The Rock Cycle

Rocks under the microscope--reading rocks.

Historians commonly read through old diaries, letters or documents in order to reconstruct the events in the life of a historical figure. An investment manager might analyze past corporate reports of a company to predict the future earnings of a company in which a client is interested. Likewise, a geologist studies rocks to interpret past events, like a historian, or to predict future events, like an investment manager. The rocks of Earth are the physical records of past events--they are Earth's diary. Therefore, a geologist will study rocks in order to chronicle this past. However, a geologist might also analyze the record of the rocks in order to predict future behavior of Earth, for example, when the next large earthquake might hit a region, or how climate might change in the future. But, to paraphrase the warning of an investment company advertisement, "past events do not necessarily reflect future events."

In order to read information from a rock a geologist is trained to carefully observe important features in rocks. Probably the most important observation to make concerns the texture of a rock. You will spend most of the lab this week trying to identify and interpret different textures of rocks.

In this pre-lab exercise you will be exposed to different textures of igneous, sedimentary and metamorphic rocks using magnified views of the rocks. These microscopic views will help you see the differences in texture between igneous, sedimentary and metamorphic rocks. Since you will only be using hand samples of rocks in lab, you should pay careful attention to these magnified views, so that you can picture what the rock looks like in detail.

What to do:

Click on Rock Cycle link in menu and read through the rock cycle information , then click on the igneous, sedimentary and metamorphic links to preview the textures and rock types you will study in lab.