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GEOL 121 Name Section ___________ Rocks 1: Introduction to Rocks and Rock Processes Scientists like to classify things - organisms, planets, stars, clouds, rocks, pretty much anything! Classification is useful because it allows scientists to identify patterns and organize information. In this lab, you will investigate rocks by developing your own classification scheme. You will then learn how scientists classify rocks, and what can be interpreted about a rock’s history based on its classification. Learning Objectives for this Lab: 1. Identifying types of observations that are useful in identifying rocks 2. Categorize rocks based on observable physical characteristics, and explain why classification is an important aspect of science 3. Classify rocks as sedimentary, igneous, or metamorphic, and justify why each rock is included in its classification group 4. Reflect on how their classification schemes compared to the one used by geologists Part 1: Rock Exploration and Differentiation 1. In your groups, observe the samples given to you by your instructor (Sample Group A). Below, brainstorm a list of the observable properties of the rocks that you might use to differentiate them. The properties could be anything that you might see and note about the rock; there is no right or wrong answer here!

GEOL 121 2. Come up with a classification scheme for your rocks; organize your rocks into 3-6 groups. In the table below, list the sample numbers in each group and write a description of the characteristics that define that group. Sample Numbers Description 1,3,12,6,11, Light colored 9,10,8,2,4,5 Dark colored 10,1,11,4,5 Shiny (with crystals) 9,8,12,2,6,3 Dull (without crystals) 3. Discuss your classification scheme with another table group. How are your classmates’ classification schemes similar to and different from the one you came up with? Describe below. Their classifications were more scientifically specific such as effervescence and between coarse and fine grain. Our classifications were broader. 2

GEOL 121 4. Your instructor will give you a new set of samples (Sample Group B). Consider how effective each of the classification schemes your group and your neighbor group \ came up with were in classifying these samples. Then, develop and describe a revised classification scheme based on your discussion and the introduction of the new data (samples). Our classifications are still effective and so were our neighbors’ group. A revised classification scheme we could use could be grain size, layers of grain, and density of the rock. 5. Instead of rocks, imagine that your instructor had asked you to classify fruit- apples, pears, cherries, blueberries, oranges, limes, blackberries, bananas, in order to determine how they are related to each other. a. Would classifying the fruit by color or size help scientists identify and distinguish between different fruit groups? What issues could arise if these characteristics alone were used? E.g., how would this impact the classification of new fruits (pineapple, melons, tomatoes, avocados, etc….) No because if you were to have two apples, one green and one red, they are both apples, but they appear different and can have different tastes. b. Identify classification schemes that could help you divide these fruits into groups that illustrate how they are related to each other. Are there any observable characteristics could you use? Shape/size of the fruit could be an observable characteristic that we could use to classify the fruits. *wait for instructor guidance before beginning Part 2 Part 2: Scientific Classification of Rocks 3

GEOL 121 1) At this point, your instructor will lead you in a discussion of the accepted scientific classifications for the three primary rock types, and subcategories within each, which is based on how the rocks form. As part of this discussion, fill out the “identifying characteristics” column of the table below. ROCK TYPE SUB-TYPE FORMATION MECHANISM IDENTIFYING CHARACTERISTICS EXAMPLES Igneous Extrusive Forms from the cooling and crystallization of molten rock on the Earth's surface. Interlocking mineral crystals Small/cannot see them Basalt Intrusive Forms from the cooling and crystallization of molten rock underneath the Earth's surface. Large interloc king crystals air bubbles Pegmati te diorite Large interloc Granite 4

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