“The Aztecs are mourning some sort of defeat in the early panels,” Torres said. “It was associated with a large number of deaths. It is unclear if the opponent was a regional enemy or the Spanish.”
“Or disease?” Madero asked.
“Quite possibly. Smallpox arrived with the Spanish and ultimately killed millions. I think it references a conventional battle, however. In the second panel, we see a group of warriors dressed in feathers and beaked helmets. These were the cua¯uhtmeh, or Eagle Warriors, an elite group of skilled veterans.”
Torres pointed to a trail of footprints painted across several pages that signified travel. “As a result of the battle, they are taking something of a major journey.”
“Their trip continued on water?” Summer asked, pointing to the next panel, which showed seven canoes at the edge of a body of water.
“Apparently so. The Aztec capital of Tenochtitlan was built on an island in a lake, so we know they used small canoes.”
“These appear significantly larger,” Madero said.
The Cuban Díaz inched forward with interest. “Numerous warriors are depicted in each boat. It also appears they have loaded provisions aboard. And that may be some sort of sail.” He pointed to what looked like a pole with a loose sheet around it.
“Yes, very curious,” Torres said. “I’ll admit, I’ve never seen an Aztec depiction of a large vessel like that. We may have to consider the possibility they were navigating in the Bay of Campeche.”
“Or beyond?” Díaz asked.
“That might explain why we found the codex in Tabasco,” Madero said. “There must have been some connection with their departing or returning point on the coast.”
“There is much we don’t know,” Torres said.
They all studied the next panel, which showed the seven canoes heading across the water toward the sun. The following image showed a single canoe returning.
“Now things get interesting,” Torres said. “The next panel shows an Eagle Warrior, presumably from the surviving canoe, describing his voyage to a stonecutter. Then we see the related images being carved into a large circular stone.”
“It resembles the Sun Stone,” Madero said.
“Where have I heard of that?” Summer asked.
“It was discovered in 1790 during renovations of the Mexico City Cathedral and is now displayed in the National Anthropology Museum. Some twelve feet across, it contains a myriad of Aztec glyphs, many related to known calendar periods.”
“If the scale is accurate,” Torres said, “this stone would be considerably smaller.”
Dirk looked at the image, still contemplating the canoes from the earlier panels. “Any idea about the nature of the voyage?”
“The purpose isn’t clear, but it appears they were transporting something of great significance. That is implied by the presence of the Eagle Warriors as escorts. Perhaps a special offering to one of the deities.”
“Would that include items of intrinsic value,” Díaz asked, “such as gold or jewels?”
“The Aztecs valued and traded such objects, and they are reflected in their religious artifacts, so that would be likely.”
The next panel showed the stonecutter with his handiwork, standing in a house, while men wearing steel helmets and breastplates assemble outside.
“And now the Spanish appear,” Madero said.
“Yes, and they want the stone.” Torres pointed to the next image. “The stonecutter cuts it in half and tries to hide both pieces. The Spaniards find one piece and then kill the stonecutter.”
The next page showed a stone fragment being loaded onto a ship with a large sail. A monkey was depicted above the bow.
“So the Spanish obtained the stone and loaded it on a galleon,” Summer said. “It must be now sitting in the basement of a museum in Seville, collecting dust.”
“I’m not aware of any such artifact,” Torres said. “And the Spaniards got only half the stone. The final panels show more Eagle Warriors transporting the remaining piece and hiding it in a cave beneath a mountain marked with a cow.”
“Any clue where that might be?”
Torres pointed to a page depicting footsteps along a flat-topped pyramid crowned by four large statues.
“That most certainly is the Pyramid of Quetzalcoatl at Tula,” he said, “which is north of Mexico City. After reaching Tula, the footsteps on the next frame indicate they continued farther. It’s difficult to gauge distances, but if the next page represents another day or two’s journey, they might have traveled another thirty or forty miles beyond Tula.”
Madero pored over the final image. “They then buried the stone in a cave, it would seem, near a mountain marked with a cow. That’s very curious.”
“That they would try to hide the stone?” Summer asked.
“No, the fact that they drew a cow. Cattle were not native to North America. They were brought over by Columbus.” He stepped to a file cabinet and returned with a folding road map of the Mexican state of Hidalgo. He pinpointed Tula near the map’s southeast corner.
“It’s probably safe to assume they traveled from the south to reach Tula. The question is, where would they have gone from there?”
He and Torres examined the surrounding place names, searching for a clue.
“Maybe Huapalcalco?” Madero pointed to a town east of Tula. “An important Toltec city that also represents one of the oldest human occupation sites in Hidalgo.”
“If they were traveling from Tenochtitlan, or the Tabasco coast,” Torres said, “they wouldn’t have needed to pass through Haupalcalco. It’s too far east.”
“You’re right. Farther north is a better bet.” Madero dragged a finger from Tula, stopping at a town called Zimapán, almost fifty miles north. He stared at the lettering, lost in thought.
“A cow on the mountain,” he said. “Or is it really a bull? Isn’t there an old Spanish mine around there called Lomo del Toro, or Bull’s Back?”
Torres’s eyes lit up. “Yes! A very early Spanish silver mine, predecessor to the big El Monte Mine west of Zimapán. I worked on a dig at a village site near there many years ago. The bull’s back refers to the rugged top of the mountain. You’re right, Eduardo, it fits the description. The cave could be on this very same mountain.”
“Could the stone still be there?” Díaz asked.
The room fell quiet. Madero finally broke the silence. “It’s a remote area. I think the chances are good.”
“There’s only one problem,” Torres said. “The Zimapán Dam, built in the 1990s, flooded the valley floor west of the mountain. If the cave is located on that side, it may be underwater.”
“Underwater, you say?” Madero turned to Dirk and Summer and winked. “Now, who do we know who could pull off an underwater search of that nature?”
Dirk and Summer looked at each other and grinned.
13
The tranquil expanse of open water appeared much like any other portion of the Caribbean. Only the occasional dead fish slapping against the bow of the Sargasso Sea gave hint of anything amiss. The NUMA research ship cut its engines and eased to a drift in the lightly choppy seas.
Two days had passed since they had slipped into Havana Bay under the watchful eye of a Cuban patrol craft and offloaded the Alta’s injured crew and oil workers. A Cuban Revolutionary Navy tender had pulled alongside and hoisted a diving bell over to the NUMA ship. The Canadian dive team climbed from the NUMA decompression chamber into the pressurized bell, which was transported back to the Cuban ship, where the men would complete their decompression cycle.
Captain Knight waited for the last of his men to debark, then approached Pitt at the gangway. “I hate to think of how many men we would have lost if you hadn’t responded to our distress call. I can’t thank you enough.”
“Lucky thing we were in the neighborhood.?
?? Pitt nodded at the antiquated ambulances beginning to pull away from the dock. “We would have been happy to drop you in Key West.”
Knight smiled. “We’ll be well treated. We’re operating under a contract with the Cuban government, so it’s probably better we’re here to sort through the repercussions. Hopefully, I’ll be able to smooth over the fact that we won’t be able to tap that exploratory well for a while.”
“I wish you luck,” Pitt said, shaking hands.
Moving at a measured pace, Knight stepped ashore, then turned and gave the crew of the Sargasso Sea a sharp salute.
As the gangway was secured and the mooring lines retrieved, Giordino approached Pitt with a box of Ramón Allones Cuban cigars under one arm.
“How did you score those?” Pitt asked. “Nobody was allowed off the ship.”
“I made fast friends with the harbor pilot. They cost me two bottles of Maker’s Mark.”
“I’d say you got the better end of that deal.”
Giordino grimaced. “Not if you consider they were my last drops of booze smuggled aboard ship.”
They stood at the rail, watching the historic Malecón slip by, as the Sargasso Sea made its way out of the compact harbor. Pitt had set foot in Havana years earlier and was struck by how similar the waterfront appeared, as if the march of time had somehow bypassed the city.
The NUMA ship soon found open water. Shedding its Cuban escort, it beat a quick turn around the island’s western tip, backtracking on a southeastern tack toward Jamaica. Reaching one of Yaeger and Gunn’s dead zones, the Sargasso Sea came to a halt and a flurry of activity began. A team of scientists took water samples, lowering collection devices to varying depths and rushing them to the lab.
In the meantime, Giordino prepped an autonomous underwater vehicle. The torpedo-shaped AUV was packed with sensors and a self-contained sonar system. With a prearranged road map, the device would dive to the bottom and skim along the seafloor in a set grid pattern, mapping the contours.
Pitt watched as Giordino released the AUV from the stern A-frame. “When will she be back?”
“About four hours. She’s on a short leash for the initial run, surveying less than a square mile. No sense in running her crazy until we can determine the source of the dead zone.”
“My very next intent.” Pitt migrated to the bridge, where he had the captain hopscotch the vessel around the area, stopping at half-mile increments for additional water samples. When it was time to retrieve the AUV, Pitt grabbed Giordino and ducked into one of the labs. A dark-eyed woman in a blue lab coat motioned for them to join her in front of a computer monitor.
“Do you have some results for us, Kamala?” Pitt asked.
Kamala Bhatt, the Sargasso Sea’s marine biologist, nodded. “We do indeed.”
She took a seat on a stool. “As you know, dead zones are common all over the world’s oceans. They are typically found near the mouth of rivers carrying polluted runoff. But this site, and the others identified by Hiram Yaeger, are far from land. Our initial testing does show a decrease of oxygen levels, but it is less than we would otherwise expect.”
Pitt shook his head. “So there is in fact no dead zone here?”
“On the contrary, the toxicity levels are quite high. It just wasn’t the animal I expected to find.” She pointed to the computer screen, where a bar graph displayed the composition of one of the water samples. “The water tests lower for oxygen content than typically found, but there seems to be another factor that is increasing the impact to aquatic life. I had to delve deeper until I found one element out of place. Its concentration is off the charts.”
“What’s that?” Giordino asked.
“Mercury. Or methyl mercury, to be precise.”
“Mercury poisoning this far from land?” Pitt asked. “Are you sure?”
“We’ve tested all but the last batch of seawater samples, and they all show highly toxic concentrations of methyl mercury. We’ve found bioaccumulation in the plankton, which then works itself up the food chain. We also sampled a number of dead fish, which seem to be present in large numbers, and confirmed the presence of mercury.”
“Mercury is nothing new,” Pitt said. “Industrial air pollution has been increasing mercury levels in the oceans for decades. But this is different?”
Bhatt nodded. “The concentration is exponentially higher. This isn’t just some general acid rain but a specific, localized incident. The only comparable toxicity I can find historically is from Minamata, Japan. A factory there dumped twenty-seven tons of methyl mercury into the bay over several decades, resulting in catastrophic damage to nearby residents and local sea life. Nearly two thousand deaths have been attributed to it.”
“But we’re fifty miles from land,” Giordino said.
“If I had to guess,” Bhatt said, “I would say that someone has been dumping industrial wastes out here.”
“If that’s the case,” Pitt said, “the AUV will show it.”
“The concentration was highest in the water sample where the AUV was launched,” Bhatt said.
“She’s due up any minute,” Giordino said. “Hopefully, the litterbugs left a calling card.”
The trio retreated to the stern deck as the AUV surfaced and was hoisted aboard. Giordino downloaded the sonar data onto a portable hard drive and returned to the lab to review the images. He quickly advanced through the AUV’s acoustic imagery, which showed hundred-meter swaths of the undulating seafloor. There were rocks, sand, and even occasional dunes, but no drums, crates, or other debris. Only an odd series of shadowy lines marred the bottom, concentrated in a slight underwater valley.
“Nothing obvious,” Giordino said, “though those lines might be worth a closer look. It’s difficult to say if they are geological features or man-made.”
“We might be dealing with something that’s buried,” Pitt said, “in which case we’ve got our work cut out for us.”
“I can reconfigure the AUV to perform a sub-bottom profile. That would give us a limited look beneath the seabed, if the sediment conditions are friendly.”
Pitt stared at the sonar screen, knowing the answer to the mystery was there somewhere. He shook his head slowly. “No, let’s move on. It looks to be a sandy bottom here, which isn’t conducive to the sub-bottom profiler. We’ve got two more dead zones to investigate, and I’ll wager the source will be evident at one of those.”
Without debate, Giordino relayed the order to the bridge, knowing from the past that Pitt’s intuition was as good as gold.
14
The battered green panel van turned off the dirt road and pulled to a stop on a high bluff. As a cloud of trailing dust settled, Dr. Torres climbed out of the driver’s seat and spread a topographic map across the hood. Dirk and Summer joined him as he took a black pen and marked an X through a square grid. A half-dozen adjacent grids were already marked.
“That was the last accessible area around the base of Lomo del Toro to survey,” Torres said in a tired voice. “Aside from the two abandoned mine shafts we crawled through, I’m afraid we’ve found nothing resembling a cave, or even a potentially buried one.”
“Dr. Madero told us it was a long shot,” Summer said.
“True. I wish he was here to see for himself.”
“He was disappointed, but he couldn’t get out of a speaking engagement in Mexico City,” Summer said. “We did promise him we’d give it our best effort.”
Torres nodded. He was certain they were in the right place. He and Madero had spent days studying the codex and comparing it to other Aztec documents, as well as reading contemporary Spanish accounts. Bit by bit, they deciphered additional clues that seemed to confirm the Aztecs had carried the half stone to Zimapán.
One notation indicated they had traveled north, presumably from their capital of Tenochtitlan. Another indicated they stopped at Tula along the w
ay. Tula was an ancient Toltec city near the northern fringe of the Aztec empire, just over twenty miles away. The codex revealed the warriors had traveled two days beyond Tula, traversing a steep ravine, before depositing the half stone in a cave near the base of a cow-shaped mountain. Everything pointed to Lomo del Toro.
But two days of searching the dry, rugged region in Mexico’s Central Plateau had led nowhere. After arriving at the mining town of Zimapán, the three drove through the narrow canyon of Barranca de Tolimán, which seemed to align with the Aztec description. At Lomo del Toro mountain, they initiated a search around its perimeter. Much was inaccessible by car, forcing them to hike the rugged terrain. They were now hot, dusty, and tired of dodging rattlesnakes.
They had explored all around the mountain, except for the El Monte Mine facility facing Zimapán, which encompassed the original Spanish digs. With most of its silver and lead deposits having been mined in excavations that stretched back to the sixteenth century, it was now a small operation. Torres conferred with mine officials and a local historian, but no one recalled any stories of an Aztec cave, or even an Aztec presence in the area. Fears that the stone was hidden in an early mine shaft were minimized when they realized the mining operation was high up the mountain.
Torres drank warm water from his canteen and shook his head. “My friends, perhaps the Aztec cow mountain is located elsewhere.”
Dirk produced a copy of the codex page that illustrated the burial site. He gazed from the mountain image to the imposing heights of Lomo del Toro. “The ridge highlines look like a match to me.”
Summer gazed at the mountain and agreed. Studying the photocopy, she noticed a faint line beneath the cave. “What’s that?”
Dirk and Torres peered at the line.
“I didn’t remember that in the original,” Torres said.
“That’s what I thought,” Summer said. “It became more visible in the photocopy.”
Torres studied the line closely. “It would appear to be a river or creek.”