Cup and ring markings are a form of prehistoric art . They consist of a concave depression, no more than a few centimetres across, pecked into a rock surface and often surrounded by concentric circles also etched into the stone. Sometimes a linear channel called a gutter leads out from the middle.
Imagine what could be so important for them to say to generations so far into the future that they just had to carve it in stone to make sure we got the message.