Volcanic processes and Landscapes

We need to look how and where a volcano is formed. They occur on land and under the sea on constructive and destructive plate boundaries. They emit magma that as it hits the surface becomes lava. At the plate the pressure under the crust builds and finally breaks through the surface in the form of a volcano.

Volcano's are frankly awesome given their power of construction and destruction. There are features of a volcano that can be taught by diagram form and annotating. Enchanted learning has a great example. Students need to know the components that are listed below.

ash cloud - an ash cloud is the cloud of ash that forms in the air after some volcanic eruptions.
conduit - a conduit is a passage through which magma (molten rock) flows in a volcano.
crust - the crust is Earth's outermost, rocky layer.
lava - lava is molten rock; it usually comes out of erupting volcanoes.
magma chamber - a magma chamber contains magma (molten rock) deep within the Earth's crust.
side vent - a side vent is a vent in the side of a volcano.
vent - a vent is an opening in the Earth's surface through which volcanic materials erupt.

These can then be inserted onto the diagram below


There are 2 types of volcanoes: Shield (constructive) and Composite (destructive). They look difference and have different effects.

Shield volcano Shield volcanoes are usually found at constructive or tensional boundaries.They are low, with gently sloping sides and formed by eruptions of thin, runny lava. Eruptions tend to be frequent but relatively gentle.

Composite volcano Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava). They are usually found at destructive or compressional boundaries. The eruptions from these volcanoes may be a pyroclastic flow rather than a lava flow. A pyroclastic flow is a mixture of hot steam, ash, rock and dust. A pyroclastic flow can roll down the sides of a volcano at very high speeds and with temperatures of over 400° C.

Many of the syllabuses in schools suggest a case study, I have seen the Mount St. Helens in a MEDC via video, Google Earth and annotation, each method brought the example to life. There are others such as Chances Peak, Montserrat, 1995-97 – an LEDC.