Thursday, October 7, 2010

Creating the "Impossible" Photo

I am at McArthur-Burney Falls in Northern California.  The trail to the base of the falls is closed for maintenance, so I can't get a good perspective.  From the remaining overlook, I am shooting down at the falls (not my favorite perspective).  The face of the falls is wide, and is bracketed by trees so that one can only see a part of the falls from any one viewpoint.  To deal with that, I took three photos, moving my tripod about 15 feet between each shot.  I then photomerged the three shots to get a composite that shows almost all of the falls as one image, a view that cannot be seen in real life.  I am happy with the result.

These falls are unusual.  One mile upstream, there is no surface flow at all.  At the falls, the flow rate is 100,000,000 gallons per day, slightly more than Blue Spring and Alley Spring in Missouri, which flow at 87,000,000 per day.  Those are set in karst topography and flow from limestone.  Here, the surrounding landscape is volcanic in origin. 

The falls flow in two layers - a primary surface flow that drops over the edge in two main streams,

and an underground river that breaks into the air in a horizontal plane separating two rock types.  The result is a thin curtan of tiny waterfalls spread over a wide front.

Pretty cool!

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