1. The Rock Cycle Fun with rocks?

2. What is this “rock cycle”? The rock cycle is a process that turns one type of rock into another type of rock.

3. Tell me why I should care! As scientists, we require knowledge…we need to understand the world around us! Knowing where certain types of rocks are can tell us where to find oil and natural gas deposits. Oh yeah…the information you learn here really will help you understand what you will see in high school and you may just discover you like learning about this stuff.

4. So…let’s get started. But with a cycle, how do you know where to start?

5. Let’s start with the different types of rocks

6. Igneous rocks The word “igneous” refers to anything relating to fire. An igneous rock is one that is made when magma cools and hardens. Slow cooling allows crystals to form. Rapid cooling can result in no crystal formation.

7. Igneous rock w/crystals

8. Igneous rock w/o crystals

9. Sedimentary rocks These are rocks that are formed when particles of other rocks and sometimes particles of once living things accumulate in the same area and are cemented together by minerals deposited between the grains.

10. Sedimentary rock (sandstone)

11. Sedimentary rock (halite)

12. Metamorphic rocks These are rocks that have been changed by heat and pressure, usually below the earth’s surface. This heat and pressure changes the texture and the chemical composition of the rock.

13. Metamorphic rock (gneiss)

14. Metamorphic rock (slate)

15. And you thought rocks weren’t exciting…shame on you.

16. How do these rocks become…well…rocks?

17. Igneous rocks Recall that igneous rocks are made from molten rock material (magma/lava) that cools and hardens. Magma can be ejected from a volcano or some other fracture in the earth’s surface (we call these EXTRUSIVE) OR it can cool and harden below the ground (we call these INTRUSIVE).

18. Imagine an igneous rock at the surface…hmmmm. You could be walking along the side of a volcano and kick a rock into the lava and watch it melt…but the rock cycle doesn’t need our help. On the surface of the earth, this rock is exposed to outside forces such as wind and water. These things break the rock down, but it takes a LONG time…this process is known as weathering.

19. Weathering The particles of these rocks are now somewhere else because of the process of transportation…the particles get dropped off or deposited with other particles from other rocks where they accumulate, get compacted, and eventually cement together.

20. Physical or Mechanical Weathering This is the disintegration of rock through direct contact with the atmosphere.This usually involves action by wind or water but can include heat, pressure, and ice! This doesn’t involve rock movement…the rock sits there and these things happen to it. Erosion, on the other hand, involves the movement of rocks.

21. Chemical Weathering Chemical weathering changes the composition of rocks, changing them when things like water or oxygen interact with minerals to create various chemical reactions. Oxidation is a common form of chemical weathering often causing rocks containing iron (Fe) to appear as if they have rusted.

22. Transportation The movement of particles from one place to another. This movement is the result of wind, water, and gravity.

23. Deposition The process of “dropping off” previously weathered or eroded sediment particles. This happens when the forces that carry the sediment particles aren’t able to carry them any farther.

24. Sedimentation The process of particles in suspension (such as in the water) to settle out and come to rest. These particles accumulate and build up over time.

25. Compaction and Lithification Sediment particles that are deposited and settle out of suspension have spaces between the particles that are often filled with water…when enough of these particles come to rest on top of one another, their mass pushes the water out, leaving the minerals behind to bind the sediments together.

26. Seriously…are we done yet? Sort of.

27. Let’s take a look at the entire cycle in a diagram. A diagram doesn’t really do it justice…but hopefully it gives you a snapshot of the cycle.

28. There is sooooo much more to the rock cycle…but these are the pieces I believe give us the best opportunity to fully understand it.