Even with a completely clean surface, the electrons can spread slightly into the vacuum, leaving behind a slightly positively charged layer of material.

The scientists are foiled by an extremely dense layer of material at the boundary between the two.

In chevron stacking, the stacker travels along the length of the stockpile adding layer upon layer of material.

In the lowest layer of material at these sites, there are used pieces of ochre estimated to be 60,000 years old.

Shallow failure occurs where a layer of material moves along planes parallel to bank surfaces.