A man-made karst landscape

I have blipped this miniature limestone landscape once before, but it changes in appearance all the time. It lies under under the modern road bridge at Ellon, a few miles inland from Newburgh on Ythan. It isn't a natural limestone feature but rather the the result of water percolating through the structure of the bridge and dissolving the lime from the mortar. When the water droplets hit the ground the dissolved carbon dioxide is lost, the acidity falls and the lime precipitates out, slowly building up a layer of limestone, known as tufa. It is exactly the same process that produces stalactites, stalagmites and tufa screens in underground limestone caves.

Use the magnifying glass to appreciate the detail.