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Examine the processes that have led to the formation of any two volcanic landforms. - Leaving Cert Geography - Question 1 - 2006
Question 1
Examine the processes that have led to the formation of any two volcanic landforms.
Worked Solution & Example Answer:Examine the processes that have led to the formation of any two volcanic landforms. - Leaving Cert Geography - Question 1 - 2006
Step 1
Naming landform: Stratovolcano
Answer
A stratovolcano, also known as a composite volcano, is characterized by a conical shape and is built from multiple layers of lava flows, volcanic ash, and other volcanic debris.
Processes leading to formation:
- Subduction Zones: The formation of stratovolcanoes typically occurs in subduction zones, where an oceanic plate is forced beneath a continental plate. This creates magma as the descending plate melts.
- Magma Ascent: The generated magma rises through the crust. As the magma ascends, it can collect in magma chambers, allowing pressure to build.
- Eruptions: When the pressure becomes too great, explosive eruptions occur, ejecting ash, lava, and gases. These eruptions contribute to the layered structure characteristic of stratovolcanoes.
Step 2
Naming landform: Shield Volcano
Answer
A shield volcano is distinguished by its broad, gentle slopes formed primarily by the flow of low-viscosity basaltic lava.
Processes leading to formation:
- Hotspot Volcanism: Shield volcanoes often form over hotspots in the mantle, where plumes of hot material rise to the surface, creating magma.
- Effusive Eruptions: The eruptions are typically less explosive, characterized by the outpouring of lava that can travel long distances, leading to the gradual build-up of the volcano's structure.
- Continuous Activity: Shield volcanoes may continue to erupt over long periods, allowing for the accumulation of many layers of lava flows, giving them their broad, shield-like shape.