Time Scales

This is not a profound post. This is more of an internal memo among bloggers.

I needed a time scale for something, so I went to the USGS and ripped two different ones. These are modified so that they are 500 pixels wide and have space on the right to slap in symbols or text (if you have the right software). They are jpeg files and moderately compressed. There is lots more room for compression.

Since they are US government products they are free of copyright. I provide them here for others to use and provide links to the sources in case you want to get an earlier version of the file (or learn about California Geology or Death Valley).

If you think these are not good enough, do not tell me. Rather, make a better one and email it to me (with any appropriate link backs) and as long as it is clearly copyright-free (in the sense that it can be freely used) I’ll post it!

The images are below the fold.




  1. #1 DDeden
    September 29, 2008

    Good enough, Greg, Thanks!

  2. #2 dogscratcher
    September 29, 2008

    Thanks, I’ll definitely make use of them.

  3. #3 Aaron Golas
    September 29, 2008

    The headers differ (era/period vs. eon/era). Am I right that the former is correct?

  4. #4 Greg Laden
    September 29, 2008

    Aha! Right, the first one is correct. I’m going to wipe out the incorrect words on the second one so that it is not incorrect.

  5. #5 NJ
    September 29, 2008

    But…but…but… you’re simply dividing the periods into early middle and late. You’re leaving out all the cool stage names like Kinderhookian and Waucoban, and…and…Champlainian!


  6. #6 Kris Rhodes
    September 30, 2008

    Also note that the second one has a much different time for the start Cambrian– 570mya vs. 543mya. That’s because the second one uses outdated dates. It’s too bad the first one is colored, since that limits its use as a graphic.