Metamorphic rocks form when existing rocks undergo transformation due to...
Metamorphic Rocks and Rock Classification - Geology Notes Lesson 8

Metamorphic Rock Formation
Ever wonder how rocks change without melting? That's metamorphism! A protolith (original rock) transforms into a metamorphic rock through pressure, temperature, and fluids - with no melting involved.
Pressure increases with depth due to the weight of overlying rocks (up to 300 MPA). Similarly, temperature rises with depth from geothermal heat. Fluids come from water trapped in cracks or contained within minerals. When a protolith experiences some partial melting, it becomes a migmatite.
During metamorphism, rocks undergo several changes. Compaction eliminates air spaces, creating denser rock. Recrystallization rearranges elements to form more stable minerals. Minerals develop a preferred orientation as they realign during compaction. Metasomatic processes involve water and heat bringing additional elements.
Remember This! Metamorphic rocks form in two main settings: regional metamorphism (affecting large areas at convergent plate boundaries) and contact metamorphism (where magma heats adjacent rock).

Metamorphic Rock Classification
Metamorphic rocks come in two main types: foliated and non-foliated. You'll ace identifying them once you know the differences!
Foliated rocks show preferred orientation of minerals. They follow a progression based on increasing pressure and temperature: shale (a sedimentary rock) transforms to slate (fine-grained, breaks into sheets), then phyllite (fine-grained with a crinkly texture), then schist (fine to coarse-grained, shiny from micas), and finally gneiss (coarse-grained with distinctive light and dark bands).
Non-foliated rocks don't show this alignment. Quartz sandstone becomes quartzite (hard enough to scratch glass), while limestone transforms into marble (fizzes in acid due to calcite content). These transformations often occur at convergent boundaries where oceanic lithosphere meets continental lithosphere.
Pro Tip: When identifying metamorphic rocks, look for foliation patterns first, then check specific properties like grain size and mineral composition to determine exactly which type you have.
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Metamorphic Rocks and Rock Classification - Geology Notes Lesson 8
Metamorphic rocks form when existing rocks undergo transformation due to pressure, temperature, and fluids - without actually melting. Understanding these processes helps us identify how Earth reshapes its materials over time, creating distinct rock types with unique properties.

Metamorphic Rock Formation
Ever wonder how rocks change without melting? That's metamorphism! A protolith (original rock) transforms into a metamorphic rock through pressure, temperature, and fluids - with no melting involved.
Pressure increases with depth due to the weight of overlying rocks (up to 300 MPA). Similarly, temperature rises with depth from geothermal heat. Fluids come from water trapped in cracks or contained within minerals. When a protolith experiences some partial melting, it becomes a migmatite.
During metamorphism, rocks undergo several changes. Compaction eliminates air spaces, creating denser rock. Recrystallization rearranges elements to form more stable minerals. Minerals develop a preferred orientation as they realign during compaction. Metasomatic processes involve water and heat bringing additional elements.
Remember This! Metamorphic rocks form in two main settings: regional metamorphism (affecting large areas at convergent plate boundaries) and contact metamorphism (where magma heats adjacent rock).

Metamorphic Rock Classification
Metamorphic rocks come in two main types: foliated and non-foliated. You'll ace identifying them once you know the differences!
Foliated rocks show preferred orientation of minerals. They follow a progression based on increasing pressure and temperature: shale (a sedimentary rock) transforms to slate (fine-grained, breaks into sheets), then phyllite (fine-grained with a crinkly texture), then schist (fine to coarse-grained, shiny from micas), and finally gneiss (coarse-grained with distinctive light and dark bands).
Non-foliated rocks don't show this alignment. Quartz sandstone becomes quartzite (hard enough to scratch glass), while limestone transforms into marble (fizzes in acid due to calcite content). These transformations often occur at convergent boundaries where oceanic lithosphere meets continental lithosphere.
Pro Tip: When identifying metamorphic rocks, look for foliation patterns first, then check specific properties like grain size and mineral composition to determine exactly which type you have.
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