“It was always big,” Harlan said, “and it’s different from the rapids upriver, because of the volcanism. Over the last 750,000 years, give or take, about a dozen huge lava flows poured down into the Colorado River. Others upwelled from beneath the surface. The magma cooled and formed these sediment-filled lava dams. Near where Lava Falls is today, there was a massive one, a thousand feet tall. They say it plugged the river and backed it all the way up to Lees Ferry—mile one. The lava dam was so enormous, they think it may have taken over twenty years to fill in the lake behind it.

“But even that colossal wall of hardened lava was eventually carved away by the river,” said Harlan. “It kept pushing and pushing until it eroded the lava and broke its way through. Nothing stops the river in the end.”

Then Rob interrupted, “Enough talk about Lava. Big E, we have some celebrating to do.”

I had turned forty-six years old that day, and the team had planned a night of revelry. At dinner, Rob was quietly heading back to his folding chair with a steak on his plate when Steven yelled over, “Raker, where’s your rock?”

Rob mumbled something about having lost it again.

“That’s the third ‘challenge rock’ you’ve lost,” said Steven. “If I didn’t know you better, I’d think you were losing them on purpose!” With that, he jumped up, blocking Rob’s way. I imagined Rob’s eyes darting left and right, desperately grasping at escape routes. Then Steven said more gently, “I guess we can make an exception, just this one night, in honor of E’s birthday, but tomorrow, don’t forget your rock at breakfast.”

I didn’t have to see to know that Steven’s statement had planted a relieved smile on Rob’s face.

For dessert, one of the guides had baked a chocolate cake in the Dutch oven, and everyone sang “Happy Birthday” as I blew out the candles. The team had thought of everything. Then Rob led Lonnie and me over to a flat area on the beach where he’d created what he called a “tactile art gallery,” comprised of natural objects he’d been collecting along the river.

“Cool,” Timmy chimed in. “It’s the Grand Canyon Natural Art Museum for the Blind. We gotta take this on the road.”

Rob excitedly pronounced that the challenge was for Lonnie and me to examine each exhibit and try to identify it. “I’ve assembled a unique collection of pieces for your Brailling pleasure.”