Paper: 60-12 Teaching Geologic Time and Rates of Landscape Evolution Session T104 - It's About TIme: Teaching the Temporal Aspects of Geoscience with Dice, Sandboxes, & Cutting-Edge Thermochronology GSA Meeting, Salt Lake City October 16-19, 2005
W l es hoo Katharine W. Ruhl (Huntington) [email protected], Massachusetts Institute of Technology, Cambridge, MA t Perry High Sc Shirley L. Ruhl [email protected], West Perry High School, Elliottsburg, PA
Abstract Sandbox landscapes are used to illustrate erosional processes, Learning Landscapes: Virtual Adventure Race Dice & Dating with Geologic "Stopwatches" the role of water in sediment transport, relief change, and how # of Dice Debates over natural resource consumption and the validity of erosion exhumes rocks from depth, while local examples are N Remaining in How do we measure rates of landscape evolution? religious and scientific views of Earth history hinge on the public's used to discuss landscapes as transient or steady over different Activity & Evaluation III: The Perryliminator Virtual Adventure Race "Parent" box How can Radioactive Decay tell us when dinosaurs conception of geologic time and rates of Earth change. Teaching time- and length scales. After Each lived, a volcano erupted, or the Earth formed? these concepts effectively remains a challenge to educators in a Your group has been nominated as event organizers Round N0 for the 3rd ANNUAL SOUTHEAST-CENTRAL Example of a Perryliminator project that incorporates digital landscape analysis variety of settings. We present labs designed to help students To convince students that the observed processes act over PENNSYLVANIA TRIATHLON (nicknamed the Learning Goals: 9th-graders should be able to 1) plot and N0 internalize these concepts using dice, sandboxes, stopwatches, Perryliminator). Your task as organizers is as follows: interpret experimental data and trends in an x-y graph, 2) describe millions of years to shape Earth's surface, quantitative dating 300 and cutting-edge thermochronologic research to study landscape the concepts of radioactive decay and half-life, 3) describe how tools are introduced. Dice experiments illustrate radioactive Parent and Daughter abundances are used to calculate relative Plan out a 10-KM COURSE over the toughest, most N0 evolution, and illustrate how the basic models can be adapted to 2 8 ∞ 0 ' " N decay and the shape of the age equation curve, and 14C dating, treacherous terrain you can find on the Perry County 250 ages for isotopic systems or "geologic stopwatches" with different challenge students in grades 9-16 with kinematical, auditory and geochronology and thermochronology are introduced as quadrangle of your choice. half-lives, 4) describe what measured dates for the C-14 system, a visual learning styles and diverse backgrounds. geochronometer, and a thermochronometer represent. "stopwatches" that start when a plant dies, a crystal forms, or a 200 rock nears the surface and cools to a certain temperature. For this TRIATHLON, include 3 different challenges Landscape evolution provides a convenient framework for dealing with 1) water, 2) steep climbs and descents, and Context: For the basic activity, students should understand how 150 3) flat runs! Include compass bearings for your to construct bar graphs and x-y plots understanding geologic time and rates because students can REMOVE The sandbox model and thermochronometer "stopwatches" are contestants so they won't get lost. Make it fun and N0 6's observe how processes like erosion and deposition shape their combined to measure erosion rates at a point, uniform and interesting! A 100 2 Materials: Blackboard, large number of dice (donated free by a surroundings, even in urban settings. In order to describe spatially variable erosion, and rates of landscape change. REMOVE 2's & casino), boxes labeled "Parent" and "Daughter." Optional: Excel Draw your course on the laminated topographic map. Write a 1-page summary detailing to the planning 2 8 ∞ 1 5 ' 0 " N 3's landscapes qualitatively and quantitatively, students build 3-D 50 N Ultimately, model rates (cm/hour) calculated from stopwatch committee the extent of your course's topography & the challenges it holds. Include the relief and % gradient 0 spreadsheet or graphing calculator. sandbox models based on topographic maps and design and times on the order of seconds can be related to geologic rates of the steepest course component. As an added visual aid, draw a CROSS-SECTION of the most grueling part 4 B START stage a "virtual adventure race." (km/My) calculated from real million-year-old samples. of the course. 0 REMOVE Basic Activity: For each round, shake "Parent" box with all dice ODD #' DICE
0T in it and have students remove the odd-numbered dice and put
} 1T
} 2T ______[ ] (4p) Latitude and Longitude of the Course Start and End } FINISH 3T them in the "Daughter" box. Plot the Round # vs. the number of dice ______[ ] (6p) Distance - requirement met (10 km) - accuracy of measure 4T 5T T 6T remaining in the "Parent" box. Plot trend of data, and find the number ______[ ] (6p) Distance between 3 course turning points noted T T time of Rounds equal to a half-life from the plot (~1 round in this case). Repeat ______[ ] (6p) Compass bearings accurate for changes of direction 600 N0 # of ) -kt Rounds for other "isotopic systems" with different half lives. d N = No e ______[ ] (2p) Steep slopes included (Up + Down) START muddy A n
Bubbly Gorge bog area u o River crossing 2 8 ∞ 1 0 ' " N ______[ ] (2p) Water crossing included (at least one) R 1 1 1
2500 k = ln = - ln2 h
m) T 2 T c ( l Incorporate the decay equation, Evaluation: Students use in-class graphs to rank relative age for different 2000 l ______[ ] (2p) Flat run included hi a
n
E
r
o 1500 artbreak -0.6931t combinations of Parent and Daughter abundances and half-lives. Students i the physics of decay, real isotopic
e e N = 600e t
______[ ] (10p) Steepest component t H f
a 1000 A
-0.4055t v N = 600e systems & data to challenge synthesize ideas from marble exhumation activity & thermochronometer - Relief calculation with Location g
e 500 n i
l 300
n N -0.1823t i 0 N = 600e - % Gradient calculation with Location E 0 advanced students stopwatches to measure erosion rates (distance over some area per time)
0 2 a Sandboxes & Topographic Maps m
______[ ] (15p) Cross-section of most "Interesting" course component 2000 4000 6000
e R
Horizontal Distance (m) e