Science Lesson: Location, Location, Location

Abstract
In this series of experiments and simulations, students will observe how the different rock types are formed.

Purpose – Exploration of different rock formations.

Objectives
Students will be able to:
1. Describe the basic formation of each of the three rock types.

National Science Education Standard:
CONTENT STANDARD D – Earth and Space Science
GEOCHEMICAL CYCLES
• The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several different chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles.
• Movement of matter between reservoirs is driven by the earth's internal and external sources of energy. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life.

THE ORIGIN AND EVOLUTION OF THE EARTH SYSTEM
• Interactions among the solid earth, the oceans, the atmosphere, and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years.

Teacher Background

Igneous Rocks
http://www.clas.ufl.edu/users/jmartin/physical_geology/igneous_rocks.html

Igneous rocks are classified into two main categories: intrusive and extrusive. Intrusive rocks are formed inside a volcano or inside the Earth. The magma cools slowly forming rocks with large crystals. Granite is a common example. Rocks that cool outside a volcano, on the Earth’s surface are called extrusive. They have small crystals. Some examples are obsidian and basalt. The crystals in obsidian are so small they must be observed with high-powered microscopes.

Sedimentary Rocks
http://www.clas.ufl.edu/users/jmartin/physical_geology/sed_rocks.html

Sedimentary Rocks are usually formed near or in water. They are formed as a result of other rocks going through four main processes: erosion, deposition, lithification and cementation. Common examples are limestone, and sandstone. Limestone is a bit different in that it is formed from chemical erosion resulting in layers of Calcium Carbonate being built up prior to cementation.

Metamorphic Rocks
http://www.clas.ufl.edu/users/jmartin/physical_geology/metamorphic_rocks.html

Metamorphic Rocks are formed when rocks are pushed underground and are subjected to intense heat and pressure. This heat and pressure rearranged the minerals in the rocks and often, but not always, results in foliated (lined) rocks. Gneiss is a nice example of a foliated metamorphic rock while marble is an example of a non-foliated metamorphic rock.

Related and Resource Websites

Physical Geology by Jonathan Martin of the University of Florida
http://www.clas.ufl.edu/users/jmartin/physical_geology/

Volcano World’s Rock and Mineral Slide Show
http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Slideindex.html

Geo Man’s Rock Identification Charts
http://jersey.uoregon.edu/~mstrick/MinRockID/RockID/RockIDChart.html

Activity
You may find that these activities overlap, but that should not distract from the learning objectives. Some experiments take little time to set up and more time to discuss than others. The following is a recommended flow, but feel free to adapt to your own classroom constraints or needs.

Igneous Rocks

1. Provide students with examples of rocks that are clearly igneous. Ask them to identify characteristics that indicate how they are formed. Ask them what they believe might have influenced the way a rock forms if it is made of magma [time it takes to cool, location it formed, minerals in the magma].
2. Tell students that today they will be simulating formation of igneous rocks. Instead of magma, they will be using saturated solution of salt water. The salt will represent the various minerals in the magma (water).
3. Students should design an experiment to test the effects of cooling (in this case evaporation) times to see how this affects crystal size in the rocks. Have students carefully write up their procedures and results.
4. Following the experiment it would be appropriate to have students review classifying igneous rocks using an identification chart. You should also discuss felsic and mafic rock formation as being a result of mineral composition. A good identification chart is available at
http://jersey.uoregon.edu/~mstrick/MinRockID/RockID/RockIDChart.html

Sedimentary Rocks

1. Provide students with examples of sedimentary rocks which clearly exemplify sedimentary characteristics. Ask them to describe how they think these rocks may have been formed.
2. Tell students they will be simulating the formation of sandstone, a common type of sedimentary rock. The sand will represent eroded material. They will use a solution of Epsom salts and water (1:2) to represent mineral rich water.
3. Students will take the sand (if possible have a variety of types of sand of different particle size and color) and layer it in a cup. They will then add the Epsom salt solution and place their cup in the window to evaporate. In a few days a sedimentary rock will have been created. As the water evaporates the Epsom salts (representing dissolved minerals in a lake or river) act as a glue to hold the sedimentary rock together.
4. From students, elicit that sedimentary rocks are made from eroded materials (organic and inorganic material) that are “glued together” by pressure and minerals that have been dissolved in water.
5. Following the experiment, have students sort through a series of sedimentary rocks. Can they identify what these sedimentary rocks are made up of? Then have them classify the rocks using an identification chart. Students should draft a chart for each rock that includes its’ description, the identification and propose how they think where and how such a rock would form. They should leave a space for information they gather in the section entitled “under what circumstances are different types of sedimentary rocks formed”. You should also discuss how limestone is formed. A good identification chart is available at http://jersey.uoregon.edu/~mstrick/MinRockID/RockID/RockIDChart.html

Metamorphic Rocks

1. Tell students that metamorphic rocks are formed when rocks are subjected to intense heat and pressure deep underground. The rocks do not melt. (This is a good time to ask what type of rock formed from other melted rock – igneous).
2. Have students place several balls of frozen plasticine on the table close together. Ask them what these represent (other rocks of any type).
3. Have the students place the brick on top of these balls. Ask them what it represents (pressure of the earth on the rocks). Students should observe what happens as the plasticine balls heat up.
4. Tell students that often when rocks go through metamorphosis, the minerals in them line up to make stripes or layers. These striped rocks are referred to as foliated. Remind students that not all metamorphic rocks are foliated. Their plasticine model was not. (Another example of metamorphism is cookie dough baking. It does not melt, but the heat changes it.)
5. Following the experiment it would be appropriate to have students review classifying metamorphic rocks using an identification chart. A good identification chart is available at http://jersey.uoregon.edu/~mstrick/MinRockID/RockID/RockIDChart.html

Closure
Ask students if they think that rocks are cycled only from one type to another, i.e. do all igneous rocks erode and become sedimentary rocks? [No] Have students draw a graphic that demonstrates the multiple ways that material can move within the system. Stress to the students that it is the PROCESS that determines the type of rock. These graphics can be used to assess how students understand the movement of material in the earth system.

Once everyone has developed their own graphic of the interrelationship among different types of rocks, work as a class to develop a graphic that includes multiple aspects of the ‘rock cycle’. Have students reflect on what they included in their individual cycle and what they didn’t. They should modify their graphic on a new sheet to include any aspects not included.

Embedded Assessment
Student sedimentary rock chart detailing what they think it is made of and ability to identify sedimentary rocks.
Individual graphic of rock cycle
Reflection of initial individual cycle and modified cycle

Homework
Write a 2-3 sentence conclusion in your science notebook. Conclusions should tell what you learned and be thought provoking.

Embedded Assessment