Is there an ancient quarry near Monument Valley?

[PoisonApple]

Basalt columns come to mind.
Not that the rock in the OP are basalt, but rock can naturally form in such shapes.

 

[Num7]

Wow, I didn't know of such stone formations. Nature usually doesn't like right angles. Stunning.

 

[8thsinner]

The more I think about it, the more I believe it is just nature doing its beautiful artwork. Look at snowflakes. We could try to say they are made
from alien technology. Nature just does some amazing things.

If they were hexagonal like the heat compression shapes in belfast and scotland's landscapes, and centres of storms I might agree. But hexagons are natures way of minimizing stressors along triangular pressure points. Fractals based often on phi ratios is how it deals with growth and expansion.
But show me anywhere in nature that designs rectangles in dimensions like the hundreds of thousands of ancient sights/pyramids and geoglyphs and temples and you might convince me. I'm not going to count bicubic crystals like salt and pyrite either.
These rocks aren't breaking off in cubes. And basalt being a volcanic based construction if anything it should be forming hexagons.

 

[8thsinner]

Wow, I didn't know of such stone formations. Nature usually doesn't like right angles. Stunning.

Fingals cave pictured above and belfasts giants causeway are made of hexagons. It just looks more rectangular as seen from the sides like that.