The pictographs were popping up everywhere now. Despite our excitement, we had begun speaking in hushed tones as if we were in a cathedral — a cathedral of sun, stone and sky infused with reverence and awe.

A deep gash in a giant rock revealed a collection of figures tucked into a dark corner.

The ascending beings, horned creatures and small animals — familiar spirits, perhaps — have led some scholars to believe they were created by shamans depicting mystical journeys into the afterlife. One theory suggests that their art was fueled by hallucinogenic mushrooms or mind-altering plants such as Sacred Datura.

It all felt a bit spooky, accentuated by the fact that we seemed alone in a place that resembled a vast, scattered jigsaw puzzle. It would have been easy to hide out here — Butch Cassidy and the Sundance Kid tried it — and just as easy to get lost forever.

But the major attraction lay just ahead. A series of stone cairns led to a curving 200-foot-long wall covered with anthromorphs, some standing more than 8 feet high.

This was the Great Gallery, a truly astonishing place in the way only a wonderful mystery can be.

There were soaring, box-shaped creatures painted green, red, white and pink. Some were colored in, others were ethereal outlines resembling mummies drifting up and down the wall. Dog-like animals gazed toward them, and a small figure blew a horn. The tallest group had haunted, hollow eyes and made up what is called the Holy Ghost panel.

With so few hard facts, strange theories have evolved about the gallery. Some even suggest these are portraits of extraterrestrials and their interactions with early canyon people.

In his book "Desert Solitaire," Edward Abbey describes the art as "apparitions out of bad dreams."

"These are sinister and supernatural figures, gods from the underworld perhaps who hover in space, or dance, or stand solidly planted on two feet carrying weapons — a club or sword. Most are faceless but some stare back at you with large, hollow disquieting eyes."

Whoever did this planned carefully. They roughed up the surface so the paint would stick and chose a spot away from the prevailing winds that ruin so much rock art. In some cases, they made grooves around the pictographs to keep the paint from running.

"In most cases these rock art panels follow logical travel routes and are found in canyons — canyons have water, shelter and better food resources," Cox said.

After marveling at all this we began the steep, laborious hike out of the canyon. My children traded theories on what they had seen along the way. They suggested this could be a burial ground or prehistoric hermitage.

The beauty of a mystery is that one guess is as good as the next.

But we were certain of one thing: This was a place of great spiritual significance, a nexus or doorway that let these ancient people experience their gods and spirits in a profound way.

And for a few hours, alone and far from anywhere, we were privileged to peer through that doorway with them.