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In short, Cairn -> many rocks piled up Duck -> 3-4 rocks stacked on top of each other. Natural -> Small rocks don't stack directly on top of each other, gravity tends to spread them out....
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In short, Cairn -> many rocks piled up Duck -> 3-4 rocks stacked on top of each other. Natural -> Small rocks don't stack directly on top of each other, gravity tends to spread them out....