Rocks With Wavy Layers Are Foliated Metamorphic Rocks!
Do you see the little wavy layers in the pictures of foliated metamorphic rocks below?
All three of these rocks formed from a sedimentary rock called shale. With different
amounts of metamorphism, shale becomes different types of rocks!
| Rock |
Picture
(click for larger image) |
Features |
How Much Metamorphism? |
| Slate |
(Courtesy NPS) |
It looks like shale because it is dark in color and will break into thin
flat layers like shale often does. Unlike shale, slate makes a ringing sound
when you hit two pieces together. |
Low |
| Schist |
(Courtesy NPS) |
There are several different types of schist such as mica schist, garnet
schist, and chlorite schist depending on which minerals are found in the
rock. All schist contains mica. |
Medium |
| Gneiss (pronounced "nice") |
(Courtesy USGS) |
This striped rock often looks a bit like fudge swirl ice cream. The light
colored layers are usually quartz and feldspar and the dark layers (the
fudge!) are mostly mica. |
High |
Last modified August 11, 2003 by Lisa Gardiner.
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