Chapter 25.3 and 25.4 Flashcards
What is the boundary that marks a density change between layers?
Discontinuity
How can discontinuities be identified?
Seismic waves
What are shadow zones?
Areas where no seismic waves are recorded
What is another term/name for shadow zones?
“dead zone”
Between what degrees do shadow zones fall?
105-140 degrees from the epicenter
Is the outer core a solid or a liquid?
A liquid
Is the inner core a solid or a liquid, and why?
Solid because of pressure
What makes up the lithosphere?
The crust and uppermost mantle
What is the asthenosphere?
A plastic like layer which Earth’s plates move.
What elements make up the mantle?
Calcium, Aluminum, Iron, and Magnesium
Which elements the core?
Iron and nickle
The measure of a fluid’s resistance to flow.
Viscosity
The chemical compound silicon dioxide which is a common ingredient in most magma.
Silica
Small volcanoes that have heights in the hundreds of meters range and have short eruption cycles.
Cinder cone volcanoes
Broad flat structures composed of layer upon layer of lava flows.
Shield volcanoes
They are large and steep-sided, often thousands of meters high and tens of kilo meters across the base, and composed of layers of both lava and ash.
Composite volcanoes
What is a volcano?
A feature that forms when magma reaches Earths surface and erupts as either lava or ash.
Where do volcanic eruptions occur?
Where plates separate along a mid-ocean ridge or where plates collide along a subduction zone.
What is the “ring of fire”?
Where most of Earth’s volcanoes are located around the Pacific Ocean.
Why does volcanic activity along divergent boundaries go unnoticed?
It occurs under water along mid-ocean ridges
What are hot spots?
Areas of volcanic activity where magma moves toward the surface in large, balloon like plumes
What is the most common ingredient in magma?
Silica
What is classified as pyroclastic material?
Any solid material that erupts from a volcano
How are volcanoes classified?
According to their size, shape, and material that erupt.
