Question

Which one of the following shows the correct order (from left to right) of decreasing magma viscosity? (remember that viscosity is resistance to flow, so you should pick the answer that has the most viscous lava type on the left, and the least viscous (most runny) on the right.
a. granite, andesite, basalt
b. andesite, granite, basalt
c. basalt, granite, andesite
d. basalt, andesite, granite

Answer 1

Answer:

a. granite, andesite, basalt

Explanation:

There are three basic different types of magma: rhyolithic, andesitic, and basaltic. These three types of magma have different properties which differs them from one another, and which cause different types of eruptions. The rhyolithic (granite) magma has very high viscosity. This magma is the thickest, managing to trap gases in it, and because of it it causes highly explosive eruptions. The andesitic magma is moderate in viscosity, and it has explosive eruptions, but also has lava flows that are relatively slow, so it is very unpredictable what kind of an eruption will the volcano have. The basaltic magma is the least viscous. This means that the eruptions of these volcanoes are not explosive, but instead they produce thin lava flows that cover the surrounding area.