Sometimes the best part of a fishing trip is underfoot


Martin Silverstone

Apr 20, 2023
The York River on Quebec's Gaspé Peninsula from above. Photo David Adams

Sometimes the best part of a fishing trip is underfoot.

How many times have we heard that exclamation, especially when someone has been less than successful in attracting salmon to the fly. It is very true, however. Anglers also enjoy the botanical, ornithological and zoological treasures that abound in wild river systems. But what about the geological features? Few anglers pay attention to what lies beneath their feet, except to wonder if it will cause them to slip or trip and fall.

Even those who do marvel at the geological formations that rivers flow over and through might be missing the wonder of the potholes of the York River. Potholes carved in riverbeds by the erosive power of water and grinding agents such as gravel, pebbles and rocks are not uncommon in Atlantic salmon rivers. This should come as no surprise, as these watercourses channel immense volumes of water, at times travelling at ferocious velocities. And pebbles, small stones and rocks are never in short supply. The same substrate that makes ideal abrasive material is the same fine gravel a hen seeks to build her redd.

Still, finding a pothole is always a thrill, as the round, often symmetrical “bowls” attest to the age of the river and to nature’s raw power. One river that I never associated with these physical characteristics was the York. There, the geology is quite unique, enough that it has its own category: The York River Formation. The riverbed is made up of sandstone, limestone and shale. To visit the river, particularly Offie and Castor pools, is to witness the effects of uninterrupted river erosion on the landscape.
Photographer and guide Dave Adams overexposed his aerial images to highlight the underwater rock formations. Photo David Adams
The York is a large river, yet at Offie and Castor it is squeezed into narrow, deep canyons. The effect is impressive and attracts salmon anglers, especially those with poor casting ability, as the tight quarters enable them to place flies over fish that might otherwise be unreachable.

So stunning is the topography there that the average angler or casual visitor might not notice the presence of some spectacular potholes. Fortunately, David Adams, a long-time salmon guide on the York River and now manager of the ZEC Baillargeon, decided to use a drone to obtain these aerial photos. He overexposed the images in order to capture the underwater rock formations.

I’m not a geologist, so to confirm that these circular formations are indeed potholes, I sent the images along to Dr. Don Baker, professor of geochemistry at McGill University.
Deep cuts in the river bed, like these on the York River in Quebec are formed over long-time periods by the erosive action of water and gravel moving downstream. Photo David Adams
“If the rocks on the base of a river are not flat and the water flow is not perfectly parallel to the river banks there is the possibility of circular eddy currents forming,” he was kind enough to respond in short order. “If rocks are caught in these eddy currents then they too take a circular path and rub and bounce against the bottom. Over long periods of time (relative to a human lifespan) these circulating, rock-containing, eddys can wear down the rocks on the bottom of the river bed and produce potholes.”

And are these York River potholes of special note?

“Those are spectacular images—wonderful potholes—but I am not an expert, only someone who appreciates their beauty.”

As are all of us.

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