COOKIE EARTHQUAKES - Destructive Forces
This is a quick demonstration/activity to show how large amounts of rock and sediment are destroyed and added to the edge of continents.
NOTE TO TEACHER: Simply explain the steps for this model rather than copying this sheet to give to students. Lead students in steps 1-3 and discuss how this simulates plate movement in an earthquake. Then have students do step 4 and again discuss how this simulates an earthquake.
What do I need?
• Cream centered cookie (e.g. Oreo, Hydrox)
What do I do?
1. Pull apart the cookie.
2. Use the part with the most cream center still attached.
3. With the cream side up, slowly slide the cookie into your mouth. While sliding, the upper front teeth should scrape off the creaming filling.
The creamy filling should be plastered onto your front teeth when you're done.
What's going on?
Your teeth represent a piece of the earth’s crust that pushes up the cookie cream
[more of the earth’s crust and sediment] causing an earthquake which destroys some of the earth’s crust and deposits some of the crust in another area .
4. Now try pushing the two pieces of cookies towards each other or grind them past each other. What happens?
When the two [cookie] plates push against each other or grind past each other, they shake the earth causing an earthquake and destroy some of the earth’s crust.
TEACHER BACKGROUNG INFORMATION - What's going on?
When an oceanic plate dives under continental plates, layers of the sea floor are often scraped off and plastered onto the edge of the continental plate next to it.
This process of adding oceanic material to the edge of a continental plate is called accretion. It's an important process in the building of continents. Much of the west coast of the Americas is composed of accreted rocks or terranes.

The diagram below shows how the edge of the continental crust bulldozes off the top layers of the subducting oceanic crust. In the cookie analogy, your teeth do the bulldozing, scraping off cream filling rather than sediments.
A diagram of subduction, showing how an oceanic plate dives under a continental plate. Lithosphere and asthenosphere are layers of the crust.