Stereogram of Navajo/Page Sandstone sand grains

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The two panels below comprise a stereogram. To view it, go 'cross-eyed' to overlap the images and then bring them into focus. To look around, drag or use arrow keys (while cross-eyed).

Production notes

The stereogram images were produced using an Olympus M.Zuiko Digital ED 60mm f/2.8 macro lens (analysed here) on a Olympus OM-D E-M5 mark II camera, which is capable of 'focus bracketing', ie., taking a sequence of photos with the focus incremented each photo. Two sequences of focus-bracketed photos were taken of a patch of sand grains, one looking at the patch at an angle of 6° and the other looking at an angle of -6° (measured using a bubble-level app in a smartphone). Each sequence (consisting of 15 photos at a focus interval of 4 'focus units', each unit being approximately 55 microns) was 'focus stacked' (merged) using Photoshop.

The field of view of the entire image (only part of which is visible above at a time) is approximately 20 mm. The grain diameters are up to around 600 microns.

These grains were collected from a large erosion pit (below) in Navajo Sandstone. Likely the grains were eroded from similar sandstone (or Page Sandstone), trapped in the erosion pit, and polished clean of cementing materials by repeated saltation.

The last time these sand grains were free to move about was probably in the Early Jurassic, about 190 million years ago. Quartz grains don't last forever, but they're tough and can get around. These grains are thought to have been transported by ancient rivers from the area of the Appalachian mountains and then blown south to what's now Utah, where they were buried and lithified. Recently the grains were freed after the area uplifted a couple of kilometers, making it subject to erosion. The few grains in the photos above were carried by me back to the east, to where I live, in the Ottawa River watershed between Ontario and Quebec, Canada. I suppose the Ottawa river, or ice of the next glaciation, will eventually give those few grains another ride, while the ones in Utah are likely to be transported to the Gulf of California via the Colorado River.