The pristine white sand dunes of the Lençóis Maranhenses National Park are bordered by thick jungle on one side and the Atlantic Ocean on the other. Thousands of lagoons fill up after the rainy season. n.pr/4qf7K1S
n.pr
M. Colin Marvin
@mcolinmarvin.bsky.social
Postdoc @Brown deciphering the environmental records encoded in sand dunes in the Namib sand sea, on Titan, and beyond
The pristine white sand dunes of the Lençóis Maranhenses National Park are bordered by thick jungle on one side and the Atlantic Ocean on the other. Thousands of lagoons fill up after the rainy season. n.pr/4qf7K1S
n.pr
Is everyone ready for the International Conference on Aeolian Research coming up starting this upcoming Sunday in Namibia?
Congratulations to newly minted Dr. @mcolinmarvin.bsky.social and Dr. Michael Hasson! I feel so lucky to have had you both as my first PhD students. Can’t wait to witness your next discoveries! #geomorphology #sedimentology #graduates #PhD @stanforddoerr.bsky.social
The January 2026 issue of #Geology is available online. Scanning electron microscope images of zircon sand grains from Algodones Dunes, California, USA. Read the full issue: geosociety.co/Geology_Jan26 #GSAPubs Photo by M. Colin Marvin.
Were Earth's deep oceans better oxygenated during the Tonian than later in the Neoproterozoic? New thallium isotope data suggest they were. Check out our new paper in Geology: doi.org/10.1130/G536...
Thallium isotopic evidence for the Tonian rise and Cryogenian fall of Neoproterozoic oxygen levels | Geology | GeoScienceWorld
Estimating dissolved oxygen (O2) concentrations in seawater during the Neoproterozoic is central to testing hypotheses about the role of O2 in animal
doi.org
Cool contrasting collapse patterns side by side on the leeward side of the crest of a sand dune in Mesquite Flats. ⚒️
@mcolinmarvin.bsky.social next explored if—and why—aeolian #dune fields, like rivers, reach a near-transport threshold state. This work has neat implications for reconstructions of wind conditions on the early #Earth and on other #planetary surfaces (12/17 am, EP31D-1678)
check out EP33A at 2:15 in Rm. 255 to see some fantastic talks on flows (especially winds!) on Earth and other planets!
More Wednesday EPSP sessions at #AGU25! Afternoon posters and early/late afternoon talks continue with coastal processes, ecohydraulics, land surface hazards, and aeolian processes shaping landscapes across Earth and the solar system. #AGUEPSP #EPSPatAGU25
Some chemists build molecules incrementally. Others make risky moves to discover new chemistry. Both succeed. We call it methodology. But it's style. And we act like acknowledging different approaches threatens scientific rigor.
Science Needs to Embrace the Idea of Style
How do individual scientists approach their work? These stylistic differences can influence the process of discovery.
f.mtr.cool
What would you share with an earlier version of yourself?
What I wish I knew: 33 thoughts for early career researchers
Thirty three reflections I wish someone had shared with me early in my research career.
predirections.substack.com
Did you know sand grains record their transport history? New research in Geology shows zircon grains reveal their journey through microscopic abrasion “microtextures”—even in billion-year-old rocks! Read more: geosociety.co/4oHG2J6 #Geology #GSAPubs
take a sec to check out our paper on zircon micro-abrasion features and what they can tell us about Earth’s surface billions of years ago (hot of the proverbial press in @geosociety.bsky.social)!
Did you know sand grains record their transport history? New research in Geology shows zircon grains reveal their journey through microscopic abrasion “microtextures”—even in billion-year-old rocks! Read more: geosociety.co/4oHG2J6 #Geology #GSAPubs
Just out: PhD candidate @mcolinmarvin.bsky.social shows that like in quartz, #zircon grains preserve microscopic archives of their transport history. But unlike in quartz, those archives remain decipherable for billions of years, unlocking first 90% of #Earth ’s history @stanforddoerr.bsky.social
Did you know that sand records its transport history as it moves across Earth's surface? We developed a new tool to investigate billion-year-old rocks by looking at microscopic features on zircon sand grains. Check out our new paper in @geosociety.bsky.social to see how! doi.org/10.1130/G537...
eBook Preview Statistical Physics of Rarefied Sediment Particle Motions and Transport: Applications to Hillslopes and Rivers Posting this preview of material from my next (unfinished) book might be a mistake. But eh… what the hell. 1/n cdn.vanderbilt.edu/t2-my/my-prd...
cdn.vanderbilt.edu
Findings from a recent study could upend the conventional view of how rivers have shaped continents over time. It’s “a significant revision to our understanding of the history of the Earth,” said lead author Michael Hasson. @marslogander.bsky.social
The rise of plant life changed how rivers move, study shows
Research reveals that unvegetated meandering rivers can geologically masquerade as braided rivers, suggesting they were much more common in the first 90 percent of Earth’s history than previously thou...
stanford.io
So proud of Michael!! 😎 This work was a collaboration with @alvitello.bsky.social at @unipd.bsky.social and A. Ielpi and @ubcokanagan.bsky.social Check also: - Perspective by J. Pizzuto: doi.org/10.1126/scie... - Stanford’s press release: sustainability.stanford.edu/news/rise-pl...
Plants change how river bends move - paper by PhD student Michael Hasson out as First Release in #Science!! Paper: doi.org/10.1126/scie... Before #plants, #meanders did not grow laterally as much but translated downstream, making them look like braided rivers in rocks. @stanforddoerr.bsky.social
Vegetation changes the trajectory of river bends
A primary axiom in geoscience is that the evolution of plants drove global changes in river dynamics. Notably, the apparent sinuosity of rivers, derived from the variance of sediment accretion directi...
doi.org
Sand grains from Coral Pink Sand Dunes State Park, Utah 🧪⚒️
Tonight is the 250th anniversary of Paul Revere’s midnight ride. May his memory remind us all to resist the tyranny forming in our government.
Postdoc Carlos Alvarez shows that Mars’s large #aeolian #ripples are not impact ripples through low-pressure #wind tunnel experiments at #NASA Ames. Very excited about this one! @stanforddoerr.bsky.social www.nature.com/articles/s41...
Ripples formed in low-pressure wind tunnels suggest Mars’s large windblown ripples are not impact ripples - Nature Communications
Low-pressure wind tunnel experiments suggest that large sand ripples on Mars are drag ripples, not impact ripples. Windblown drag ripples constitute an untapped record of atmospheric evolution under t...
nature.com
PhD student Sophie Silver's first paper shows that crack geometry betrays presence of water on other planets! www.pnas.org/doi/10.1073/... There's a nice write up in Penn Today here: penntoday.upenn.edu/news/penn-ca...
PNAS
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...
pnas.org
New paper by PhD student @mcolinmarvin.bsky.social uses #patterns formed by #dunes to better understand sources, pathways, and sinks of #sand on #Titan. Spoiler: #Xanadu has outsized influence on #eolian sediments, and sand travels far!! @stanforddoerr.bsky.social
Check out our paper in @agu.org where we provide evidence for a continuous transport pathway around Titan’s equatorial dune fields, only interrupted by the Xanadu region (with implications for the nature of Titan’s sand grains!) agupubs.onlinelibrary.wiley.com/doi/full/10....
Check out our paper in @agu.org where we provide evidence for a continuous transport pathway around Titan’s equatorial dune fields, only interrupted by the Xanadu region (with implications for the nature of Titan’s sand grains!) agupubs.onlinelibrary.wiley.com/doi/full/10....
8th International Planetary Dunes Workshop is held in Sassari/Alghero, Italy, from 19–22 May: www.hou.usra.edu/meetings/dun... 🔔 Important Deadlines: 📌 Abstract submission: 12 March 📌 Registration: 31 March
Mars Wore Blue Velvet The dark-blue and purple colors indicate coarse-grained sands that are comprised of basalt, an iron and magnesium-rich volcanic rock that formed from cooled lava millions of years ago. uahirise.org/hipod/ESP_05... NASA/JPL-Caltech/University of Arizona #Mars #NASA #science
Had a wonderful time today! It was really great meeting you and thank for the invite to visit your fantastic department (and beautiful campus!)
Colin gave a talk at SCU ESS today on what sand dunes can tell us about environmental changes -- really interesting research and amazing imagery (including of Titan)!
dune find of the day: laterally linked and lone barchans in the Bodélé Depression, Chad (near 17.12°N, 17.87°E)
Final stop with postdoc Carlos Alvarez on the "Aerodynamic #roughness of rippled beds under active #saltation at low atmospheric #pressure" (EP54A-03, 146 B). Fr 4:20-4:30 pm. #Wind tunnel work reveals impact of #bedforms and #saltation on #Mars. #AGU24 (10/10)