Dendrochronology: History Written in Wood
Core Idea: Every year a tree grows, it writes a line in its autobiography — a single ring of wood. Dendrochronology is the science of reading those lines to unlock secrets about time, climate, fire, and even volcanic eruptions.
1. What Is Dendrochronology?
Dendrochronology (from the Ancient Greek dendron = tree, khronos = time, -logia = the study of) is the scientific method of dating tree rings to the exact year they were formed. It is one of the most precise dating tools available to science.
Think of a tree trunk as a time capsule. Each ring records not just the passage of one year, but the conditions of that year — rainfall, temperature, fire, even the fallout from a distant volcanic eruption.
Key Vocabulary
| Cambium | A thin layer of actively dividing tissue just beneath the bark; the source of all new wood cells. |
| Earlywood | Large, thin-walled cells produced in spring — appears as the pale band of a ring. |
| Latewood | Small, thick-walled cells produced in late summer — appears as the dark band of a ring. |
| Annual ring | One earlywood + one latewood band = one year of growth. |
| Crossdating | Matching ring-width patterns between trees to assign each ring to its exact calendar year. |
| Increment borer | A hollow drill that extracts a thin core from a living tree without killing it. |
Interactive visualization — available in the full lesson