John Taylor, Professor of Economics at Stanford University and developer of the "Taylor Rule" for setting interest rates | Stanford University
John Taylor, Professor of Economics at Stanford University and developer of the "Taylor Rule" for setting interest rates | Stanford University
A recent review conducted by Stanford University researchers has unveiled a significant gap in the geological record, challenging existing models of ancient climate change. The study, published in Earth-Science Reviews, analyzed hundreds of studies and found little to no sediment from 34 million years ago across the margins of all seven continents. This period was marked by a major drop in sea levels and cooling, which conventional models suggest should have resulted in extensive continental erosion.
Study senior author Stephan Graham, from the Stanford Doerr School of Sustainability, remarked on the unexpected findings: “The results have left us wondering, ‘where did all the sediment go?’” He emphasized that understanding this anomaly could provide deeper insights into sedimentary systems and their response to climatic changes.
Zack Burton, lead author and assistant professor at Montana State University, highlighted the novelty of their global analysis: “For the first time, we’ve taken a global look at an understudied response of the planet’s largest sediment mass-movement systems during the extreme transition of the Eocene-Oligocene.”
During this transition period, Earth experienced substantial cooling with giant ice sheets forming in Antarctica. However, contrary to expectations based on early Eocene conditions that showed abundant sand-rich deposits due to intensified weathering and erosion, Burton noted: “We didn’t see abundant sand-rich deposition... Instead... gaps in the rock record had developed during the extreme climatic cooling.”
The researchers propose several theories for this lack of deposition. They suggest that vigorous ocean currents might have eroded sediments or that exposed continental shelves allowed sediments to bypass closer basins. Regional processes like glacial erosion around Antarctica may also have contributed.
These findings underscore what researchers refer to as global controls—profound climatic changes affecting both landmasses and oceanic depths alike. While human-induced climate change today is occurring at a much faster rate than during the Eocene-Oligocene transition, Graham stated: “Our findings can help inform us of the kinds of radical changes that can happen on the Earth’s surface in the face of rapid climate change.”
The research received support from Stanford's industrial affiliates programs funded by company membership fees.
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