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#PhotoOfTheDay is of a USGS elevation benchmark disk on the summit of Mauna Kea, the tallest summit in Hawaii & the largest mountain on earth when measured from its base on the ocean bed.

Favorite fact:The elevation shown (13,796') is measured using traditional methods. That's from sea level. But GPS elevation is 100 or 200' higher (I forget which.) Why? Sea level here is higher as Mauna Kea is so massive it has its own gravity, which pulls the ocean up on its flanks! 😮

#photo #photography