A group of researchers has selected Conservation Halton’s Crawford Lake in Milton, ON, as the site defining the epoch of the global impacts of recent human activity known as the Anthropocene. .“Now, the latest geological findings add a macro, planetary perspective to the stories told at Crawford Lake,” said Conservation Halton President and CEO Hassaan Basit in a Tuesday press release..“These local and global narratives are of incredible importance — they shape our understanding of the past, connect us in the present, and frame possibilities for the future.”.The Anthropocene Working Group (AWG) selected Crawford Lake — from 12 sites given consideration — to be the most suitable location for the proposed golden spike, which is a global reference point in the Earth’s history indicating the start of a new geological unit of time. .Under the leadership of Brock University earth sciences professors Francine McCarthy and Martin Head and Carleton University earth sciences professor Tim Patterson, Conservation Halton said a team has been studying sediments found on the floor of the lake to uncover clear evidence of the Great Acceleration — a period of intense resource use, population growth, and environmental impact in the mid-20th century. .The AWG has identified evidence of a tipping point in Earth's systems at this period in history, with conditions different from the Holocene Epoch which began about 12,000 years ago. .The AWG will present its proposal to the Sub-commission on Quaternary Stratigraphy and the International Commission on Stratigraphy, suggesting the Holocene Epoch has come to an end and proposing the Crawfordian as the first age of the Anthropocene epoch..If the proposal receives a supermajority in votes of the two bodies and by the International Union for Geological Sciences, it will be ratified as the latest epoch and Crawford Lake will become one of more than 70 golden spike sites recognized around the world to define boundary points in geological time. .Conservation Halton said McCarthy, Patterson and a team of other researchers from various institutions led three sediment sampling projects at Crawford Lake between 2019 and 2023. .Laboratory analysis of the lake’s sediment cores revealed a mid-20th century plutonium fallout signal related to nuclear weapons testing occurring in the Pacific Ocean from the 1950s through 1963, which is consistent with other samples collected worldwide..This plutonium signature coincides with the Great Acceleration and is the primary marker used to identify the start of the Anthropocene epoch. .Conservation Halton acknowledged additional biological and environmental indicators found in the cores show evidence of large-scale changes in Earth’s atmosphere and other systems since 1950, supporting the lake as the candidate site to define the start of the proposed Anthropocene. .Whether or not the Anthropocene is ratified as the official current epoch, sediment cores and research collections from Crawford Lake will be curated for scientific research in the permanent collections of the Canadian Museum of Nature and the Royal Ontario Museum to preserve this record. .Patterson said he was “proud that my lab’s expertise in collecting and analyzing freeze cores was able to play a central role in this project.”.Students in his group analyzed the deposited layers in the Crawford Lake sedimentary record to establish its chronology and to document yearly changes in lake productivity and climate influences on sediments. .“This permitted us to clearly illustrate the story of the Anthropocene epoch archived in the lake,” he said.
