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Scaling up to mountainous change. Explore p. 650 - 662. Part 1: Paper plates. 4. At a rate of 2 cm/second how long did it take your plate to move across your work table? About 75 seconds, or 1 minute 15 seconds
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Scaling up to mountainous change Explore p. 650 - 662
Part 1: Paper plates • 4. At a rate of 2 cm/second how long did it take your plate to move across your work table? • About 75 seconds, or 1 minute 15 seconds • 6. Let’s scale up the velocity from 2cm/second to see how far the plate moves in a year. • 7. Using the rate above (km/yr) how long would it take your plate to move to different states?
Part 1: Paper plates • 8. Tectonic plates move at a rate of 3cm/year. How long would it take a tectonic plate to move across your work table? • If the table is 150cm long, it would take 50 years. • 150cm x 1year/3cm = 50 years • S&T #1a: Continents move about 3cm/yr. What step from #6 has units that are easiest to compare with the velocity of continents? Why? • S&T #1b: Is the paper plate’s or continent’s velocity faster? How much faster? • The paper plate is about 21,000,000 times faster • 63,115, 200 cm/yr / 3 cm/yr = 21,038,400
Part 2: Ups and downs of mountains • Learning Target: I can distinguish between uplift and erosion processes in mountain belts. • Skills: • I can analyze coral terraces and graph elevation changes • I can calculate uplift rates from this graph • I can compare uplift, erosion, and erosion half-life
Part 2: Ups and downs of mountains • Read Introduction p. 654 • Some vocabulary: • Glacial period – periods where the overall global climate is cold. Glacials are characterized by low sea levels and the widespread extent of ice sheets. • Interglacial period – periods where the overall global climate is warm. Interglacials are characterized by high sea level and a limited extent of ice sheets. • Radiometric dating - is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.
Part 2: Ups and downs of mountains • kya means thousands of years ago • mya means millions of years ago
Part 2: Ups and downs of mountains • Work with your partner to complete P&P #1-10. p.654-662 (2 days to complete) • Make sure you answer all questions in your science notebook. • Graphs should be done on graph paper and taped into your science notebook! • Must get through step 6 today • HW: Read “Weather to Erode” p. 659 and take notes! Don’t forget a summary at the end!
REMINder! • If you are planning to take the retest for the dimensional analysis quiz, the review worksheet is due today. • You must schedule a time to take the quiz either before school, after school, or during lunch on Monday.
Part 2: Ups and Downs of Mountains • First, you used the diagrams of the coral terraces in Papua New Guinea and Barbados to create a data table (elevation vs. age of coral). • You measured the distance (in mm or cm) from sea level to the top of the coral terrace on the sketch. • You used the scale as a conversion factor to calculate the elevation in meters. (New Guinea: 200m/15mm) (Barbados: 50m/11mm)
Part 2: Ups and Downs of Mountains Then you graphed elevation vs. age. What did the slope correspond to? What can you say about the uplift rates of the two locations?
Part 2: Ups and Downs of Mountains • (Step 6) Then you began with an uplift rate of 2.5 mm per year (m/yr), and converted it first to meters per thousand years (m/kyr), then to kilometers per million years (km/Myr). • What did you find?
Part 2: Ups and Downs of Mountains • (Step 8) You used the uplift rate of 2.5 mm per year (m/yr) to calculate how much uplift would occur in a mountain chain over 1 Million years. (It was helpful to refer back to your table from step 6). • You repeated this to calculate uplift over 10 Myr. • You compared your calculations to the actual elevation of Mt. Everest (8,850m) over 30 Myr. • Why are they different?
Part 2: Ups and Downs of Mountains • (Step 9) You applied the concept of erosion half-life to see how a mountain chain that is not being uplifted changes over time. • How did the mountain profile change?
Part 2: Ups and Downs of Mountains – Summary! • You should be able to • use a geologic diagram to determine elevation vs. age • graph elevation vs. age • calculate an uplift rate from your graph • Convert uplift rates from mm/yr to m/kyr to km/Myr • Calculate how much uplift occurs in a given amount of time, given an uplift rate • Explain why the calculated uplift may be different than the actual elevation of a mountain • Predict the elevation of peaks and valleys given an erosion half-life (before and after) • Compare erosion half-lives and discuss why they are different for different areas • Discuss how erosion and uplift affect mountains