15 Questions
How are igneous rocks formed?
By the cooling and solidification of magma
What makes magma rise to the Earth's surface?
It is less dense and more buoyant than surrounding rock
Where are melts commonly found?
In boundaries between tectonic plates or hot spots
What conditions are required for rocks to melt and form magma?
High temperature, decrease in pressure, and presence of volatiles
What type of rocks are formed when magma is trapped underneath the surface and slowly cools?
Intrusive or plutonic rocks
What is the main characteristic of batholiths?
Irregularly shaped and can reach up to hundreds of kilometers long
What distinguishes sills from dikes?
Sills are horizontally oriented parallel to the rock beds and foliations
Which statement best describes the formation of dikes and sills?
They are formed when magma intrudes on a pre-existing rock body and starts to crystallize as sheet intrusions
What type of rocks are commonly observed in batholiths?
Granite, quartz monzonite, or diorite
What is a notable example of a sill formation mentioned in the text?
Yellowstone National Park in Wyoming, USA
What is the main difference between volcanic and plutonic igneous rocks?
Volcanic rocks form from molten material that reaches the Earth's surface, while plutonic rocks form from magma trapped underneath the Earth's surface
What is the main reason for the fine-grained or glassy texture of volcanic rocks?
The rapid cooling of the molten material on the Earth's surface
Which mineral is a significant component of pumice, an example of extrusive igneous rock?
Quartz
What is the primary reason why granite, an example of intrusive igneous rock, has a coarse-grained texture?
The slow cooling of the magma underneath the Earth's surface
What is a pluton in the context of igneous geology?
A large igneous body that cools and solidifies near the Earth's surface
Learn about the definition and formation of igneous rocks in this lesson. Understand how magma solidifies to form igneous rocks and how they are interconnected with other rock types.
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