25.3 & 25.4 Flashcards
What is the boundary that marks a density change between layers?
Discontinuity
How are discontinuities identified?
Seismic Waves
What are shadow Zones?
Areas where no seismic waves are recorded
What is another term or name for Shadow Zone?
Dead Zone
Between what degrees do Shadow Zones fall?
105-140 degrees
Is the outer core a solid or a liquid?
Liquid
Is the inner core a solid or a liquid?
Solid, because of so much pressure.
What makes up the lithosphere?
- Crust
2. Uppermost mantle
What is the asthenosphere?
Plastic like layer which Earth´s plates move.
What elements make up the mantle?
- Calcium
- Aluminium
- Iron
- Magnesium
What makes up the core?
- Iron
2. Nickel
What is the measure pf fluid´s resistance to flow?
Viscosity
What is the chemical compound that is silicon dioxide?
Silica
What kind of volcanoes tend to be small, have heights in the hundreds of meters range, and have short eruption cycles?
Cinder Cone Volcano
What kind of volcanoes are broad, flat structure composed of layer upon layer of lava flow?
Shield Volcano
What kind of volcanoes are large and steep-sided, often thousands of meters high and tens of kilometres across the base, and composed of layers of both lava and ash?
Composite Volcano
What is the sources for molten material inside Earth?
magma
What determines the eruptive style of a volcano?
Magma, temperature, viscosity, volume, and water and gas.
What is the relationship between volcanoes and plate tectonics?
They form when the tectonic plates move.
How do volcanoes form?
Volcanoes form when molten rock rises from deep within Earth and erupts from a crack in the crust.
What is molten liquid or rock called that is stored in the Earth?
Molten, or liquid, rocks stored inside Earth is called magma.
Where can melting occur
Melting can occur in the asthenosphere.
What kind of rock is less dense which causes it to rise?
Magma is less dense than surrounding rock, causing it to rise.
What has to happen for magma to possibly reach Earth´s surface?
Rising magma may reach Earth’s surface if pressure conditions allow and the rock has conduits through which it can flow.
When magma reaches Earth´s surface and erupts as either lava or ash what is formed?
A volcano is a feature that forms when magma reaches Earth’s surface and erupts as either lava or ash.
What happens when plates separate along the mid-ocean ridge or where plates collide along a subduction zone?
Volcanic eruptions occur where plates separate along a mid-ocean ridge or where plates collide along a subduction zone
Most of Earth´s volcanoes are located along plate boundaries that the surround the pacific ocean, this is called what?
Ring of Fire.
Volcanoes in the northwestern United States and Alaska form along what?
subduction zones within the Ring of Fire.
There are places where volcanic activity occurs on land due to divergence, where are such places?
the East African Rift Valley
Hot spots are areas of volcanic activity where magma moves toward the surface in large, in large what´s?
balloon like plumes
Hot spots are ________, unlike the plates that move above them.
stationary
_______ is a measure of a fluid’s, such as lava, resistance to flow.
Viscosity
What is molten or lava rock stored inside of the earth called?
Magma
Where is the ring of fire located?
Pacific Ocean
What are two specific locations where volcanic activity occurs due to divergence?
- East African Rift Alley
2. Mid-Atlantic Ridge
Are Hot Spots stationary?
Yes
What is the measure of fluid´s, such as lava, resistance to flow?
Viscosity
If magma has a high viscosity will it contain more or less silica?
More
What is pyroclastic material?
Any solid material that erupts from a volcano
What is the smallest form of pyrcolastic material?
Ash
What is the largest form of pyroclastic material?
Blocks and bombs
What are the types of gasses that erupt from a volcano?
- Water Vapor
- Carbon Dioxide
- Sulfur Dioxide
How are volcanoes classified?
- Size
- Shape
- Materials that erupts form them
What are the three types of volcanoes?
- Cinder Cone
- Shield
- Composite
