Lost Worlds In The Living Dark

The lost sloth and the vast silence offer a glimpse of extinction and persistence in Kartchner Caverns

I stop to study a fantasy formation of stalactites oozing out of a fissure in the ceiling, mirrored by the blind groping upward from the floor of the stalagmites.

I stop to study a fantasy formation of stalactites oozing out of a fissure in the ceiling, mirrored by the blind groping upward from the floor of the stalagmites. Photo by Pete Aleshire. |

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One of the 10 most diverse caves in the world, Kartchner Caverns harbors a great diversity of rock forms like the draperies and stalagmites.

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One of the 10 most diverse caves in the world, Kartchner Caverns harbors a great diversity of rock forms like the fried egg formations.

I drop back from my little group of amiable explorers, all the way back to where the state park minder watches me warily lest I extend my hand toward the damp, warm, misshapen tissues of stone, which hunker like goblins along the path.

But I don’t intend to touch the drip-castle speleothems. I don’t intend to leave skin cells and microfibers and hand lotion smears. I don’t intend to disturb the balance of eons gleaming on the surface of the limestone formations built a drip at a time over 200,000 years in the absolute darkness of Kartchner Caverns.

I am merely hungry for the silence at the edge of the darkness in the turbulent wake of our little international group, drawn to this crown jewel of the state parks system just south of Benson in southeastern Arizona.

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Dissolved limestone in water dripping from cracks in the ceiling created this formation in the last 200,000 years.

The lights along the trail have been positioned artfully, shining through paper-thin, curtains of limestone, refracted through trembling droplets pregnant with calcite, glowing on the damp surface of 20-foot-tall spears of stone. The cavern remains a hallucinogenic fantasy of stone. I should feel trapped, oppressed, frail. But the cave seems alive, full of intent and long dreams. I sense the life in the darkness — the hidden bats, the 2,000 species of bacteria, the writhing nematodes, the warm, animate, anthropomorphic surfaces of the rocks themselves.

I stop to study a fantasy formation of stalactites oozing out of a fissure in the ceiling, mirrored by the blind groping upward from the floor of the stalagmites. They look organic, like I’m trapped in the bowels of some incomprehensible creature. And why should they not be alive? They formed, after all, from the fused skeletons of tiny sea creatures that settled to the bottom of a vanished sea some 330 million years ago.

The dissolved limestone has assumed a riot of forms, cave bacon, draperies, soda straws, fried eggs, totem polls, moonmilk, frostwork, helictites, boxwork, pillars, scallops, cave popcorn, calcite rafts, cave pearls, flowstone and rimstone. Because of the diversity of minerals that seep through the fissures of Kartchner Caverns, it’s considered one of the 10 most mineralogically diverse caves in the world.

But just when it seems the cave is a safe womb, I remember the giant ground sloth and shudder. For life comes bound up with extinction, which waits in the darkness. Already in my wisp of a life, the people who I have loved and lost threaten to jostle aside those who remain to me. So I think of the sloth in wonder and sorrow.

The first explorers of Kartchner Caverns made a startling discovery in the mud of a long-sealed back room of the 2.4-mile-long network of tunnels dissolved by faintly acidic groundwater in the layers of sea bottom Escabrosa limestone buried in the Whetstone Mountains. They found the 86,000-year-old carcass of a Shasta Ground Sloth, a ponderous, plant-eater covered with long, shaggy red hair.

Somehow, the 9-foot-long, 400-pound sloth made its way into the cave, although in modern times the largest opening discovered could barely let a human being wiggle through. Apparently the entrance she used collapsed about 36,000 years ago. She died there in the dark, perhaps lost — perhaps wounded before she entered. Her kind sought out such caves. Perhaps they bore their young there. In the Grand Canyon, the remains of a sloth turned up in a cavern that also harbored the stick figures of animals created by the descendants of the big game hunters. We humans apparently hunted the giant sloths to extinction at the end of the Ice Age some 11,000 years ago, along with mammoths, camels, horses and a host of other “megafauna.” In several places, spear points lie scattered with their bones. They apparently survived the wrenching climate changes that attended the end of the Ice Age, but couldn’t withstand us.

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The dissolved limestone has assumed a riot of forms, cave bacon, draperies, soda straws, fried eggs, totem polls, moonmilk, frostwork, helictites, boxwork, pillars, scallops, cave popcorn, calcite rafts, cave pearls, flowstone and rimstone.

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Photo courtesy of Kartchner Caverns State Park

The Kartchner Caverns Visitor Center offers this life-size model of a 9-foot-tall Shasta Ground Sloth that died in the vast limestone cavern 86,000 years ago. Scientists think ancient hunters exterminated the sloths and many other large animals 11,000 years ago.

Cave explorers have also discovered the remains of an ancient horse, a pronghorn, a roadrunner, coyotes, a javelina, rabbits, frogs, lizards, snakes and rodents, all creatures of the sunlight who died in that inexpressible darkness.

Researchers from the University of Arizona have collected bacteria from the stone columns, cataloging at least 2,000 species adapted to this lightless world of damp stone. The bacteria populations differ sharply from one set of stalactites to the next, each ecosystem marooned on its own continent in the stillness in a world where it can take a century for a rock formation to grow another inch.

The cave has a whole ecosystem based on bat guano, since about 1,000 bats maintain a spring and summer roost in one of the larger caverns. Bacteria and fungi grow in the guano, forming the food chain for a welter of nematode species, the wormlike rulers of the world. Some nematodes live in guano, others in the stomachs of ground sloths. Scientists have described 28,000 species of nematodes, although more than a million species probably exist. They cover the living world like an invisible skin, peerless recyclers and lethal parasites. They account for 90 percent of the life on the ocean floor and live in both the deepest ocean trenches and high atop mountains.

And they live in this animate cave as well, thriving in the bat guano, frozen in the sloth dung, trembling in the droplets thick with calcium carbonate.

Up ahead, the tour group has stopped to arrange themselves on benches that face into the vast darkness of the Throne Room for the finale of the tour. I take my seat last, reluctant to leave the living silence of the vast cave, which has recorded the end alike of the ground sloths and the nematodes that lived in their dung. We ourselves have risen up and colonized the planet in the time these formations have grown. Will they grow still, an inch a century, when we have gone?

The light show begins, building to the full revelation of Kubla Khan, a 58-foot-high stone sculpture that rises from the shadowed floor and stands in timeless splendor. I try to understand that the Earth built it one drip at a time from the dissolved skeletons of microscopic sea creatures that died out before the dinosaurs rose.

I can’t, really.

I can’t imagine 200,000 years.

I cannot even comprehend the blind persistence of the nematodes. But I do understand the sloth in the darkness.

For I have stood in that same dark — remembering lost worlds of my own.

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