Minutes to Burn

The sun hammered down on them. Rex felt his skin baking even through the thick layer of sunblock. They finally arrived at a flat wedge of pahoehoe onto which the surrounding saltbush had not yet encroached. Though it was an older flow, it had remained coherent, having survived the cooling with minimal cracking. It had already been instrumented, and Rex toed the weatherproof case of the old seismo-graph with disdain.

A pair of waved albatross clattered through their courtship dance, nuzzling beaks, sky-pointing, and exchanging squawks, but Rex hardly noticed. He focused instead on the basalt, taking into account its align-ment with the slope, and the readings from the Brunton compass. It looked stable, the lava less vesicular and porous than that surrounding it. He banged on it with his rock hammer and got back a nice "ping." More fractured rock would have absorbed the sound, giving off a duller "thud," but this stretch of lava was, for the most part, unjointed. He finally rose, tapping the rock hammer in his palm. "This'll do."

Cameron swung the heavy backpack off her shoulders, setting it down on the ground with a thump. "What the hell's in this?" she asked. "Concrete?"

"Actually, yes." Rex removed a small bag of cement, then a gas-powered hand drill. He went to work on the ground, drilling out a circu-lar, six-inch indentation.

"What does this do exactly?" Cameron asked, indicating the equip-ment with a sweep of her hand.

Rex leaned back, sitting on his heels. He removed a brass plate from the backpack, to which was attached a one-inch hollow rod that extended vertically downward. A U.S. Geological Survey seal was stamped in the metal, and the center was notched with a broad cross. He drilled the plate into the ground, burying the rod in the lava.

"This plate is what we refer to as a 'benchmark,' " he said. "The GPS units as a whole measure the rates of deformation of the earth's crust, using the benchmark sites as reference points."

Rex signaled for the tripod, and Derek handed it to him. Once snapped open, the tripod was about five feet tall. Rex screwed a tribrach mounting plate into the top of the tripod, then centered it above the benchmark. He poured water from his canteen into the Redi-Mix sacrete and began stirring.

"These units are capable of capturing the latitude, longitude, and ver-tical position of this point down to millimeter accuracy. Once we get five more GPS units in place, we'll have a whole network by which to judge any surface deformation. If the earth trembles, shifts, slides, cracks, or wiggles, we'll know it."

Derek leaned over and helped him cement the legs of the tripod in place. When they finished, Rex stood and carefully unzipped the padded nylon case, revealing a thin, discoid antenna. He mounted it atop the tri-brach, snapping it into place with its built-in clamps, then connecting it with a cord to a computer he pulled from Cameron's bag. He placed the computer in a tough, yellow briefcase, took off his Panama, and wiped his brow with his shirt sleeve.

Derek clapped his hands once. "All right," he said. "Let's hit it."

Rex smiled. "Oh no," he said. "That was the easy part. The antenna has to be perfectly horizontal." He began to turn the knobs on the tri-brach, delicately adjusting the tilt and glancing at the leveling bubbles.

Cameron took a gulp from her canteen and tossed it to Derek. When it became clear that Rex's meticulous adjustments would take a while, she sat down on the ground. Feeling a fleck of dirt beneath her right contact, she removed it, cleaned it in her mouth, and popped it back in. When she ran a sleeve across her forehead, it felt tender. The beginnings of a sunburn.

A mockingbird bounced out from the cover of a saltbush. Pausing, Rex raised his hand, forming a loose fist and kissing his curled index fin-ger, making a shrill, squeaking call. The mockingbird bounced up to Derek, fluttering its dusty brown wings. It peered up at the shiny metal canteen, and he pulled it back out of sight.

"You won't find many shy animals here," Rex said, turning his attention back to the tripod. "They've grown up in a paradise of sorts. No native predators, abundant food, little exposure to man."

In a sudden burst, the mockingbird flew up and landed on Derek's head, its white underbelly brushing against his hair. It leaned over Derek's forehead and took a hesitant peck at one of his eyebrows, the jet of its tail feathers shooting straight up in the air.

Cameron laughed. Derek tossed the canteen on the ground, and the mockingbird flew over, balancing carefully on it and pecking it curiously.

Having established the baseline position, Rex engaged the antenna's self-leveling mechanism and stepped back. He glanced up at the sun, his squint resembling a scowl. "All set," he said.

A wave of fatigue struck Cameron when she stood, leaving her light-headed. She resisted the urge to rest a hand on her stomach.