This zone occurs at depths of about 200 to 1,000 metres, depending on local circumstances.

Each zone represents several bison jumps over relatively little time, perhaps no more than 50-100 years, but the two zones occurred nearly 7500 years apart.

Crustal composition will also affect the depth at which this zone occurs.

This zone occurs by reefs on continental shelves.

If the water was deep enough and the sound velocity excess was present at depth, these zones commonly occurred about every thirty miles.

However, restricted zones of high grade mineralisation with more than 1% uranium occurred.

This zone occurs between about 6,200 and 9,500 feet above seal level.

Mucocutaneous zones occur in animals, at the body orifices.

These zones occur because most metamorphic minerals are only stable in certain intervals of temperature and pressure.