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Posted by
Steven (Chicagoland, United States) on 28 September 2011 in Landscape & Rural and Portfolio.

Desert varnish, or rock varnish is a orange-yellow to black coating found on exposed rock surfaces in arid environments. Desert varnish forms only on physically stable rock surfaces that are no longer subject to frequent precipitation, fracturing or wind abrasion. The varnish is primarily composed of particles of clay along with iron and manganese oxides. There is also a host of trace elements and almost always some organic matter. The color of the varnish varies from shades of brown to black.

Originally scientists thought that the desert varnish was made from substances drawn out of the rocks it coats. Microscopic and microchemical observations, however, show that a major part of varnish is clay, which could only arrive by wind. Clay, then, acts as a substrate to catch additional substances that chemically react together when the rock reaches high temperatures in the desert sun. Wetting by dew is also important in the process.

An important characteristic of black desert varnish is that it has an unusually high concentration of manganese. Manganese is relatively rare in the Earth's crust, making up only 0.12% of its weight. In black desert varnish, however, manganese is 50 to 60 times more abundant. This significant enrichment is thought to be caused by manganese-oxidizing microbes (mixotrophs) which are common in environments poor in organic nutrients.

Even though it contains high concentrations of iron and manganese, there are no significant modern uses of desert varnish. However, some Native American tribes created petroglyphs by scraping or chipping away the dark varnish to expose the lighter rock beneath, like those seen above.

I couldn't help but think of this photo that I captured back in December of last year when seeing the swirls on the sandstone above.

Photo captured June 20, 2011.

NIKON D7000 1/250 second F/8.0 ISO 100 25 mm

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Spotlight Images

Curly from South Shields, United Kingdom

You might have found the blueprint here Steven!

28 Sep 2011 7:11am

Heinz from Hamm, Germany

ganz hervorragend.

28 Sep 2011 7:20am

Stefanie from Paris, France

Interesting shot!

28 Sep 2011 7:51am

klausz from Kustein, Austria

a part of history you found in an so unbelievable landscape and steven, this blue is so extraordinary and together with this different colors of the rock .... TOP!!!! 5*****

28 Sep 2011 9:48am

Mariana M. from Waterloo, Canada

fabulous .

28 Sep 2011 9:57am

Siepi from Perk, Belgium

Very beautiful!

28 Sep 2011 10:27am

Roman from Thiersee, Austria

stunning find, and so very well captured.
your blue and orange colors in this series are outstanding.

28 Sep 2011 11:08am

Sarito from Basingstoke, United Kingdom

Excellent details.. thanks for the information.

28 Sep 2011 11:25am

Laurette from Johannesburg - Fourways, South Africa

A wonderful capture with beautiful colours . Well captured and presented. Thank you for very intresting information.

28 Sep 2011 11:59am

Jason Politte from Conway, AR, United States

Very cool photo and information about the varnish. I'd be curious to know how long those marking have been there. Excellent shot!

28 Sep 2011 1:27pm

Sam from Chennai, India

Great capture. Excellent details. And interesting information. :)

28 Sep 2011 2:40pm

Stephen from Canberra, Australia

So well documented - and the textures are stunning with this beautiful ocre.

28 Sep 2011 2:53pm

Rick from Toronto, Canada

"Ancient astronaut theorists" would have a field day with this gorgeous shot!

28 Sep 2011 2:59pm

Visualaccent from somewhere in the, United States

Hi Steven - great and well documented picture. It seems like we were tracking each other.

28 Sep 2011 3:06pm

alex centrella from California, United States

whoops..nice shot ..

28 Sep 2011 5:10pm

franz from Baden, Austria

interesting and absolutely fascinating patterns and designs, very informative introduction!

28 Sep 2011 6:48pm

Denny Jump Photo from Easton, PA, United States

AH yes, I remember that lollipop ;-) BEautiful image here, Steven...and amaziong text..I did noe=t know any of this..as much as I enjoy petroglyphs I guess i never picked up on this data and information...thank you so much....lovin' this series ;-)

28 Sep 2011 6:58pm

tataray from france, France

Excellentes couleurs .
Merci pour l'explication.)

28 Sep 2011 8:07pm

Philou04 from Manosque, France

Great find ! Nice colours and petroglyphs which I unfortunately couldn't decipher (lol).
Thanks for all your physical and chemical explanations.

28 Sep 2011 9:21pm

....peter from Canada

What a magnificent find Steven..... you have framed your photo of the petroglyphs very well with great detail..... i enjoyed the history that you provided also..... thanks for taking the time to include it....peter:)

28 Sep 2011 10:31pm

Ronnie 2¢ from Atlantic Shores, United Kingdom

Amazing formations . . like a living history in many ways . . .

29 Sep 2011 3:39pm

Steve Rice from Olympia, United States

Beautiful ancient art. The desert varnish has fascinated me for a while the way it streaks huge rock walls. An excellent photo.

3 Oct 2011 6:39am