: A series of volcanoes formed by a hot spot as a lithospheric Q54: gabbro A6-40: A type of rock made from silica-poor magma
plate moves over the hot spot (has large crystals)

Q37: mantle plumes? Q55: obsidian?

A37 Narrow channels of magma that rise up through the mantle A55: Volcanic glass – cools quickly & has no crystals

Q38: Loihi? Q56: welded tuff?

A38: A new volcanic island forming underwater next to Kilauea in A56: Orange-tan in color; left over from a pyroclastic flow
Hawaii
Q57: weathering?
Q39: island arc?
A57: The process of breaking down rocks
A39: A string of volcanic islands that forms close to a plate