Making Skeleton Plots


When skeleton plotting ring-width variation of a core, note that:
  • Narrow rings merit marks on the skeleton plot
  • The narrower the ring, the longer the mark
  • Very wide rings occasionally merit a little "b" mark (for big)
  • Normal or average rings DO NOT merit marks on the skeleton plot
  • For example, compare the core and skeleton plot below:
    • The narrowest ring is connected (blue line) with the longest skeleton mark
    • The widest ring is connected (green line) with a "b" mark (for big)
    • Note the red line:
      1. Points to a ring of average width, but it seems narrow compared to the preceding ring
      2. Perhaps it merits a small mark because of the large year-to-year difference
  • Good idea: Hit the "Try Again" button to see more examples



How to make marks when you try skeleton plotting for yourself:
mouse action options
  • You'll see a panel of circle options, as on the left:
    • You can either draw or erase marks with your mouse
    • Marks may be either:
      1. normal lines for narrow rings
      2. a "b" for wide rings
      3. a mark for the ring-growth anomalies of absent or false rings
    • Practice making normal marks on the right:
      1. Align tip of cursor on vertical line of choice
      2. Adjust height of cursor in bottom two-thirds of graph
      3. Mouse click just once!
      4. "Try Again" as necessary
  • If you mark something mistakenly:
    • Just mouse click on the "Erase" circle option
    • Put mouse over the mistake and click it away
    • Don't forget to mouse click back onto "Draw" to continue plotting



Paul R. Sheppard
Laboratory of Tree-Ring Research, The University of Arizona
Tucson, Arizona 85721 USA
office: (520) 621-6474, fax: (520) 621-8229
Comments to: sheppard@ltrr.arizona.edu