Volcanoes, among the most destructive forces on Earth, have a fascinating history. But long before they stretch high above the treetops and spit, sputter, and spew lava, steam, and gas into the air, volcanoes are forming deep below the Earth's crust and oceans.
1. Have an adult help you cut the cereal box so that you have a long strip that's about 2" wide.
2. Punch several random holes along the length of the cardboard.
3. Punch two more holes very close to one of the other holes, so that there is a cluster of three holes.
4. Next, with your adult helper, hold the toothpaste under the strip of cardboard, so the nozzle is gently touching the cardboard.
5. The person holding the cardboard should move the cardboard over the toothpaste nozzle very slowly while the person holding the toothpaste squeezes. It's a good idea to cover the floor or table with newspapers to catch any 'falling molten rock'.
If you like, repeat steps 4 and 5 using mustard, ketchup, Easy Cheese or shaving cream.
If you were to split the Earth down the center, you'd find that it's comprised of three different layers. The top layer is known as the crust and it's where we live. The crust is covered by land (continents) and water (oceans) and made up of smaller sections called tectonic plates, which are basically huge slabs of rock. The plates shift over time (mere centimeters each year) spreading apart and coming together. Volcanoes typically form at locations where tectonic plates meet. However, scientists believe volcanoes can also form above something called a mantle plume. Plumes are theorized to be hot, upwelling (or rising up) of unusually hot rock within the mantle. Hot spots are sources of extreme heat rising from deep within the Earth and they form above plumes.
Beneath the crust is the middle layer, called the mantle. The mantle is thick and hot and filled with heavy rocks. In fact, sometimes parts of the mantle get hot enough to melt the rocks within it, creating magma.
At the center of the Earth is the deepest layer—the inner and outer core. This part of the Earth is made up of molten (liquid) and solid iron.
In this experiment, the toothpaste represents a hot spot and the cardboard represents a tectonic plate. The holes punched in the cardboard represent weak spots in the Earth's crust. The toothpaste emerging through the holes demonstrates how eruptions of magma rise through cracks in the Earth's crust to form volcanoes. As the tectonic plates move across the hot spot over time, chains of volcanoes and seamounts (mountains beneath the ocean) form. The Hawaiian islands are an example of a volcanic chain.
Scientists determine the speed and direction that tectonic plates move by comparing the age of the volcanic islands in relation to the hot spot location. Newer volcanoes are found closer to a hot spot, while older volcanoes are located farther away. In this project, which "volcanoes" are oldest? Which are youngest?
Project adapted from Volcanoes Alive.