It was there all along, although they were slow to realize it. In many rooms, one wall or another was overgrown with black-green mold. Munro noticed that this mold did not grow in relation to light from a window, or air currents, or any other factor they could identify. In some rooms, the mold grew thickly halfway down a wall, only to stop in a sharp horizontal line, as if cut by a knife.
"Damn strange," Munro said, peering at the mold, rubbing his finger against it. His finger came away with traces of blue paint.
That was how they discovered the elaborate bas-reliefs, once painted, that appeared throughout the city. However, the overgrowth of mold on the irregular carved surface and the pitting of the limestone made any interpretation of the images impossible.
At lunch, Munro mentioned that it was too bad they hadn't brought along a group of art historians to recover the bas-relief images. "With all their lights and machines, they could see what's there in no time," he said.
The most recent examination techniques for artwork, as devised by Degusto and others, employed infrared light and image intensification, and the Congo expedition had the necessary equipment to contrive such a method on the spot. At least it was worth a try. After lunch they returned to the ruins, lugging in the video camera, one of the infrared night lights, and the tiny computer display screen.
After an hour of fiddling they had worked out a system. By shining infrared light on the walls and recording the image with the video camera - and then feeding that image via Satellite through the digitizing computer programs in Houston, and returning it back to their portable display unit - they were able to reconstitute the pictures on the walls.
Seeing the bas-reliefs in this way reminded Peter Elliot of the night goggles. If you looked directly at the walls, you saw nothing but dark moss and lichen and pitted stone. But if you looked at the little computer screen, you saw the original painted scenes, vibrant and lifelike. It was, he remembered, "very peculiar. There we were in the middle of the jungle, but we could only examine our environment indirectly, with the machines. We used goggles to see at night, arid video to see during the day. We were using machines to see what we could not see otherwise, and we were totally dependent on them."
He also found it odd that the information recorded by the video camera had to travel more than twenty thousand miles before returning to the display screen, only a few feet away. It was, he said later, the "world's longest spinal cord," and it produced an odd effect. Even at the speed of light, the transmission required a tenth of a second, and since there was a short processing time in the Houston computer, the images did not appear on the screen instantaneously, but arrived about half a second late. The delay was just barely noticeable. The scenes they saw provided them with their first insight into the city and its inhabitants.
The people of Zinj were relatively tall blacks, with round beads and muscular bodies; in appearance they resembled the Bantu-speaking people who had first entered the Congo from the highland savannahs to the north, two thousand years ago. They were depicted here as lively and energetic: despite the climate, they favored elaborately decorated, colorful long robes; their attitudes and gestures were expansive; in all ways they contrasted sharply with the bland and crumbling structures, now all that remained of their civilization.
The first decoded frescoes showed marketplace scenes: sellers squatted on the ground beside beautiful woven baskets containing round objects, while buyers stood and bargained with them. At first they thought the round objects were fruit, but Ross decided they were stones.
"Those are uncut diamonds in a surrounding matrix," she said, staring at the screen. "They're selling diamonds."
The frescoes led them to consider what had happened to the inhabitants of the city of Zinj, for the city was clearly abandoned, not destroyed - there was no sign of war or invaders, no evidence of any cataclysm or natural disaster.
Ross, voicing her deepest fears, suspected the diamond mines had given out, turning this city into a ghost town like so many other mining settlements in history. Elliot thought that a plague or disease had overcome the inhabitants. Munro said he thought the gorillas were responsible.
"Don't laugh," he said. "This is a volcanic area. Eruptions, earthquakes, drought, fires on the savannah - the animals go berserk, and don't behave in the ordinary way at all."
"Nature on the rampage?" Elliot asked, shaking his head. "There are volcanic eruptions here every few years, and we know this city existed for centuries. It can't be that."
"Maybe there was a palace revolution, a coup."
"What would that matter to gorillas?" Elliot laughed.
"It happens," Munro said. "In Africa, the animals always get strange when there's a war on, you know." He then told them stories of baboons attacking farmhouses in South Africa and buses in Ethiopia.
Elliot was unimpressed. These ideas of nature mirroring the affairs of man were very old - at least as old as Aesop, and about as scientific. "The natural world is indifferent to man," he said.
"Oh, no question," Munro said, "but there isn't much natural world left."
Elliot was reluctant to agree with Munro, but. in fact a well-known academic thesis argued just that. In 1955, the French anthropologist Maurice Cavalle published a controversial paper entitled "The Death of Nature." In it he said:
One million years ago the earth was characterized by a pervasive wilderness which we may call "nature." In the midst of this wild nature stood small enclaves of human habitation. Whether caves with artificial fire to keep men warm, or later cities with dwellings and artificial fields of cultivation, these enclaves were distinctly unnatural. In the succeeding millennia, the area of untouched nature surrounding artificial human enclaves progressively declined, although for centuries the trend remained invisible.