“Mo-ho-ho and a barrel of funds!”
—SUNG BY MEMBERS OF THE AMERICAN GEOLOGICAL SOCIETY
WHEN I WAS SIX OR SO, I still believed that we could dig to China. In particular, Stephanie Buswell and I could do it. We had in fact agreed to do it together. It is true that the previous week we had succeeded in losing a hamster behind the immense cabinets of her parents’ garage and were utterly helpless to retrieve it, until we called upon my father. Rigging a paper sack with string and placing grain in the bottom, he lowered it to the terrified rodent, airlifting the beast to safety.
Still, I had no doubt that Stephanie and I were technically capable of reaching China, since the previous week, digging potatoes with my best friend Grant’s dad, I had had my first taste of the long-handled shovel. The sandbox would never feel the same again.
We had selected a back corner of the empty lot near school, a suitable place to keep the project private. Our works would be effectively concealed in the tall grass, and few unwitting kids would be likely to fall screaming into the hole, only to emerge head-first in China.
Why did we want to dig to China? Why does every kid want to dig to China? And why was I so positive that when you fell through the Earth feet-first, you would come out the other side head-first? To answer the first question, we were joining the proud company of the second-century scientist Eratosthenes, who on looking into the well near Alexandria when the sun shone into it, succeeded in extrapolating the circumference of the earth. We wanted to live in the presence of wonder and immensity. The second question is easy: in order for a kid to get anywhere without an adult, he or she has three choices: walk, ride a bike, or dig. The shortest, fastest route to China was by digging. As to the third question, it would be absurd to arrive in China standing on one’s head. And as six-year-olds, we knew that life was meaningful, not absurd.
The same motives, I think, recently drove grown men to seek to drill to the Moho. The Mohorovicic discontinuity is the boundary between the thinnest layer of the earth, the crust, and the 1,800-mile-thick middle layer, the mantle. It was first noticed in 1909 by the Croatian geophysicist Andrija Mohorovicic as the place where seismic waves, traveling through the earth, suddenly slowed and bent. In fact, it was Professor Mohorovicic’s noticing this that first fixed a boundary depth for the earth’s crust.
To a lot of people that might have been enough. Indeed, many earth scientists are happy enough to know that the Moho is there and to keep firing off deep explosions to observe the seismic waves and how they travel. Everything they need to know, they reason, can be inferred by studying the way the waves are bent and refracted as they pass through different layers of the Earth’s insides.
Other more recent researchers have sought their bliss in the creation of extraordinary core-surpassing pressures at the Earth’s surface. Using anvils made with diamonds or with a strange geodesic-shaped molecule called buckminsterfullerine, and heated by lasers, they have simulated pressures that equal or exceed those at the Earth’s solid core. This is a pressure on the order of 3,600,000 times the pressure at the surface.
At such a pressure, alchemy, the conversion of one element into another, becomes a commonplace. Certain rare metals have been observed changing into one another in these anvils, and it is thought that with just a touch more squeeze, diamond itself will change into a metal. When the pressure is relieved, however, it changes back. If Stephanie and I had succeeded in our quest, perhaps we would have gone through this electronic looking glass and so really come out of the ground head-first, for proper scientific reasons!
There are people who like to sense the center of the Earth, and people who like to imitate it in their labs. But there still are those who, like Stephanie and me, have to hold a piece of it in their hands. Like the Bible’s Doubting Thomas, we have to feel the flesh of that inner earth, pass through ourselves and come out on the other side. In 1958, a group of scientists casting around for something useful to study in the earth sciences conceived that they would rather hold the Moho’s rock in their hands than simply know what it did to waves. Like Stephanie and I, they quickly decided to begin, although they were vaguely aware that the deepest well yet drilled was less than half as deep as the six-mile hole they would need.
Neither were they daunted by the fact that they would have to drill this hole starting in water more than a thousand feet deep in the open ocean. The reason is that the Moho comes closer to the surface there, where the crust is thinner. Where land surfaces and mountains occur, their above-ground weight is surpassed by a bulge of mass underground, so that while the Moho is six miles down in an ocean trench, it is twenty or more miles down on the North American continent. They invented a new technique, called dynamic positioning, to hold a ship in one exact spot on the ocean in any weather for the duration of drilling.
Nevertheless, when push came to shove, they were not much more successful than were Stephanie and I. (And they spent a great deal more money.) The project did succeed in positioning a ship and drilling a few holes to a depth of several hundred feet and in recovering interesting core samples from the ocean sediment and basalt rock.
These basic experiments were the foundation for the deep-drilling ships that would later map the ocean floor, helping to establish the tenets of plate tectonics, but soon the focus shifted to extrapolation, not piercing the Earth’s crust.
Stephanie and I, on the other hand, took turns with the shovel for the better part of an autumn afternoon, while the wind bent the brown grass and made a hissing whisper all around us. The work and her blond ponytail made me dizzy. It was hard: the ground would not let us through.
How was I to know that to make this suburb they had scraped off the millennial accumulation of topsoil, in order to render the land flat and tractable, then sprinkled a foot of it back on. Wherever we dug, we hit hardpan, caliche. It was going to be more difficult to reach China than we had thought.
It was not a good year for the essentialists. The Mohole people lost their money. Stephanie and I barely got hip-deep. How were any of us ever going to hold the truth in our hands?