This week’s “sciencey” tourist picture is of a gypsum pedestal in White Sands National Monument, in New Mexico (USA).
If you recall from back in ST#1, the white gypsum dunes move just a few inches each year, allowing some vegetation to adapt to the changing situation. Gypsum pedestals are one result of this adaptation.
As the dunes slowly encroach, some plants manage to keep their tops above the sand and root tips below it. In the case of plants with fairly widely-spread root structure, they can hold a column of gypsum in place, even after wind has blown surrounding sand away. The pedestal is still fairly soft, so it’ll erode and crumble eventually — but the combination of sand and fine roots can persist for years. In this image, a skunkbush sumac (Rhus trilobata) stars at the top of its own pedestal (this one is about 1-1/2 meters tall and a few meters in diameter).
If you were curious, the skunkbush sumac gets its name from the fact that in autumn, the plant gives off a musky smell. It’s a close relative of poison ivy and poison oak, but isn’t poisonous itself. In fact, local tribes made a lemonade-like drink from its berries [ref: U.S. National Park Service “Dune Life Nature Trail Guide”]
As usual, click on the above picture to get to the Flickr version of this image — it’ll give you lots of options for resizing and otherwise manipulating the source photo.