Volcanoes
I. Molten rock
A. Magma- beneath the Earth’s
surface
I. Molten rock
B. Lava- magma that extrudes
onto the surface of the Earth
Lava
C. Types of Lava
1. Pahoehoe- (pa-ho-ay-ho-ay)
freely flowing lava
forms a thin skin with wrinkles
looks like twisted rope when solid
Can walk on it if cool
Pahoehoe
lava
C. Types of Lava
2. Aa- (ah-ah)
rough, jagged surface
dangerously sharp edges
walking on it very perilous
!
Aa lava
D. Different types of Cones
1. Shield Volcanoes
a. built by a steady supply of
very fluid basaltic lava.
b. Have a broad, gently sloping
cone that resembles a shield.
c. E.g. Mauna Loa in Hawaii
- largest volcano on earth
Shield Volcano
Shield Volcano - Mauna Loa
Shield volcano
Mauna Loa
D. Different types of Cones
2.Cinder Cones
a.very steep, but not high
b. formed from explosive
eruptions from a single vent.
c. E.g. Sunset Crater- Arizona
d. E.g. Paricutin- Mexico
Cinder Cone
Sunset Crater- Arizona
Paricutin- Mexico
Paricutin- Mexico
Cinder Cone - Capulin Mtn.
3. Composite Cone
D. Different types of Cones
3.Composite Cone
a. a.k.a. Stratovolcano
b. erupts both lava and ash
c. has a steep summit
Composite Cone
Mt. Rainier
Composite Cone
Mt. St. Helens
D. Different types of Cones
3.Composite Cone
d. has gently sloping sides
e. erupts explosively
f. E.g. Mt. Vesuvius
Mount Pele,
Mt. St Helens
Mt. Pinatubo
III. Craters
A. formed at the
central vent of
an erupting
volcano.
B. Increase in size
during eruptions
III. Craters
III. Craters
C. Calderas
1. Remnant of a volcano that
erupted
2. very large crater > 5km in
diameter
Caldera
Caldera
Caldera- Santorini, Italy
Caldera (location unknown)
Caldera – Kilauea (Hawaii)
III. Craters
C. Calderas
3. E.g. Yellowstone National
Park
a. Remnant of a volcano that
erupted 600,000 yrs ago.
b. Hot springs, bubbling mud,
steaming pools, geysers
Yellowstone National Park
Caldera - Yellowstone
National Park
Caldera – Olympus Mons
(Mars)
III. Craters
C. Calderas
4. E.g.Bahia de Banderas
a. The bay at Puerto Vallarta
b. Outer edge - islands in bay
c. Inner edge is the coastline
d. Volcano no longer active
Bahia de Banderas