desert varnish

American  

noun

1. the dark, lustrous coating or crust, usually of manganese and iron oxides, that forms on rocks, pebbles, etc., when exposed to weathering in the desert.

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Etymology

Origin of desert varnish

First recorded in 1900–05

Example Sentences

Many of the images were carved into desert varnish, a thin red to black coating found on exposed rock surfaces.

From Los Angeles Times • Jul. 19, 2021

One unique weathering product of deserts is desert varnish.

From Textbooks • Jan. 1, 2017

Newspaper rock, near Canyonlands National Park, has many petroglyphs carved into the desert varnish.

From Textbooks • Jan. 1, 2017

Some scientists have speculated that desert varnish, a peculiar dark-coloured coating of unknown origin found on many desert rocks, could be a product of a shadow biosphere.

From Nature • Mar. 28, 2012