A presentation on Volcanoes, Plate Tectonics and Igneous Rocks for high school use.
Compiled by James Campbell with resources from the Geological Society of the UK which has wealth of useful material.
3. Volcanic bombs: large lumps of rock and molten
blobs of magma thrown out from the volcano
Ash, steam & gas: material erupted from the volcano
Geyser: vent that shoots steam and boiling water
into the air
Sill: flat sheet of igneous rock formed underground
Ash, steam & gas
Crater
Secondary vent
Volcanic bombs
Lava
Sills
Magma chamber
Geysers
Conduit
Main vent
Dykes
4. • Magma collects in
magma chamber
• As magma is added the
pressure increases
causing fractures
• Magma is less dense than
surrounding solid rock so
rises
• Erupts on the surface
through a volcano as
lava, ash and gas
5. Outer
core
(liquid)
Inner
core
(solid)
• Plates are made from the
lithosphere
• The lithosphere is broken up
into tectonic plates which
move around on top of the
asthenosphere
• Lithosphere is rigid and
brittle so can fracture and
buckle
• Asthenosphere is solid rock
but is plastic and can flow
8. Plates moving AWAY
from each other
Volcanoes
Magma
New ocean
crust
David Karnå / CC by 3.0
Iceland
LithosphereAsthenosphere
(lower mantle)
9. Magma
Plate melts
Volcano
Plate is subducted
Oceanic and
Continental plates
Mount St. Helens,
Washington, USA
Oceanic crust
~2.9 g/cm3
Continental crust
~2.7 g/cm3
10. Oceanic and
oceanic plates
Older
oceanic plate
Younger
oceanic plate
Oceanic
island arc
Magma
Plate melts
Plate is subducted
Ocean trench
Mount Mayon,
Philippines
14. Olympus Mons on Mars
Shallow slopes
made from lavaRunny basalt
magma
Kilauea lava lake,
Hawaii
Wolf Volcano, Galapagos
Islands
Erta Ale Volcano, Ethiopia
Photo: filippo_jean/CC-By-2.0
15. Steep slopes
made from
lava and ash
Sticky magma
Mount St. Helens,
Washington, USA
Mount Fuji, Japan
Mayon Volcano,
PhilippinesCotopaxi, Ecuador
16. ´A´a lava, Guatemala
Photo: Librex/CC-By-2.0Pahoehoe lava,
Hawaii
Columnar joints,
Isle of Mull
Pillow lava,
Cornwall
23. • Mid Atlantic Ridge –
divergent plate
boundary
• North American and
Eurasian plates moving
apart at 25mm/year
• Iceland also lies above a
‘hotspot’
• Eyjafjallajökull is in
Iceland's Eastern
Volcanic Zone
• 200km thick ice cap
24. David Karnå / CC by 3.0
Fissure eruption at
Fimmvörðuháls
Ash column after explosive
eruption
Explosive eruption at
Eyjafjallajökull
20th March 2010
10km high plume
Boaworm / CC by 3.0
25. • European airspace was closed from 15-21 April 2010.
107,000 flights were cancelled, airline industry lost £1.1
billion (International Air Transport Association)
• Many industries relying on air freighted products were
badly affected → shortages of imported fruits, flowers
and electronic hardware
• River levels raised by 3m
• Agricultural land, roads, bridges and buildings damaged
by flooding
• 800 people were evacuated
26.
27. • Mount Nyiragongo is in the
Democratic Republic of Congo
• Part of East African Rift Valley, a
developing divergent plate
boundary
• Crater contains persistent lava
lake
• The lava emitted in eruptions at
Nyiragongo is often
unusually fluid (nephelinite -
very low SiO2 content)
29. • Nyiragongo erupted on 17th January 2002
• 13km fissure opened up on the south side of the
volcano
• Lava flows reached speeds of 60km/hr in the direction
of Goma and Lake Kivo
• 14-34 million m3 of lava
• Eruption of lava stopped after ~12 hours but lava
continued to flow towards and into Lake Kivo for a 3
days
• 45 fatalities in first 24 hours due to lava flows and CO2
asphyxiation
30. THE PRESENTER
A huge thank you and acknowledgements to the Geological
Society of the UK from which this material was chiefly drawn
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James Campbell has spent over 30-years in the diamond industry in a variety of
leadership roles both in major and junior companies. He is currently Managing
Director of Botswana Diamonds plc and also a Non-Executive Director of Shefa
Gems ATM. Previously he held leadership roles at Rockwell Diamonds Inc, Stellar
Diamonds plc, Lucara Diamond Inc, African Diamonds plc, West African Diamonds
plc and De Beers where he spent over 20-years with notable appointments
including General Manager Exploration and Nicky Oppenheimer's Personal
Assistant. James is also Chairman of the leadership development Non-Profit
Organisation Common Purpose SA.
James holds a degree in Mining & Exploration Geology from the Royal
School of Mines (Imperial College, London) and an MBA with
distinction from Durham University. James is a Fellow of the IOM3,
SAIMM and IODSA. He is also a C.Eng (UK), C.Sci (UK) and Pr.Sci.Nat.