Few episodes in history are as widely recognized as the Cretaceous-Paleogene, or K-Pg, boundary 66 million years ago. Most Geoscientists can recall the large bolide impact and mass extinction that killed the dinosaurs and gave rise to the Age of Mammals. Yet, regarding the quarter-century debate over whether the Chicxulub impact or Deccan volcanism caused the K-Pg extinction, “as the evidence mounts, it becomes more convincing that both could’ve played a role,” Prof. Blair Schoene states.
Since the Industrial Revolution, humans have been releasing nitrogen into the atmosphere and, from there, into the ocean, where it acts as a nutrient but also poses dangers to aquatic ecosystems in high quantities. Now, new research finds that far less human-generated nitrogen is reaching the open ocean than previously thought.
Thousands of years ago, the Earth was going through an ice age and conditions were harsh: it was much colder and windier compared to today, and large amounts of dust were being scattered in the air and much of it contained iron. The iron eventually found its way into the oceans and many scientists believe that the extra iron increased the growth of tiny forms of marine life. One part of the puzzle of iron fertilization of the oceans has been evaluated by an international team of researchers.
Previous studies suggested that plate tectonics began somewhere between 3.8 and 3.2 billion years ago. However, scientists have found very few unmodified cratonic rocks on Earth older than 3 billion years. In a new paper published in Nature Geoscience, Katie Smart (University of the Witwatersrand, South Africa) and colleagues present analyses of three diamonds derived from 3 billion year old sediments from the Kaapvaal craton in South Africa. (Dr. Lewis D. Ashwal *79, co-author)
The Department of Geosciences and Princeton University congratulates Brandon T. Stackhouse on successfully defending his Ph.D. thesis: "The Effects of Physical and Biogeochemical Changes on Carbon Emissions from Mineral Cryosols from the Canadian Arctic."
Frederick Muller Schall, Jr. graduated from Princeton University in 1937 with a degree in Geology. He subsequently spent a year studying Geology at Cambridge University, England. The "Houston Chronicle" news hosts his obituary listing.
Princeton University will commemorate the legacy of Martin Luther King Jr. with its annual King Day celebration on Monday, Jan. 18, in Richardson Auditorium of Alexander Hall. A webcast is also scheduled: https://mediacentral.princeton.edu/
A new study finds that human activities are likely contributing far less nitrogen to the open ocean than many atmospheric models suggest. That's generally good news, but it also nullifies a potential side benefit to additional nitrogen, says Meredith Hastings, associate professor of Earth, environmental and planetary sciences at Brown University and one of the study's co-authors. (Co-author Prof. Daniel Sigman et al)
Colleen (nee Sinclair Hargraves) Guimes, youngest daughter of the late emeritus Robert Hargraves, died suddenly last month. Her obituary was publicly announced on NJ.com. A memorial gathering is planned for Saturday, January 9 on Princeton University campus.
Deforestation threatens to upset the delicate water balance within the Amazon rainforest by altering not just ground cover but patterns of rainfall overhead, according to a new study by AOS graduate student Jaya Khanna.