Metamorphic Rock activities

This is a great activity I saw all over on Pinterest---the Metamorphic Snickers Bar. You start with a Snickers Bar, representing a sedimentary rock. (You can see distinct layers, as well as inclusions like fossils.) Put the "rock" in a ziploc bag and add intense heat and pressure.

I had the children put a book on top of the bag (to distribute the pressure more evenly) and count to 30.

Your sedimentary rock has metamorphosed into a metamorphic rock! You can see the mineral components are basically the same, but they look totally different. This new "rock" exhibits foliation! And now you can eat it; yum!

Seb's drawing of his two "rocks"

Here's another way to demonstrate foliation and metamorphosis (via The Happy Scientist. As I've said before, his site is so great. He explains all this stuff way better than I do. Well worth the subscription price!). Make a bunch of different minerals and sediment by rolling little balls out of a few different colors of playdough. (I had each boy roll out several balls of one color, and then they traded around so everyone had some balls of each color.)

Group several balls together and add some gentle pressure, to make these minerals and sediments stay together in a consolidated "sedimentary rock." You can cut your rock gently in half with a butter knife to see how it looks in cross section.

Now press down on your sedimentary rock to simulate the heat and pressure created deep inside the earth.

Cut the rock in half again. Now you can see foliation of the minerals!

You can metamorphose the rock again to see more foliation and marbling! (Some metamorphic rocks metamorphose again into a new rock when even more pressure is added to them.)