How do we know?
↻ One of the pages with a moving picture
Rings are like a tree’s diary.
- A thin layer of cells just inside the bark adds new wood around the trunk every year.
- In spring, the tree grows fast and makes a wide, light-colored band of wood.
- In late summer, growth slows and the wood comes out narrower and darker.
- One light band plus one dark band make one ring = one year. The oldest rings sit in the middle.
Rings are like a tree’s diary. At Aztec Ruins in New Mexico, scientists compare ring patterns in old wooden beams to help tell when the buildings were made.
Scientists counted 4,862 growth rings in a bristlecone pine called Prometheus. It was about 4,900 years old!
Methuselah, in the White Mountains of California, is more than 4,800 years old. It is the oldest named single tree.
Wow number
4,862 Scientists counted 4,862 growth rings in a bristlecone pine called Prometheus. It was about 4,900 years old!
Myth or fact?
Every tree in the world has easy-to-see rings. Myth. Many tropical trees grow all year, so they don’t make the light-and-dark pattern.
A wide ring often means a good growing year. Fact. Wide, light rings usually mean warm days and lots of rain in spring.
Think about it
What do you think a very thin ring might tell you about that year?
Where in the world?
Great Basin National Park, Nevada, USA where Prometheus grew on Wheeler Peak. Methuselah, more than 4,800 years old, grows in the White Mountains of California — 38.9833° N, 114.3° W.
Where these facts come from
Every number on page 66, and who measured it
This page tells us how a tree adds light and dark wood each year.
Read the Rings — The Minnesota Department of Natural Resources
dnr.state.mn.us/forestry/education/foresttreasures/readtherings.html
We checked it on 31 October 2026
This page tells us that one light and one dark layer make a year, and why many tropical trees don't have rings.
Tree Rings and Climate — UCAR, a group of U.S. universities that study the air and weather
scied.ucar.edu/learning-zone/how-climate-works/tree-rings-and-climate
We checked it on 31 October 2026
This page tells us the story of Prometheus and its 4,862 rings.
The Prometheus Story — The U.S. National Park Service
nps.gov/grba/learn/historyculture/the-prometheus-story.htm
We checked it on 31 October 2026
This page tells us about Methuselah, a very old bristlecone pine.
Oldest living tree species — Guinness World Records, which keeps lists of world records
guinnessworldrecords.com/world-records/oldest-living-individual-tree
We checked it on 31 October 2026
This page tells us how tree rings in old beams help date Aztec Ruins.
Dendrochronology — The U.S. National Park Service
nps.gov/azru/learn/nature/dendrochronology.htm
We checked it on 31 October 2026
Has this changed?
How trees make rings is not going to change.
Age records can be beaten. Prometheus is gone, and Methuselah is the oldest named single tree so far.
Words from this page
- growth ring
- One light band plus one dark band of wood in a tree trunk: one year of growth.
- bristlecone pine
- A tree that can live for thousands of years.
Try it!
Draw your own life rings.
1. Draw a small dot in the middle of a paper. That’s the year you were born. 2. Draw one ring around it for each birthday you’ve had. 3. Make a ring wide for a great year and thin for a tough one. Color them in!
What happens: you made a ring diary of your life, just like the one a tree keeps inside its trunk.
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