Geologic periods

• National Park Service
  • Maybe get this one printed out?
• Geologic TimeScale Foundation
  • Standard Color Codes for the Geological Time Scale — Reference.
• Australian Environmental Education
• International Chronostratigraphic Chart — Authoritative.
  • TODO: Is there any way for me to merge in information about the organisms present, such as this or this?
• British Geological Survey
• GSA Geologic Time Scale — Good one-page reference. [amazon]
• Amazon
• “A Glimpse Through Time” by S.E. House
• HTML