"Beachmarks" are a unique feature found in many fatigue fractures, and their presence is a positive means of identifying fatigue fractures. Beachmarks also have been called "stop marks," "arrest marks," "clamshell marks," and "conchoidal marks," all in an attempt to describe their origin or characteristic appearance. The term "beachmarks" is the most commonly used term but is not really as descriptive as some of the others.

At any rate, this term is used to describe macroscopically visible marks or ridges that are characteristic of interruptions in the propagation periods (stage 2) of fatigue fractures in relatively ductile metals. Beachmarks must not be confused with striations, although they frequently are present on the same fracture surface; there may be many thousands of microscopic striations between each pair of macroscopic beachmarks. - Internet Partner