Chapter 6 Flashcards
What three factors determine the violence of interruption?
- Composition of a mag.
- Temperature of the magma.
- Dissolved gases in the magma.
What is viscosity?
The measure of a material materials resistance to flow
(higher viscosity = less fluid= more sticky
Lower viscosity = more fluid)
Is high silica Felsic or Mafic?
Felsic
Is low silica felsic or mafic
Mafic
True or false. high silica equals high viscosity
True
What temperature of magma is more vicious?
Colder magma
What are two types of basaltic lava flows?
- Pahoehoe lave
- aa lava
What type of lava resembles braids in ropes and is smooth and ropey?
Pahoehoe lava
What type of lava is rough and jagged?
aa lava
What does pyroclastic mean?
Fire fragments
True or false. Types of pyroclastic material are defined by their size.
True
What are the different sizes of pyroclastic materials?
- Ash and dust. (fine, glassy fragments.)
- Pumice (from “frothy” lava.)
- Lapilli (“walnut” sized)
- Cinders (“pea-sized”)
What are particles larger than lapilli?
-blocks: hardened lava
- bombs: ejected as hot lava
What is a cone shaped mountain through which interruption occurs called?
A volcano
What is a volcanic neck?
A conduit, or pipe, that carries gas-rich magma to the surface
What is the surface opening that is connected to the magma chamber via pipe called?
Vent
What is a crater?
A steep wall, depression at the summit left behind after the volcano erupts
What is a summit depression greater than 1 km in diameter called
A Caldera
What are three main types of volcanoes?
- Shield volcanoes.
- Cinder cone (a.k.a. Scoria cone)
- Composite volcano. (a.k.a. Stratovolcano.)
