In the early 1020's, a Muslim scholar named Avicenna wrote a book about how rocks are created. He proposed that rocks weather and erode, and that eventually new rock is formed from the resulting sediments. He also suggested what an enormous amount of time it would take for this process to occur.

These ideas were considered very radical for their time, and did not take hold at first. It was only centuries later that his theories became widely accepted.

## Exploring the Rock Cycle

In this activity, you will explore the many ways that rock can change from one type to another.

1. In the Gizmotm, click the SIMULATION tab, and then click Start again. Six different components of the rock cycle are displayed.
1. Click the Magma button. Magma is molten rock that is found deep beneath Earth's surface. What temperature is typical of magma? (Read the text at the top of the DESCRIPTION pane.)
2. Magma can undergo two possible transitions, which are shown on the two buttons in the pane at the right. What are these possible transitions?
3. Click Crystallization (above ground). What type of rock results from this transition?
4. What are some specific examples of extrusive igneous rock? Examine the sample of extrusive igneous rock shown in the pane at the right. What are some distinguishing features of this type of rock?
5. What are the possible transitions that extrusive igneous rock can undergo?
6. Click Increase temp. and pressure. This can occur when surface rock is exposed to tectonic events or faulting. What types of changes can occur in rock that is exposed to these forces? What rock type is created as a result?
7. Metamorphic rock can undergo two types of transitions. What are these transitions?
8. Click Melt. This transition occurs deep beneath Earth's crust under extremely high temperatures. What type of rock is the outcome of the melting process?
9. Click the PATH tab to display the rock types that were produced by this series of changes. Notice that the sequence is also displayed graphically in the diagram. What is the first and last rock type in the series? A sequence like this, in which the first and last rock types are the same, is an example of a cycle. Cycles are common in many areas of nature. Other examples include the water cycle, the carbon cycle, and the nitrogen cycle.
2. Click the SIMULATION tab and then click Start again. The six different components of the rock cycle are again displayed. On a sheet of paper, sketch a diagram like the one shown below, including each component of the rock cycle. (You can also print this document if you like.)

1. Click Magma. Then click Crystallization (below ground). What is the outcome when magma undergoes this transition process? In your diagram, draw an arrow from Magma to Intrusive Igneous Rock. Label the arrow "Crystallization (below ground)."
2. Click Start again. Then click Magma and, this time, click Crystallization (above ground). What is the outcome when magma undergoes this transition process? In your diagram, draw an arrow from Magma to Extrusive Igneous Rock. Label this arrow "Crystallization (above ground)."
3. Click Start again. This time click on Intrusive igneous rock. What are the possible transitions that this type of rock can undergo? Find the outcome of each of these possible transitions just as you did for magma in the preceding steps. For each possible transition, add an arrow to your diagram and label it with the type of transition.
4. Continue through the remaining four starting points, adding arrows to your diagram until every possible transition has been included and labeled.
5. Refer to your diagram to answer the following questions. How many different rock transitions can result in metamorphic rock? Which rock types can be reduced to sediments via weathering? Which rock types do not have weathering as an option? Explain why.