GEOLOGY Revised 11/95 Mw Program Goal: Each Student Will
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Fall and Spring/Physical Science Title: GEOLOGY Revised 11/95 mw Program Goal: Each student will gain a deeper understanding and appreciation of their “place”, including their community, their regional surroundings, their planet, and the universe. Class Goals: Students will gain an appreciation and understanding of the Earth’s processes, geologic history and dynamic nature. Class Theme: “Every rock tells a story, and we can learn how to read those stories with the science of geology.” Correlation with California Science Framework Themes: Systems and Interactions, Energy, Scale and Structure, Patterns of Change, and Evolution. Green Meadows themes: Sense of Place. Objectives: - 1. Students will recall the three main types of rock and how they are formed 2. Students will become aware of the vast nature of geologic time, and gain an approximate knowledge of the sequence of events in the geologic history of the Sierra Nevada. 3. Students will be able to describe the origin of granite (plutonic vs. volcanic rock) and name the four main minerals that compose granite. 4. Students will become acquainted with various geomorphic process, and will be able to name at least 5 ways rocks can change due to these processes. Materials: Samples of various igneous, metamorphic, and Timeline cards sedimentary rocks Poster of Earth layers Rock hammer(s) Oreo Cookies Goggles Erosion Boxes (set up and leave up) Hand lenses Each One Teach One cards Mineral samples: Biotite, Hornblende, Feldspar, Quartz Course Description I. Introduction: Know Your Rock Supply each student with a rock from the pack. Give the students about one minute to get familiar with their rock. Tell them that they need to get to know their rock so well that they can identify it later. Ask them to feel the texture, to look at the color, shape. size and to think of words to describe their rock. Have the students give their rocks back to the instructor. Mix up the students, help them get into a circle and then sit down with their hands behind their backs. The instructor then gives each student a rock and calls out “pass” at about two second intervals. The students must pass the rocks clock-wise. As soon as someone believes that they have their original rock they call out “rock.” They check and keep it in front of them if it is theirs. Then they continue passing rocks behind their back. The game continues until everyone has found their original rock. A shorter version is to simply pile the rocks in the center and mix them up, then have each student find their rock. This happens very quickly. II. Rock cycle A. Rock Cycle Role play Tell the students that far below the surface of the earth, where this journey begins, it is hot enough that rock is molten. This hot liquid rock underground is called magma. Your students begin their role play as a swirling mass of magma. After they have swirled sufficiently, they get shot out of a volcano and land on the earth’s surface. To demonstrate this, have them run from one area to another. Once they get there, they begin to cool and slow down because they are hardening into rock. The rock that they become, lava rock, is an igneous rock because it forms from cooled magma. To symbolize a large mass of igneous rock, have the students clump together connecting hands to shoulders. You then become the forces of erosion (wind, water) and begin to erode the mass of students. As you disconnect students from each other have them follow you, telling them that they are now tiny pebbles flowing downstream towards the ocean. Once you get to the “ocean” (another area) the pebbles will start to settle to the bottom. The larger pieces will sink first and the smaller later. To simulate this, break the group up into three or four smaller groups, line each group up shoulder to shoulder, and have them “settle out” as a group. One group will stop settling on a line that represents the bottom of the ocean. Each successive group will line up behind the first group. As they settle, they will compact close together in their respective lines and will form sedimentary rock. Sedimentary rocks are formed by the compaction of tiny pieces of pre-existing rocks. As their rock gets compacted further this pressure coupled with the increased heat from being buried can change the rock once again. A rock that has undergone change due to heat and pressure is called metamorphic rock. Simulate this by compacting the students even more and pushing in on the sides giving their lines a rippled effect. They have just undertaken one possible trip through the rock cycle. Ask the students how the cycle could continue. Possibilities include: the metamorphic rock could get buried further, melt and reform into an igneous rock. The magma could cool beneath the Earth’s surface and form granite instead of lava. The rocks on top of the metamorphic rock could erode exposing the metamorphic rock to the forces of erosion. It is important to note that rocks change from one type to another in many ways and this simulation is just ,one possibility. B. Rock Type Game .Teach the students hand motions for each type of rock as follows: Sedimentary = slap one hand on top of the other, alternating hands, while saying “layer after layer after layer after layer.” Metamorphic = slap hands together and simultaneously rub and push while saying “heat and pressure, heat and pressure.” Igneous = make an exploding motion with arms while saying “volcano! volcano!” The students sit in a circle with one person as “it” standing in the center of the circle. “It” tries to catch students off guard by choosing someone and saying one of the three rock types three times fast (e.g., “igneous, igneous, igneous!”). The chosen student must make the correct hand motion and statement about how that rock type is formed before “it” has finished saying the rock type the third time. If the student fails to say the correct rock type in time, they become the new “it.” C. Review Original Rocks and classify As a follow up/check for understanding, have the students take the rocks they got to know in the first activity and have them try to classify them based on what they know. Remind them of the possibilities: igneous rock could have formed intrusively, that is, below the surface of the Earth, and cooled very slowly, thus allowing time for crystals to form, or it could have formed extrusively, that is, cooled on the surface of the Earth, very quickly, with no time to form visible crystals, but there may be gas bubbles. Sedimentary looks like the sediment it was formed from (sandstone looks like sand, mudstone like mud, etc.) and shows layers. Metamorphic may have layers, but they will show some crystals and be shiny, sparkly, or be wavy. Metamorphic rocks are harder than sedimentary rocks because of the pressure. III. Hike to stream (behind V-ball, near Miwok, or past beaver pond area) A. Examine cobbles 1. Why are they round? The creek moves and smoothes the rocks by rolling them and knocking them against each other. Most movement occurs in large floods. 2. Erosion: Water moves more than rocks --- lots of sediments from up hill get washed into creek and carried downstream and deposited. All of the fertile soil of the Central Valley came from the mountains originally. As the river carries materials, it scours out its bed, deepening the channel and eventually the valley. B. Break apart granite rock 1. Examine fresh face: What do students notice about it? Get descriptive words, such as speckled, shiny, rough, etc. Why is it like that? What are the speckles? 2. Minerals in granite: there are four main types of minerals in all granitic rocks. They are present in varying amounts and crystal sizes, creating the different types of granitic rocks such as diorite, granite and granodiorite. The minerals can be found as sand grains on the beach, or by examining larger rocks, especially if any freshly broken pieces can be found. The four minerals are as follows: a. Biotite Mica: A flat, finely layered mineral which is black (sometimes with a gold sheen --- it is often mistaken for “fool’s gold” in Big Creek), shiny and has a hexagonal or round shape when viewed from the “top.” The layers can be split apart with a fingernail if you can find isolated grains in the sand. b. Hornblende: Also black, but, not shiny or flat. Less dark, almost charcoal in color, forming little oblong shapes or rectangles in the granite. c. Feldspar: An opaque white or pink mineral with faces that shine at certain angles. Turn your sample in the light to see the shiny faces. Forms rhombus (squashed square) shaped crystals. d. Quartz: Glassy in appearance. In granite, usually a whitish, glassy looking pebble rather than a well-defined six-sided quartz crystal. C. Hunt for same minerals in sand: See how many of the four minerals students can find lying loose in the sand. Who can find the best specimens? You might want to keep some to add to our collection. How did the minerals get out of the rocks and into the sand? IV. Play Mineral Tag A large outdoor playing area with visible landmarks is designated: this bush is Big Creek, this tree is Secret Meadow, this rock is Observation Mountain, this tree is White Chief Mountain. The teacher calls out a landmark. Everyone must run to the landmark before the count of five.