1. Open Earth Systems: An Earth Science Course For Maryland Teacher Professional Development EARTH HISTORY AND THE FOSSIL RECORD DAY 1 - Weds. July 8 AM Instruction: Solar System Origin Activity 1: Period of planetary orbits Activity 2: Planets on your birthday Instruction: Early Earth & Habitability -lunchtime- PM Instruction: Major Events in Earth History Activity 3: Exploring Geologic Time with TS-Creator Instruction: Concepts in Radioisotope-dating Activity 4: Simulating Radioactive Decay DAY 2 - Thurs. July 9 AM Instruction: Climates of the Past Activity 5: JHU Soil Profile Instruction: Fossil Record of Life -lunchtime- PM Instruction: Conversation with Steven Stanley Activity 6: Fossil Identification LINDA HINNOV, Instructor

2. Radioisotope dating Year 1896 Discovery of Radioactivity Discovery of radioactivity led to geological applications and measurement of parent-daughter isotope ratios in specific rock minerals. * Absolute ages of rocks Improved global correlation of rocks Refinement of Earth history timeline Ability to assess rates of major geologic processes

3. Radioisotope dating Isotopes = atoms with the same number of protons but different numbers of neutrons. This one is radioactive (decays to He 3 )

4. Radiosotopes do undergo spontaneous radioactive decay, following an exponential decay law: where N o is the initial number of atoms, T 1/2 is the half-life of the isotope, and t is the time that has elapsed since decay started. Radioisotope dating =N =N o - N

5. Parent Isotope Stable Daughter Product Currently Accepted Half-Life Uranium-238 Lead-206 4.5 billion years Uranium-235 Lead-207 704 million years Thorium-232 Lead-208 14.0 billion years Rubidium-87 Strontium-87 48.8 billion years Potassium-40 Argon-40 1.25 billion years Samarium-147 Neodymium-143 106 billion years Carbon-14Nitrogen-145,730 years http://pubs.usgs.gov/gip/geotime/radiometric.html Zircons from a volcanic ash bed, human hair for scale. M. Schmitz website: http://earth.boisestate.edu/ home/markschmitz/ U-Pb dating of zircons Radioisotope dating

6. http://earth-time.org/k12.html Radioisotope dating Determining the Age of Things These video clips, also developed jointly with the Denver Museum of Nature and Science, show how and why scientists determine the age of things. This module comprises seven video clips in Quicktime® format. Scroll down to: click here Browsers that work: Safari Version 7.1.7 Or open“Earthtime-Bowring.rmvb” supplied by OES with: RealPlayer Version 11.0.1

7. Geologic Time Scale 2015

8. Number of radioisotopic dates used in GTS2012 Gradstein et al., 2012

9. Geologic Time Scale 2012 toweroftime.pdf