Rock Varnish

Some cliffs look like they've been painted. They have a dark red, brown, or black coating. It takes thousands of years to form. It is called 'desert varnish' or 'rock varnish.'

The pictures below show rock varnish.

Rock varnish is made of clay and minerals. Wind blows these things on the rock. They stick to the rock surface with living bacteria. The bacteria lives in the coats of varnish. Some people think the varnish is used to guard the living things inside. It acts like a sunscreen.

Rock varnish forms very slowly. The varnish becomes thicker and darker as it gets older. Varnish can be many thousands of years old.

People measure the varnish. They can find out the age of the coating.

Ancient peoples pecked pictures in the rock varnish. They used rock tools. These pictures are called petroglyphs. some petroglyphs can still be found today.

More Information

Note: All photographs taken with a digital camera in Utah.
Developed by Annette Lamb and Larry Johnson, 04/02.