Geobites – Page 14 – Down-to-Earth Geoscience Writing

December 3, 2020December 8, 2020

Deep Sea Bacteria have Thrived for Millions of Years

Featured Image courtesy Yannis Papanastasopoulos, Unsplash.

Paper: Atribacteria reproducing over millions of years in the Atlantic abyssal subseafloor

Authors: Aurèle Vuillemin, Sergio Vargas, Ömer K. Coskun, Robert Pockalny, Richard W. Murray, David C. Smith, Steven D’Hondt, William D. Orsi

If you, like me, imagine the seafloor to be inhabited by strange, mysterious creatures like vampire squids and goblin sharks, think again: bacteria continue to surprise us with their resilience in the oddest of environments. Scientists have detected microbes living in the mud and rocks on the seafloor, but we don’t know much about them. Are they alive? How do they get energy in such a nutrient-poor environment? Given the inhospitable conditions in the sub-seafloor, scientists have thought that most of these microbes were close to the energy limit for life, which is an estimate of the minimum amount of energy required to sustain life as we know it. For this reason, we’ve assumed that subseafloor microbes die faster than they grow because there simply isn’t enough energy in the deep sea to sustain life long-term.

December 1, 2020January 21, 2021

The strange case of the Kansas earthquake

Featured image: Karst rocks in Segovia, Spain. Photo by Luis Fernández García, CC-BY-SA 2.1.

Paper: Injection-induced earthquakes near Milan, Kansas controlled by karstic networks
Authors: Charlène Joubert, Reza Sohrabi, Justin L. Rubinstein, Gunnar Jansen, Stephen A. Miller

On November 12^th, 2014, a magnitude 4.9 earthquake rattled the city of Milan, Kansas. This event was the largest earthquake ever recorded in Kansas, adding to a trend of increasing seismic activity in the state since 2012. What could cause this kind of tectonic excitement in the stable central US?

November 26, 2020November 26, 2020

It’s LeviOsa, Not LevioSA: The Science Of Levitating Mud On Mars

Featured image: A mud volcano and mud flows in Azerbaijan. Credit: CAS/ Petr Brož/ CC BY-SA 4.0.

Paper: Mud flow levitation on Mars: Insights from laboratory simulations

Authors: Petr Brož et al.,

The Mariner spacecraft’s first images of Mars in the 1960s and 70s showed large volcanoes and flow features, most likely lava or mud. These features were largely interpreted to be lava flows because they look similar to those seen on Earth. However, a 2020 study by Brož et al., shows that mud flows may be more prevalent on Mars than first hypothesized.

November 25, 2020January 7, 2021

Unveiling the Mysterious Patterns of Arctic Cobalt

Featured Image: Fractured sea ice. Image courtesy Pink Floyd 88 a, accessed through Wikimedia Commons GNU Free Documentation License

Paper: Elevated sources of cobalt in the Arctic Ocean

Authors: Randelle Bundy, Alessandro Tagliabue, Nicholas Hawco, Peter Morton, Benjamin Twining, Mariko Hatta, Abigail Noble, Mattia Cape, Seth John, Jay Cullen, Mak Saito

Imagine navigating the Beaufort Sea to the North Pole, crossing icy and treacherous waters through the untamed North, all to chase a metal that is so rare that you have a better chance of finding 5 grains of sand in an Olympic swimming pool*. This is exactly what Bundy et al. accomplished in their work identifying cobalt amounts in the Arctic Ocean and how these amounts vary based on ocean depth, distance from land, and over a time period of 6 years.

November 19, 2020November 19, 2020

Iceland’s constantly changing landscape: A Book Review

Featured Image: Lake in a volcano’s crater at Mývatn, Iceland. Photo by Philipp Wüthrich on Unsplash.

Book: Iceland: Tectonics, Volcanics, and Glacial Features, Geophysical Monograph 247 (First Edition, 2020)
Author: Dr. Tamie J. Jovanelly
Figure Illustrations: Nathan Mennen
Additional Text: Emily Larrimore
Publisher: American Geophysical Union, John Wiley & Sons, Inc.

I have always wanted to go to Iceland and travel the countryside marveling at the island’s unique geology and icy wonder. Reading through Iceland: Tectonics, Volcanics, and Glacial Features by Dr. Tamie J. Jovanelly, I felt like I got my chance to tour Iceland; this time with a very experienced guide. Dr. Jovanelly has been to Iceland more than ten times since 2006 to explore and study and her familiarity with the place and the people who live there is engrained in this text.

November 16, 2020November 17, 2020

New instrument maps and preserves frozen habitats on Earth- and potentially icy worlds

Featured Image: Iceberg in North Star Bay, Greenland by Jeremy Harbeck – NASA, Public Domain

Paper: Subsurface In Situ Detection of Microbes and Diverse
Organic Matter Hotspots in the Greenland Ice Sheet

Authors: Michael J. Malaska, Rohit Bhartia, Kenneth S. Manatt, John C. Priscu, William J. Abbey, Boleslaw Mellerowicz, Joseph Palmowski, Gale L. Paulsen, Kris Zacny, Evan J. Eshelman, and Juliana D’Andrilli

Like the rings of a tree, core samples extracted from glacial ice preserve a unique record of past events. But instead of recording seasonal growth, the ancient ice sheets of Antarctica and Greenland have preserved the conditions of long gone climates and ecosystems. Some sheets have continuously accumulated so much snowfall over the past series of millennia that in some places the ice can reach depths that are miles deep. Analyzing this immense glacial record can inform us about not just the global patterns of climate change, but also the evolution of microbial life on Earth, and maybe even the icy worlds of our Solar System.

November 12, 2020November 12, 2020

Where’s the plastic gone?

Featured image: Plastic pollution in Ghana. Photo courtesy Wikimedia Commons/ Muntaka Chasant, CC BY-SA 4.0 license.

Paper: The global biological microplastic particle sink

Authors: K. Kvale, A. E. F. Prowe, C.-T. Chien, A. Landolvi & A. Oschlies

Scientists estimate that about 4% of the plastic waste generated globally ends up in the ocean, much of it in the form of microplastics. These tiny plastics, smaller than the width of a pencil, are a major pollution problem: because of their small size, they are extremely difficult to remove and can be transferred up the food chain to species that humans eat. Furthermore, harmful chemicals have been shown to adsorb onto microplastics, so consumption of microplastics may have indirect health impacts. While scientists have put together a “plastic budget” for the ocean by estimating inputs of plastic to the ocean and fragmentation rates of larger plastics into microplastics, models based on observations of the amount of plastic waste in the ocean suggest that there is less plastic in the surface ocean than expected based on these budgets. The authors of this study used a model to test two possible explanations for this ‘missing’ plastic, zooplankton ingestion and sinking to the sea floor with marine particles, and find that these biological pathways can account for 100% of the observed “missing” surface microplastic, even in simulations where these processes are modeled as being inefficient.

November 11, 2020November 11, 2020

Ancient ocean temperatures outline a puzzling period in Earth’s climate history

Paper: The enigma of Oligocene climate and global surface temperature evolution

Featured image: Figure 1 from O’Brien et al. (2020). Paleogeographic reconstruction of the late Oligocene world, with continents and oceans in slightly different positions than today. Symbols indicate paleo-locations of ocean sediments that these scientists discuss in their paper, with stars indicating sites where they estimated Oligocene temperatures.

Authors: Charlotte L. O’Brien, Matthew Huber, Ellen Thomas, Mark Pagani, James R. Super, Leanne E. Elder, Pincelli M. Hull

We know that the amount of carbon dioxide in the atmosphere strongly affects climate –and temperature – on Earth. As carbon dioxide concentrations increase, so does average global temperature; this pattern is clear from direct historical measurements and ice core records going back hundreds of thousands of years. Nevertheless, it’s important to understand how this relationship operated in the past (for example, during times when there was less ice in the cold polar regions of the globe). A new study suggests that, millions of years in the past, the simple relationship between carbon dioxide and temperatures may not have been so clearcut.

October 30, 2020October 30, 2020

The early evolution of the bird-hipped dinosaurs

Featured image: Landscape mountain sky by Enrique Lopez Garre, Pixabay License.

Paper: A paraphyletic ‘Silesauridae’ as an alternative hypothesis for the initial radiation of ornithischian dinosaurs

Authors: Rodrigo Muller and Maurício Garcia

Dinosaurs dominated terrestrial ecosystems for nearly 170 million years in the Mesozoic. There were three major groups of dinosaurs. The long-necked sauropodomorphs, which included the largest animals ever to live on land, could grow as long as a Boeing 737 aircraft. The meat-eating theropods, which included the famous Tyrannosaurus rex, have evolved into the modern dinosaurs: birds. And the bird-hipped ornithischians, an assorted group of herbivorous dinosaurs, evolved some of the most bizarre anatomy known in evolutionary history. This ranged from the plate-backed Stegosaurus, to the thumb-spiked Iguanodon, and from the exaggerated crests of Triceratops to the walking coffee table that is Ankylosaurus.

October 29, 2020October 29, 2020

What lies beneath: tracing human migrations through stone tools, India

A map demonstrating possible migration routes of modern humans

Featured image: Katerina Douka, Michelle O’Reilly, Michael D. Petraglia – On the origin of modern humans: Asian perspectives; Science 08 Dec 2017: Vol. 358, Issue 6368, DOI: 10.1126/science.aai9067 [1], CC BY-SA 4.0 (Wikimedia Commons) with minor edits

Paper: Human occupation of northern India spans the Toba super-eruption ~74,000 years ago

Authors: Chris Clarkson, Clair Harris, Bo Li, Christina M. Neudorf, Richard G. Roberts, Christine Lane, Kasih Norman, Jagannath Pal, Sacha Jones, Ceri Shipton, Jinu Koshy, M.C. Gupta, D.P. Mishra, A.K. Dubey, Nicole Boivin & Michael Petraglia

Modern humans evolved around 200,000 years ago in Africa, and dispersed from there to other parts of the globe. The Out of Africa theory is a well-established model that explains the early dispersal of Homo sapiens or modern humans from Africa, into Asia and Oceania. Among the routes proposed is the Southern Route migration from East Africa to the Near East, across the Red Sea, and around Arabia and the Persian Plateau to India, and then finally with modern humans settling in Asia and Australasia.

India’s geographic location is a key piece of this puzzle. Mitochondrial DNA of contemporary populations in India indicate that the country was an important stepping stone in the colonisation of Australasia. However, the timeline for the proposed Southern Route migration is still a matter of debate – could dating the arrival and settlement of modern humans in India provide some clues?