Landforms And Volcanos Flashcards
What are the landforms at constructive margins?
Sea floor spreading
Rift valley
How does Sea Floor Spreading occur?
• 2 plates move away from each other
• molten magma rises, creating new crust
• submarine volcanoes can form
• eg Mid-Atlantic Ridge
How is a Rift Valley formed?
• 2 plates move away from each other
• molten magma rises, creating new crust
• eg Great African Rift Valley
What are the landforms at a destructive margin?
Deep Sea Trench
Island Arcs
How are Deep Sea Trenches formed?
• Continental and oceanic plates meet
• oceanic plate is subducted underneath
• eg Mariana Trench
How are Island Arcs formed?
• Magma pushes up from the trenches creating a volcano
• the magma solidifies creating an island
• eg The Caribbean
What is the landform at a collision margin?
Young Fold Mountains
How are Young Fold Mountains formed?
• Continental plates meet
• Both plates push upwards
• eg Himalayas
What are the landforms at conservative margins?
Fault lines
How are fault lines formed?
• Two plates move parallel to each other
• crust is neither created or destroyed
• eg San Andreas Fault, California
What is magma?
Molten rock below the surface
What is lava?
Molten rock above the surface
What is meant by extrusive?
When lava and other materials reach the surface
(Extrusive rocks formed on the surface of the Earth from lava)
What is meant by intrusive?
Materials that are injected into the crust
(Intrusive rocks formed from magma that cools and solidifies within the crust of the planet)
What is igneous rock?
Rocks that form from cooled magma
What is pyroclastic material?
Material ejected from the volcano in fragmented form
Where do fissure eruptions occur?
Constructive margins
Describe a fissure eruption
Where does a fissure eruption occur?
Constructive margin
Describe a fissure eruption
• Occur when 2 plates move apart
• lava is ejected through fissures
• normally comprised of basalt
• the slow cooling of the lava produces columnar jointing
• lava fills up the hollow rather than creating a dome shape
• eg Giant’s Causeway, N. Ireland
Where is a shield volcano found?
Constructive margins
Describe the formation of a shield volcano
• Lava flows from a central vent
• lava spreads over a large area before solidifying
• results in a cone with long gentle sides
• volcano is made up of many layers
• eg Mauna Loa, Hawaii
Where is a dome volcano formed?
Destructive margins
Describe the formation of a dome volcano
• Lava flows from a central vent
• acid lava quickly solidifies
• steep sided, convex cone
• volcano is made up of many layers
• eg Mt St Helens, USA
Where is an ash and cinder cone formed?
Destructive margin
Describe the formation of an ash and cinder cone
• Fine ash and cinder is ejected from a central vent
• Layers of ash and cinder build up
• Shallow sided, concave sides
• volcano is made up of many layers
• eg Mt Etna, Italy
Where is a caldera volcano formed?
Destructive margin
Describe the formation of a caldera volcano
• Gas builds up in the magma chamber causing an explosion
• the sides of the subside
• craters can be flooded by the sea, creating lagoons
• eg Mt Mazama, USA
