After an injury, the surrounding wood grows over the damaged area. This seals it off from healthy tissue, forming callous tissue.
Injuries caused by, for instance, snow breakage, rockfall, fire, lightning or browsing by game, are usually overgrown within a few years.
Through the microscopic analysis of wafer-thin wood slices, researchers usually date these effects to the exact season. However, they cannot always reliably identify the cause of an injury.
The callous margin that grows over the injury is not visible here since the branch very likely broke off further up the stem.