Download 18.1 volcanism power point

Today: 11/30/15 Monday
 Pick
up a copy of the guided notes paper on the
front stool. We’ll be starting volcanism today. I’ll
give you guys/gals a heads-up on the model project
you’ll be working on for this unit.
Today: 12/1/15 Tuesday
 Honors:
 CP:
Turn in your text book to page 248.
Get a copy of the data sheet on the front stool.
Chapter 18 - Volcanoes
18.1 Volcanism
Volcanism
 Describes
all processes associated with the
discharge of magma, hot fluids, and gases
http://images.google.com/imgres?imgurl=http://ww
w.kidsgeo.com/images/volcanicim.jpg&imgrefurl=
http://www.kidsgeo.com/geology-for-kids/0049volcanism.php&h=200&w=300&sz=10&hl=en&st
art=5&tbnid=2qhJLJRLrxKp3M:&tbnh=77&tbnw
=116&prev=/images%3Fq%3Dvolcanism%26gbv
%3D2%26hl%3Den
Magma
 Slushy
mixture of molten rock, mineral crystals,
and gases
 Lava
= magma that reaches the surface
http://www.stmarys.ca/conted/webcourses/GEO
/GEO99/pubigneous/liquidlava.jpg
Volcanoes
 Distribution
of volcanoes is not random
 Most from at Plate Boundaries
 Majority
are at convergent and divergent boundaries
Convergent Volcanism
 Occur
at subduction zones
 Oceanic
 Magma
plate descends into mantle
moves upward
 Mixes with rocks, minerals, and sediment
 Form explosive volcanoes
Subduction Zone
Two Major Belts of
Convergent Volcanoes
 Circum-Pacific
Belt
 Mediterranean Belt
http://survivoralert.com/images/platesAndVolcanoes.gif
Divergent Volcanism
 Occurs
where plates are moving away from each
other
 New floor forms as magma rises
 Non-explosive, Large amounts of lava
 Mostly underwater volcanoes
Hot Spots
 Unusually
hot regions of mantle where hightemperature plumes of magma rise to the surface
 Ex: Hawaiian islands
 Rate of plate movement can be calculated from
position of volcanoes
Hot Spot Formation
 Hot spot remained stationary but Pacific plate
slowly moved northwest
 Left trail of islands
Flood Basalts
 Non-viscous
lava that flows through surface of
Earth out of cracks called fissures
http://www.fas.org/irp/imint/docs/rst/Sect17/lipmap2.gif
Notes 18.1 B
Continue “Volcanoes”
Anatomy of Volcano
 Conduit
= tubelike structures through which lava
flows
 Vent = opening where lava reaches surfae
 Lava cools and solidifies
 Over
time it accumulates to form a volcano
Anatomy of Volcano
 Crater
= bowl-shaped depression at top of volcano
http://www.cpluhna.nau.edu/images/wupatk1.jpg
 Calderas
= large depressions formed when magma
chamber is emptied
Caldera
http://volcanoes.usgs.gov/Imgs/Jpg/Aniakchak/dds40-039_large.jpg
Types of Volcanoes
 Shield
 Cinder
cone
 Composite/Stratovolcano
Shield Volcanoes
 Broad,
gently sloping sides
 Circular base
 Formed as layers of lava accumulate from nonexplosive eruptions
Shield Volcano
http://vulcan.wr.usgs.gov/Imgs/Jpg/Hawaii/Ima
ges/MaunaLoa79_mauna_loa_shield_volcano_05
-79_med.jpg
http://www.dkimages.com/discover/previews/793/51
03249.JPG

Mauna Loa,
Hawaii

Shield Volcano
Cinder Cone Volcanoes
 Steep
slopes, generally small
 Form as small pieces of magma are ejected into the
air
 Pieces = tephra – pile around vent
Cinder Cone
http://images.google.com/imgres?imgurl=http://www.cotf.edu/
ete/images/modules/volcanoes/typesa.GIF&imgrefurl=http://w
ww.cotf.edu/ete/modules/volcanoes/vtypesvolcan1.html&h=236
&w=265&sz=13&hl=en&start=4&tbnid=1cbnv3DoRKQHNM:&tb
nh=100&tbnw=112&prev=/images%3Fq%3Dcinder%2Bcone%
2Bvolcano%26gbv%3D2%26hl%3Den
http://192.107.108.56/portfolios/m/m
uscara_j/toolsvis/images/colorcinderc
one2.jpg
Composite Volcanoes
 Cone-shaped
with concave sides, much bigger than
Cinder Cone
 Formed of layers of hardened chucks from violent
erupts alternative with layers of lava oozing down
slope
Composite Volcanoes
http://www1.moe.edu.sg/learn@/Quest/winn
ers/primary/yu_neng_pri_volcano_nc/xplopix
9.gif
http://www1.moe.edu.sg/learn
@/Quest/winners/primary/yu_
neng_pri_volcano_nc/versuviu
s.htm
Mount Vesuvius
http://www.assessrisk.com/italy2006/d9_14.jpg
In-Class Assignment
 Volcano
Cube