Wednesday, July 19, 2023

A Marker For The Anthropocene

Environmental & Science Education, STEM, Earth & Space Science, Earth Systems, Geology, Paleontology, Nature of Science, History of Science.

Ed Hessler

You may recall that it is expected soon that " a working group (of scientists) will submit three ideas to the Subcommission on Quaternary Stratigraphy. First, Crawford Lake should serve as the golden spike for the Anthropocene’s start, with the year to be determined. Second, the Anthropocene should become a geological epoch ending the Holocene; the name of its first age could be the Crawfordian age. And finally, some of the eight sites that didn’t win the golden-spike designation could serve as supplementary sites to help define the Anthropocene across geological environments."

Nature News's Alexandra Witze writes about this important site and the search for a marker, "the golden spike" of the Anthropocene. It is a small Canadian lake known as Crawford Lake, which is the basis for this recommendation after 14 years of debate. 

The choice is contentious with Witze writing that "Sihailongwan Lake, China is relatively undisturbed by local influences and thus contains a broader record of change," says Yongmin Han, a geochemist at the Institute of Earth Environment of the Chinese Academy of Sciences in Xi'an." He continued saying, “I cannot understand the outcome, when a more globally representative candidate for defining the Anthropocene was rejected.” 

The difference in the proposed beginning date for the Anthropocene epoch "could be either 1950 when several environmental changes accelerated — or 1952, when plutonium levels rose sharply a distance of only two millimeters on the core sample rose sharply." It will add another epoch to the smaller parts of the Cenozoic (66 mya) which are described very nicely here, providing an idea of what the planet and its life was like.
If the decision is made, it is not likely to be this ending of the Cenozoic era we expected or wanted. There is a photograph in Witze's article on how years are marked in a core sediment. For your review here are the four eras of the geological time scale. Geologists divide the history of the earth into eons, eras, periods, epochs and ages. The Anthropocene Epoch would follow the Holocene Epoch which started ~ 11,700 ya with the ending of the ice age.

No comments:

Post a Comment