[Narrator] In Southern Ontario, Canada, a small lake presents a big story about human impacts on the environment.
Crawford Lake's sediments reveal a motherlode of information about environmental changes over time.
Researchers in Canada, including Paul Hamilton at the Canadian Museum of Nature, are taking note.
They are building on decades of research to propose Crawford Lake as a global reference site to define a new geological epoch.
[P. Hamilton] The Anthropocene is a term used to examine human disturbance, but in scientific terms, it has no status.
[text: Paul Hamilton, Phycologist, Canadian Museum of Nature] [P. Hamilton] Anthropocene, as a definition, is a geologic time.
We are currently in the Holocene. [Text: The Holocene: derived from the Greek words holos, for "whole", and cene, for "new".]
[P. Hamilton] The Crawford Lake Project, and 11 other projects are designed
to develop the scientific data to evaluate whether we should initiate a new epoch called the Anthropocene.
[Text: The Anthropocene: derived from the Greek words anthropo, for "man", and cene, for "new".]
[P. Hamilton] Today, I'm at Carleton University in the Steacie Building, looking at a freeze core from Crawford Lake.
The core is a frozen core that was collected from the deep part of the lake.
It represents a section of mud from the bottom of the lake. [Text: The sediment core was sampled at a depth of 21.5 metres.]
[P. Hamilton] We have this rectangular core that we fill with dry ice.
It's extremely cold and immediately will freeze.
We drop that down to the bottom sediment into the mud, into the sediment, and let it sit for a half-hour.
During that time, the sediment at the bottom will freeze to the side of this rectangular tube, or core.
At the end of that half-hour period, 45 minute period, we bring that core up slowly,
and what you have as a result is a frozen section attached to the side of the core.
Crawford Lake is a special lake it's found within the UNESCO's site in the Niagara Escarpment.
What's special about the bottom sediment of the lake? This core here?
It’s that the layering that you see in the bottom of the core is every year annual, just like tree rings.
So therefore, you can go back and count the sections in the core.
When we do that, we find the history of the lake.
Crawford Lake is a good candidate for the Anthropocene project,
the establishment of a potential epoch called Anthropocene
because the lake captures regional impacts,
local impacts and global impacts.
It captures historic impacts from First Nations.
It captures the impacts of European settlement into North America.
And it's located in the industrial heartland during the 1950s of global development.
[Narrator] The sediment analysis shows many signs of human impacts,
including the signature of plutonium, the byproduct of nuclear explosions marking the dawn of the Anthropocene.
[P. Hamilton] My contribution to the Crawford Lake project is to look at the diatoms.
Diatoms live in the water column, they live in the bottom sediments.
They're very common. So we have lots to look at. They act as time capsules.
These fossil records in the bottom of the lake can tell us about the past.
What we've been doing with diatoms in this particular project is to look at the compositional changes in the diatoms
and to try and link it to environmental parameters.
By looking at the community structure, the species, we're able to see changes through time from 1942 to the 1980s.
And in the process of looking at those changes in the community through time
with the diatoms , we are able to assess the environmental changes that are going on. [Text: Staurosira binodis. Amphora ovalis. Cyclotella distinguenda.]
[P. Hamilton] Through these, we can start to link to climate
and to human disturbance, which is what the Anthropocene project is about.
[Narrator] The official sediment core used to study the lake and the onset of
the Anthropocene will be curated for scientific study at the museum's
National Biodiversity Cryobank of Canada in Gatineau, Quebec.
[P. Hamilton] Crawford Lake, and this core from Crawford Lake, has significance
not only to the public, but also to the scientific community.
The museum's responsibility is to be the future caretaker of the core
for the First Nations, for Canada, and also for the world.
[Text: The Crawford Lake Anthropocene Project includes contributions from researchers at a number of Canadian universities (led by Brock University and Carleton University), as well as the Canadian Museum of Nature, the Royal Ontario Museum, Conservation Halton and Indigenous partners.]
Crawford Lake is located on the traditional territory of the Attawandaron, Wendat, Haudenosaunee, Anishinaabe, and Métis peoples.