The Cycles of Sand

I wlll look at the sandstone boulders behind the house in a new way after reading this:

Most of us are used to the idea that sand is created from rock by weathering, but less familiar is the idea that it can be turned back into rock again. "Sand grains originally born from granite long ago", Welland explains, “may accumulate, be buried, and become naturally glued together, lithified (from the Greek for stone or rock) into . . . a sandstone. When this, in its turn, is exposed at the surface, it is attacked by weathering and the sand grains are liberated again. The whole process is cyclic, over and over again." He estimates that half of all quartz sand grains have completed that circuit—been turned to stone and then reborn—six times.

From a fascinating review article, "The Magic of Sand."