Encore - Moqui Marbles and Martian Blueberries

January 12, 2019

Moqui Marble Madness

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

: Bret Webster
Summary Author: Bret Webster 

The photo above shows moqui marbles in their native habitat of southern Utah. These curious rocks are actually concretions having iron (hematite) rinds. Very similar rocks, called blueberries, have been observed repeatedly on Mars by the rovers. Click here to see an image taken by the Opportunity rover of the blueberries. Some scientific papers implicate the possibility of life on Mars playing a role in their formation while others do not. Discussions about the pros and cons of their formation have been quite lively at times. However, the consensus seems to be that both the marbles and the blueberries were created beneath the surface as naturally occurring substances, most likely minerals, precipitated from flowing groundwater. Pictured with the marbles is a Devil's-Claw cactus (Sclerocactus parviflorus).

Photo Details: Camera: Canon EOS 5D Mark II; Lens: EF24-105mm f/4L IS USM; Focal Length: 24mm; Focus Distance: 0.64m; Aperture: f/8.0; Exposure Time: 0.0013 s (1/800); ISO equiv: 200; Software: Adobe Photoshop CS5.1 Windows. 

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