A River Never Sleeps

Over the years, as I tramped around British Columbia looking for trout, I have enjoyed sifting through coastal fossil beds. I have gradually come to understand how the Central Coast has changed over the past 160 million years. Often when I’m fishing I gaze up at the mountains and marvel about what the world is like.

Up until about 160 million years ago, the spot I was standing on, atop Hotnarko, would have been under open ocean. Then, as a result of shifting and colliding land masses or crustal plates, islands, volcanoes, and mountains began to rise out of the sea. On the islands, and on the continental land mass to the East, there were forests of primitive conifers with an understory of ferns. Reptiles were dominant on land, sea, and in the air. Shrew-like archaic mammals, could be seen scrambling around, hiding out in the underbrush to avoid being eaten by dominant reptilian predators. Insects were abundant and many would have been recognizable to the flyfisher. Mayflies, grasshoppers, dragonflies and damselflies, stoneflies, flies, true bugs, ants, wasps, bees were all well developed by 160 million years ago.

In the oceans there were small herring-like fish. From these archaic bony fish would evolve the salmon, trout, whitefish, herrings, ooligans, and twenty to thirty thousand different living species. The descendants of these bony fish have invaded every possible marine habitat from the strand line to the abyssal depths, and in freshwater they constitute almost the entire fish population.

Ten million years ago, coastal British Columbia had changed a lot from what it was like 150 million years earlier. Except for large prehistoric inland seas to the East which were rapidly being drained away, much of Continental British Columbia looked as it does today.

There were active volcanoes to the East.And the Rainbow Mountain Range volcano was beginning to be active to the North. A large river flowed through a recognizable lower Bella Coola Valley, out through Burke Channel and emptied to the ocean out near Bella Bella, on what is now the outer coast. The Talchako, Atnarko, and Hotnarko rivers flowed east to the Fraser River drainage system. The Coast Range Mountains were starting to rise to the West.

The climate 10 million years ago on the Central Coast of British Columbia was subtropical, similar to that found in Florida today. Magnolia's and fig trees grew as far north as Alaska. Flowering plants (angiosperms) were well established by this time. The Pacific Northwest was largely covered with deciduous hardwoods. Relatively common trees included maple, birch and alder , beech, ash, poplar , elm ; relatively common shrubby plants included serviceberry , hawthorn , oregon grape , willow , rose, currant and gooseberry. The rise of flowering plants was accompanied by proliferation of pollinators such as bees, wasps, birds, butterflies and moths.

Ten million years ago dinosaurs, pterosaurs and the various marine reptiles were extinct. Birds and mammals had taken over as the dominant animal groups
in the world. Primitive, typical and aberrant kinds of opossums, insectivores, rodents (including primitive beavers), rabbits, and whales were all present in western North America. Modern subfamilies of camels, rhinoceroses, horses, peccaries, prong horns, mastodons, cats and dogs were particularly common on inland, continental plains and savannas. Primitive whitefish, salmon, trout and char could be found living in cool streams, lakes, and brackish inland seas of the cooler northern corners of North America. It was, in other words, slowly getting to be a pretty good place for humans.

Over the next 10 million years, the Central Coast continued to be geologically very active. The Rainbow Mountain Range volcano was erupting up until 6.5 million years ago. The Ilgachuz Mountain Range volcano was spewing out ash, conder, pumice, rhyolite, trachyte and basaltic lava 4.0 million years ago, while the Itcha Mountain Range volcano was doing the same thing 1.1 million years ago. Earthquakes were common. The overall climate was becoming cooler and drier. The Coast Range mountains were rising rapidly. Uplifting of coastal mountains modified the climate of the area even further, and this in turn modified the flora of the area. By producing a dry rain shadow effect to the east (30 to 35 inches of rain per year) and a wet maritime climate to the west (60 - 100 inches of rain per year), conditions became unsuitable for the hardwoods but ideal for the conifers. Rapid erosion on the west side of the rising mountains resulted in the capturing of the Atnarko and Talchako Rivers, and forcing them to flow west into the Bella Coola River system.

The cooling trend of the past 10 million years was good for the primitive salmon, trout and char and they began to spread down along the Pacific coast. Recognizable, but primitive trout are present in the fossil record 3.5 million years ago, and likely cutthroat trout and steelhead trout evolved from this common ancestor. Recognizable salmon species were appearing 2 million years ago. Chum salmon seem to have been one of the first modern salmon species to develop, the pink and sockeye developed later from a common ancestor, while the coho and chinook developed even later.

Two million years ago the climate was only slightly warmer than it is today. The trees, shrubs, and herbs closely resembled what we now have. Primitive forms of bear, deer and horse were present in North America.

The last two million years is known as the Ice Age. There were three or four major glaciers that ebbed and flowed over the Bella Coola Valley over this period. These glaciers shaped the modern geography of the central coast, including the trout lakes of the Anahim area. As the glaciers receded from the valley, and back across the Chilcotin plateau glacial material was deposited along the way. This is why one can find deposits of sand, gravel, large boulders and rocks in places far from any stream or mountain.

Since much of British Columbia was covered in a deep ice sheet at the peak of the last Ice Age, the present plants and animals were derived from species that came from ice-free refuges along the coast or from the southern two thirds of the Columbian River system. The great glaciers of the Ice Age captured and held so much water that ocean levels dropped hundred of metres - periodically exposing a land bridge linking Siberia and North America known as Beringia. Deer, sheep, bison, mountain goats, and humans were temperate zone mammals which reached North America from Siberia sometime over the past 2 million years. Spreading from North America to Eurasia were the true horses, camels and tapirs.

It is believed humans originally came to the area following game, although I like to think they were really looking for good fishing. They certainly found it in rivers like the Bella Coola, and in the lakes that are scattered through the Anahim region.

For a fly fisherman, this region seems like paradise now. But all you have to do is look up at the mountains, to be reminded the earth beneath your feet wasn’t always this way.