possible. Driving to Skardu will be one long amazing geology lesson, with
the mountains as teachers. We will cut through several mountain chains
covering about four hundred miles from south to north, and together
called the Himalayas.1 The different ranges have very different geological
histories, but they are all associated with what may be the greatest geo-
logical event in the recent history of Earth: the collision of the Indian
continent with Asia and the obliteration of the sea between them. In this
When the Mountains Grew | 69
Earth
6,400 km
radius
Crust
continental
Crust oceanic crust
5–70 km
crust
10 km
thick
erehpso
Mechanically rigid
htiL
part of continental plate
Core
3,400 km radius
eltna
includes crust and top of mantle
M
100 km
Top part of asthenosphere
Mantle
(up to 350 km) is
2,800 km radius
Asthenosphere
650 km thick
mechanically
plastic and weak
sthenosphereA
figure 27. Cross-section of the earth, with a tiny section near the surface enlarged
to show the different layers. All numbers rounded and approximate.
sea whales originated, and from its bottom the Himalayas rose. All along
the way, the effects of this process will be on display. Even cooler, the
process is still going on. The Himalayas are still rising.
If you could cut through a continent with a giant knife, you would
see that the part that we walk on is just a thin shell, the crust of the earth
(figure 27). There are two kinds of crust: continental crust, which makes
up most of the land and underlies the shallow ocean near the coast, and
oceanic crust, which forms most of the deeper ocean floor. The conti-
nental crust is between twenty-five and seventy kilometers thick,
whereas oceanic crust is only five to ten kilometers. On the globe, there
is much more oceanic crust than continental crust. The two types of
crust behave differently and are part of large independent masses that
move with regard to each other. Geologists call these plates, and the
process of their movement is called plate tectonics. Imagine that the
crust is like ice on a frozen-over swimming pool. When the ice breaks,
slabs of it will move with respect to each other. When two slabs collide,
one will go underneath the other, and the top one may rise out of the
water. On Earth, if one of those pieces is continental crust and the other
oceanic crust, the oceanic crust, being heavier, will go underneath the
continental crust, a process called subduction. The subducted slab will
slowly melt as it goes deeper underneath the crust. The molten rock,
now lighter than its surroundings because it has expanded, will rise,
break through the layers above it, and form rows of volcanoes all along
the margin where the subduction is taking place. When two slabs of
continental crust collide, neither goes down in an orderly fashion.
70 | Chapter 5
Instead, their edges fray, crumble, and crash on top of one another in a
chaotic pattern. This is mountain formation.
The reason that the plates move at all is much deeper below the sur-
face. Some one hundred kilometers underneath the surface of the Earth,
there is a zone where rocks are in a semi-solid, semi-liquid state. That
zone is continuous around the earth and is called the asthenosphere.
The asthenosphere flows, and the plates with their continents and oce-
anic crust float on this layer. In our swimming-pool analogy, the slabs of
ice move because the water that they are floating on actually flows.
The concept that the earth’s crust is not constant but consists of
plates that are movable with respect to each other was revolutionary,
and led to a tidal wave of insight in geology in the 1960s. However, it
all started with a German scientist, Alfred Wegener. Wegener was trained
as an astronomer, but worked most of his life studying the weather.
While in his university library in 1911, Wegener found a list of fossil
animals and plants that occurred on both sides of the Atlantic Ocean.
An important clue was Mesosaurus, a dog-sized reptile (not to be con-
fused with the more famous and unrelated Mosasaurus). Fossils of Mes-
osaurus are only found on the western side of southern Africa and the
eastern side of southern South America. Mesosaurus only lived in fresh-
water, and it was not clear how it could have crossed the Atlantic Ocean.
Wegener searched for evidence from other fields of science, and he
found it in geological structures. The Scottish Highlands were similar in
structure to the Appalachian Mountains, for instance. He then found
records of fossils in places where the present climate certainly would
not support them—fern fossils from Spitsbergen, for instance. This kind
of evidence led him to believe that the continents moved. He called his
theory continental drift, and published it in 1915. Wegener was taken to
task for his idea by other scientists. Rollin T. Chamberlin of the Univer-
sity of Chicago commented: “Wegener’s hypothesis in general is of the
footloose type, in that it takes considerable liberty with our globe, and
is less bound by restrictions or tied down by awkward, ugly facts than
most of its rival theories.”2
Wegener’s theory had its problems, especially that he did not know
by which mechanism the plates moved. At that time, it seemed prepos-
terous that such giant objects as continents could drift. But plate tecton-
ics is now generally accepted by scientists and laypeople alike. I find
Wegener’s story interesting because it took somebody from a discipline
outside of geology to get a great insight that tied together a large body
of incoherent facts within geology. It seems that geologists at the time
When the Mountains Grew | 71
could not see the forest for the trees. It took an outsider to stand back
and see the forest.
With India, it all started 140 million years ago, when dinosaurs were
the dominant anima
ls on Earth. Currents in the half-molten depths
underneath Africa pulled on the solid rock above them, breaking apart
the African plate by means of two giant cracks. The African plate split
in three, from west to east: Africa, Madagascar, and India. The cracks
grew, and the ocean flooded them. As the continents drifted apart, the
growing cracks between them were filled in with new oceanic crust:
molten rock moved up, solidifying when it reached water and making
new ocean floor. These are the mid-ocean ridges.
The first rift, between Africa and Madagascar, was short-lived. It
stopped growing and resulted in a narrow strait between Madagascar
and Africa. The second rift, on the other hand, continued to open, and
is still growing. The Indian plate is moving north on one side, away
from Africa and Madagascar on the other.
Plate tectonics is on my mind as we drive north, away from Islama-
bad, toward the edge of the Indian Plate (figure 1). It gets cooler as the
Karakorum Highway enters the front ranges of the high mountains. The
Indus rages here, and rips into the mountains that tower along it. It is a
different river from the sluggish, broad, mature one I know in the plains.
On the second day of our drive, we enter the Kohistan region of the
Hindu Kush mountains, and the Indus canyon widens into a broad val-
ley. It is a wild region. There have been kidnappings of foreign trekkers,
and the Pakistanis in my group, all from Punjab Province, say Kohistani
people cannot be trusted. The landscape is monotonous, colorless. The
name of these mountains means “Hindu killer” and refers to the fact
that, some generations ago, no non-Muslim could travel here and live.
The mountains are broad and barren, brown and beige. I imagine them
as the enormous shoulders and heads of an army of giants that has been
buried here upright. Small villages become visible between the shoulders
of the giants, in small side valleys, with buildings made of local rock, all
brown and beige. Mountain streams crash from the heads of the giants
into the Indus. They are brown too, eroding the giants’ brow. In spite of
those streams, the land is dry, lacking plants; beige dust covers build-
ings, men, and beasts, like an old faded postcard. Everything is in shades
of brown. The red jeep is not red anymore. The Land Rover is even
beiger than it was as it drives on the dust-caked asphalt.
Kohistan was an island before the India-Asia collision—it was posi-
tioned in the sea that separated the continents. As the collision took
72 | Chapter 5
place, Kohistan was clamped by a vice made of the northern edge of
India and the southern edge of Asia. Kohistan is large. We drive for the
better part of a day to cross it. I can see far down the long and straight
valley, but the mountains to the sides frame my view. My eyes get used
to the hues. It seems peaceful and slow.
Suddenly, I sit up with a shock, blinking and staring. Down the val-
ley, far away, where the brown mountains meet the horizon, another
object appears. There is a new and massive mountain, not brown, but
made from black rocks and topped by white snow, much farther away
than the familiar Hindu Kush, but still easily towering over them. The
color scheme is unsettling and discordant.
It is Nanga Parbat that asserts itself with majestic dominance: the
ninth-highest mountain in the world, nearly twice as high as the moun-
tains near it. It is rarely climbed. The weather is treacherous. Storms
materialize very quickly, giving climbers no time to find shelter. The geol-
ogy of Nanga Parbat is fascinating. This mountain is part of the Hima-
laya Mountains, not the Hindu Kush. The Himalayas, in their strict
sense, are the mountains at the northern part of the Indian Plate, south
of the Hindu Kush island. The continental collision started about fifty
million years ago when the advancing Indian Plate captured the island
blocks between it and Asia and sutured them into one landmass. In the
process, the northern fringe of the Indian Plate was crushed too, making
the Himalaya Mountains. All of these continental blocks, India, Asia, as
well as the islands, had continental shelves—the shallow seas surround-
ing the land mass that are geologically more like continents than like
oceans. The beginnings of the collision sutured continental shelves
together, while a shallow sea still separated land masses. As the collision
proceeded, it resembled less the mutual crumbling and crushing of two
colliding cars, and more the collision of a large truck and a car, where
much of the car was forced underneath the truck. India was the car, and
about two thousand kilometers of its northern edge was forced down,
underneath the truck, the Asian Plate. However, one stubborn part of the
car refused to go down, and managed to override the truck. That part is
Nanga Parbat. There it stands, different from its surroundings and proud
of it. It is not often that I am humbled by what I see, but here, I am.
The geology relates to the fossils in a very direct way. The whales
were living in and around the shallow continental shelf along the edge
of Indian plate. The sea that they knew, the Tethys, would disappear
within a few million years; but before that, they would go extinct,
replaced by the whales that would conquer all of Earth’s oceans.
When the Mountains Grew | 73
Kohistan is a rough country, and it grates on the tempers of our crew.
I ride in the red jeep. Its driver is Munir, a tall Sunni Muslim in his thir-
ties. He stops in a small village. Behind us is the Land Rover. Its driver,
Raza, is older, smaller, and a Shiite. He stops, too. He has the frame of a
street fighter. He runs to Munir and starts shouting. Munir screams
back, there is pushing, Raza punches, Munir ducks and punches back.
Little Mr. Arif, much older and smaller and a very thin man, jumps
between the fighters. They drop their fists. Munir runs to his car shout-
ing the word bohti over and over again. His passengers, Rookoon and
I, also run, not wanting to be left behind by Munir. We speed away, bil-
lowing brown dust, much too fast to avoid potholes. Munir speaks
angrily to Rookoon but eventually calms down in what appears to be
desperation, even though I cannot understand a word he says. I do not
get the story till
we stop, hours later, when Arif explains that the village
where we stopped is known in the rest of Pakistan for biting black flies
that carry disease. Munir was hungry— bhoti is Punjabi for “meat
chunk”—but Raza was afraid of getting bitten and getting sick. Kohistan
pushed their muted dislike for one another into a fistfight.
Nanga Parbat is now close and looms over us. We are nearing the
place where it slid over the rocks it conquered. Geologically, there is
chaos here. Blocks the size of houses and composed of all different rock
types have been strewn around as the battle raged between the giants
over who would be subducted and who uplifted. The fight continues,
and blocks tumble down into the Indus Valley as Nanga Parbat reaches
higher into the sky. The brown Indus fumes angrily as it seeks passage
around obstacles. It reminds me of a van Gogh painting from late in his
life: too wild to be real, broad brush strokes that shout for attention out
of tune, drowning out the big pattern unless you step way back and
squint your eyes.
Nanga Parbat has pushed the Indus off course. The river was running
east-west, but the mountain pushed it to the north, so now it flows around
the mountain on three sides before continuing west. We follow the river
upstream, leaving the Karakorum Highway. The river now is in a nar-
rower valley that will lead us to Skardu. We enter a third set of moun-
tains, the Karakorum Range, originally part of the Asian Plate, with high,
sharp peaks, and the home of K2, the second-highest mountain in the
world. Forced into its narrow valley, the Indus is now incessantly furious.
The villages are tiny, perched on small fans of rock rubble tumbling out
of small side valleys. Their houses are built on top of each other—one
person’s roof is another person’s floor, slightly offset, like steps of stairs.
74 | Chapter 5
The villages on the south wall of the valley are always in the shadow of
their cliff. Each village has it is own hewn-out terraces, with narrow, steep
paths connecting them. We stop and are surrounded by kids. Just as the
terrain is a blend of geological terrains, so are the kids a blend of races.
There are some with the coffee-colored skin of South Asia, some with
The Walking Whales Page 11
