Title: Viscosity Brown 24-25
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# Viscosity Volcanism vs. Volcano
Volcanism refers to the activity of magma forming and coming toward surface A Volcano is the landform created when magma reaches the surface through an opening in Earths crust
> Volcanism Volcano
## Magma vs. Lava
Magma is hot, molten or semi-molten rock located underground .
Lava is hot, molten or semi-molten rock that has reached the surface .Liquid Hot Magma Magma
Magma is made up of solid, liquid, and gas: the liquid portion is referred to as the melt
the solid portion is made of minerals that crystallize directly from the melt; known as the crystal mush solid rocks picked up on the way out called xenoliths or inclusions
the gaseous portion is dissolved into the magma Lava
Only liquid and solid - Most dissolved gases have escaped Igneous Rock Descriptions
Three general ways to describe igneous rocks, based on their mineral composition:
1) Felsic - high silica content (felsic stands for feldspar and silica), generally lighter in color
2) Intermediate - in between felsic and mafic
3) Mafic - low silica content but high magnesium and iron content (mafic stands for magnesium and iron), generally darker in color
> Intermediate
> Felsic
> Mafic
## Silica Content and Viscosity
Viscosity measures a liquids resistance to flow Thicker = High Viscosity High viscosity flows slowly Low viscosity flows fast The more silica a magma has in it, the thicker and more viscous it is Not all lavas are the same
The type of lava depends on many factors, like viscosity and temperature. We will talk about two types of lava:
Aa Pahoehoe Aa Lava
Aa is lava with a rough, jagged surface composed of broken lava blocks called clinkers .Aa lava forms when lava has cooled and its viscosity has been increased. Clinkers Pahoehoe Lava
Pahoehoe is lava that has a smooth (yet often wrinkled) surface. Pahoehoe
Many appearances:
Coil
Toe
Ropy
Entrail Which lava type is this?
Which lava type is this?