Objective of this demonstration is to show how folds can originate in metamorphic rocks and to help strengthen understanding of the rock cycle.
Properties of Earth Materials (physical properties of rocks), Changes in Earth and Sky (weathering), and Structure of the Earth System (the rock cycle).
Materials: One foot long piece of paper towel and spray bottle of water
(1) Tell the students that the piece of paper towel represents a layer of sedimentary rock.
(2) Push the paper towel together from its ends, causing a bulge.
(3) Flatten the paper towel back down on a table.
(4) Spray the paper towel with some water.
(5) Apply the same pressure to the sheet of paper towel and it will wrinkle, or produce folds.
Science Behind It: Metamorphic rocks often have different folds from the deformation they are put through. The first bulge of the paper towel is analogous to a geologic uplift event. After weathering has occurred (sprayed water) and additional pressure, the paper towel has become a metamorphic rock containing folds. The folds are evidence of the changes the rock has endured. This demonstration will hopefully allow students to understand the process of the rock cycle better as well as the processes involved related to the formation of metamorphic rocks.