The Call of Everest Page 4

  The bedrock geology of Mount Everest is decidedly more complex than its topography. Everest is not a layer cake of rock units; it is not an eroded remnant of horizontal strata like those exposed in the walls of the Grand Canyon. On the contrary, Everest is dissected by major faults that juxtapose different types of rock. Any color photograph of Mount Everest shows four distinctive intervals of rock differing in color and layer characteristics. From top to bottom:

  • Gray limestone makes up the summit pyramid;

  • The Yellow Band, the most distinctive band of rock on Everest, encircles the peak like a gold wedding ring;

  • Dark gray, thinly bedded, fine-grained, weakly metamorphosed, sedimentary rock of the Everest Series is broadly exposed below the Yellow Band; and

  • White granite and high-grade metamorphic rocks (gneiss and schist) form the lower portions of the mountain.

  SUMMIT ROCKS

  Forming the highest outcrop on Earth are sedimentary rocks consisting of gray, finely laminated, silty limestone and dolomite, first identified as ancient marine sedimentary rocks by Noel Odell and described by Augusto Gansser as fine-grained, thin-bedded, gray “platy limestone” or “calc-schist,” distinguished by the presence of crinoidal fossil fragments. Gansser used these fragments to support his contention that the summit limestone was late Paleozoic in age, around 300 million years old, although he recognized that fossil preservation was not good enough to determine an accurate age. More recent geologists have noted other invertebrate fossils from summit limestone samples, and a distinctive white-weathering, 200-foot-thick thrombolite bed—common microbial deposits found in ancient marine carbonate rocks—has been described at the base of the Third Step on the Northeast Ridge. These fossils, in addition to stratigraphic studies in southern China, establish an Ordovician age for the summit limestone on Mount Everest: roughly 470 million years old.

  YELLOW BAND

  The distinctive Yellow Band is arguably the most recognizable feature of Mount Everest, forming a high ring of yellow-tan marble around the peak right below the summit. I like to think of it as a gold wedding ring. The Yellow Band lies immediately below the Chomolungma detachment fault and crops out below the South Summit on the Southeast Ridge and below the First Step on the Northeast Ridge. About 650 feet thick, it is a succession of interbedded dolomitic marble and phyllite, a fine-grained metamorphic rock with a silky sheen, suggesting that these rocks were subjected to higher temperature and pressure than the overlying formation. The Yellow Band is believed to be Middle Cambrian in age, about 30 to 40 million years older than the Ordovician rocks of the summit pyramid.

  EVEREST SERIES

  Across most of the three faces of Everest, below the Yellow Band, lies the Everest Series, primarily low-grade metamorphic rocks derived from mudstone or shale, including metamorphosed sandstone and minor thin beds of marble. Common minerals found in these rocks include albite, chlorite, epidote, biotite, and quartz. These rocks likely represent deep-water sediments, mostly mudstone and clayey sandstone, deposited on the continental shelf somewhere north of Gondwana. A major river system may have been the source for the sand, silt, and clay in the original rocks, much like the modern Mississippi River, which dumps its load of muddy, silty sediment into the waters of the Gulf of Mexico.

  GREATER HIMALAYAN SEQUENCE

  The base of Mount Everest is composed of igneous and metamorphic rocks that form the metamorphic core of the Himalaya, a giant slab of rock called the Greater Himalayan Sequence, easily observed along the trekking route from Lukla to Everest Base Camp. Dark metamorphic gneiss, a banded rock similar to granite, stripes the walls of deep gorges cut by the Dudh Kosi River. On the steep switchback trail leading up to Namche Bazar you notice swirled migmatites, a metamorphic rock that was once partially molten. The stone steps cut into the near-vertical hillsides between Namche Bazar, Phortse, and Tengboche provide fresh exposures of the metamorphic minerals and fabrics. As you approach Ama Dablam and beyond to the lower Khumbu Glacier, the proportion of white granite in boulders along the trail increases significantly. At Base Camp the landscape becomes monochromatic, a black-and-white vertical world of white granite and ice. This is the exhumed core, the innards, of the mountain belt—the upper crust of India that was detached, metamorphosed, and thrown back on itself to the south to form the Greater Himalaya.

  SOUTH TIBETAN DETACHMENT SYSTEM

  Two great faults, the Chomolungma and Lhotse detachments, are exposed across the Southwest Face of Mount Everest. Together they are called the South Tibetan Detachment System. In geologic terms, a fault is a fracture in the Earth’s crust that results in a demonstrable offset between the types of rock to either side of it. The narrow, brittle Chomolungma detachment lies at the top of the Yellow Band and carries the summit pyramid in its hanging wall. The wider fault zone of the Lhotse detachment lies between the granites and gneisses of the Greater Himalayan Sequence and the overlying Everest Series. North of Everest, these two faults merge and extend east-west for at least 400 miles.

  Geologists have determined that the Greater Himalayan slab was uplifted and tectonically unroofed through simultaneous motion on a major thrust fault at the base of the slab (exposed over 30 miles south of Everest) and the South Tibetan Detachment System at the top of the slab (in the Everest region). Called channel flow tectonics, the process is something like squeezing toothpaste from a tube, and the Greater Himalaya were literally extruded southward between these two great fault systems. What a story to ponder as one trudges in the rarefied air above the Western Cwm to higher regions on Everest! One is not merely climbing a mountain but climbing through the uppermost crust and across a major fault system that has literally detached the roof of the world from its deeper roots below.

  The relatively new model of channel flow tectonics has revolutionized our thinking about the structural geology and tectonic evolution of mountain systems. We now understand that great mountains not only wear away through the slow but relentless surface processes of glacier and stream erosion; they can also become tectonically eroded through large-scale detachment faults that literally decapitate the highest terrain.

  Three factors contribute to the modern-day uplift of the Himalaya:

  1. Continued collisions between the Indian and Eurasian plates at a rate of about 1.5 inches per year;

  2. Tectonic unroofing and erosion of the Himalaya; and

  3. Relentless erosion of the southern aspect of the Himalaya caused by the annual summer monsoon from the Indian Ocean.

  The fact that climate, through long-term precipitation and erosion, can influence tectonic process operating miles down in the crust is a revolutionary concept. In this way, mountains are master teachers of geologic knowledge, and the Karakoram-Himalayan-Tibetan belt is truly one of the greatest geologic laboratories on Earth.

  I can think of no more fitting tribute to the poetry of Earth’s tectonic engine than the fact that this region, now called the top of the world, was once a tranquil seafloor, a subtropical habitat for the invertebrates that thrived in the warm, clear waters of the Tethys Ocean. Today modern rivers carry sediment, dissolvedions, and nutrients from the roof of the Himalaya back to the Indian Ocean, just as rivers did on Gondwana more than 400 million years ago. Perhaps some calcium ions, dissolved from the limestone on Everest, will make their way down the great river systems to the Indian Ocean and be used in the construction of a new calcium-carbonate shell of another seafloor creature. Perhaps this little creature will find its way to the top of a new mountain range formed by the eventual closure of the Indian Ocean as another continent crashes into India in a couple of hundred million years or so. This is how it works and how it has always worked with the Earth: a grand circle of recycling and evolution that includes both the organic and inorganic world, interwoven through deep geologic time.

  A MOUNTAIN IS BORN

  Of the Karakoram-Himalayan-Tibetan belt, we can cite a number of geologic superlatives: It contains the highest mountains on Earth
(14 are higher than 8,000 meters, just over 26,000 feet), the greatest relief of any continent, the highest uplift rates, the largest concentration of glaciers outside the polar regions, the world’s highest and biggest plateau, and the source of many of the world’s greatest river systems. Little wonder that this region has attracted geologists since the early days of exploration and surveying. We can see the evidence of past collisions on continents around the world, but the enormous elevation of the Himalaya, coupled with deep erosion, provides unparalleled opportunities to study the inner workings of an active, evolving collisional mountain belt, a veritable tectonic work in progress.

  Mount Everest is a magnificent testimony to the power of nature. It boggles the mind to think that, through the complete rearrangement of Earth’s continental and oceanic plates, ancient ocean-floor sediments could be lifted up into the summit of the highest mountain on Earth over the course of 400 million years. As I stood at the foot of Mount Everest in the Western Cwm, the mountain seemed everlasting and solid, built on a base of granite and capped by a crown of limestone. Chomolungma, the goddess mother mountain, will surely endure all that nature throws at her, just as her summit parts the jet stream with a flowing banner of snow.

  But Chomolungma is only a temporary mark on the landscape, like everything in geology. Chomolungma is an unfinished geologic symphony. She will continue to morph and change through time, perhaps growing higher before eventually succumbing to erosion, gravity, and glaciers. It’s impossible to predict when, but another Himalayan peak will eventually assume the title of roof of the world, and then another after that, and another after that. Such change is inevitable on a dynamic, living planet. Change is why we exist in the first place, and why we have the privilege to ponder it all.

  SHOPPERS SPEND TIME looking for goods at Saturday’s open-air market in Namche Bazar. Perched on a steep mountainside, the Sherpa town is important for the local economy.

  In the fall of 1984 I trudged northward across a broad, flat snowfield. Its highest point arose in the form of a stout wooden pillar, marking the border between Nepal and Tibet. This was the legendary Nangpa La, the 19,050-foot (5,800-meter) pass located in the shadow of Cho Oyu, a peak that rises to the west of Mount Everest. I tied a kata prayer scarf to a tangle of others on the post and recited Buddhist mantras common to Tibetans of the Tibetan Plateau and to the Sherpas of Nepal to the south. Retracing my steps, I caught a fragrance that blew in gently from the south: pine and juniper forests warmed by the sun, melded with dust and incense and wood smoke from the lowlands of Nepal and the Gangetic Plain of India.

  Descending on the Nepal side of the border, I followed a maze of granite rubble that had been churned up and deposited on the glacier’s surface. Yaks can follow the scent left by previous caravans, but lone travelers must decode their way through the monochromatic scree. I found no sign of yak dung—every scrap had been thrown onto the loads of the yak trains for use as cooking fuel. And the cairns meant to mark the trail were just as the Tibetan traders had described them: imaginary piles of stones that moved and disappeared like phantoms.

  The route over the Nangpa La has long been a conduit of history, trade, and culture for Tibetans and their Sherpa kin—the people of Everest. I was entering Khumbu, the Sherpas’ homeland—a region circumscribed by the headwater valleys that drain the Nangpa La and the south side of Mount Everest. Khumbu’s waters eventually merge into the Dudh Kosi River and flow toward India. One monk described the outline of Khumbu and its veins of rivers as “shaped like a flower bud about to bloom.”

  Nearly 500 years ago, Sherpa legend says, hunting dogs belonging to a man named Kira Gombu Dorje chased a wild sheep across the Nangpa La. The dogs, in turn, were pursued by the hunter—the first Tibetan to settle in Khumbu’s fertile, temperate valleys. The south side’s greener pastures soon drew a pioneer community of shar-pa, “people of the east,” who became citizens of Nepal.

  In winter, when farming and herding is relatively dormant in Tibet, people from the north side of Everest still climb over the Nangpa La. They are either traveling on Buddhist pilgrimage or as refugees from China, seeking opportunities in India or the West. Their bid to reach the outside world—by scaling the spine of the Himalaya—underscores the Tibetans’ irrepressible desire to experience the freedom that the Sherpas to the south enjoy.

  THE SPIRIT OF KHUMBU

  The Sherpas of Khumbu barely number more than 3,500, with a parallel population of 17,000 more in Solu, a region three days’ walk to the south. For at least a century these two enclaves, distinguished by subtle differences in dialect and dress, have been closely linked by marriage. From the mid-19th to mid-20th centuries, the arcane laws of Nepal’s Rana oligarchy restricted trade with Tibet to men who lived in border districts. This made Khumbu husbands especially desirable to brides from Solu, by allowing their families to marry into a valuable trade connection.

  But the Sherpas’ connection with Tibet was maintained as much for religion as it was for trade. Beginning in the early 1900s, many of the Khumbu Sherpas sent their boys north, back across the Nangpa La, for monastic training at the Buddhist monastery of Rongbuk, near Everest’s Base Camp on the Tibet side of the mountain. From this monastery the Sherpas drew much of their formal religious traditions.

  Tenzing Norgay, who climbed Everest with Ed Hillary in 1953, grew up in the Tibetan village of Kharta, directly to the northeast of Everest. After studying briefly at Rongbuk, he crossed the Nangpa La, in the 1920s, and settled with his parents in the Khumbu village of Thame. At age 18, he left Khumbu to search for work in Darjiling—a hiring and staging point for foreign climbing expeditions to Everest.

  Tenzing’s nephew Nawang Gombu—who climbed Everest with Jim Whittaker in 1963—also studied at Rongbuk for two years, until he could no longer endure the strict monastery regimen. One night he bundled up his clothes, sneaked out through the hole of a latrine, and walked over the Nangpa La to Khumbu.

  The Cultural Revolution began in 1966—seven years after the uprising against the Chinese in Lhasa. During that chaotic period, the Rongbuk monastery was destroyed. Fortunately, most of Rongbuk’s arcane and colorful Buddhist traditions had already regerminated, with a distinctive flair, and were thriving in the Sherpa monasteries of Solu and Khumbu.

  SACRED SITES

  Below the Nangpa La lies no ordinary mountain valley. I was now descending into a beyul: one of several “hidden valleys” of refuge designated by Padmasambhava, the ninth-century “lotus-born” Indian saint, revered by the Sherpas as Guru Rinpoche, who subdued the often wrathful territorial deities of the mountains and converted them into defenders of the Buddhist faith.

  In order to protect Buddhist beliefs and teachings during times of adversity, Guru Rinpoche’s female consort is believed to have hidden “treasure texts” in the valleys’ forests and hillsides. These sacred documents are time capsules, essentially. When revealed in future eras, devout people will be able to recover their faith and relearn the wisdom of the ancients.

  These beyul are blessed with spiritual energy, and the Sherpas say that one should behave with reverence when passing through this sacred landscape. Here the karmic effects of one’s actions are magnified, and even impure thoughts should be avoided.

  Sites of spiritual power are scattered throughout Khumbu: ancient meditation caves, “self-emanated” handprints and footprints impressed in rock, and curious snakelike intrusions that for Sherpas represent the lu serpent spirits. Small shrines and bamboo wands, adorned with prayer flags, are set up at springs, wells, and stream confluences—places graced by the nourishing flow of water. Villagers say that the rain from the sky and the water in their springs can dry up if these sites are defiled—for instance, if a lowlander were to slaughter a goat nearby and dress the meat in the water source. This offends the lu and can cause them to flee.

  Khumbu’s harsh environment only seems to invigorate the Sherpas’ faith. Just as the Himalaya were formed by intersections and accretions of geologic
material, the religion of the Sherpas is accretionary—a blend of shamanism, pre-Buddhism, and Bon and Tibetan Buddhism—while pantheons of clan gods and territorial deities lurk and cavort on the hillsides.

  THE YETIS

  In 1974, a woman named Lhakpa Drolma spotted a yeti while herding yaks along a stream in a valley above Khumjung. In her account, it advanced quickly toward her and attacked, knocking her out. She awoke, half submerged in the stream, and found three of her yaks dead—with their heads missing. Lhakpa Drolma still becomes edgy and fearful when people around her speak of the yeti.

  “Yeti” derives from ya-te, abominable animal of the glaciers. It is surpassed in fearlessness, though, by the mhi-te, a long-haired, dwarf-size humanoid that eats people. The Sherpas say that even a glance from the mhi-te—especially if viewed from below—can cause illness or possibly death, and even saying the names of these dreaded creatures should be avoided. Another variety of dwarf hominid is known as min-jung-tale. It is said to have a monkeylike face and short, stubby feet. A necklace of human ears (or bones) graces its chest, and it uses a femur as its walking stick.

  Some Sherpas say that the yeti are associated with a class of deities known as the Dharma Protectors and may be emanations of a wrathful cemetery goddess called Du- to Lhamo, and perhaps other deities. Yetis are not always dangerous, however, and are sometimes said to be playful tricksters, prone to petty thievery.

  The Tengboche Lama suggested that one expedition looking for yetis in the 1950s leave behind a camera so that he could take a picture. “They don’t seem to come out when foreigners are around,” he explained. Sherpa trek leaders make sure that the legend of the yeti remains alive among clients—by dramatically rattling their tents on occasion, once the trekkers settle into their sleeping bags.