1. Images courtesy of Sarah Penniston-Dorland
Some of the prettiest rocks in the world form inside a subduction zone!

2. Activity directions
Each group will spend 3 minutes at each of four stations. During that time your group will describe each rock.
You will be asked to describe and compare the rocks at the end.
You should describe:
colors
mineral sizes
textures (e.g. layering, foliation, veins)
identify minerals
density

3. Rock comparison
Rock
Colors
Minerals
Mineral sizes
Textures
Density

4. What do these rocks represent?
These rocks represent a sequence of progressive metamorphism of a basalt passing from the ocean floor down through different depths within a subduction zone.
Order the rocks from the surface to depth.
Which rock do you think represents the protolith (unmetamorphosed parent rock)?
Which rock do you think has made it to the greatest depth? Why?