The Rock

METEOR CRATER

The sun highlighted the desert to the west in a purplish haze. The old woman stood on the top of the rim, with the class gathered below her, their breath puffing out into the chill air. She was nothing more than a silhouette to them, but that was enough to display her deformities. Her right shoulder was hunched down as if she were permanently trying to squeeze her body through a narrow opening. That arm ended in a withered stalk instead of a hand. As she turned her gaze, the right side of her face absorbed the dying light across a series of slashes and wrinkles, as if the skin had been burned badly a long time ago and healed poorly. Where the right eye had been, there was simply the same scarred skin in the socket.

The class was looking up at her because she stood on the lip of the crater, the bowl before her, filling the horizon. Her voice was gravelly, as if her throat had also been afflicted by whatever disaster had befallen her. "Meteor Crater used to be called by several names, Coon Butte being the most popular. While it was known to the Indians of the area for generations, it first attracted the attention of the white man in the 1880s when it was thought there might be silver here. Although unfounded, the rumor interested A. E. Foote, a geologist from Philadelphia. He made the first scientific study of the crater in 1891."

She gestured with her dead hand as she spoke. "The far rim is twelve hundred meters away. It's roughly one hundred seventy-five meters from the surface level to the bottom, but, as you can see, the rim I am standing on adds another forty-five meters in height from the plain." The hand stabbed down and eighteen pairs of eyes followed. "There is no standing water in the bottom, but flat-lying sediments found there contain small shells, which indicates that a lake once filled the crater.

"The earliest studies of the crater initially speculated that it was formed by either a volcano or an underground steam explosion. However, the discovery of some iron fragments lying very close to the surface soon challenged that theory. In November 1891 two members of the U.S. Coast and Geological Survey examined the area intensely. They speculated that because the crater is round, a meteorite must have struck at a nearly perpendicular angle.

"They did a careful magnetic survey of the crater floor and discovered little evidence of buried metal. Using what I could best describe as the myopic-eyeball estimating technique, one of the men postulated that the amount of material on the rim would fill the crater completely." A snort indicated what the old woman thought of that. "Later, other more scientific studies clearly showed that the rim material is not sufficient to fill the crater.

"In 1895 at the symposium of the Geological Society of Washington, the geologist Grove Karl Gilbert made a presentation on Coon Butte. He presented the various hypotheses and the evidence supporting each one, ranging from volcanic origin, to steam explosion, to meteor impact. His conclusion was that one could make no definitive conclusion based on the evidence, but that the crater most likely had been formed by a steam explosion."

She was interrupted for the first time by a stocky figure sporting an Indiana Jones hat and a full beard. "Note how carefully Dr. Pencak describes Gilbert's presentation to the Geological Society. You will be required to read Gilbert's presentation before our next class meeting. It is a masterpiece of scientific inquiry."

Dr. Susan Pencak continued without missing a beat. "Your professor is quite correct about the substance of Gilbert's address. Let us hope you read it more carefully than it was received in 1895. The common feeling by those listening to Gilbert was that he was definitively stating the crater was formed by a steam explosion. For over a quarter of a century the theory that Coon Butte was formed by a steam explosion stood with no challenge-blindly accepted by all."

She turned and pointed behind her at the large boulders lying haphazardly on the rim. "It was not until many years later that the pattern of rock fragments scattered around the rim itself was examined. Large boulders, some weighing as much as five thousand tons, are found as far away as a mile from where I am standing. No steam explosion could have created that much force.

"Massive amounts of pulverized rock known as silica are found both in the rim and in the crater. It takes tremendous pressure and heat to make silica out of solid rock. Additionally, fused quartz sandstone found in the crater indicates that a temperature at least as high as three thousand nine hundred degrees Fahrenheit occurred here at one time."

Dr. Pencak paused and peered at the students, some of whom were diligently taking notes, others of whom seemed quite bored. She focused her single eye on a young man whose attention was wandering to the distant plain. "You there. Yes, you. Given all the evidence I have just presented and that which is laid out before your eyes, what do you think of the steam explosion theory?"

The student blinked and spoke slowly as he tried sorting out the data, desperately wishing he had done the required reading for this road trip. "Well, Doctor, I suppose that might be an adequate theory, but I don't think a steam explosion could have fused quartz sandstone. Some sort of thermal effect or explosion had to have occurred to produce temperatures that high-much higher than could be caused by steam."

"Ah!" she exclaimed. "A thermal explosion. Very good. Someone tell me what could cause such an explosion and leave a hole such as we have here."

A few students tentatively raised their hands. Pencak pointed her hand at one to reply.

"A meteorite would have a sufficient amount of kinetic energy that could be transformed into thermal energy upon impact." The student flipped a page in her textbook. "Gifford's table of energy in calories per gram of weight indicate that a meteor moving at ten miles per second would have almost thirty thousand calories of energy per gram."

Pencak's face lopsidedly twitched in what might have been a smile or a grimace. "True. Very true. And someone tell me the latest theory. How fast was the meteorite traveling that is supposed to have formed this crater?"

"Uh, twelve miles per second?"

"Are you answering me or asking me?" Pencak didn't wait. ''Yes. Twelve miles per second, or seven hundred twenty miles per hour. And some number cruncher figured out that the meteor must have been about forty-one meters in diameter at strike and weighed some three hundred thousand tons. The blast would have been the equivalent of five hundred thousand tons of TNT. Quite impressive."

She paused and surveyed the group. They were scribbling the numbers in their notebooks as if her word were law. "So, if a meteor actually had hit, what else should we find here besides a big hole, fused and pulverized rock, and big boulders thrown miles away?"

There was a long pause and then a hand went up. "Yes?"

"There should be some fragments of the meteor."

"Correct." She waved her hand around the crater. "And have they been found?"

"Not in any substantial amount," was the reply.

"So what happened to the material that made up the meteor? What happened to that three hundred thousand tons of nickel and iron? Where is it?"

Her questions were met with silence. The professor was fidgeting, uncomfortable with her questioning of the class. They were here for information, not intellectual challenge. These young minds were in pursuit of a grade, not knowledge.

She changed her angle of attack, trying to dredge up some sense of creative thought from the gray mass in front of her. "Can someone tell me what else could have caused this crater? Something that could make such a hole in the earth; fuse quartz sandstone; pulverize solid rock into powder; and not leave a trace fifty thousand years later?"

A quiet voice ventured something unheard at the back of the group.

"What was that?" Pencak tried to peer through the gathering dusk at the source of the voice.

A young man with a scraggly beard stepped forward. "I said a nuclear explosion."

"Yes. On the order of magnitude of five hundred megatons. Shoemaker in 1963 did something very interesting. I knew him then. Quite a man. He had this marvelous capacity to approach problems in reverse and oftentimes he came up with quite startling results. He studied a crater formed in Yucca Flat, Nevada, by a nuclear explosion and compared it to this crater here. Interestingly enough, he found numerous points of similarity. In fact, they were practically identical, although, of course, they were different in size because of the lower yield of the weapon used in Nevada."

"But as you said, this was formed approximately fifty thousand years ago," a confident voice from the front of the small crowd noted.

"Yes, I did," Pencak concurred.

The speaker grew bolder. "Then it could not have been a nuclear explosion."

"Why not?"

The speaker laughed. "Because nuclear weapons weren't invented until 1945."

"If you mean by man, you are quite correct." Doctor Pencak was about to continue when the professor quickly stepped forward.

"Thank you very much for a most fascinating day touring the crater, Dr. Pencak. I regret to say that we must be going now in order to make it back to the university on time." With a few muttered thanks from the students the group was gone, trudging over the rim where their bus waited, ready to whisk them back to the academic world where answers were as pat as those that were printed on the pages of the textbook.

Susan Pencak watched the taillights of the bus disappear into the growing darkness. The sun was almost completely down and the temperature had taken the quick dive it always does on a winter desert night. She could hear the noises of the night creatures coming alive out in the flatlands.

They always cut her off when she started challenging their reality. She found it quite discouraging. She was widely recognized among her colleagues as the foremost expert on the geological aspects of Meteor Crater, yet she infuriated them by not toeing the party line and blindly accepting that the crater had been formed as its name indicated.

She reached up with both arms toward the stars that were beginning to appear overhead. The five fingers on her good hand reached higher and higher, as if she were trying to touch the stars. Her withered hand was inches below, forced down by the ruined shoulder. Slowly, she lowered her arms and turned her eye back to earth. With a slight limp she headed for the Jeep parked just off the rim road. Off in the distance she could hear the discordant thump of a helicopter headed in her direction and she paused and waited.