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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

Instant classic!

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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

I also like to use some of their examples from previous underwater experiments (Reffet et al., 2010; doi.org/10.1130/G308...) to show how acute and obtuse diverging winds result in different dune types (inspired by @agunn.bsky.social 's Sharp Lecture last year):

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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

Their results totally line up with the Rubin and Hunter model too! "As defined, the resulting dune orientation yields to the maximum gross transport normal to the bedform trend, as proposed by Rubin and Hunter"

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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

Their underwater experiments and model comparison with modern aeolian dunes shows that the orientation relative to the RDD is the one that maximizes the growth rate. Also explains how dunes of different morphologies can exist under the same wind regime:

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M. Colin Marvin @mcolinmarvin.bsky.social · 6d

cool stuff! Courrech du Pont et al. (2014) took this a step further by showing that the dune type (elongating vs migrating) is dependent on sediment supply. doi.org/10.1130/G356...

doi.org

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Reposted by M. Colin Marvin

david jon furbish @davidjonfurbish.bsky.social · Sep 1

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.

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cdn.vanderbilt.edu/t2-my/my-prd...

cdn.vanderbilt.edu

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Reposted by M. Colin Marvin

Stanford Doerr School of Sustainability @stanforddoerr.bsky.social · Aug 25

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

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Aug 22

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...

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Aug 22

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

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Reposted by M. Colin Marvin

Zoltán Sylvester @zzsylvester.bsky.social · May 16

Sand grains from Coral Pink Sand Dunes State Park, Utah 🧪⚒️

A few semi-transparent grains of sand on a black background, with a frosted texture characteristic of wind abrasion

A lot of semi-transparent grains of sand on a black background

The microscope and camera setup I used to take the photos

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Reposted by M. Colin Marvin

Rick @rickylongthread.bsky.social · Apr 19

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.

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M. Colin Marvin @mcolinmarvin.bsky.social · Apr 9

we ❤️ dunes

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Mar 27

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...

www.nature.com

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Reposted by M. Colin Marvin

Doug Jerolmack @dougjerolmack.bsky.social · Mar 6

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...

www.pnas.org

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Mar 5

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 · Mar 4

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....

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M. Colin Marvin @mcolinmarvin.bsky.social · Mar 4

with @marslogander.bsky.social, Jani Radebaugh, and Wen Bo

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M. Colin Marvin @mcolinmarvin.bsky.social · Mar 4

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....

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Reposted by M. Colin Marvin

International Association of Sedimentologists @sedimentology.bsky.social · Mar 4

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

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Reposted by M. Colin Marvin

HiRISE Beautiful Mars (NASA) @uahirise.bsky.social · Feb 5

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

Enhanced color cutout shows a closeup of a thick sand sheet draped over bedrock in Melas Chasma on Mars. The dark-blue and purple colors indicate coarse-grained sands that are comprised of basalt. The scene is less than 1 km across. (NASA/JPL-Caltech/University of Arizona)

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M. Colin Marvin @mcolinmarvin.bsky.social · Jan 23

Had a wonderful time today! It was really great meeting you and thank for the invite to visit your fantastic department (and beautiful campus!)

C.J. Gabbe @cjgabbe.bsky.social · Jan 22

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)!

M. Colin Marvin @mcolinmarvin.bsky.social · Jan 7

dune find of the day: laterally linked and lone barchans in the Bodélé Depression, Chad (near 17.12°N, 17.87°E)

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M. Colin Marvin @mcolinmarvin.bsky.social · Jan 7

dune find of the day: laterally linked and lone barchans in the Bodélé Depression, Chad (near 17.12°N, 17.87°E)

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Dec 10

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)

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Dec 10

Back to #Mars with PhD student Claire Blaske asking "Were #boulder fields along Mars' putative #ocean paleoshoreline deposited by a #tsunami?" (EP51B-06, 146
B).

Fr 9:25-9:35 am.

Or perhaps #floods? #glaciers? #impacts?

#AGU24

(9/10)

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Reposted by M. Colin Marvin

Mathieu Lapôtre @marslogander.bsky.social · Dec 10

PhD student Timmy Lui will take us to #Mars for his " #Segmentation of #dune crestlines using #convolutional #neural #networks"
(EP51D-1378, hall B-C).

Fr 8:30 am-12:20 pm.

A challenging task with potential to reveal much about #Mars #climate!

#AGU24

(7/10)

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