Magma

Does the picture show the formation of magma or lava?

• Magma because it is formed under the Earth's surface in the upper mantle and lower crust

• Lava because it is formed on the Earth's surface

What temperatures are necessary for magma to form?

• At the same temperature that water boils, which is 100⁰C

• Between 200⁰C and 800⁰C

• Between 800⁰C and 1200⁰C

• Since magma is a "liquid rock", it must at a temperature similar to our Sun (which is greater than 5,000⁰C)

• True

• False

True or False. Magma is composed of a slushy mixture of molten rock, mineral crystals, and dissolved gases.

• True

• False

Magma is made of minerals that make up the Earth's crust. Some of these minerals are Aluminum (Al), Iron (Fe), Calcium (Ca), Sodium (Na), Potassium (K), Magnesium (Mg) and:

• H₂ gas and Sulfur (S)

• F₂ gas and Argon (Ar)

• O₂ and Silicon (Si)

• Cl₂ and Uranium (U)

There are four factors that affect magma formation. They include:

1. Temperature
2. Pressure
3. Water content

What is the fourth?

• Weather

• Nitrogen content

• pH

• Mineral Composition

What happens to the pressure the further you go down into the Earth's crust and mantle?

• It decreases because there isn't that much rock above to push down (from above)

• It increases because the weight of the rock above presses down

As a solid begins to melt, the particles that were previously locked into place, begin to slide past each other.

The deeper you travel into the Earth's crust, the pressure increases. The increased pressure "contains" or "prevents" the molecules from moving. This increased pressure prevents the solid rock from turning into a liquid. In order for the rock to become a liquid, what happens to the melting point?

• The melting point of the solid rock must increase so that the particles have enough energy to move past into each other as they convert into a liquid

• The melting point decreases because the particles that make up the rock can already move

• It has no effect on the melting point

Water has a high specific heat capacity. This means that water can _____

• Absorb a lot of heat energy

• Absorb very little heat energy

When oceanic crust moves under continental crust in a process called subduction, water is brought down to the mantle. (See picture).

Recalling that water has a high specific heat capacity, as it enters the rock, does it increase or decrease the melting point of the magma?

• The presence of water and it's high specific heat capacity, lowers the melting point, allowing magma to form

• The presence of water and it's high specific heat capacity, raises the melting point, allowing magma to form