“Hmm,” he pondered, looking at the latest output. “Looks like the tremors weren’t so bad this time, even though we increased power. Maybe we’re getting the hang of this.”
New maps indicated many zones below where raw power waited to be tapped, as soon as their network was complete. It’s a whole world down there, Alex thought. And we’ve only just begun exploring it.
Now the border between liquid core and mantle was shown in such detail, it appeared like the surface of an alien planet. There were corrugations which looked startlingly like mountains, and rippling expanses that vaguely resembled seas. Shadow continents mimicked thousands of kilometers below the familiar ones. Far under Africa, for instance, an intrusion of nickel-iron bobbed like an echo of the granite frigate floating far above.
There was “weather,” too — plumes of plasti-crystalline convection circulating in slow-motion currents. Occasionally, unpredictably, these streamways flickered into that astonishing, newly discovered state, and electricity flowed in perfect strokes of lightning.
It even “rained.” Long after most of Earth’s iron and nickel had separated from the rocky minerals, settling into the deep core, metal droplets still coalesced and migrated downward, pelting the boundary with molten mists, drizzles, even downpours.
I shouldn’t be surprised. Convection and change of state would have to operate down there, too. Still, it all seemed eerie and suggested bizarre notions. Might there be “life” on those shadow masses? Life to which the plastic, tortured perovskites of the mantle made up an “atmosphere”? To whom the overhead scum of granite and basalt was as diaphanous and chill as high cirrus clouds were to him?
“Ten minutes.” June Morgan gripped her clipboard plaque nervously. And Alex noticed others glancing his way with similar looks. Still, in his own heart he sensed only icy calm. A grim, composed tranquility. They had studied the monster, and now teratology was finished. It was time to go after the thing, in its very lair.
“I’d better get ready then. Thanks, June.”
He reached for his subvocal, fitting the multistranded device over his head and neck. As he adjusted the settings, he recalled what Teresa Tikhana had said to him back in the Waitomo Caves, just before they parted.
“… It’s a long way to the next oasis, Dr. Lustig. You know that, don’t you? Someday we may find other worlds and perhaps do better with them. But without the Earth behind us, at our backs, we’ll never ever get that second chance…”
To which Alex mentally added, If we lose this battle, we won’t deserve another chance.
He showed none of this, however. For the sake of those watching him, he grinned instead and spoke with a soft, affected burr.
“All right, lads, lassies. Shall we invite our wee devil out to dance?”
They laughed nervously.
Swiveling in its gimbaled supports, the resonator turned with accuracy finer than any human eye could follow. It aimed.
And they began.
PART VII
PLANET
A tug of war began, between sea and sky and land.
In the ocean, life was carnivorous and simple, a pyramid founded on the very simplest forms, the phytoplankton, which teemed in great colored tides wherever sunlight met raw materials. Of the elements they needed to grow and flourish, hydrogen and oxygen could be taken from the water, and carbon from the air. But calcium and silicon and phosphorus and nitrates… these had to be acquired elsewhere.
Some you got by eating your neighbor. But sooner or later, everything suspended in the sea must drop out of the cycle to join the ever-growing sediments below. Cold upwelling currents replenished part of the loss, dragging nutrients back up from the muddy bottoms. But most of the deficit was made up at the mouths of rivers, draining rain-drenched continents. Silt and minerals, the raw fertilizer of life, dripped into the sea like glucose from an intravenous tap.
On land, it took a long time for life to gain a foothold. And for a very long time there were just frail films of cyanobacteria and fungi, lacing the bare rock surfaces with filaments and tiny fibers. These first soils kept moisture in contact with stone longer, so
weathering hastened. The flow of calcium and other elements to the sea increased.
Plankton are efficient when well fed. And so, after the breakup of Gondwanaland, when many great rivers fed shallows teeming with green life, carbon was sucked from the air as never before. The atmosphere grew transparent.
At that time the sun was less warm. And so, deprived of its greenhouse shield, the air also cooled. Ice sheets spread, covering more and more of the Earth until, from north and south, glaciers nearly met at the equator.
This was no mere perturbation. No mere “ice age. ” Reflecting sunlight into space, the icy surface stayed frozen. Sea levels dropped. Evaporation decreased because of the chill. There was less rain.
But less rain meant less weathering of continental rocks… less mineral runoff. The plankton began to suffer and grew less efficient at taking carbon out of the air. Eventually, the removal rate fell below replenishment by volcanoes and respiration. The pendulum began to swing the other way.
In other words, the greenhouse grew back. Naturally. Within a few tens of millions of years the crisis was over. Rivers flowed and warm seas lapped the shorelines again. Life resumed its march — if anything, stimulated by the close call.
A tug of war… or a feedback loop . . . either way it succeeded. What matter that each cycle took epochs, saw countless little deaths and untold tragedies? Over the long term, it worked.
But nowhere was it written, in water or in stone, that it absolutely had to next time.
□ Dear Net-Mail User [□ EweR-635-78-2267-3 aSp]:
Your mailbox has just been rifled by EmilyPost, an autonomous courtesy-worm chain program released in October 2036 by an anonymous group of net subscribers in western Alaska. [□ ref: sequestered confession 592864 -2376298.98634, deposited with Bank Leumi 10/23/36:20:34:21. Expiration-disclosure 10 years.] Under the civil disobedience sections of the Charter of Rio, we accept in advance the fines and penalties that will come due when our confession is released in 2046. However we feel that’s a small price to pay for the message brought to you by EmilyPost.
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