Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Scientists use a tool called an increment borer to remove cyllindrical tree cores from living trees. The cores show the tree's rings and help scientists learn about its growth.
Public Domain.
