The light-coloured areas are occurring almost in all cracks. This phenomenon is a contamination effect, which is caused by the transported material. The cracks are results or a consequence of the thermal impact of the transported material on the conveyor belt in combination with the cyclically repeated process of the belt closing and disclosing in the idler housings. The
gradual penetration of the material particles into the belt carcass is evident from the both points of view. This process causes a breaching of a consistence among the individual layers of the conveyor belt. A high density of the defects in this sample is determined by a fact that this sample was selected from such place of the belt, which is in a permanent contact with
the large amount of the transported material, see the Top view in Fig. 7.