Natural History

It is hard to imagine that the towering peaks that dominate the skyline above the Whistler Valley have only taken their present form in the last few million years. In fact the entire province of British Columbia has really only come in to its present being over the past two hundred million years. Considering that the earth is estimated to be over 3.8 million years old this is considered to be a very short span of time in geologic terms. Now you don’t need to be a geologist to appreciate the magnitude of change that the elements have brought to the western edge of the North American continent.

Two hundred million years ago ancient fish such as the now extinct five eyed Anomalocaris inhabited a shallow sea that covered most of what is now British Columbia. The northwestern edge of North America sloped gradually into this sea somewhere around present day Calgary in the south and Dawson Creek in the north. For over one and a half billion years hundreds of species of ancient sea creatures called this sea their home. As their life cycles came to an end their bodies would come to rest in the soft sediment that comprised the sea’s shallow bottom. Over time their bodies were slowly covered with the sediment being deposited by the westerly flowing rivers that drained a massive continent.

As it is now it would have been hard to imagine that change in this landscape would be possible but that is exactly what was about to happen. The bizarre looking Anomalocaris and all its neighbors were about to lose their home and go the way of the dinosaurs. The main culprit of this change would be the force of Plate Tectonics. Since before the creation of the continents the surface of the earth had been in motion.

While it would have been inconceivable at the time, North America was on the move. Ever so slowly it was on a journey westward, a journey that will eventually see it meet its sister continent Asia. However first it would have to pick up some passengers, for just off the Alberta coastline lie several island groups that we know refer to as Terranes. As North America moved westward these Terranes piled in to the continent instead being subducted under like most present day oceanic plates. These resulting collisions created the Rocky Mountains first which are primarily comprised of the sedimentary layers of the sea bottom which had been push up and under great pressure been melted and squeezed. Evidence of this can been seen today in places such as Mount Rundle in Banff and Mount Stephens in Field.

Over the course of the next one hundred and forty million years the interior mountain ranges of British Columbia were formed into their present day grandeur. These ranges include the Monashees, Purcells, Selkirks, Bugaboos and Columbias. As these collisions were going on the Coast Mountain range which now makes up the mountains we now see was being formed below the earth’s surface. Approximately forty-five million years ago the Coast Mountain Range emerged above the earth’s surface to form a low mountain chain that reached from Washington to Alaska. However it hasn’t been until the last five million years that the range has taken it’s present form. Over the past five million years the mountains around Whistler have been uplifted almost two vertical kilometres.

Meanwhile a period of ice ages allowed ice to fill the valleys and scour the highest peaks. The last such episode ended a mere ten thousand years ago. Since that time everything alive that one sees around Whistler including all of the plants and animals has moved in from Oregon and Western Vancouver Island, places that avoided being glaciated.

While this was going on a range of volcanic peaks was forming to the south, west and east of Whistler. These volcanoes are an extension of the Cascades further to the south in Washington State. The Black Tusk and Mount Garibaldi are remnants of this volcanic activity and while the volcanoes around Whistler have been silent for thousands of years the volcanoes are not yet extinct.

Presently the Coast Mountain Range is still being uplifted as the Juan de Fuca plate off the coast of BC is subducted under the North American Plate. And while these mountains are growing the glaciers that cover their flanks continue to shrink due to a period of global warming. However while many of us are preparing for a continually warming climate, scientists expect that the ice will again flow down from the peaks and fill the valleys around Whistler.