The presence of old splits is often indicated by a ridge of callous, the result of the cambium's effort to occlude the wound.

Frost splits not only affect the value of lumber, but also afford an entrance into the living tree for disease and decay.
SHAKES, GALLS, PITCH POCKETS _Heart shake_ occurs in nearly all overmature timber, being more frequent in hardwoods (especially oak) than in conifers.

In typical heart shake the centre of the hole shows indications of becoming hollow and radial clefts of varying size extend outward from the pith, being widest inward.

It frequently affects only the butt log, but may extend to the entire hole and even the larger branches.

It usually results from a shrinkage of the heartwood due probably to chemical changes in the wood.
When it consists of a single cleft extending across the pith it is termed _simple heart shake_.