Flying in to the Esquel airport, I initially recognized those parallels. The aerial view does look like my home in southwestern Montana. But once I was on the ground, being shuttled through erratic stands of hardwood—lenga and mayten—the veneer of that analogy crumbled.
Later that night, over plates of beef Wellington and heaping glasses of Malbec, my hosts at Lago Rosario Lodge gave me an overview of the history and landscape of the region. After dinner, the owner showed me a slightly tattered relief map of Patagonia he had rescued from the basement of a public high school and hung in the lodge. This map exposed a geologic quandary that would unsettle me for weeks.
The movement of some Argentine rivers is the opposite of those in Montana. Certain waters on the east slope of the Andes, such as Rio Rivadavia, do not flow away from the mountains; they flow westward into the mountains, a characteristic even more surprising than big browns sleeping in sunny shallows.
In order to understand how water could possibly flow toward massive elevations of rock, rather than away from them, I must enlist the assistance of a colleague in the Geology department at Montana State University, Dr. James Schmitt: “The drainage evolution in the Patagonian Andes is complex and confusing.” Having read some of the research literature, I can attest to his summation.
The short explanation is “glaciers.” Between 25,000 and 27,000 years ago, the most recent ice age peaked. Much of the Americas were covered in icy sprawl. About 17,000 years ago, the climate of the planet warmed enough to begin significantly melting all that ice, but that thawing was neither even nor consistent. The glaciers were whole continents of frozen water with a topography of their own, mountains, valleys, and plateaus that did not correspond to the ground below. They moved and shifted both vertically and laterally, mounding and scouring the terra beneath.
…we’re anchored beside an eddy so clear that I can see the individual branches of sticks lying six feet deep. I can also see a dozen rainbows milling and feeding on drifting nymphs.
As they melted, the huge quantity of freed water further shaped the landscape of both ice and earth. The Andes Mountains, which now appear so towering and immense, were buried, bullied, and gouged by the frozen forces above. As the glaciers covering those mountains became liquid, they pooled in huge, watery basins and channels the ice had previously dug. These channels were lower in elevation than the relatively ice-free eastern plains, and so water from those plains pushed westward, through trenches scraped by flowing ice. Today’s precipitation still follows those ancient paths.
As Dr. Schmitt says, “It’s a complex process and hard to visualize if you are not a geologist (even if you are).”
I’m definitely not a geologist, and though I have a thin narrative explaining how these rivers came to flow against my logic, I can’t actually say I understand them. My understanding, however, is moot. The water persists westward, as does our raft after I finish harassing fish that simply want a sunny spot in which to sleep.
Several hours later, we’re anchored beside an eddy so clear that I can see the individual branches of sticks lying six feet deep. I can also see a dozen rainbows milling and feeding on drifting nymphs. The biggest fish hides in the shade against the bank, giving glimpses when a fin touches sunlight or breaks the surface. Twice I miss the hook set when it eats my swinging soft-hackle fly, but it hasn’t felt any sting and continues to feed.
Gustavo, the guide, speaks only when he has something to say. He worked as a banker in Buenos Aires before moving to his wife’s homeland and immersing himself in the waters of the Chubut Province, where he takes his clients, his friends, and his children fishing every day of the year that temperature permits.
“Wait,” he instructs before I send my wet fly back toward the shade line and the big rainbow pushing water.
Gustavo points to a single caddis fluttering beside the boat.
“A hatch.” He smiles.
I stop casting and bug-hunt for a few minutes, seeing only two or three of the aquatic moths.
“Not much of a hatch,” I respond, accustomed to rivers where caddis have to be thick enough to snort before fish start looking up.
“In Patagonia, this is a hatch.”
I cut off the soft-hackle and tie on an Elk-Hair Caddis, still skeptical but happy to cast a dry fly. The first half-decent drift gets swallowed, and I etch another reason why Patagonia is not Montana.
Miles Nolte fishes and guides more than 100 days a year on Montana waters.
