Zones of mylonite occur around the world and vary greatly in size. In Nevada, deposits of mylonite have been found that are not more than a centimeter thick, while in Canada, a mylonite zone exists that is several kilometers thick and several hundred kilometers long. No matter their size, deposits of mylonite can reveal important clues regarding the geological history of the region in which they are found. The rocks are, for example, clear indicators of the presence of a shear zone that was previously active, and close examination of samples may bring to light details concerning the type and extent of shearing that transpired.