Core Samples Tell Tales
demonstrationactivity exercisesuggested grade levels: 7- 8
view Idaho achievement standards for this lesson

Overview:
Sedimentary rock is rock made up from smaller pieces of other rocks. Pieces of rock are eroded away by water or wind and these pieces can be deposited on top of one another. Through time these separate small pieces form a single rock. Sedimentary rocks found today were once sand, gravel, mud, or silt that became lithified, or turned to stone. Sedimentary rock forms in layers, with the newer layers forming on top of the older layers. Living things can become buried and form fossils in these layers. Geologists take core samples of rock and can tell much about the earth and its life forms by analyzing the layers in these core samples. By doing this activity, students will become familiar with the process and formation of sedimentary rock.

Objectives:
1. Students will understand that rocks can form in layers.
2. Students will be able to tell which layers are older when compared with other layers.

Materials:
Various colors of clay Clear plastic tubes or straws
Salt and Pepper Exacto knife
Container  

Procedure:
This activity is related to the fossil and sedimentary rock sections of the Digital Atlas. To get there: Click on Atlas Home, mouse-over Geology, then click on Fossils. Encourage students to read through the introduction on fossils. Have them click on the pictures of the different fossil types at the left side of the screen. This will help the students to see the dazzling variety of life forms to be discovered in the study of fossils.

1. Encourage your students to put various layers of colored clay in a container. Layers can vary in their thickness. The salt and pepper can be mixed within some of the layers to represent different types of fossils.

2. Divide the class into groups of 3-4 students, each group will stick a plastic tube into the clay as far as it will go. Remove tube and let students observe the different layers of "rock" that they have in their core sample.

3. If the straw is not easy to see through, teachers should cut away the tube with an Exacto knife and allow the students to draw their layers on paper. Students should indicate where various "fossils" are found. Have students label their drawing with the relative ages of each layer or stratum.

4. Have groups of students compare core samples with other groups. See if each group can correlate the layers within each core sample. Not all core samples should be alike because samples were chosen at different places within the clay.

5. Try twisting or folding the clay in the container to represent the geologic forces that convert sedimentary rock into metamorphic rock, or cut the clay and move the layers to represent an earthquake. Take another core sample and let students observe the changes.

Handouts/Activity links:
These are links to access the handouts and printable materials.
Fossils

Related Lesson Topics:
Geology: Geology Topics

Lesson plan by Vita Taube, 2000
Idaho Achievement Standards (as of 7/2001) met by completing this activity:
798.04
804.01