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Finney Overseeing Examination Of Adding Geologic Time Scale

Published: August 1, 2011

Have human activities so impacted the Earth that their actions deserve a new official geologic time segment called Anthropocene?

It’s a question facing geologists around the globe and one of particular importance to Stanley Finney, chair of the International Commission on Stratigraphy (ICS) of the International Union of Geological Sciences (IUGS). Finney, a professor and past chair of the Department of Geological Sciences at CSULB, is responsible for overseeing discussions of this proposal as well as the commission’s continuing work in identifying the boundaries of other geologic time periods.

In April, the Geological Society of America named Finney a Fellow, its top honor for distinguished contributions to the geosciences. In addition, he has been invited to speak at a panel discussion on the Anthropocene at the Annual Meeting of the Geological Society in Minneapolis in October. The meeting’s overarching theme is “Archaean to Anthropocene: the past is the key to the future.”

Finney likens the role of ICS to historians trying to answer the question, “When was the beginning of the Renaissance?” When the Geologic Time Scale was developed in the 19th century, there were no firm definitions of boundaries to its units and, for some time intervals, different sets of units were established for different continents, he said. “So, the International Commission on Stratigraphy was set up in the late 1970s to agree upon a single set of standard global units for the time scale and to define their precise boundaries based on the rock records formed over Earth’s history and signals within them—typically fossils—and say, ‘This level in the rocks represents the passage of time from one named interval to another. We can put our finger on a spot in the rocks and say, ‘This is the beginning of Jurassic or Holocene,’ and so forth.”

The ICS organizes the Geologic Time Scale that is composed of a hierarchy of units; from eons to eras, periods, epochs and finally the smallest segments, ages. Formally defining each segment is a detailed process that starts within one of 15 ICS subcommissions, one for each period, and goes through its executive committee, which Finney chairs into 2012. Final decisions must be approved by the IUGS executive committee, after which they are considered as global geostandards.

After Paul Crutzen, a Nobel laureate and atmospheric chemist at the Max Planck Institute for Chemistry in Germany, began using the word Anthropocene with respect to human activity, the concept has gained worldwide scientific and media attention, including a feature story in National Geographic in March and a cover story in The Economist on May 28. As some geologists began embracing the term, the ICS Subcommission on Quaternary Stratigraphy formed a working group to begin evaluating a proposal to add the Anthropocene to the Geologic Time Scale.

“A small group in the geologic community is pushing this, but I have to set the procedure,”
Finney explained. “The people who are promoting it are giving all the reasons for it, but my concern is that they critically look at it. Is it really geologic time or human time? How would you define it and what rank should it be? I have directed the head of the working group and the Quaternary Subcommission chair that, ‘You need to evaluate this critically at your level before it comes to our level.’ I don’t want it to come to the level of the full commission and find that the working group and subcommission haven’t asked the critical questions.”

Because their decisions will set a global standard, the ICS needs to be convinced that the case for adding Anthropocene is solid. They’ll examine evidence of changes in the rock record of fossils, chemistry, composition, magnetism, layering and other factors, and they will deliberate on various times on which it should be begin and the changes in Earth systems and/or the rock record on which its beginning will be defined.

Finney Overseeing Examination Of Adding Anthropocene To The Geologic Time Scale
PHOTO COURTESY OF STANLEY FINNEY
Geological Sciences’ Stanley Finney on site in Argentina.

“Is this geological history or human history? That’s the biggest question,” Finney said. “Our geologic history comes from the rock record and some would say that humans have a left a record within rocks that you can see. For example, with the spread of human-controlled agriculture, the plants of an area have been greatly changed and the pollen from these plants can get into lake bed sediments that eventually harden into rock. We have fossils of humans, and humans may be altering the climate. The carbon dioxide in the atmosphere can be preserved in rocks on the seafloor. The human impact is leaving a signal, but it’s just now.

“It’s my feeling that the human effect is best recorded in our human history—in our own literature, notes, observations, and data gathered from instrumentation—and that the geologic record of this change into what’s called the Anthropocene is so minimal that it may be millennia before it’s recognized,” Finney continued. “Some would say, ‘The Anthropocene is necessary to recognize that humans as a species are impacting the Earth.’ But other species also have greatly impacted the Earth and we don’t name specific intervals of the time scale after those biological groups. For example, when land plants evolved and forests developed and spread, the ratio of carbon dioxide to oxygen in the atmosphere was greatly altered. So, there’s a case where organisms affected the Earth dramatically.

“On the other hand, I think Anthropocene is a very valuable term because it recognizes our impact,” he said. “If it becomes part of the time scale and the public uses it, then it becomes accepted that humans have impacted the Earth. I see benefits to using the term, but should it be part of the geological time scale or not? That’s a question for the voting members to decide. My opinion is one vote out of 18, but I have to make sure the process is open, deliberative, that all points of view are considered at all levels, and that every point of view is challenged.”

Meanwhile, Finney has other ICS duties. One of the most pleasurable is when the commission holds a Golden Spike ceremony to officially mark a location called a Global Stratotype Section and Point (GSSP) representing the boundary between two time ages. Since the 1970s, more than 60 GSSP sites have been identified around the globe. He’ll be in the Austrian Alps near Innsbruck on Aug. 20 to help pound in the spike representing the beginning of the Jurassic Period at an event including government officials, geologists and the public. Spike locations are marked with plaques and often include public information signs describing the significance of the site.