Killing Hour - Lisa Gardner [71]
“Are metabasalts rare in the park?” Mac asked York.
“Not at all. You can view them as road outcroppings as you drive from the northern entrance of the park all the way to Thornton Gap, then there’s another good twenty-mile stretch from Stony Man to Swift Run Gap, then there’s more all the way to the southern point of the park.”
“Are there any kinds of rocks that are rare in the park?” Kimberly spoke up.
York had to think about it. “Well, the Shenandoah National Park actually involves three major types of bedrock. The metabasalts are found in the north and south, which we’ve discussed. But there are also siliciclasts, which are found in the southern section of the park or around Thornton Gap. Then we have the granites, which are in the central part of the park. The siliciclasts, which are sedimentary rocks containing abundant amounts of silica, probably have the smallest area of distribution. The granites probably have the most definable area, however, being bunched in the middle to north section of the park. Now, within each bedrock type, there are variances. For example, certain kinds of granites will have more of one mineral or another, depending on where they are found in the park. Same with the metabasalts and same with the siliciclasts.”
“Not all rocks are created equal?” Mac asked.
“Exactly.” She gave him another warm smile, a teacher bestowing praise on her favorite student. “Geologists analyze rocks all the time. Basically, you take a cross section of the rock sample and view it under a polarizing microscope. By breaking the rock down to its mineral components, you could pinpoint more precisely from where in the park it probably came. In some cases, in fact, the distribution range might be very small. Of course, we don’t have that kind of equipment here, but if you had a rock, I’d be happy to make a few phone calls . . .”
“We don’t exactly have a rock . . .”
She arched a brow. “No rock?”
“No.” He added helpfully, “But we do have a travel brochure for Hawaii.”
York blinked her eyes, obviously trying to follow that thought, then finally gave up. “Well, without an actual rock sample, I’m not sure what to tell you. Yes, there are lots of rocks in the Shenandoah National Park. And yes, some of them are similar to those found in Hawaii. But I don’t know how to break things down for you any more than that. The wilderness area of the Shenandoah National Park encompasses nearly eighty thousand acres, you know. That’s a lot of rock types and areas of geologic interest.”
“Do you have a book or a rock guide we could take with us?” Kimberly asked. “You know, that way once we did have a sample, we could look up more information.”
“It wouldn’t be specific enough. With your naked eye, the best you would be able to determine was if the stone in question were basalt versus granite versus siliciclast. That would only cut your search area in half, leaving you with forty thousand acres. No, to truly analyze a rock, you need to be able to look at its mineral components through a microscope.”
“Do you have a microscope we could borrow?” Kimberly attempted weakly.
“They cost a couple pennies. I think the U.S. government might notice.”
“Darn government.”
“Get the rock,” York said. “Give me a call. I’d be very happy to help.” Her gaze was once more locked on Mac.
“We’ll try,” Mac said diligently, but Kimberly knew he was just being polite. They would never have access to the rock found in the victim’s hand; they were outsiders no longer privy to such helpful little tidbits as real evidence.
“One last question,” Kimberly said. “Are there rattlesnakes in the Shenandoah National Park?”
York appeared surprised. “More than a few. Why do you ask?”
“Just checking. Guess I better put on a thicker pair of boots.”
“Watch out for rocks,” York advised. “Rattlers like to curl up in the nooks and crannies between boulders. Or even sleep out on the sun-warmed surface once it’s dusk.”
“Got it.”
Mac shook the woman’s hand. York gave him a dazzling smile, while managing to once more arch