Core Curriculum/Georgia 93 © 2007 AIMS Education Foundation

Key Question

How do natural forces shape the rock layers of the Earth’s crust?

Learning Goals

• make a model of rock layers in the Earth’s crust, and

• use the model to learn how natural forces shape the rock layers.

Rye Bread—Brown Sandstone

Jelly—Limestone

Whole Wheat Bread—Shale

Chunky Peanut Butter—ConglomerateChunky Peanut Butter—Conglomerate

White Bread—White Sandstone

Core Curriculum/Georgia 94 © 2007 AIMS Education Foundation

1. Here we have an area of igneous bedrock. A river is fl owing swiftly along, carrying a load of white sand eroded from white rocks some distance away. The river channel gets wider, so the river slows down as it spreads out. The more slowly the water moves, the less load it can carry, so it drops its load of white sand along the bottom. As the years pass, this sand becomes cemented together, forming a layer of white sandstone.

2. A major fl ood occurs. Tons of mud, rocks of all sizes, and debris come pouring through this area and cover the white sand. The mud is represented by peanut butter; chunky, because of all the rocks it carries. The raisins are the boulders wrenched loose by the fl ood.

(white bread)

(chunky peanut butter and raisins)

Core Curriculum/Georgia 95 © 2007 AIMS Education Foundation

Rye Bread—Brown Sandstone

Jelly—Limestone

Whole Wheat Bread—Shale

Chunky Peanut Butter—ConglomerateChunky Peanut Butter—Conglomerate

White Bread—White Sandstone

4. Meanwhile, the Earth is warming and glaciers are melting. The ocean rises and covers the area we are observing. The salt water brings with it millions of little marine organisms. Their shells begin to line the ocean fl oor, forming a new layer. In time, the ocean will recede, leaving a calcium-rich layer that will become limestone.

5. It is a time of severe drought. Mighty winds pick up eroded bits of brown rocks. These rocks sandblast other rocks, until fi nally a layer of brown sand covers the area we are observing. In time, this layer will become brown sandstone.

3. In time, a slower, more gentle river fl ows across the area. Even though it’s a calmer river, it still carries a load. It has traveled through clay and is carrying a large amount of fi ne clay particles known as silt. As the river slows down and becomes shallower, this silt is dropped to the bottom, forming another layer. In time, this silt will become the sedimentary rock called shale. (wheat bread)

(jelly)

(dark bread)

Core Curriculum/Georgia 96 © 2007 AIMS Education Foundation

Sandwich Layers Corresponding Layers of Rock

Use this space to describe the processes of weathering, transport, and deposition as illustrated in this activity.

Follow the directions found in the story to answer this question.

HowHow dodo naturalnatural forcesforces shapeshape thethe rockrock layerslayers ofof EarthEarth’s crust?crust?

Core Curriculum/Georgia 97 © 2007 AIMS Education Foundation

1. It took about 10 minutes for all pairs to build their sandwiches. What is the oldest part? Why do you say that?

2. What is the youngest layer of the sandwich? Why do you say that?

Connecting Learning

3. What is the age of the shale or wheat bread?

4. Why can’t we say that it is half as old as the oldest layer and twice as old as the top layer?

5. What is the best way to determine the age of the limestone layer? …the conglomerate layer? In any sandwich that is right side up (or a layer not overturned), how can we best describe the age of any particular layer?

6. What processes built our rock layers?

7. What are you wondering now?