There are many different types of geologic arch. Shown above is a waterfall arch, which directly contradicts the classic arch definition of a curved structure that gains strength from the curve. Uniquely, this one consists of a straight row of discrete cubic forms and has had enough strength to stand for perhaps ten thousand years. This particular cobblestone structure is made of Salt Wash Sandstone, part of the Morrison formation and is located in Arches National Park.
Visited Arches National Park in 2016 but my photo doesn't do it justice. lol