Mathieu Lapôtre

All Publications

• Automated determination of transport and depositional environments in sand and sandstones. Proceedings of the National Academy of Sciences of the United States of America Hasson, M., Marvin, M. C., Lapôtre, M. G. 2024; 121 (40): e2407655121

  Abstract

  As sand moves across Earth's landscapes, the shapes of individual grains evolve, and microscopic textures accumulate on their surfaces. Because transport processes vary between environments, the shape and suite of microtextures etched on sand grains provide insights into their transport histories. For example, previous efforts to link microtextures to transport environments have demonstrated that they can provide important information about the depositional environments of rocks with few other indicators. However, such analyses rely on 1) subjective human description of microtextures, which can yield biased, error-prone results; 2) nonstandard lists of microtextures; and 3) relatively large sample sizes (>20 grains) to obtain reliable results, the manual documentation of which is extremely labor intensive. These drawbacks have hindered broad adoption of the technique. We address these limitations by developing a deep neural network model, SandAI, that classifies scanning electron microscope images of modern sand grains by transport environment with high accuracy. The SandAI model was developed using images of sand grains from modern environments around the globe. Training data encompass the four most common terrestrial environments: fluvial, eolian, glacial, and beach. We validate the model on quartz grains from modern sites unknown to it, and Jurassic-Pliocene sandstones of known depositional environments. Next, the model is applied to two samples of the Cryogenian Bråvika Member (of contested origin), yielding insights into periglacial systems associated with Snowball Earth. Our results demonstrate the robustness and versatility of the model in quickly and automatically constraining the transport histories recorded in individual grains of quartz sand.

  View details for DOI 10.1073/pnas.2407655121

  View details for PubMedID 39284038

• Complementary classifications of aeolian dunes based on morphology, dynamics, and fluid mechanics EARTH-SCIENCE REVIEWS du Pont, S., Rubin, D. M., Narteau, C., Lapotre, M. A., Day, M., Claudin, P., Livingstone, I., Telfer, M. W., Radebaugh, J., Gadal, C., Gunn, A., Hesp, P. A., Carpy, S., Bristow, C. S., Baas, A. W., Ewing, R. C., Wiggs, G. S. 2024; 255

  View details for DOI 10.1016/j.earscirev.2024.104772

  View details for Web of Science ID 001263215600001

• Direct Measurements of Dust Settling Velocity Under Low-Density Atmospheres Using Time-Resolved Particle Image Velocimetry GEOPHYSICAL RESEARCH LETTERS Alvarez, C. A., Gunn, A., Swann, C., Trimble, S. M., Ewing, R. C., Lapotre, M. A. 2024; 51 (15)

  View details for DOI 10.1029/2024GL109958

  View details for Web of Science ID 001279763200001

• The Geochemical and Mineralogical Signature of Glaciovolcanism Near þórisjökull, Iceland, and Its Implications for Glaciovolcanism on Mars JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Bedford, C. C., Rampe, E. B., Thorpe, M. T., Ewing, R. C., Mason, K., Horgan, B., Rudolph, A., Lapotre, M. A., Sinha, P., Nachon, M., Champion, E., Berger, L., Reid, E., Gray, P. C. 2024; 129 (7)

  View details for DOI 10.1029/2023JE008261

  View details for Web of Science ID 001281276700001

• Locomotion as manipulation with ReachBot. Science robotics Chen, T. G., Newdick, S., Di, J., Bosio, C., Ongole, N., Lapôtre, M., Pavone, M., Cutkosky, M. R. 2024; 9 (89): eadi9762

  Abstract

  Caves and lava tubes on the Moon and Mars are sites of geological and astrobiological interest but consist of terrain that is inaccessible with traditional robot locomotion. To support the exploration of these sites, we present ReachBot, a robot that uses extendable booms as appendages to manipulate itself with respect to irregular rock surfaces. The booms terminate in grippers equipped with microspines and provide ReachBot with a large workspace, allowing it to achieve force closure in enclosed spaces, such as the walls of a lava tube. To propel ReachBot, we present a contact-before-motion planner for nongaited legged locomotion that uses internal force control, similar to a multifingered hand, to keep its long, slender booms in tension. Motion planning also depends on finding and executing secure grips on rock features. We used a Monte Carlo simulation to inform gripper design and predict grasp strength and variability. In addition, we used a two-step perception system to identify possible grasp locations. To validate our approach and mechanisms under realistic conditions, we deployed a single ReachBot arm and gripper in a lava tube in the Mojave Desert. The field test confirmed that ReachBot will find many targets for secure grasps with the proposed kinematic design.

  View details for DOI 10.1126/scirobotics.adi9762

  View details for PubMedID 38630805

• Vegetation enhances curvature-driven dynamics in meandering rivers. Nature communications Finotello, A., Ielpi, A., Lapôtre, M. G., Lazarus, E. D., Ghinassi, M., Carniello, L., Favaro, S., Tognin, D., D'Alpaos, A. 2024; 15 (1): 1968

  Abstract

  Stabilization of riverbanks by vegetation has long been considered necessary to sustain single-thread meandering rivers. However, observation of active meandering in modern barren landscapes challenges this assumption. Here, we investigate a globally distributed set of modern meandering rivers with varying riparian vegetation densities, using satellite imagery and statistical analyses of meander-form descriptors and migration rates. We show that vegetation enhances the coefficient of proportionality between channel curvature and migration rates at low curvatures, and that this effect wanes in curvier channels irrespective of vegetation density. By stabilizing low-curvature reaches and allowing meanders to gain sinuosity as channels migrate laterally, vegetation quantifiably affects river morphodynamics. Any causality between denser vegetation and higher meander sinuosity, however, cannot be inferred owing to more frequent avulsions in modern non-vegetated environments. By illustrating how vegetation affects channel mobility and floodplain reworking, our findings have implications for assessing carbon stocks and fluxes in river floodplains.

  View details for DOI 10.1038/s41467-024-46292-x

  View details for PubMedID 38438390

• Martian Exploration of Lava Tubes (MELT) with ReachBot: Scientific Investigation and Concept of Operations Dil, J., Cuevas-Quinones, S., Newdick, S., Chen, T. G., Pavone, M., Lapotre, M. A., Cutkosky, M., IEEE IEEE. 2024: 36-41

  View details for DOI 10.1109/iSpaRo60631.2024.10687389

  View details for Web of Science ID 001327765400006

• Grain Size Measurements of the Eolian Stimson Formation, Gale Crater, Mars and Implications for Sand Provenance and Paleoatmospheric Conditions JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Preston, S., Siebach, K., Lapôtre, M., Banham, S. 2024; 129 (11)

  View details for DOI 10.1029/2024JE008369

• Automatic Characterization of Boulders on Planetary Surfaces From High-Resolution Satellite Images JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Prieur, N. C., Amaro, B., Gonzalez, E., Kerner, H., Medvedev, S., Rubanenko, L., Werner, S. C., Xiao, Z., Zastrozhnov, D., Lapotre, M. A. 2023; 128 (11)

  View details for DOI 10.1029/2023JE008013

  View details for Web of Science ID 001107339300001

• A depositional model for meandering rivers without land plants SEDIMENTOLOGY Hasson, M., Marvin, M., Gunn, A., Ielpi, A., Lapotre, M. A. 2023

  View details for DOI 10.1111/sed.13121

  View details for Web of Science ID 001041940500001

• Dune interactions record changes in boundary conditions GEOLOGY Marvin, M., Lapotre, M. A., Gunn, A., Day, M., Soto, A. 2023

  View details for DOI 10.1130/G51264.1

  View details for Web of Science ID 001046897700001

• Modelling fire-induced perturbations in sediment flux based on stream widening and accelerated bank migration CATENA Ielpi, A., Lapotre, M. A. 2023; 228

  View details for DOI 10.1016/j.catena.2023.107173

  View details for Web of Science ID 000989254900001

• Large sinuous rivers are slowing down in a warming Arctic Nature Climate Change Ielpi, A., Lapôtre, M., Finotello, A., Roy-Léveillée , P. 2023

  View details for DOI 10.1038/s41558-023-01620-9

• A distinct ripple-formation regime on Mars revealed by the morphometrics of barchan dunes. Nature communications Rubanenko, L., Lapotre, M. G., Ewing, R. C., Fenton, L. K., Gunn, A. 2022; 13 (1): 7156

  Abstract

  Sand mobilized by wind forms decimeter-scale impact ripples and decameter-scale or larger dunes on Earth and Mars. In addition to those two bedform scales, orbital and in situ images revealed a third distinct class of larger meter-scale ripples on Mars. Since their discovery, two main hypotheses have been proposed to explain the formation of large martian ripples-that they originate from the growth in wavelength and height of decimeter-scale ripples or that they arise from the same hydrodynamic instability as windblown dunes or subaqueous bedforms instead. Here we provide evidence that large martian ripples form from the same hydrodynamic instability as windblown dunes and subaqueous ripples. Using an artificial neural network, we characterize the morphometrics of over a million isolated barchan dunes on Mars and analyze how their size and shape vary across Mars' surface. We find that the size of Mars' smallest dunes decreases with increasing atmospheric density with a power-law exponent predicted by hydrodynamic theory, similarly to meter-size ripples, tightly bounding a forbidden range in bedform sizes. Our results provide key evidence for a unifying model for the formation of subaqueous and windblown bedforms on planetary surfaces, offering a new quantitative tool to decipher Mars' atmospheric evolution.

  View details for DOI 10.1038/s41467-022-34974-3

  View details for PubMedID 36418350

• The Role of Seasonal Sediment Transport and Sintering in Shaping Titan's Landscapes: A Hypothesis. Geophysical research letters Lapôtre, M. G., Malaska, M. J., Cable, M. L. 2022; 49 (8): e2021GL097605

  Abstract

  Titan is a sedimentary world, with lakes, rivers, canyons, fans, dissected plateaux, and sand dunes. Sediments on Saturn's moon are thought to largely consist of mechanically weak organic grains, prone to rapid abrasion into dust. Yet, Titan's equatorial dunes have likely been active for 10s-100s kyr. Sustaining Titan's dunes over geologic timescales requires a mechanism that produces sand-sized particles at equatorial latitudes. We explore the hypothesis that a combination of abrasion, when grains are transported by winds or methane rivers, and sintering, when they are at rest, could produce sand grains that maintain an equilibrium size. Our model demonstrates that seasonal sediment transport may produce sand under Titan's surface conditions and could explain the latitudinal zonation of Titan's landscapes. Our findings support the hypothesis of global, source-to-sink sedimentary pathways on Titan, driven by seasons, and mediated by episodic abrasion and sintering of organic sand by rivers and winds.

  View details for DOI 10.1029/2021GL097605

  View details for PubMedID 35860461

  View details for PubMedCentralID PMC9285677

• Ancient Winds, Waves, and Atmosphere in Gale Crater, Mars, Inferred From Sedimentary Structures and Wave Modeling JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Rubin, D. M., Lapotre, M. G., Stevens, A. W., Lamb, M. P., Fedo, C. M., Grotzinger, J. P., Gupta, S., Stack, K. M., Vasavada, A. R., Banham, S. G., Bryk, A. B., Caravaca, G., Christian, J. R., Edgar, L. A., Malin, M. C. 2022; 127 (4)

  View details for DOI 10.1029/2021JE007162

  View details for Web of Science ID 000783437700001

• The impact of vegetation on meandering rivers Nature Reviews Earth & Environment Ielpi, A., Lapôtre, M., Gibling, M., Boyce, C. 2022

  View details for DOI 10.1038/s43017-021-00249-6

• Mars as a time machine to Precambrian Earth Journal of the Geological Society Lapotre, M., Bishop, J., Ielpi, A., Lowe, D., Siebach, K., Sleep, N., Tikoo, S. 2022

  View details for DOI 10.1144/jgs2022-047

• Accumulation of windblown sand in impact craters on Mars Geology Gunn, A., Rubanenko, L., Lapotre, M. 2022; 50 (9): 981-985

  View details for DOI 10.1130/G49936.1

• Drainage initiation, expansion, and channel-head arrest in heterogenous bedrock landscapes of the Colorado Plateau GSA Bulletin Steelquist, A., Lapôtre, M., Hilley, G. 2022

  View details for DOI 10.1130/B36375.1

• Linking sediment flux to river migration in arid landscapes through mass balance Journal of Sedimentary Geology Ielpi, A., Lapotre, M. 2022; 92 (8): 695-703

  View details for DOI 10.2110/jsr.2022.118

• An evolving understanding of enigmatic large ripples on Mars Journal of Geophysical Research: Planets Lapôtre, M. G., Ewing, R. C., Lamb, M. P. 2021

  View details for DOI 10.1029/2020JE006729

• Martian dunes: A crucial record of present and past Mars surface environment and aeolian processes Treatise on Geomorphology Diniega, S., Burr, D. M., Chojnacki, M., Lapôtre, M. G., Swann, C. 2021
• Automatic detection and segmentation of barchan dunes on Mars and Earth using a convolutional neural network IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Rubanenko, L., Pérez-López, S., Schull, J., Lapôtre, M. 2021

  View details for DOI 10.1109/JSTARS.2021.3109900

• Modern Mars' geomorphological activity, driven by wind, frost, and gravity Geomorphology Diniega, S., Bramson, A. M., Buratti, B., Buhler, P., Burr, D. M., Chojnacki, M., Conway, S. J., Dundas, C. M., Hansen, C. J., McEwen, A. S., Lapôtre, M. G., Levy, J., Mc Keown, L., Piqueux, S., Portyankina, G., Swann, C., Titus, T. N., Widmer, J. M. 2021

  View details for DOI 10.1016/j.geomorph.2021.107627

• Planform-asymmetry and backwater effects on river-cutoff kinematics and clustering EARTH SURFACE PROCESSES AND LANDFORMS Ielpi, A., Lapotre, M. A., Finotello, A., Ghinassi, M. 2020

  View details for DOI 10.1002/esp.5029

  View details for Web of Science ID 000593036000001

• Channel mobility drives a diverse stratigraphic architecture in the dryland Mojave River (California, USA) EARTH SURFACE PROCESSES AND LANDFORMS Ielpi, A., Lapotre, M. A., Finotello, A., Ghinassi, M., D'Alpaos, A. 2020

  View details for DOI 10.1002/esp.4841

  View details for Web of Science ID 000518369900001

• The pace of fluvial meanders on Mars and implications for the western delta deposits of Jezero crater AGU Advances Lapôtre, M. G., Ielpi, A. 2020; 1 (2)

  View details for DOI 10.1029/2019AV000141

• Probing space to understand Earth Nature Reviews Earth & Environment Lapôtre, M. G., O'Rourke, J. G., Schaefer, L. K., Siebach, K. L., Spalding, C., Tikoo, S. M., Wordsworth, R. D. 2020; 1: 170-181

  View details for DOI 10.1038/s43017-020-0029-y

• A probabilistic approach to determination of Ceres’ average surface composition from Dawn VIR and GRaND data Journal of Geophysical Research: Planets Kurokawa, H., Ehlmann, B. L., De Sanctis, M. C., Lapôtre , M. G., Usui, T., Stein, N. T., Prettyman, T. H., Raponi, A., Ciarniello, M. 2020

  View details for DOI 10.1029/2020JE006606

• A tenfold slowdown in river meander migration driven by plant life Nature Geoscience Ielpi, A., Lapotre, M. G. 2020; 13: 82-86

  View details for DOI 10.1038/s41561-019-0491-7

• Biotic forcing militates against river meandering in the modern Bonneville Basin of Utah SEDIMENTOLOGY Ielpi, A., Lapotre, M. A. 2019; 66 (5): 1896–1929

  View details for DOI 10.1111/sed.12562

  View details for Web of Science ID 000477915100016

• BARREN MEANDERING STREAMS IN THE MODERN TOIYABE BASIN OF NEVADA, USA, AND THEIR RELEVANCE TO THE STUDY OF THE PRE-VEGETATION ROCK RECORD JOURNAL OF SEDIMENTARY RESEARCH Ielpi, A., Lapotre, M. A. 2019; 89 (5): 399–415

  View details for DOI 10.2110/jsr.2019.25

  View details for Web of Science ID 000470078200002

• Model for the Formation of Single‐Thread Rivers in Barren Landscapes and Implications for Pre‐Silurian and Martian Fluvial Deposits Journal of Geophysical Research - Earth Surface Lapotre, M. G., Ielpi, A., Lamb, M. P., Williams, R. E., Knoll, A. H. 2019; 124 (12): 2757-2777

  View details for DOI 10.1029/2019JF005156

• Curiosity's Investigation of the Bagnold Dunes, Gale Crater: Overview of the Two-Phase Scientific Campaign and Introduction to the Special Collection GEOPHYSICAL RESEARCH LETTERS Lapotre, M. A., Rampe, E. B. 2018; 45 (19): 10200–10210

  View details for DOI 10.1029/2018GL079032

  View details for Web of Science ID 000448656800021

• Morphologic Diversity of Martian Ripples: Implications for Large-Ripple Formation GEOPHYSICAL RESEARCH LETTERS Lapotre, M. A., Ewing, R. C., Weitz, C. M., Lewis, K. W., Lamb, M. P., Ehlmann, B. L., Rubin, D. M. 2018; 45 (19): 10229–39

  View details for DOI 10.1029/2018GL079029

  View details for Web of Science ID 000448656800024

• Sand Grain Sizes and Shapes in Eolian Bedforms at Gale Crater, Mars GEOPHYSICAL RESEARCH LETTERS Weitz, C. M., Sullivan, R. J., Lapotre, M. A., Rowland, S. K., Grant, J. A., Baker, M., Yingst, R. 2018; 45 (18): 9471–79

  View details for DOI 10.1029/2018GL078972

  View details for Web of Science ID 000447761300016

• Sand Mineralogy Within the Bagnold Dunes, Gale Crater, as Observed In Situ and From Orbit GEOPHYSICAL RESEARCH LETTERS Rampe, E. B., Lapotre, M. A., Bristow, T. F., Arvidson, R. E., Morris, R. V., Achilles, C. N., Weitz, C., Blake, D. F., Ming, D. W., Morrison, S. M., Vaniman, D. T., Chipera, S. J., Downs, R. T., Grotzinger, J. P., Hazen, R. M., Peretyazhko, T. S., Sutter, B., Tu, V., Yen, A. S., Horgan, B., Castle, N., Craig, P. I., Des Marais, D. J., Farmer, J., Gellert, R., McAdam, A. C., Morookian, J. M., Sarrazin, P. C., Treiman, A. H. 2018; 45 (18): 9488–97

  View details for DOI 10.1029/2018GL079073

  View details for Web of Science ID 000447761300018

• The Bagnold Dunes in Southern Summer: Active Sediment Transport on Mars Observed by the Curiosity Rover GEOPHYSICAL RESEARCH LETTERS Baker, M. M., Lapotre, M. A., Minitti, M. E., Newman, C. E., Sullivan, R., Weitz, C. M., Rubin, D. M., Vasavada, A. R., Bridges, N. T., Lewis, K. W. 2018; 45 (17): 8853–63

  View details for DOI 10.1029/2018GL079040

  View details for Web of Science ID 000445727500018

• Ancient Martian aeolian processes and palaeomorphology reconstructed from the Stimson formation on the lower slope of Aeolis Mons, Gale crater, Mars SEDIMENTOLOGY Banham, S. G., Gupta, S., Rubin, D. M., Watkins, J. A., Sumner, D. Y., Edgett, K. S., Grotzinger, J. P., Lewis, K. W., Edgar, L. A., Stack-Morgan, K. M., Barnes, R., Bell, J. F., Day, M. D., Ewing, R. C., Lapotre, M. A., Stein, N. T., Rivera-Hernandez, F., Vasavada, A. R. 2018; 65 (4): 993–1042

  View details for DOI 10.1111/sed.12469

  View details for Web of Science ID 000434172100001

• Substrate controls on valley formation by groundwater on Earth and Mars GEOLOGY Lapotre, M. A., Lamb, M. P. 2018; 46 (6): 531–34

  View details for DOI 10.1130/G40007.1

  View details for Web of Science ID 000433513800016

• Coarse Sediment Transport in the Modern Martian Environment JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Baker, M. M., Newman, C. E., Lapotre, M. A., Sullivan, R., Bridges, N. T., Lewis, K. W. 2018; 123 (6): 1380–94

  View details for DOI 10.1002/2017JE005513

  View details for Web of Science ID 000438505700003

• Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Lapotre, M. A., Ehlmann, B. L., Minson, S. E., Arvidson, R. E., Ayoub, F., Fraeman, A. A., Ewing, R. C., Bridges, N. T. 2017; 122 (12): 2489–2509

  View details for DOI 10.1002/2016JE005133

  View details for Web of Science ID 000419993400006

• Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Ewing, R. C., Lapotre, M. A., Lewis, K. W., Day, M., Stein, N., Rubin, D. M., Sullivan, R., Banham, S., Lamb, M. P., Bridges, N. T., Gupta, S., Fischer, W. W. 2017; 122 (12): 2544–73

  Abstract

  The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large-ripple lee slopes. Lee slopes were ~29° where grainflows were present and ~33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter-scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune-field pattern dynamics and basin-scale boundary conditions will dictate the style and distribution of sedimentary processes.

  View details for DOI 10.1002/2017JE005324

  View details for Web of Science ID 000419993400008

  View details for PubMedID 29497590

  View details for PubMedCentralID PMC5815379

• Chemistry, mineralogy, and grain properties at Namib and High dunes, Bagnold dune field, Gale crater, Mars: A synthesis of Curiosity rover observations JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Ehlmann, B. L., Edgett, K. S., Sutter, B., Achilles, C. N., Litvak, M. L., Lapotre, M. A., Sullivan, R., Fraeman, A. A., Arvidson, R. E., Blake, D. F., Bridges, N. T., Conrad, P. G., Cousin, A., Downs, R. T., Gabriel, T. J., Gellert, R., Hamilton, V. E., Hardgrove, C., Johnson, J. R., Kuhn, S., Mahaffy, P. R., Maurice, S., McHenry, M., Meslin, P., Ming, D. W., Minitti, M. E., Morookian, J. M., Morris, R. V., O'Connell-Cooper, C. D., Pinet, P. C., Rowland, S. K., Schroeder, S., Siebach, K. L., Stein, N. T., Thompson, L. M., Vaniman, D. T., Vasavada, A. R., Wellington, D. F., Wiens, R. C., Yen, A. S. 2017; 122 (12): 2510–43

  Abstract

  The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45-500 μm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by visible/near-infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or H2O- or OH-bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (<40 μm; represented by Rocknest and other bright soils) that are Fe, S, and Cl enriched with low Si and adsorbed and structural H2O.

  View details for DOI 10.1002/2017JE005267

  View details for Web of Science ID 000419993400007

  View details for PubMedID 29497589

  View details for PubMedCentralID PMC5815393

• Martian aeolian activity at the Bagnold Dunes, Gale Crater: The view from the surface and orbit JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Bridges, N. T., Sullivan, R., Newman, C. E., Navarro, S., van Beek, J., Ewing, R. C., Ayoub, F., Silvestro, S., Gasnault, O., Le Mouelic, S., Lapotre, M. A., Rapin, W. 2017; 122 (10): 2077–2110

  View details for DOI 10.1002/2017JE005263

  View details for Web of Science ID 000416507000008

• Advanced concept for a crewed mission to the martian moons ACTA ASTRONAUTICA Conte, D., Di Carlo, M., Budzyn, D., Burgoyne, H., Fries, D., Grulich, M., Heizmann, S., Jethani, H., Lapotre, M., Roos, T., Castillo, E., Schermann, M., Vieceli, R., Wilson, L., Wynard, C. 2017; 139: 545–63

  View details for DOI 10.1016/j.actaastro.2017.07.044

  View details for Web of Science ID 000411299700059

• A probabilistic approach to remote compositional analysis of planetary surfaces JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Lapotre, M. A., Ehlmann, B. L., Minson, S. E. 2017; 122 (5): 983–1009

  View details for DOI 10.1002/2016JE005248

  View details for Web of Science ID 000403491300010

• What sets the size of current ripples? GEOLOGY Lapotre, M. A., Lamb, M. P., McElroy, B. 2017; 45 (3): 243–46

  View details for DOI 10.1130/G38598.1

  View details for Web of Science ID 000396125100012

• Regularization of Mars Reconnaissance Orbiter CRISM along-track oversampled hyperspectral imaging observations of Mars ICARUS Kreisch, C. D., O'Sullivan, J. A., Arvidson, R. E., Politte, D. V., He, L., Stein, N. T., Finkel, J., Guinness, E. A., Wolff, M. J., Lapotre, M. A. 2017; 282: 136–51

  View details for DOI 10.1016/j.icarus.2016.09.033

  View details for Web of Science ID 000388545500013

• Canyon formation constraints on the discharge of catastrophic outburst floods of Earth and Mars JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Lapotre, M. A., Lamb, M. P., Williams, R. E. 2016; 121 (7): 1232–63

  View details for DOI 10.1002/2016JE005061

  View details for Web of Science ID 000381632500006

• Large wind ripples on Mars: A record of atmospheric evolution SCIENCE Lapotre, M. A., Ewing, R. C., Lamb, M. P., Fischer, W. W., Grotzinger, J. P., Rubin, D. M., Lewis, K. W., Ballard, M. J., Day, M., Gupta, S., Banham, S. G., Bridges, N. T., Des Marais, D. J., Fraeman, A. A., Grant, J. A., Herkenhoff, K. E., Ming, D. W., Mischna, M. A., Rice, M. S., Sumner, D. A., Vasavada, A. R., Yingst, R. A. 2016; 353 (6294): 55–58

  Abstract

  Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter- to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

  View details for DOI 10.1126/science.aaf3206

  View details for Web of Science ID 000378816200033

  View details for PubMedID 27365444

• Hydraulics of floods upstream of horseshoe canyons and waterfalls JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE Lapotre, M. A., Lamb, M. P. 2015; 120 (7): 1227–50

  View details for DOI 10.1002/2014JF003412

  View details for Web of Science ID 000359870300005

• Mars Reconnaissance Orbiter and Opportunity observations of the Burns formation: Crater hopping at Meridiani Planum JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Arvidson, R. E., Bell, J. F., Catalano, J. G., Clark, B. C., Fox, V. K., Gellert, R., Grotzinger, J. P., Guinness, E. A., Herkenhoff, K. E., Knoll, A. H., Lapotre, M. A., McLennan, S. M., Ming, D. W., Morris, R. V., Murchie, S. L., Powell, K. E., Smith, M. D., Squyres, S. W., Wolff, M. J., Wray, J. J. 2015; 120 (3): 429–51

  View details for DOI 10.1002/2014JE004686

  View details for Web of Science ID 000352855100006

• The root of branching river networks NATURE Perron, J., Richardson, P. W., Ferrier, K. L., Lapotre, M. 2012; 492 (7427): 100-+

  Abstract

  Branching river networks are one of the most widespread and recognizable features of Earth's landscapes and have also been discovered elsewhere in the Solar System. But the mechanisms that create these patterns and control their spatial scales are poorly understood. Theories based on probability or optimality have proven useful, but do not explain how river networks develop over time through erosion and sediment transport. Here we show that branching at the uppermost reaches of river networks is rooted in two coupled instabilities: first, valleys widen at the expense of their smaller neighbours, and second, side slopes of the widening valleys become susceptible to channel incision. Each instability occurs at a critical ratio of the characteristic timescales for soil transport and channel incision. Measurements from two field sites demonstrate that our theory correctly predicts the size of the smallest valleys with tributaries. We also show that the dominant control on the scale of landscape dissection in these sites is the strength of channel incision, which correlates with aridity and rock weakness, rather than the strength of soil transport. These results imply that the fine-scale structure of branching river networks is an organized signature of erosional mechanics, not a consequence of random topology.

  View details for DOI 10.1038/nature11672

  View details for Web of Science ID 000311893400053

  View details for PubMedID 23222614