She tapped the overhead. "Ries Basin hasn't been solved conclusively either. By the present school of thought sixty percent of researchers regard meteors as the agent that formed Ries Basin; forty percent volcanic action. Correct, Dr. Batson?"
Don was startled to be called on. "Well… yes, that's true."
"Thank you. The bottom line is neither answer fits exactly." The marker crept south to Africa. "Vredefort Dome. Here the experts are very confused. The topography and the geology fit no existing pattern. No crater there, but the earth around the dome appears to have been buckled and in many places literally inverted by some massive force a long time ago. Unexplainable?" She laughed. "Of course not. The accepted theory is multiple meteor strikes.
"Funny, isn't it? Multiple meteor strikes. Throughout recorded history we have never had even the slightest mention of a single large-scale meteor strike. But here they are saying several major strikes occurred at approximately the same time on the cosmic scale."
Pencak pointed down at the tent floor. "Do you know that less than twenty miles from here there's a place called Henbury Craters? Twelve craters of various sizes. The explanation was a shower of meteorites. All landing within a half mile of one another and a hair's breadth away from this very spot, when you consider the surface area of the Earth."
Pencak sighed. "Ladies and gentlemen, this is the point at which I am usually asked to shut up and the class professors give their students the information they need to ingest to get an A on their next test."
"This isn't a test," Hawkins said quietly. "We need to know what the connection may be among these sites. What you think the connection is."
Pencak regarded him for almost half a minute and then nodded. "All right. I think there is little doubt but that meteors have occasionally hit the Earth over the course of millions of years. But most of those strike sites have traces of the meteor somewhere in them. Others occurred so long ago, or are so massive, that it is impossible to tell. Indeed it was only when we were able to look back down on the Earth from space that we were able to see some of the patterns.
"There are those who believe that a massive meteor once hit Earth near what is now the east coast of Hudson Bay. There is a four-hundred-mile-long indentation in the Earth's crust, called the Nastapoka Arc that suggests an impact. This might even have been the meteor that scholars have postulated helped cause the extinction of the dinosaurs. But that occurred much longer ago than the sites we are concerned with here.
"Our atmosphere eats up well over 99.9 percent of all meteors that come close. Those that get through have to be rather large and on a very direct azimuth; otherwise the atmosphere bounces them back into space.
"That latter occurrence happened back in 1972, although most don't know about it. On August tenth of that year a meteor traveling at about ten miles a second and estimated to be about fifteen feet in diameter and weighing almost a ton hit Earth's atmosphere. The first visual sighting was over Nevada, although I would assume that NORAD in Colorado Springs had been tracking it for a while.
"Ninety seconds after being seen over Nevada it was over eastern Canada and then bouncing back out into space. A meteor of that size-if it had had the slightest change in trajectory and actually hit the Earth-would have had the explosive force of about twenty kilotons. If it had landed on Las Vegas you could have said good-bye to the entire city and an area twenty miles around it.
"The government kept word of this secret for over two years and then released it in a manner calculated to generate as little attention as possible. Think about it!" Pencak leaned forward and Fran found herself drawn in by the older woman. "Las Vegas came within a hair-at least by astronomical measurement-of being obliterated and nothing was mentioned for two years.
"So what else hasn't been said? The sad thing is that when we can't explain something by knowns, we throw out the possibility of the unknown. We ignore it." Pencak then proceeded to outline the same theory about the physical evidence concerning Meteor Crater that she had for the class the previous week. That made Hawkins sit up and take notice.
"You're saying that the most likely cause of Meteor Crater was a nuclear explosion?"
"It is the only thing that fits all the evidence-the intense heat; the silica; the fused quartz sandstone; the lack of meteor fragments; the shape of the crater-all of it. The same is true of Campo del Cielo, Ries Basin, and Vredefort Dome. All explained away so glibly as the result of meteor strikes, yet there isn't sufficient evidence to conclusively demonstrate it."
"Vredefort Dome is not a crater," Don Batson pointed out. "How can you link it with the other sites?"
"The Dome itself is not a crater," Pencak agreed. "But what do you know of the Bushveld Igneous Complex?"
"It's one of the richest, perhaps the richest, mining areas in the world, most particularly for diamonds."
"And what forms diamonds?" Pencak asked.
"Intense heat and pressure," Batson replied testily.
"And what is the shape of the Bushveld Complex?"
"An elongated circle," Batson replied. "But that doesn't mean-"
"Patience, young man. How was the Complex formed?"
"Well, that's not quite certain. Some suggest massive lava flows along with strong magnetic effects in the area." Batson shifted uncomfortably in his seat, used to being on the other side of the questioning.
"And the Dome?" She turned her attention from Batson when he didn't answer. "It's been called one of the most unique geological structures in the world. About sixty miles southwest of Johannesburg a ring of hills rises, surrounding an almost flat plain. Research has shown that the subsurface rock of the plain has been upturned to a depth of almost seven miles, thus forming the Dome. Imagine the forces involved to do that! Again, no one can quite explain this phenomenon occurring naturally."
"But how could all these formations have been caused by nuclear explosions?" Fran wanted to know. "How old are they?"
"Estimates vary from site to site. Anywhere from five to thirty thousand years old; some perhaps much older. That sounds like a large span of time, but when you balance it against the age of the Earth, in astronomical terms, it's almost the blink of an eye."
Fran shook her head. "Then I repeat my question: How could these craters and formations have been caused by nuclear explosion? That doesn't occur spontaneously in nature."
"No, it doesn't," Pencak agreed. "My theory is that the explosions were caused by some extraterrestrial life-form."
"What!" Batson could no longer sit still. "You're saying Earth got nuked thousands of years ago by aliens?"
"Putting it in layman's terms-yes."
Fran looked at the other members of the team. Debra was just staring at the old woman, as if soaking in her words. Don was shaking his head angrily. Hawkins was looking between Pencak and Lamb, whose face indicated his obvious disbelief. Fran wasn't sure how she herself felt.
Pencak explained herself further. "Originally, I'm not sure whether the explosions were deliberate-by which I mean weapons; or accidental-perhaps mishaps aboard nuclear-powered spacecraft. Based on the events you have witnessed here, though, I now believe the majority of the explosions to have been deliberate."
"But"-Hawkins paused and shook his head-"I'm just a dumb soldier. I don't quite understand this."
Pencak gave her twisted smile. "I'm sure you are anything but a dumb soldier, Major, or else you would not be here. I don't understand it either. Mind you, I am not saying I am certain that these craters were formed by extraterrestrial life-forms or even that they are the result of nuclear explosions. It is simply the solution that most closely fits the facts.