The Basics
What does "metamorphic" mean?
"meta" = change
"morphe" = form
What are the two types of metamorphism?
Shale, which is a sedimentary rock
What is foliation?
Foliation is to form into thin, leaflike layers.
What is metamorphism?
The process of forming metamorphic rock
What is contact metamorphism and what does it look like?
Contact Metamorphism is when magma pushing up through Earth’s crust heats nearby rocks
Draw a picture that shows that the magma bakes the rock it comes into contact with.
What type of metamorphism (low, medium, high grade) is slate formed from?
Low-grade metamorphism
What is a non-foliated rock?
A non-foliated is one that does not have thin, leaf-like layers because it is composed of one mineral that deforms at the same temperature.
What is a metamorphic rock?
A metamorphic rock is a rock that has changed from another rock because of heat, pressure, or a chemical reaction.
What is regional metamorphism and what does it look like?
Regional Metamorphism is metamorphism over a large area, most often due to high pressure.
Draw a picture that shows large regions of rock deep in the Earth’s crust experiencing high pressure.
What type of rock is schist formed from and what type of metamorphism must this source rock undergo to create schist?
Formed from various igneous and sedimentary rocks, must undergo medium-grade metamorphism to form schist
What is an example of a foliated rock we have seen?
Gneiss, Slate, Schist
What are the three processes that can form a metamorphic rock?
Heat, pressure, and chemical reactions
What is a similarity between regional and contact metamorphism?
Both can change the composition of the rock by:
- forming new minerals
- changing existing minerals
- causing fossils to disappear
What is the only rock we have learned about that requires high-grade metamorphism to form?
Gneiss
What can foliation tell us? How is it useful to geologists?
Foliation provides information about the conditions under which the rocks formed. Geologists can study the foliation of rocks to learn more about Earth's history, including how tectonic plates have moved and how the Earth's crust has been shaped over millions of years.
How did we model metamorphism in class? Explain each part of the model.
We used a candy crusher/closed syringe as the pressure due to tectonic plate forces. We used candy as the crust/rock undergoing metamorphism. We used hot water to represent heat under the crust. When we applied pressure to the candy without heat, the candy did not melt. However, after dipping the syringe into the hot water and then applying pressure, the candy melted and changed more radically.
The source rock for schist is slate, and the source rock for slate is shale. How can that be?
It depends on how much metamorphism has occurred/how much heat and pressure. If shale changes a little, it becomes slate. If it changes a lot, it becomes schist.
What type of metamorphism is gneiss formed from?
Regional
Marble and Quartzite.
They do not show thin, leaf-like layers