Remember how our planet is more or less made up of a bunch of rocks of varying sizes and types (sedimentary, igneous, and metamorphic*) piled on top of each other? Those different types of rocks didn’t just fall out of the sky, though, so how did the different types form? This nifty Demo Science science demo will help you explain the “life cycle” of metamorphic rock to your students.
I Wanna Metamorphic Rock All Nite…
All that is required for this experiment is a length of paper towel (a foot is certainly enough…if you only want to do the bare minimum—personally, I use no less than 15 feet when demoing this one) and a spray bottle filled with liquid. Water is the obvious choice, but any liquid will do.
Lay your paper towel on your desk and tell your students that it represents a layer of sedimentary rock. (Feel free to use hypnosis if they refuse to go along with it.) Then, gently push the paper towel together from the ends; this will form a bulge in the middle. Release the ends and flatten the paper towel out as best you can.
Now, spray the paper towel with water. Applying the same pressure as before, push the ends together again. This time, instead of a stately and manageable bulge, your paper towel will wrinkle and fold. Now that’s metamorphic!
And Science Every Day
Real metamorphic rocks, deep in the bowels of the Earth as they are, experience many different types of deformation. The bulge created in the first part of this “experiment” is roughly analogous to a geologic uplift event. Spraying the paper towel with liquid loosely approximates the weathering process that rocks constantly endure, and the resulting folds and wrinkles are the evidence of the changes they undergo as a result.
* The Larry, Curly, and Moe of geology.