Originally these flat pieces get created as the top layer on the beach where water pulls back (low tide), leaving the sand to dry on the Sun. The top layer dries and creates a separate layer, making these flat solid pieces.
Sometimes these flat crumbles are extremely thin, with a thickness of only around 4 grains. I cannot understand how these stay in one piece after they dry completely:
first I thought it was simply moisture, but if I let them dry completely on the Sun, they become dry throughout. When I brake them apart, even the crack looks and feels completely dry throughout.
then I thought maybe it is salt, somehow the salty ocean water sticks the grains together, and after they dry, the salt stays in between the grains as some kind of glue
the grains are themselves edgy crystals that can somehow lock together because there might be vacuum
Same thing happens in microwave, the sand piece stays solid, like a rock, and won't fall apart. This makes me think it shouldn't be water that keeps it in one piece.
- What keeps dry flat pieces of sand crumbles together (even if you microwave them)?