CHAPTER 1.1: THE GLOBAL DISTRIBUTION OF VOLCANOES
Page 9-13
I.
Volcanoes beneath the sea
A. Volcanic activity
1. About ___ of Earth’s ___ historically active volcanoes erupt
each year
2. Volcanic rocks on all ocean basin floors
a. Indicates volcanoes are more _________ under water
than on land
B. Mid-ocean ridge
1. A continuous _________ _________ extending through the
North and South Atlantic Oceans, the Indian Ocean, and the
South Pacific Ocean
2. In water depths of ______ to ______ meters
C. Rift valley
1. The deep central cleft in the crest of the __________ ridge
2. Where _______ rises up to form submarine volcanoes
D. Magma
1. Naturally occurring ________ ________ material generated
within the Earth
Paste Mid-Ocean Ridge
Diagram Here
II.
Volcanoes on land
A. Much more dangerous than volcanoes beneath the ocean
B. Cascades volcanic mountain range
1. Formed by eruptions along the _______ edge of the United
States
C. Aleutians in Alaska
1. _______ chains formed by volcanoes
III.
Ring of fire
A. Volcanoes found in a narrow belt all around the ________ Ocean
B. Mt. St. Helens in Washington in _______
1. Dramatic eruption along the Ring of Fire
C. About ____ of volcanoes on land form where one plate slides
beneath another plate
IV.
Volcanoes formed by ______ on the continents
A. East African rift valley volcanoes
1. Form where two parts of _______ continent are moving apart
from each other
2. Similar to mid-ocean ridges
a. Continental plate is stretched and broken
b. Main break opens to form rift valley
B. Tall cliffs on west bank of Hudson River
V.
Volcanoes at hot spots
A. Hot spot
1. Fixed source of abundant rising magma that forms a volcanic
center that has persisted for tens of millions of years
2. Hawaiian Islands
a. Older to the northwest because of _______ Plate
movement away from _______ _______ Ridge
b. Sharp bend in chain formed with abrupt change in plate
movement
B. Seamount
1. A peaked or flat-topped underwater _________ rising from
the ocean floor
2. Emperor seamounts northwest of _________
VI.
Map projections
A. Map projections
1. The process of systematically transforming positions on the
Earth’s _______ surface to a ______ map while maintaining
spatial relationships
2. All have some kind of _______
B. Mercator projection
1. A map projection in which the Equator is represented by a
straight line true to scale, the meridians by parallel straight
lines perpendicular to the Equator and equally spaced
according to their distance apart at the Equator, and the
parallels by straight lines perpendicular to the meridians and
the same length as the Equator. There is a great distortion
of distances, areas, and shapes at the ______ regions.
2. The USGS map cuts off the mid-ocean ridge north of
_______
3. The larger the area covered by the map, the less detail the
map can show
CHECK YOUR UNDERSTANDING PAGE 13 #1-6