The Kätkävaara area has been a seabed in ancient times. The boulders in Kätkävaara were originally sand that deposited in the shallow coastal waters more than 2 000 million years ago. The water currents formed meandering bumps in the sand – wave signs. Layers of sand gradually accumulated from a thickness of hundreds of meters.
In the earths’s crust, the sand gradually hardened into rock – quartzite. Later, the layers on top eroded away, and boulders came off the
rock. Stone is, in fact, a material that tends to adapt to the conditions around it. Changes in the stone are affected by temperature, pressure, mechanical compression, stretching or rubbing, and the presence of fluids. For example, as the sandstone recrystallizes, the quartz sand grains grow into larger quartz crystals, tangled tightly around each other.