Mathieu Lapôtre
@marslogander.bsky.social
Associate Prof @ Stanford, Planetary Geologist. I study planetary surface processes and what they can tell us about hydrology, climate, and habitability. 🏳️🌈 http://epsp.stanford.edu
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
Busy week for @stanforddoerr.bsky.social EPSP at #AGU25! Started with PhD student Vittorio Colicci looking for clues about #Archean environments through the deposits of some of Earth’s oldest #coastal #dune fields in South Africa (12/16 am, EP21E-1659)
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...
Over 100 planetary scientists from around the Bay Area recently gathered at Stanford to connect and discuss their research. Highlights: 📸 Laura Schaefer and Michelle Hill
Jusqu’ici, les géologues pensaient que les plantes avaient fait naître les rivières en méandres - ces grands cours d'eau en forme de S. Une nouvelle étude montre qu’elles existaient déjà avant : la végétation a seulement modifié leur façon de bouger 🌱 Explications avec du GIF végétal ⬇️
La végétation a sculpté la forme des rivières
Jusqu’ici, les géologues pensaient que les plantes avaient fait naître les rivières en méandres - ces grands cours d'eau en forme de S. Une nouvelle étude montre qu’elles existaient déjà avant : la vé...
radiofrance.fr
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
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
Our results suggest that on Mars, values of the aerodynamic roughness length may reach up to 1 cm—up to two orders of magnitude larger than typically assumed. #NASA Ames, @stanforddoerr.bsky.social, @marslogander.bsky.social
Excited to share our latest publication in @natcomms.nature.com, where we analyze the aerodynamic roughness length over equilibrated rippled sand beds with active saltation under atmospheric pressures intermediate between those of Earth and Mars. www.nature.com/articles/s41...
Aerodynamic roughness of rippled beds under active saltation at Earth-to-Mars atmospheric pressures - Nature Communications
Low-pressure wind tunnel experiments suggest that the aerodynamic roughness length on Mars, over rippled beds and under active saltation, may be dominated by form drag, reaching values up to two order...
nature.com
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
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
M. Colin Marvin@mcolinmarvin.bsky.social · last yr.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....
I'm giving a talk at Stanford tomorrow! If you're around, come join us. I think Zoom is an option too—details here: events.stanford.edu/event/earth-...
Mars’ thin atmosphere makes large windblown sand ripples, like water shapes ripples on Earth’s riverbeds! New paper by @stanforddoerr postdoc @Liorruba, with colleagues R. Ewing @TAMUGeosciences, @LoriKFenton @SETIInstitute, and former postdoc @_algunn now @MonashUni x.com/NatureComms/st…
Congratulations to @mhasson7 for a brilliant qualifying exam!!! First PhD candidate from @StanfordEarth EPSP 🎉🥳 Time to celebrate with @Liorruba, @nilscp, @mcolinmarvin, and @b_amaro_!
A long time coming - “#Mars as a Time Machine to Precambrian Earth” - now open access in J. @GeolSoc! Was such a fun one to write with inspiring coauthors @KirstenSiebach @smtikoo + others not on Twitter. @StanfordEarth jgs.lyellcollection.org/content/early/…
Mars as a time machine to Precambrian Earth | Journal of the Geological Society
As Mars transitioned from an early Earth-like state to the cold desert planet it is today, it preserved a near pristine record of surface environments in a world without plate tectonics and complex life. The records of Mars’ Earth-like surfaces have ...
jgs.lyellcollection.org
Active saltation at Great Sand Dunes NP with @mcolinmarvin and @Liorruba! @GreatDunesNPS x.com/mcolinmarvin/s…
Just off the press: new paper by former @StanfordEarth postdoc @_algunn, now lecturer @MonashEAE analyzing spatial and temporal patterns in sand accumulation in impact craters on #Mars. Suggests enhanced sediment production in L. Noachian-E. Hesperian! doi.org/10.1130/G49936…
Accumulation of windblown sand in impact craters on Mars | Geology | GeoScienceWorld
Abstract. Loose sand, blown away from source regions by winds, is transported across Mars's surface into sand sheets and dunes and accumulates within
doi.org
Loved working with @mike_malaska and @starsarecalling on my first #Titan paper! We propose that a global sedimentary cycle, driven by seasons, could explain the distribution of Titan’s landscapes. Model inspired by how ooids form on Earth (cc: @lizzy_t) @StanfordEarth @NASAJPL x.com/stanforddoerr/…
A really cool study led by Dave Rubin I’ve had a lot of fun participating in. We showed that Mars’ atmosphere had thinned (at least temporarily) before the last episode of subaqueous deposition in Gale crater! #Mars @MarsCuriosity @StanfordEarth x.com/jgrplanets/sta…
Undergrads interested in #planetary surface processes, impact cratering, and #MachineLearning are invited to apply to @StanfordEarth‘s SURGE summer program (deadline Feb 4)! Come work with us! A list of projects is available @🌔☄️🪨💻 earth.stanford.edu/dei/surge#gs.n…
Sustainability Undergraduate Research in Geoscience and Engineering Program (SURGE)
Join us this summer for 8 weeks of fully funded mentored research and graduate school preparation. SURGE is a program for undergraduate students who are new to research and want to explore the field of sustainability in a community that celebrates inclusion. SURGE is funded in part by the National Science Foundation and the Stanford Doerr School of Sustainability.
earth.stanford.edu
Having LOTS of technical difficulties at #AGU21 this morning but that won’t stop us! Pic of @radjanirad being creative here to allow those on Zoom to see her slides 😅
Don’t take all the credit @SarcasticRover, you were helped by hundreds of other government employees @NASA here on Earth! 😜 x.com/SarcasticRover…
Wrapping up a week of #Mars analog fieldwork in 🇮🇸 with the incredible SAND-E team @TAMU @PurdueEAPS @StanfordEarth @MissionCtrlSS @NASA w/ Ryan Ewing, Liz Rampe, @ironywithab @MasonKashauna @MarionNach @mikethorpe_geo @bedford_candice @mhasson7 @rudolpa and many others!
Back from a fun and productive week in the field with @mhasson7 and @_algunn!
Congratulations to @mcolinmarvin, incoming PhD student at @StanfordEarth, for this accomplishment! Looking forward to working with you on extraterrestrial sedimentary processes! x.com/ASU/status/139…
Wanna learn more about how to map surface winds on Mars from dunes using machine learning? Make sure to check out @Liorruba’s #vEGU21 invited presentation @ 9:05 am CEST/12:05 am PDT! Abstract:@EuroGeosciences @StanfordEarth meetingorganizer.copernicus.org/EGU21/EGU21-12…
CO Meeting Organizer EGU21
The surface of Mars is riddled with dunes that form by accumulating sand particles that are carried by the wind. Since dune geometry and orientation adjust in response to prevailing wind conditions, the morphometrics of dunes can reveal information about the winds that formed them. Previous studies inferred the prevailing local wind direction from the orientation of dunes by manually analyzing spacecraft imagery. However, building a global map remained challenging, as manual detection of individual dunes over the entire Martian surface is impractical. Here, we employ Mask R-CNN, a state-of-the-art instance segmentation neural network, to detect and analyze isolated barchan dunes on a global scale.We prepared a training dataset by extracting Mars Context Camera (CTX) scenes of dune fields from a global CTX mosaic, as identified in the global dune-fields catalog. Images were cropped and standardized to a resolution of 832x832 pixels, and labeled using Labelbox’s online instance segmentation platform. Image augmentation and weight decay were employed to prevent overfitting during training. By inspecting 100 sample images from the validation database, we find that the network correctly identified ~86% of the isolated dunes, falsely identifying one feature as a barchan dune in a single image.
meetingorganizer.copernicus.org