New York State High School Regents Exam Prep
Earth Science

What does the Rock Cycle tell us about the formation of rocks?

The rock cycle is a model used to describe the changes to rocks that take place on the earth. These changes show how each type of rock is formed. Some of the processes occur at or near the earth's surface such as weathering, erosion and deposition. Other processes occur deep below the surface such as melting and increased heat and pressure.

This chart also shows that most rocks are formed by other rocks and a "rock" may take more than one path through the rock cycle. For example, sedimentary rocks can be weathered, eroded and turned into sediments. It could also be melted and turned into an igneous rock. Use the rock cycle diagram to answer the question below.

The recrystallization of unmelted material under high temperature and pressure results in
1. metamorphic rock
2. sedimentary rock
3. igneous rock
4. volcanic rock

Think of your answer before you scroll down any farther. Don't cheat!!

Three things tell us that the correct answer is number 1, metamorphic rock. First, the word "recrystallization" means that the minerals in the rock had already crystallized once and the crystal structure has changed for a second time. This also tells us the rock could not be a sedimentary rock because they do not contain crystals. Second, the word "unmelted" tells us the rock could not be an igneous rock because according to the rock cycle diagram melting must take place for an igneous rock to form. Third, the use of the words "high temperature and pressure" tells us this rock is a metamorphic rock because heat and/or pressure is used in association with the formation of metamorphic rocks.

Use the rock identification charts on pages 6 and 7 in your reference tables and the rock diagrams below to answer the following questions.

Rock Diagram 1
The diagram below represents the characteristics of four different rock samples.

1. Which sample could be the rock granite?

2. What characteristic do number 2 and number 4 have in common?

Rock Diagram 2
The diagram below represents the characteristics of four different rock samples.

1. Which rock sample is foliated ?

2. Which rock sample is the most obvious choice as a sedimentary rock?

3. Describe how rock sample number 2 formed.


New York State High School Regents Exam Prep Center: Earth Science