Subsequent growth over the damaged portion does not cohere with the wood previously formed by the old cambium.

The defect resulting is termed rind gall.

The most common causes of it are fire, gnawing, blazing, chipping, sun scald, lightning, and abrasions.
_Heart break_ is a term applied to areas of compression failure along the grain found in occasional logs.

Sometimes these breaks are invisible until the wood is manufactured into the finished article.

The occurrence of this defect is mostly limited to the dense hardwoods, such as hickory and to heavy tropical species.
It is the source of considerable loss in the fancy veneer industry, as the veneer from valuable logs so affected drops to pieces.
The cause of heart break is not positively known.