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Whose Faces do we See in Geology Textbooks?

Student standing on textbooks in library

Author’s Note: The last few weeks have left us grappling with the profound effects of systemic racism, as seen in the wake of the recent protests and violence all over the USA and the world, as well as the disproportionate effect of COVID-19 on Black communities. This week’s post is dedicated to exploring the impact of another effect of systemic racism: lack of representation in educational spaces, made apparent in geology textbooks. 

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Rivers of Memory: India

Paper: Evolution of modern river systems: an assessment of ‘landscape memory’ in Indian river systems

Authors: Vikrant Jain, Sonam, Ajit Singh, Rajiv Sinha, S. K. Tandon

“A river cuts through rock not because of its power, but because of its persistence.”

James N Watkins

In geomorphology, the persistence of rivers is etched into the very landscape – a memory of the forces that once shaped it, and continue to do so, slowly, and inexorably. Landscape memory, as Gary John Brierley once wrote, is the imprint of the past upon contemporary landscapes, which include geologic, climatic, and anthropogenic factors.

The rivers of the Indian subcontinent bear witness to forces that shaped them over millennia – and a recent publication in the Journal of International Geosciences traces the evolution of India’s river systems at different time scales.

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Humans most likely drove Madagascar’s megafaunal extinction

Featured image: Deforestation in Madagascar, image credit: Gregoire Dubois, CC BY-NC-SA 2.0, on Flickr.

Paper: Relationships between climate change, human environmental impact, and megafaunal extinction inferred from a 4000-year multi-proxy record from a stalagmite from northwestern Madagascar
Authors: L. B. Railsback, L. A. Dupont, F. Liang, G. A. Brook, D. A. Burney, H. Cheng., and R. L. Edwards

Madagascar is so large and ecologically unique that it has been dubbed a continent in its own right. It wasn’t occupied by humans until 3,000 years ago and the island’s megafauna died out comparatively recently. Just 1000 years ago sloth lemurs the size of pandas, 10-foot tall elephant birds, and a puma-like predator called the giant fossa roamed the island.

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Climate records written on the seafloor

Featured image: A perspective view of the seafloor at the East Pacific Rise, 9N. Made with GeoMapApp (www.geomapapp.org, CC-BY), and GMRT topography data (Ryan et al. 2009, CC-BY).

Paper: Do sea level variations influence mid-ocean ridge magma supply? A test using crustal thickness and bathymetry data from the East Pacific Rise
Authors: B. Boulahanis, S. M. Carbotte, P. J. Huybers, M. R. Nedimovic, O. Aghaei, J. P. Canales, and C. H. Langmuir

Many of our records of past sea level come from local measurements from coastal towns logged over decades or centuries, or are estimated from ice or sediment cores spanning the last few thousand years, but new research suggests that much longer records can be found in an unlikely place: imprinted deep underground in the oceanic crust.

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Sediment riding on ice to the rescue of vulnerable salt marshes

Featured image by Jennifer Crowder from Pixabay.

Paper: Enhanced, climate-driven sedimentation on salt marshes
Authors: D.M. FitzGerald, Z.J. Hughes, I.Y. Georgiou, S. Black, A. Novak
Journal: Geophysical Research Letters

Accelerated sea level rise threatens to drown many of the world’s salt marshes, but sediment riding on ice rafts might be coming to the rescue. Continue reading “Sediment riding on ice to the rescue of vulnerable salt marshes”
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Ancient microbes engineered sedimentary deposits

Cambrian Stromatolites from New York State

Featured image: Cambrian stromatolites from New York State. Image attribution: James St. John / CC BY 2.0; Wikimedia Commons

Paper: Evidence for microbes in early Neoproterozoic stromatolites

Authors: Zhongwu Lan, Shujing Zhang, Maurice Tucker, Zhensheng Li, Zhuoya Zhao

Stromatolites are ancient, layered deposits of sediments that are characterized by thin, alternating light and dark bands. While microbial fossils have been found in many stromatolites, the biological origin of these structures has been debated. Continue reading “Ancient microbes engineered sedimentary deposits”

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How to locate oceanic earthquakes without getting your feet wet

Photo of a fence offset by fault slip on the San Andreas during the 1906 San Francisco earthquake

Featured image: A fence broken by the 1906 San Francisco earthquake, by G. K. Gilbert. Public domain.

Paper: Absolute Centroid Location of Submarine Earthquakes from 3D Waveform Modeling of Water Reverberations
Authors: Jorge C. Castellanos, Zhongwen Zhan, Wenbo Qu

For the millions of people living near the San Andreas fault zone in California, the billion-dollar question is when the next “big one” is going to happen.

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Do melting glaciers release extra sediment?

Featured image: Pitztal Glacier, Austria by annca on Pixabay

Paper: Increased Subglacial Sediment Discharge in a Warming Climate: Consideration of Ice Dynamics, Glacial Erosion, and Fluvial Sediment Transport
Authors: Ian Delaney and Surendra Adhikari

The world’s glaciers are shrinking, sending great quantities of water downstream in a geologic instant. But new research shows a lesser-known effect of climate warming: a large increase in sediment released from melting glaciers that might rearrange the shape of Earth’s surface. Continue reading “Do melting glaciers release extra sediment?”
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What Caused the Flood that (Possibly) Gave Rise to an Empire?

Featured image: The Yellow River Breaches its Course by Ma Yuan, Public Domain

Paper: Uranium isotopic constraints on the nature of the prehistoric flood at the Lajia site, China
Authors: Le Li, Jun Chen, David William Hedding, Yuanhe Fu, Maolin Ye, Gaojun Li

A small sand deposit might hold the key to dating the rise of China’s first dynasty. Continue reading “What Caused the Flood that (Possibly) Gave Rise to an Empire?”
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How Algae Emissions Could Affect the Weather

Featured image by Jesse Allen and Robert Simmon, Public Domain

Paper: Unprecedented DMSP Concentrations in a Massive Dinoflagellate Bloom in Monterey Bay, CA
Authors: Ronald P. Kiene, Brent Nowinski, Kaitlin Esson, Christina Preston, Roman Marin III, James Birch, Christopher Scholin, John Ryan, and Mary Ann Moran

Tiny marine organisms have been showing up in higher and higher numbers in bodies of water. These organisms also emit sulfur-containing compounds – and if they emit enough sulfur, their emissions could affect the climate. Continue reading “How Algae Emissions Could Affect the Weather”