Archive for the ‘sand dune’ Tag

Single-image Sunday: Patterns in Sandstone   5 comments

Since the Foto Talk this week was all about not getting too caught up in the search for abstract patterns in your photography, I thought I’d post an image whose sole aim was to abstract the subject.  But is this really an abstract?  I could have made it more so, for example by moving the camera or otherwise blurring details and color.  Or by getting experimental in post-processing.  But I wanted the close-up features of this dune sandstone to be very clear.

The abstraction is created by simply getting  close with my macro lens and framing so as to exclude the tiny flaws that are scattered through the rock.  I captured this at the famous Wave in southern Utah’s Vermilion Cliffs National Monument.  The sandstone has been worn smooth by water and wind erosion, but up close you can see how rough it is, like sandpaper.

The tiny sand grains are frosted by winds that blew them into dunes during the early Jurassic Period nearly 200 million years ago when this whole region of the American southwest was a vast desert similar to the Sahara of today.

The thin layers (laminae) of alternating color are at an angle to the main sandstone beds.  This is called cross-bedding and is characteristic of dune sands.  The wind blew in grains that had been stained brick-red by iron.  Then it turned around and blew in cleaner, lighter-colored grains from a different source.  These grains would cascade down the steeper lee side of dunes, creating the cross-beds.

The flatter, thicker layers have been eroded into steps, a characteristic of the Wave.  Because of variation in their hardness, their ability to resist erosion, the layers stand out or are recessed.  This differential erosion is caused by variation in the amount and hardness of cement binding the sand grains together.

So what this image shows on a micro-scale is an ancient sand dune in cross-section that is now being sculpted by present-day winds.  In other words, it shows winds in a desert of the distant past, when early dinosaurs roamed the area.  And it shows what the desert of today is doing to those ancient dunes

So an abstract image can tell you something real about the subject.  I believe that’s the best kind of abstract in fact.  I’m hoping the image shows what nature can do, not what me or my camera can do.  Please let me know whether or not I succeeded.  I hope your weekend was a lot of fun.  Thanks for reading.

Undulations

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