Tree-rings (image) University of Arizona Share Print E-Mail Caption A cross section of wood shows the annual growth rings trees add with each growing season. Dark bands of latewood form the boundary between each ring and the next. Counting backwards from the bark reveals a tree's age. Credit Daniel Griffin/Laboratory of Tree-Ring Research Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.