Santa Cruz Mountain Cave Perfectly Aligns Sunlight Within On Summer Soltice

CASTLE ROCK STATE PARK, Santa Cruz County (KPIX 5) -- A small cave in Castle Rock State Park appears to align the sun's rays inside its width, as well as completely through the space and onto a natural sundial during the summer soltice.

Rock climber David Smith knows the Santa Cruz Mountains about as well as anybody. "I've spent a lot of years up here. 1980, easily, was probably the first year I started climbing here," says Smith, making his way up a rocky path to one of the area's popular climbing spots.

After decades of climbing, his perspective on these rocks changed when he had a chance encounter with a Stanford archeology student. "He points out a petroglyph, and where there is one there are usually more," recounted Smith. "Then, on June 20th I'm standing in the cave and the light is going all the way through, and I'm like 'wow' is this a coincidence?"

With piqued curiosity – and imagination - Smith started paying close attention to the cave, the sunlight and the calendar, and things started getting interesting. He points to the particular contours of the cave, which cast light and shadows as the sun crosses the sky. He noticed that the evening light lands precisely on one specific rock during the shortest day of the year. The big show, however, is the summer solstice, and sure enough, it happens.

"The light is coming through this aperture, crossing the room and heading out across the valley," described Smith, as the longest day of the year sends a beam of light through the small cave, and out a hole on the other side. "It's one of these things you have to see to believe. Nobody believes me. You have to see it and say, 'that's pretty strange,'" said Smith, as the peculiar shadow moved across the valley.

Smith readily admits he is no archeologist, and has no explanation for the phenomenon, but watching the perfectly aligned shadows on June 20th he's certainly right when he says "it's pretty cool to see."