Geobites – Page 8 – Down-to-Earth Geoscience Writing

August 25, 2021August 25, 2021

Mysterious methane on Mars

Featuring image: northern rim of Gale Crater viewed by Curiosity. NASA/JPL-Caltech/MSSS, public domain (CC0)

Paper: Day-night differences in Mars methane suggest nighttime containment at Gale crater

Authors: C. R. Webster, P. R. Mahaffy, J. Pla-Garcia, S. C. R. Rafkin, J. E. Moores, S. K. Atreya, G. J. Flesch, C. A. Malespin, S. M. Teinturier, H. Kalucha, C. L. Smith, D. Viúdez-Moreiras and A. R. Vasavada

Methane is a gas often connected to life on Earth. NASA’s Mars rover reported the detection of methane, but discrepancies with other missions puzzled researchers. Is there methane on Mars or not? A new study tries to answer this question in a windy way.

Methane is a possible biosignature for extraterrestrial life and therefore, one of the goals of the Mars rover Curiosity was to search for methane. Curiosity was able to detect varying amounts of this gas over the years, but the existence of methane in the Martian atmosphere could not be confirmed by analysis from satellites. Now, Christopher Webster and his group were able to explain the variations as well as the discrepancy between ground-based and satellite analysis by developing a detailed model of the wind systems at Gale crater.

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August 24, 2021August 24, 2021

Mysteries of the deep (and bumpy) seafloor

Featured image: Elevation map of a seamount in the central Pacific, shown in a persepctive view. Image courtesy of the NOAA Office of Ocean Exploration and Research (public domain).

Paper: Fluid-rich subducting topography generates anomalous forearc porosity
Authors: Christine Chesley, Samer Naif, Kerry Key, Dan Bassett

Open any geology textbook, and you’re guaranteed to find a cartoon of a subduction zone showing how an incoming oceanic plate dives down beneath another tectonic plate (either continent or ocean) on its way back into Earth’s deep interior. These simple sketches typically show the top of the incoming plate as a smooth, gently curved line meeting and joining another smooth line at the base of the overriding plate – and that’s not exactly wrong, given the enormous scale of a subduction zone compared to the smallness of the drawing. But if you zoom in far enough on oceanic tectonic plates, the seafloor is often rough and bumpy. What happens, then, when rough seafloor heads into a subduction zone?

August 19, 2021August 20, 2021

The Search for Life on Mars Begins on Earth

Self portrait of NASA's Curiosity rover. Curiosity is currently climbing Moount Sharp, which can be seen rising on the right-hand side of the image, seeking signs that Mars have been a habitable planet in the past.

Article: Fatty Acid Preservation in Modern and Relict Hot-Spring Deposits in Iceland, with Implications for Organics Detection on Mars

Authors: Williams, Amy J., Kathleen L. Craft, Maëva Millan, Sarah Stewart Johnson, Christine A. Knudson, Marisol Juarez Rivera, Amy C. McAdam, Dominique Tobler, and John Roma Skok.

The quest to find signs of life on Mars is one of the greatest scientific challenges of our time. For some researchers, the quest is a chemical one. A search for the biomolecular remains of life that may have lived when Mars was warmer and wetter billions of years ago. However, finding and recognizing molecular fossils is no easy task, even for a rover as sophisticated as Curiosity. Now, new research from Dr. Amy Williams and her colleagues provides fresh insights into where Mars rovers should look for these fossils, what the signatures may look like, and a simple procedure for how to detect them.

August 11, 2021August 11, 2021

Landscapes get depressed too: limestone depressions pattern a wetland landscape

Aerial view of the Big Cypress National Preserve

Feature Image: Limestone depressions cover the landscape in the Big Cypress National Preserve in Florida, USA. (C) Google.

Article: Competition Among Limestone Depressions Leads to Self‐Organized Regular Patterning on a Flat Landscape
Authors: Dong, X., Murray, A. B., & Heffernan, J. B.

Patterns are abundant in nature, from evenly spaced termite mounds and vegetation patches to repeating series of ridges and valleys to sand dunes. The questions of why these patterns are so uniform and why they are found in disparate settings has been the subject of intense scientific interest over the last decades. Mathematical tools have given scientists the ability to study these “complex systems,” where behavior of the whole system emerges from interactions between smaller parts. While many different systems have been studied, recently researchers from the Duke University and the University of California at Davis investigated a patterned landscape with mysterious origins: the large, evenly spaced depressions in limestone bedrock that cover nearly 3000 square kilometers of the Big Cypress National Preserve in the Florida Everglades.

August 6, 2021August 6, 2021

Saving sandbars in the Grand Canyon

Featured image: A sandbar along the Colorado River in the Grand Canyon. Photo by the author. CC-BY-SA.

Paper: A morphodynamic model to evaluate long-term sandbar rebuilding using controlled floods in the Grand Canyon

Authors: Erich R. Mueller and Paul E. Grams

Journal: Geophysical Research Letters

The Grand Canyon is famous for its stark, bare-bedrock landscapes. But those who make the hike, mule ride, or raft trip into its depths are rewarded with a different view: the green, inviting banks of the Colorado River where ancestral Puebloans once grew corn and where rafters now collect overturned boats between rapids. The Canyon owes its bucolic river-bottom landscape to an unsung hero: sand deposited during large floods that creates hospitable habitat for plants and aquatic animals. Since the building of Glen Canyon Dam just upstream in the 1950s, the Grand Canyon has been starved of sand, damaging its fragile ecosystems. Now, a new study quantifies how controlled floods could help restore sandbars to the Grand Canyon.

August 4, 2021August 6, 2021

Glacial Lake Outburst Flood (GLOF) Drowns Villages Along Its Path In The Central Himalayas

Featured Image: Gori Ganga River near Munisiari, Pithoragarh district, Uttarakhand from Wikipedia under CC BY-SA 4.0.

Paper: Lake Evolution, Hydrodynamic Outburst Flood Modeling and Sensitivity Analysis in the Central Himalaya: A Case Study

Authors: Ashim Sattar, Ajanta Goswami, Anil. V. Kulkarni and Adam Emmer

What could be worse than waking up one morning to find yourself drowning in water? People living in the Himalayan terrain experience this fear every time flash floods occur in the valleys. Glacial retreat induced by climate change led to the formation and evolution of glacial lakes in the Himalayan region. The emerging threats possessed by these lakes result in the incidence of Glacial Lake Outburst Floods (GLOF) which wash away villages along its path. One such incident took place in June 2013 in Kedarnath Valley in Uttarakhand, India with a death toll of as many as five to six thousand people. This eventually led to the strong need for risk assessment and management related to the occurrences of such GLOF events.

July 29, 2021July 28, 2021

Throwing Earth Off Balance: Evidence Grows that Our Planet is Heating Up Faster than in the Past

Feature image: A satellite looks down at the surface of Earth. Image from Unsplash

Paper: Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate

Authors: N. G. Loeb, G. C. Johnson, T. J. Thorsen, J. M. Lyman, F. G. Rose, and S. Kato

At the most fundamental level, what causes climate change? Simply put, climate change is a symptom of an energy imbalance with more energy coming into Earth’s atmosphere than is able to go out. This imbalance drives changes in our climate system that scientists around the world study, including warming temperatures, rising sea levels, melting glaciers, and coral reef bleaching. Using two different kinds of observational data, a recent study has found evidence that the energy imbalance is increasing, which suggests climate change will only worsen.

July 22, 2021July 22, 2021

Breaking the ice — Climate systems during Snowball Earth

Featuring image: modern sea ice at Antarctica. Denis Luyten (Wikimedia Commons), public domain (CC0).

Paper: Orbital forcing of ice sheets during snowball Earth

Authors: R. N. Mitchell, T. M. Gernon, G. M. Cox, A. R. Nordsvan, U. Kirscher, C. Xuan, Y. Liu, X. Liu, X. He

When you think about the Earth, you might imagine a blue and green globe orbiting the Sun. But the face of Earth has changed significantly over its life time and in the past, there were times when the Earth resembled more to a frozen, white snowball. Geologists, studying the climate during these cold epochs, found a connection between climate conditions in frozen oceans and variations of Earth’s orbit.

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July 14, 2021July 14, 2021

A New Paradigm in Decision Making?

Paper: Quantifying Topological Uncertainty in Fractured Systems using Graph Theory and Machine Learning

Authors: Gowri Srinivasan, Jeffrey D. Hyman, David A. Osthus, Bryan A. Moore, Daniel O’Malley, Satish Karra, Esteban Rougier, Aric A. Hagberg, Abigail Hunter & Hari S. Viswanathan

Geophysics problems are as difficult as Nobel Prize-winning physics problems.
Dr. Jérõme A.R. Noir

This quote from Dr. Jérõme Noir has stayed with me throughout my career. The idea: while physicists face extreme math, but also have extremely precise data for unknown phenomena, geoscientists must find vital solutions for known phenomena using just a few data points on a planet. With very little data, how can complex problems in geoscience be solved? And, how do we assess the risk of being wrong? An uncertainty quantification framework recently developed by researchers at Los Alamos National Lab uses machine learning to help geoscientists arrive at quality decisions using limited data.

July 7, 2021July 7, 2021

One of the Moon’s most prominent features is older than we thought

Featured image: the Moon by Pedro Lastra on Unsplash

Paper: Černok, A., White, L.F., Anand, M. et al. Lunar samples record an impact 4.2 billion years ago that may have formed the Serenitatis Basin. Commun Earth Environ 2, 120 (2021). https://doi.org/10.1038/s43247-021-00181-z

About 4 billion years ago, the inner Solar System fell prey to an apocalyptic assault by asteroids. These asteroids slammed into the terrestrial planets—Mercury, Venus, Earth, Mars—and the Moon, leaving behind the scars and basins that make up the planets’ landscapes today. This attack, called the Large Heavy Bombardment, helps explain the genesis of a majority of the formations decorating the inner planets of the Solar System. Previous dating of Moon rocks helped pindown the occurrence of the Bombardment somewhere around 3.8 billion years ago. While this window of time is widely accepted in the planetary science community, one of the Moon’s most iconic features, the Serinatits Basin, might poke a hole in it.