Driving east from Prince George, into Mt. Robson Park, you come to many mountains which rise above the tree line.
Mt. Robson is the first and most prominent of these but there are others as you continue towards Edmonton. They are very distinctive. Looking at Mt. Robson from the roadside parking lot - on a sunny day - it is quickly apparent it has layers.
Lots and lots of layers of sedimentary rock laid one on top of the other.
What you are observing in these successive layers is time. What scientists like to call "geologic time."
Each layer is a moment in the vast stretches of time during which sediment from the land accumulates on the floor of oceans and the slightly less vast stretch of time where this rock was pushed up out of the ocean to form the Rocky Mountain range.
Indeed, Mt. Robson is a map to the past with each layer telling us something about the climate, conditions, chemistry and life as each layer accumulated. Or may be a book would be a better analogy with each layer another page in the history of this world.
It is a book scientists have learned to read. Chemical and physical analysis of the material in each layer - on each page - tells us something about the past. It is fascinating story.
On those pages are points where the world turned. Epochs, periods and eras are all written in the layers. We can see the Hadean giving way to the Archean and the Archean giving way to the Proterozoic. We, modern humans, presently live in the Holocene Epoch of the Quaternary Period of the Cenozoic Era.
Or, at least, that is where we have been living some geologists would argue.
They would argue that there is enough evidence to designate a new epoch. There's no disputing the fact that humans are leaving their mark on the planet but is this imprint distinctive and enduring enough to be designated as a new epoch: the Anthropocene, the "Age of Man"?
Many geologists and other scientists would argue yes.
Most people are aware of the boundary between the Cretaceous-Tertiary boundary, when an asteroid wiped out the dominant life forms on this planet and dinosaurs went extinct. However, that is only the most recent time that life was almost wiped out and it was not even the worst extinction event. In past 540 million years, there have been five events in which more than 50 per cent of the species alive were relegated to history.
Are we on the cusp of the sixth great mass extinction of life on this planet?
It is questions like these that keep geologists, ecologists, biologists and anyone else interested in the state of the planet up at night.
It is questions like these that should be worrying our leaders - particularly politicians responsible for our environment.
It is questions like these that science is trying to grapple with, considering we have only a short window of data to work from.
The evidence that we are changing the planet shows up in a number of subtle ways. For example, carbon naturally occurs in two isotopes - one that is called "carbon-12" and has a nucleus with six protons and six neutrons and another called "carbon-13" which has six protons and seven neutrons in its nucleus. There is also a radioactive isotope of carbon, carbon-14, that is used in dating artifacts.
They are virtually indistinguishable. Under most circumstances, carbon is carbon. However, the world is presently being flooded with carbon-12 due to fossil-fuel burning and there is now a measureable difference in the carbon composition of biological specimens such as sea shells, coral and such.
Like it or not, we are changing the planet.
The oceans are more acidic now than they have been at any time in the past 800,000 years and probably beyond. Over 80 per cent of the surface of the planet has been remodeled by human activity. Our atmosphere has 392 ppm of carbon dioxide - a 100 ppm higher than at any time in the past 400,000 years.
To a geologist, while the question is still not totally settled, these sorts of changes point to a major shift in geologic strata. Indeed, we may quite possibly have entered a new epoch.
To other scientists, the evidence that we are changing the planet at many different levels is irrefutable. We have only had modern instruments for about 100 years but during that time we have learned to read much from the story of the planet. We are always learning more.
Geologic time moves slowly and it may be centuries before we know that we are truly in a new epoch but it should be obvious by now that we are changing this planet. It is the great story written in the record of the Earth.
