Download The Changing Earth: Chapter 3 Mountains and Volcanoes

The Changing Earth:
Chapter 3 Mountains and
Volcanoes
3.2 (Part 1) Volcanoes form as
molten rock erupts.
Volcano
• Opening in Earth’s crust through which
molten rock, rock fragments, and hot
gases erupt
Parts of a Volcano
• Magma Chamber – Magma that rises
towards Earth’s surface collects in a
magma chamber, Magma remains here
until it either cools and forms igneous rock
or erupts
Parts of a Volcano
• Main Vent – The point on the surface
where magma leaves the volcano
• Side Vent – Magma is sometimes forced
out through an opening on the side
• Crater – Bowl shaped area that forms
around the volcanoes vent
Parts of a Volcano
• Lava – Magma that has reached the
surface
• Lava Flow – River of lava that pours down
the side of the volcano
Parts of a Volcano
• Rock Fragments – A lot of the material
erupted from a volcano comes as rock
fragments of different sizes
– Large fragments fall quickly but ash can be
carried long distances by winds
Parts of a Volcano
– Volcanic Ash (smallest – less than 2 mm in
diameter) Ranges from the sizes of dust to
the size of rice grains
Parts of a Volcano
– Volcanic Cinders (Medium) Contain holes
and tunnels left by escaping gases
Parts of a Volcano
– Volcanic Bombs and Blocks (largest) Bombs
are molten when they are thrown out and
harden as they fly through the air, Blocks are
solid pieces of rock and can be the size of
houses
Parts of a Volcano
• Volcanic Gases – Water Vapor and
Carbon Dioxide, what looks like smoke
rising from a volcano is actually ash and
gases
• Pyroclastic Flows – dense cloud of
superhot gases and rock fragments that
races downhill, up to 800 °C and 160
KM/Hr
– Most dangerous type of volcanic eruption