Grand was just a few feet from the mouth of the cave. The light from the swallow hole was blocked by the ledge; even with the night-vision goggles it was difficult to see.

"I'm looking inside the fissure now," he said. "It's dark, but from what I can see, the walls look blistered. They remind me of the collapsed lava tube at Bandera Volcano in New Mexico."

He wondered if the volcanic art on the wall represented something that had happened here instead of to the north. This was going to cause some eruptions of a much different sort among the conservative old guard in the UCSB geology department. Elma Thorpe would have two reasons to be angry at him.

Volcanism in Southern California was a contentious subject. There were volcanoes well north of this region up through Canada-in Black Butte, Clear Lake, Gorda Ridge, and over a dozen others. But volcanism in the north was due to subduction zones, crustal plates moving together from opposite directions. That convergence caused earthquakes as well as huge gaps that released magma. Tectonics in the south were mostly transform faults, with one plate sliding past another like grinding teeth. The horizontal scraping caused earthquakes but it did not cause lava to vent.

Or so many geologists had always assumed. Armed with computer simulations, a few scientists believed that millennia of heavier earthquake activity had simply obliterated calderas and other signs of ancient eruptions in Southern California. They suspected that smaller subduction zones were hidden deep in the crust of the southlands, beneath strata that distorted or swallowed sound waves from acoustic mapping instruments.

Grand stopped just outside the opening; he thought he heard something under the trickling water. He listened. After a few seconds he heard it again. The sound was coming from deep inside the runnel.

"I don't know if the mike is picking this up," he whispered, "but there's a noise in the fissure."

The runoff from the swallow hole was washing slowly down the center of the tunnel Grand stepped inside. He was careful to place his feet on either side of the flow, which ran along a shallow, foot-wide trench in the center. Sinkholes often formed beneath these trenches. The rock underfoot was brittle, eroded. He stood still and listened.

"There it is again," he said. "A deep, intermittent gurgling. I can't tell what it is or exactly where it's coming from because of the echo. Maybe it's a Chumash spirit," he joked. "I'm going to see if I can find the source of the sound."

The scientist began walking slowly along the fissure. It was almost completely dark and he proceeded cautiously, looking around with each step. There were wide cracks in the tunnel floor where sinkholes were forming-probably leading to a network of similar tunnels-and there were occasional stalactites like those at the Bandera site. In some places the walls closed in suddenly and he had to move sideways to get through. The walls themselves were thickly pocked and bubbled. Grand didn't think he'd be finding any art in here.

After he had taken less than a dozen steps the light vanished completely. Removing his goggles, Grand snapped on the penlight and continued ahead. The gentle step of his boots and the rubbing of the harness against his pants echoed locally. They blended with the distant, hollow groan that he still couldn't identify while everything around him was solid and soundless. It was a strange combination, a hip-hop underbeat in a tomb.

But Grand didn't stop. He was driven by more than just curiosity. For most of his life Grand had worked on skills that most people never got to use. His senses had been refined and heightened by years spent reproducing prehistoric tools and using them to hunt small game for food on remote savannas and chaparrals. His endurance, his balance, his instincts had been pushed and enhanced by moving through dozens of caves and tunnels, by climbing mountains and hacking his way through unmapped jungle.

Something about this place had turned those senses on. The penlight roamed the walls like an eye looking back at him. It illuminated dark, narrow fissures on both sides. The rents were jagged, vertical cracks about five feet high and glistening with water seepage from the surface of the mountain. They were classic earthquake fractures; each successive split had relieved some of the stress caused by the shifting earth. By measuring the angles at which they had cracked, geologists could plot the direction of the underlying tremor.

But Grand also felt things that scientists couldn't plot. He knew that non-Chumash were not welcome in the caves. Not welcome by surviving Chumash and not welcome by the spirits that were said to dwell in the mountains. There were times in some of these caves when Grand knew that he wasn't alone. Reason told him that it was an animal hiding in the shadows. But isolation, eerie noises in the dark, and tunnels that were often the size and smell of a grave had a way of convincing one otherwise. There were times Grand could swear that it was not cold he felt but the delicate tail of an animal spirit brushing the small of his back.

Maybe you shouldn't have made that crack about it being a Chumash spirit, he reprimanded himself. He wondered if the sound might be an underground geyser sputtering awake, perhaps the one pictured in the cave painting.

About twenty yards in the tunnel suddenly forked. On the left it continued as before. On the right the ground dropped away sharply and the ceiling was less than five feet high. The water went mostly to the right. Grand turned an ear toward that opening. The gurgling was coming from there.

"It figures," he murmured, looking at the steep, wet passageway.

The sound was much clearer now, with less echo. It couldn't be very far away. Grand also heard dripping water, which didn't surprise him. The antediluvian flows that carved caves and tunnels like these often created underground streams and lakes as well. Many of those became part of other subterranean water systems and survived.

Grand crouched and shined the light down the passage. The stone was very smooth here, definitely an ancient channel. It sloped down like a children's slide for about twenty feet and then leveled off. He ran his hand across the top of the tunnel; the rock seemed solid, not in danger of collapsing. Then he shut off the penlight. There was no other illumination. That meant this tunnel was the only immediate access to the lower level.

He switched the light back on. Jim Grand was not a reckless man, but he had never started an exploration he hadn't finished. Unhooking the videocassette recorder from his belt, he left it on the tunnel floor. He didn't want it damaged if he slipped or fell. And if anything did happen to him, at least the search-and-rescue personnel would know exactly where to look.

Holding the penlight in his mouth, Grand started creeping down. He kept his left hand on the ground and his right hand on the tunnel wall. There were small outcrops that helped him to steady himself.

The wall and its projections were warm and damp and a bit slippery. The warmth made sense. This section was located in the northeastern face of the mountain. Foliage was relatively low-lying here and the sun hammered it for a good part of the day. There was obviously enough water below to evaporate during the day and condense when it cooled at night.

The gurgling sound and the dripping water were much louder now. So was his own breathing, which echoed back at him in the tight passage. It took only a few minutes to crawl down the tunnel. Stopping when he reached the bottom, Grand took the penlight from his mouth and shined it around.

The scientist was in a small, rank, muggy cavern, about twenty feet high and perhaps forty feet across. He couldn't be sure since his light didn't quite reach the other side.