What are metamorphic rocks?
Metamorphic rocks are rocks that have transformed into another type of rock through geological processes. Metamorphic rocks were once either igneous rocks or sedimentary rocks.
How do sedimentary rocks and igneous rocks change?
When rocks are under pressure, heat within the rock builds up. This causes the rocks to transform into metamorphic rocks. Therefore, metamorphic rocks are created by either the physical or chemical alteration through heat and pressure of an igneous or sedimentary rock into a denser form.
When rocks are under pressure, heat within the rock builds up. This causes the rocks to transform into metamorphic rocks. Therefore, metamorphic rocks are created by either the physical or chemical alteration through heat and pressure of an igneous or sedimentary rock into a denser form.
This chart depicts metamorphic rock types, their texturture, grain size, and characteristics. It also reveals the parent rocks (either igneous or sedimentary rock).
What causes rocks to change?
Rocks can be deformed and warped due to plate tectonics, compression ,stress, and shearing forces over long periods of time. This causes the rocks to become compacted into a smaller volume of space. Thus, metamorphic rocks are denser than their original rock form and are less likely to erode.
Rocks can be deformed and warped due to plate tectonics, compression ,stress, and shearing forces over long periods of time. This causes the rocks to become compacted into a smaller volume of space. Thus, metamorphic rocks are denser than their original rock form and are less likely to erode.
Where do metamorphic rocks form?
Metamorphic rocks form deep within the Earth. Metamorphic rocks form deep within the earth because the temperature deep within the earth is very high. Metamorphic rocks begin to form at 12-16 kilometers beneath the Earth's surface. The heat that causes the rocks to change comes from magma, while the pressure that causes the rocks to change comes from layers of rock piled on top of one another.
Metamorphic rocks form deep within the Earth. Metamorphic rocks form deep within the earth because the temperature deep within the earth is very high. Metamorphic rocks begin to form at 12-16 kilometers beneath the Earth's surface. The heat that causes the rocks to change comes from magma, while the pressure that causes the rocks to change comes from layers of rock piled on top of one another.
Listed on the left are examples of sedimentary and igneous rocks that transform/change into metamorphic rocks.
Characteristics of Metamorphic Rocks
- Classified by texture and composition
- Can have layers of visible crystals
- Can react with acids
- Rarely has fossils
- Has bent or curved foliation
- Rarely has pores or openings
Textures of metamorphic rocks
- Foliated- Foliated metamorphic rocks are formed from aligned mineral grains. This type of texture is formed when the rock undergoes pressure. Foliated metamorphic rocks are the largest groups of metamorphic rocks.
- Non-foliated- Non- foliated metamorphic rocks are formed from non-aligned mineral grains. This type of texture is formed under direct pressure and elevated temperatures. These types of metamorphic rocks are dependent upon the composition of their parent rock.
Examples of Metamorphic Rocks
- Gneiss: Pink or gray color, foliated
- Marble:Very light color, non-foliated
- Slate: Light colored,non- foliated
- Quartzite: Dark gray or black, foliated
Dear Geologists,
I hope you enjoyed learning about metamorphic rocks! Click here to view your assignment on metamorphic rocks. Don't forget your science journals!
- Geologist Joe
I hope you enjoyed learning about metamorphic rocks! Click here to view your assignment on metamorphic rocks. Don't forget your science journals!
- Geologist Joe