Up we climb.

Through time we climb.

Across mystery we scramble.

Huffing and puffing, I lead my grandchildren through the jumble of ancient boulders, in search of a mystery. I pause to catch my breath, feeling old.

“I want to show you something at the top,” I say.

Ilana cocks her head, with her rad haircut, blue-rimmed glasses and alert, intelligence — her eyes sparkling like she just got the joke.

Liam looks up, thinking mostly of cave trolls. “What?” he says.

“You’ll see,” says I.

My son Seth shakes his head — onto my tricks.

I lured them up the hill with the promise of a high castle of sandstone and bat caves. What better way to make yourself feel young than climbing the Great Nonconformity with the grandkids?

Here’s the deal: The Tapeats Sandstone cliffs atop the ridge behind my house are more than 500 million years old. They sit directly on top of a great jumbled mass of Payson Granite, which is 1.4 billion years old. Billion. With a B.

So what happened to the billion years of missing stone?

But wait — it gets even better.

At just that juncture, something astonishing happened: The Cambrian Explosion.

Roughly 540 million years ago, life’s diversity exploded. In maybe 25 million years, the ancestors of almost every living form emerged — insects, shellfish, sponges and all we who flaunt backbones.

What happened? Are these two mysteries linked?

More important: Can I blow the minds of my grandchildren to ensure they’ll remember me long after I’m gone?

No pressure.

Fortunately, I’ve been reading up on the Great Nonconformity, which has puzzled geologists ever since John Wesley Powell happened upon it in the bottom of the Grand Canyon in his epic, 1,000-mile voyage in 1869.

The same layer of Tapeats Sandstone — laid down on the shores of a shallow sea — is one of the defining layers of the Grand Canyon and sits atop basement rocks like the Vishnu Schist.

This same billion-year gap in the geological record shows up at the surface scattered across the globe and apparently stems from the destruction of no less than a supercontinent.

Turns out, the continents of the Earth are in constant motion, with the lighter rock embedded in the conveyor belt of the Earth’s crustal plates. The currents in the Earth’s molten core and semi-molten mantle bubble up against the thin, cool crust — driving the movement of the plates. Every 500 million years or so, the movement of the plates collects the continents into a single land mass — a supercontinent.

A billion years ago, the supercontinent Rodinia included North and South America, India, Siberia, China and parts of Africa and East Antarctica. Rodinia lasted for about 300 million years before plate movements once again broke it into pieces, which went drifting off on their conveyor belt of crustal plates.

That titanic process somehow created the Great Nonconformity.

One theory holds that Rodinia was like a great plateau, where little new rock was created for hundreds of millions of years. Eventually, the plateau continent fractured, the uplift creating fissures that turned into great cañons that stripping away layers of rock two to four miles thick.

Another theory starts with the supercontinent, but cites evidence that much of the Earth was covered by ice caps and glaciers — dubbed “Snowball Earth.” The massive glaciers could have scrapped off vast quantities of rock — bulldozing mountains down into the oceans.

It was probably all those things — the breakup of a supercontinent, planetary ice sheets, uplift, volcanoes, subsidence. The process likely worked in fits and starts — first one area then another.

Such a complicated process left its mark in the Grand Canyon, according to one recent study by researchers from the University of Colorado Boulder and summarized on the Science Daily website. Some 700 million years ago, violent faulting events uplifted to the surface layers of basement rock in the west. However, the matching bedrock layers at the east end of the canyon remain buried under a mile of sediment.

But how could all this cause an explosion in life’s diversity?

That’s another mystery. Maybe the erosion changed the ocean’s chemistry — allowing for the evolution of shellfish and creatures with skeletons.

Maybe the shifting positions of the continents changed the climate and created new niches for life to occupy. Perhaps the process boosted the oxygen content of the atmosphere past some vital threshold. The scientists do love to argue.

Likely, a combination of factors triggered the change, the way Liam’s love of Godzilla birthed a fascination with dinosaurs and who knows what next.

But for now, I’m focused on getting to the top without making everyone stop so I can rest.

“So where is it, grandpa?” asks Liam.

“Oh, yeah,” I say, having forgotten all about the Great Nonconformity.

His timing’s perfect. We have just entered the Slot of Doom above that fateful juncture between granite and sandstone.

Ilana and Liam pause, expectant.

I point to the discontinuity of rock and launch into my spiel.

They listen patiently until I finish with a flourish.

“Hmm,” says Ilana.

“Where’s the cave?” asks Liam. I had promised him a cave with bats.

Seth just smiles. His childhood had been punctuated by such windy explanations, invariably interrupting worthy adventures. He also always sought the cave with bats. “That’s cool, pops,” he says, sympathetically.

And so we climb onto the top of the world. Balanced on layers of mystery, I study the tumbled boulders below. I wonder if the stones remember the ungainly rise of life from the algal mat to a fond dream of grandchildren.

I feel so fleeting.

And yet, oddly satisfied, here astride the Great Nonconformity, with Liam and Ilana and Seth.

We are each but a layer laid down one after another — full of mystery and yearning for that view of forever.

Contact the writer at paleshire@payson.com

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