13
1. Internal geological processes
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Understand
32.
Explain why shield volcanoes are so flat.
33.
Pumice stone is a very porous volcanic rock that floats inwater.What type of
eruption most often throws out this type of rock? Explain your answer.
34.
Make a table with the different types of materials that volcanoes eject.
4.2.
Volcanism in Spain
In the Iberian Peninsula there are areas of recent volcanism (8million years ago) in Cabo
de Gata and Campo de Calatrava, and very recently (< 1 million years) in La Garrotxa,
but the Canary Islands are the only volcanically active areas. The last submarine eruption
on the islands took place in 2011 off the coast of El Hierro; on the surface, the last
eruption was the Teneguía volcano on the island of La Palma, in 1971. The Canary
Islands are located far away from the plate boundaries. Their volcanic origin appears
to be due to the rupture zone running from east to west that periodically opens and
allows magma to rise. Successive volcanic activity over the last twenty million years
has caused the islands to emerge from the ocean floor.
Key concepts
❚❚
The viscosity of the magma
determines the type of
eruption and relief.
❚❚
The Canary Islands are
volcanically active.
zone
of Olot
Campo de
Calatrava
Southeast
zone
Columbretes
Islands
Cabo de
Gata
Alboran
Island
volcanic zone
1,6
0,75
12,0
15,7
13,7
19,0
16,6
N
S
W E
0 25 50 75 100
km
Areas of recent volcanism in the Iberian Peninsula
‘Organs’ on La Gomera
: when the lava
cools, it contracts and develops fractures that
form prismatic blocks.
SantaMargaridavolcano
: although it has
been extinct for thousands of years, the volcanic
originof theGarrotxa (Girona) is still recognisable.
Timanfaya National Park, Lanzarote
:
in this volcanic landscape, there are many
cinder cones
, small volcanic cones with a
wide crater that eject lava pulverised by gases,
that accumulated around it in the form of
lapilli or small lava streams.
This area of Lanzarote was erupting from
1730 until 1736.
Historic eruptions in the Canary Islands, in red; in figures, the age of the oldest
rocks in millions of years
Analyse
29.
Look at themap. Write the islands in order from the oldest to the
most recent.
Some exceptional examples of Spanish volcanic relief
Analyse
30.
Listen and identify volcanic relief in the photos.
31.
What causes many volcanoes on Lanzarote to be in a line?
