Kate Ruhl

Teaching geologic time and rates of landscape evolution with dice part of Rates and Time:GSA Activity Posters
Landscape evolution provides a convenient framework for understanding geologic time and rates because students can observe how processes like erosion and deposition shape their surroundings. In this example, students build 3-D sandbox models based on topographic maps and design and stage a "virtual adventure race." Sandbox landscapes are used to illustrate erosional processes,while local examples are used to discuss landscapes as transient or steady over different time- and length scales. Dice experiments illustrate radioactive decay and the shape of the age equation curve, and 14C dating, geochronology and thermochronology are introduced as "stopwatches" that start when a plant dies, a crystal forms, or a rock nears the surface and cools to a certain temperature. The sandbox model and thermochronometer "stopwatches" are combined to measure erosion rates and rates of landscape change. Ultimately, model rates (cm/hour) calculated from stopwatch times on the order of seconds can be related to geologic rates (km/My) calculated from real million-year-old samples.