Do You Get My Drift? How the Earth's Continents Formed
Millions of years ago our continents were not shaped the way they are today. As a matter of fact, they were not separate continents at all! Scientists now believe that the earth's land masses were once all one giant land mass called Pangaea. Over the last 250 million years the continents have broken up and drifted to where they are today. Scientists call this Continental Drift.
If you look at all the continents on a map, you can see how they all once fit together. Try it! Copy a map and cut out all the continents. Now try and piece them together looking at a map of Pangaea as a guide. Can you make the first super continent?
Is the Ground Moving Under Us?The continents drift because the ground under your feet is not made up of the solid, unmoving land you might think. The earth's crust is made up of a series of plates. Over time the plates move, though very slowly — sometimes less than an inch a year. This is called “plate tectonics.” It may not seem like much, but the movement of these plates is what forms mountain ranges and volcanoes, and causes earthquakes. When the edges of two plates collide, they can form a mountain range. Don't get out your hiking books yet — this takes millions of years. When two underwater plates move away from each other, that forms a mid-ocean ridge. Sometimes two plates slide over one another. This forms a fault, like the San Andreas Fault in California.
Create Your Own Volcanic Eruption
You will need one old mayonnaise jar, some baking soda, liquid dish soap, ketchup (optional), vinegar, and a sandy pile in your yard (optional). The carbon dioxide that is released when you mix the baking soda and vinegar is like a volcanic gas eruption!
Put the jar in the sink, or in a lasagna pan that can collect the “lava flow.” You can bury the jar in a volcano-shaped pile of sand in your yard if you want to make this look like a real volcanic eruption. Maybe try it in the sink first as a trial run.
Add ⅛ cup baking soda to the jar.
Squirt in some liquid soap.
Pour in ⅛ cup vinegar (you can mix the ketchup in with the vinegar before you add it, if you want to make the lava flow look red).
Stand back and watch your volcanic eruption!
Plate movement at a fault can cause earthquakes and volcanic activity like the eruption of Mount St. Helens in Washington State in 1980. There are more than 500 active volcanoes in the world and most of them are found where two plates come together. Volcanic eruptions are most dangerous because of the toxic gases they release. Volcanic eruptions are thought to be responsible for putting about 110 million tons of carbon dioxide into the atmosphere every year — all resulting from some drifting plates!
