Indeed, it's a close up of some sand on the beach!

Ah, yes. I'm sure if the human civilization disappears it won't take long for nature to erase anything we've drawn on the canvas we call our world. As Heraclitius says, "All is flux."

Btw, I see your avatar is a dragonfly (and your username!) - you may enjoy some of @ocrdu's photos, if you haven't already!