A bird’s eye view of Fraser River’s past

Published on Wed, Jan 13, 2010 by Steve Booth

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Picture yourself suspended high over what is now the Fraser River delta.

It is a cloudless day and you can see clearly from horizon to horizon. It is a perfect day to travel. Make yourself comfortable for we are about to embark on a very long journey.

Oh, we won’t be traveling far. In fact, we are going to hover here at a safe altitude of a mile or so, stationary over the delta. Instead we are going to witness the passage of geological time over the landscape below.

Forget minutes, hours and days, our clock ticks off seconds in millennia. Absolute dates will be meaningless, what matters is the sequence of events and how they unfold below as a gradual process.

The earth is thought to be about 4.5 billion years old. If its entire history were to be compressed into a 24-hour clock the step back we are about to take would bring us back to about 10 p.m., our starting point. It is from here we will begin to fast forward. Hold steady for things will not appear as they do today…

200 million years before present  and we begin our journey. Floating high above what in time will become the delta we are puzzled by what we see, or rather what we don’t see. Stretching out below us from horizon to horizon is deep blue Pacific Ocean, the nearest land is almost 400 miles to the east. We brought along a powerful telescope and so we scan that distant shoreline.

Great lumbering creatures come into focus, dinosaurs! We recognize many from fossil reconstructions we have seen in museums. The landscape looks tropical and marshy, giant tree ferns dominate the forests.

There are no mountains and the seashore is shallow and we can sense the water is warm. As the clock begins ticking forward, great islands begin coming into view from the West and South over the Pacific.

Slowly they pass underneath us and appear to drift to the east as the distant shoreline moves closer. First one passes then another. Each successive one collides into the distant shore with such enormous force we can see the earth’s crust buckle and break, crumpling up like a carpet pushed into a doorjamb.

To our amazement more of these oceanic terranes collide as mountains stack up behind them. In places where the crust is thin lava pours out onto the surface and we watch vast areas being covered in thin layers.

In other areas, the lava seems much thicker and volcanoes grow and in still others the magma is full of gas and comes shooting out of vents forming massive cinder cones. The sulphurous smell of these gases permeates the air.
Then suddenly, in a flash followed by what seems just a moment of darkness, the great dinosaurs and coal forming swamps are gone, and our clock shows half past eleven.

As the dust settles, a new landscape begins to take shape. At first glance, it appears rather stark and empty. The coastline is still many miles to the east but much closer than when we began our journey.

Clearly something catastrophic had taken place with the cost of much life but, as we examine the shoreline more closely, we notice small creatures scurrying about. In time they diversify into many shapes and sizes until at last we recognize they are mammals, covered in hair, some with tusks, horns or antlers.

Many are living in great herds grazing over newly forming grasslands. Toothy predators find an opportunity and fill their niche. We can recognize the Rocky Mountains far to our east and the Coastal Mountains to the north.

A very young Mount Baker is only a swollen mound building in height as magma pushes from below. A new oceanic terrane arrives from the south, it appears to be Vancouver Island in a rough form.

The mountains continue to grow in size as does the coastline now well to the west of our position. Over the distant horizon we can make out plumes of hot gases lifting above active volcanoes.  The clock shows 11:45 p.m.

Shortly before midnight, and the present we left behind, the climate begins to feel noticeably cooler. There are many more kinds of plants than before. We see changes of color through the years and what must be the first well defined seasons.

As time moves forward the first snows arrive and disappear. Each successive winter comes sooner and lasts a little longer. Soon the snow remains on the mountains throughout the year, slowly creeping downslope towards the valley bottoms, and our breath condenses in a cloud as we exhale.

A peculiar feature of ice is that when it reaches a certain depth it begins to spread and creep away from the center of accumulation. Its margins begin to flow like an incredibly slow river in a process known as plastic deformation.
It is this flow away from its source that gives moving ice its enormous power to sculpt the landscape. As the polar ice sheet far to our north spreads the shallow inland sea retreats back to the Pacific.

Successive waves of glaciers reach down from the north like embracing appendages smothering the mountains and valleys so that only the tops of the highest peaks remain outside their grasp.

Then, in warmer periods, the ice retreats again only later to advance. Between such advances the land opens up to
prairies and grassland. It is then that we spot Woolly Mammoths, Giant Ground Sloths, enormous bears and herds of wild horses roaming the countryside.

Once again, the ice reaches a depth of nearly a mile over the landscape below us. At such depth the weight and force of its movement carves out the straits of Georgia and Juan De Fuca and all the deep valleys and fiords of our coast. Huge mounds of earth are pushed out before them and berm up along their sides.

We can see the landforms folding as they are pushed down into the earth’s crust under the enormous weight of ice.
Many times they melt and recede dumping huge quantities of entrained rock debris like giant conveyor belts only to push forward again with a new load carved from the coastal mountains well to the north. 

They leave behind ribbons of hills and outwash planes composed of boulders, gravel and fine sediments in their wake. Less than a minute before the clock strikes twelve and we are delivered back home, the last great glacial advance begins to withdraw leaving behind the geogaphy familiar to us in its modern form.

The great Fraser River now occupies the same valley that just moments before was carved by rivers of ice. The Pacific Ocean finds its way back through the straits as sea level rises and chases the last remaining ice deep into the fiords. Landforms spring back relieved of their burdens.

Seconds before the clock strikes twelve a continuous belt of green spreads away to the north. Wildlife abounds in the rich watershed below us.

The temperature is mild and combined with an abundance of natural resources the stage is set for the development of a complex Northwest Coastal culture. We begin to see the smoke of campfires on the horizon as the first human settlers arrive.

They make use of the enormous runs of wild salmon, stalk deer and elk and hunt the millions of waterfowl that use the delta as a migratory staging ground each fall and spring. A historical context is born.

The rest of what we see from our vantage high over the delta happens in the blink of an eye…

Steve Booth was born in Seattle  and received his bachelor’s of science in Biology from The Evergreen State College in Olympia in 1986.

Steve works as a wildlife biologist, wilderness guide and science educator and has spent the last twenty years exploring the planet while organizing and leading expeditions. His travels have taken him throughout Africa, South East Asia, China, Australia and the Americas. He remains faithfully in orbit around Point Roberts, which he has always called home.