Metamorphic rocks have undergone changes over the course of time.
Metamorphic rocks refer to rocks that have changed over time. Metamorphic rocks may be igneous or sedimentary in form at first, but because of the high temperature and pressure of the earth above, these rocks change into a new form. This happens 12 to 16 kilometers below the earth's surface where the temperature is above 100 degree Celsius.
Kinds of Metamorphic Rocks
Marble is a transformation from dolomite or limestone, but marble is much harder than either of its parent rocks. Marble's different colors are caused by impurities during the metamorphosis. Sandstone that comes in contact with magma becomes a quartzite, which is harder than the original stone. Slate is a low-grade metamorphosis of shale that is easy to split. Schist, on the other hand, is a medium-grade rock because of the heat and pressure it experiences. Gneiss is a high-grade conversion of granite.
Experiment 1
You will need several colors of modeling clay, wax paper and three books. Create 24 pieces of pea-sized balls from clay. These clay balls represent the rock particles. Place the clay balls on a piece of wax paper, cover them with another sheet of wax paper and then stack books on top of the paper. The weight of the books simulates the pressure rocks place on rock particles. Remove the books and the top layer of wax paper and look at the clay, which has changed into a new form. The same happens to sedimentary rocks changing into metamorphic rocks.
Experiment 2
When metamorphic rocks are formed, they do so with several layers of dirt and lava. As a result, if you cut a rock in half, you will see many different colors and forms; sometimes you can even find preserved skeletons of bugs and insects. Demonstrate this concept by gathering three balls of colored clay or play dough. Roll the three balls of clay together into one big ball so the colors mix together. Next, press or pound on the newly formed clay ball until it is almost flat. Finally, cut the flattened ball into four or five pieces. Examine how the colors have mixed together and formed layers of colors, just as rocks formed under the pressure of the earth combine together like the minerals found in metamorphic rocks.
Experiment 3
This is a simple experiment for younger students that shows how ingenious rocks are formed. You will need wax paper and chocolate chips. Melt the chocolate chips in the microwave as an example of magma or lava. Next, pour out the melted chocolate onto a piece of wax paper for each child. Have the students watch the chocolate as it hardens and then cools down.
Tags: rocks formed, chocolate chips, clay balls, different colors, harder than, into form
