Quietly they waited as the sun climbed in the east, spilled over the mountains, and streamed its rays toward the cliff face before them. They watched in amazement as the first shaft of sunlight funnelled like a flashlight beam through a 3-sided notch in the cliff overhang and struck the center of a sun symbol on the left side of the panel. As they watched in awe, the beam pushed the shadow from left to right, slowly bathing the entire message in sunlight like a prehistoric neon sign announcing yet another Christmas, as it has done for centuries. Before their eyes, they had received a message across the ages.
Subsequent visits showed that the phenomenon only occurred at the winter solstice; and at other times of the year the sun only partially lit the message.