Boulder Fall Ejecta: Present Day Activity on Mars

Abstract

Boulder falls and their tracks are typically observed on Mars and the Moon using high-resolution images (McEwen et al., 2007;Robinson et al., 2010). These falls indicate recent active mass wasting processes on these bodies. Such tracks are ubiquitous on steeply sloping terrain, and where particularly abundant have been used to infer active seismicity (Bickel et al., 2019;Brown & Roberts, 2019;Taylor et al., 2013), giving insight into endogenic processes. Repeat temporal imaging has shown that boulder falls are ongoing on Mars, as first observed by the Mars Global Surveyor-Mars Orbiter Camera images from the southern hemisphere and Valles Marineris (https://www.msss.com/mars_images/moc/2005/09/20/bouldertracks/). Subsequently, several studies have used repeat temporal imaging using HiRISE to identify and study recent boulder falls (Dundas &

A Mechanistic Model and Experiments on Bedrock Incision and Channelization by Rockfall

“…Ice‐cemented sediment near the melting point has tensile strengths similar to our applied foam ( σ foam = 0.1 MPa), whereas colder permafrost can have tensile strengths again similar to basalt (Akagawa & Nishisato, 2009; Azmatch et al., 2010; Yuanlin & Carbee, 1987). Given dry regions on Earth, absolute dryness on the Moon, and current dry conditions on Mars (Figures 1a–1d), together with abundant rocky hillslope areas and rockfall activity (Bickel, Aaron, et al., 2020; Bickel, Conway, et al., 2020; Dickson & Head, 2009; Kumar et al., 2013; Vijayan et al., 2022; Xiao et al., 2013), the rockfall abrasion process has potential to be a local to regional sculptor of planetary hillslopes. Shattered rocky crater walls and caprock‐topped badlands are ideal sites for the process to occur.…”

“…Rockfall is a ubiquitous, gravitational‐driven process in steep terrain. There is evidence for dry rockfall and rock avalanches on Earth (e.g., Stock et al., 2013), as well as on the Moon and Mars (Bickel, Aaron, et al., 2020; Bickel, Conway, et al., 2020; Kumar et al., 2013; Vijayan et al., 2022; Ward et al., 2011; Figures 1a–1d). There has been a wealth of research into its preconditioning and cause, both on vertical walls and on mountain slope topography (e.g., Benjamin et al., 2020; D’Amato et al., 2016; Frayssines & Hantz, 2006; Grenon & Hadjigeorgiou, 2008; Matasci et al., 2018; Messenzehl et al., 2017; Wieczorek et al., 1992; Williams et al., 2019).…”

A mechanistic model and experiments on bedrock incision and channelization by rockfall

“…Ice-cemented sediment near the melting point has tensile strength similar to our applied foam (𝜎𝜎 𝑠𝑠𝑜𝑜𝑔𝑔𝑚𝑚 = 0.1MPa), whereas colder permafrost can have tensile strengths again similar to basalt (Akagawa and Nishisato, 2009;Azmatch et al, 2010;Yuanlin and Carbee, 1987). Given dry regions on Earth, absolute dryness on the Moon, and current dry conditions on Mars (Figure 1), together with abundant rocky hillslope areas and rockfall activity (Bickel et al, 2020a(Bickel et al, , 2020bDickson and Head, 2009;Kumar et al, 2013;Vijayan et al, 2022;Xiao et al, 2013), the rockfall abrasion process has potential to be a local to regional sculptor of planetary hillslopes. Shattered rocky crater walls are ideal sites for the process to occur.…”

“…Rockfall is a ubiquitous, gravitational-driven process in steep terrain. There is evidence for dry rockfall and rock avalanches on Earth (e.g., Stock et al, 2013), as well as on the Moon and Mars (Bickel et al, 2020a(Bickel et al, , 2020bKumar et al, 2013;Vijayan et al, 2022;Ward et al, 2011;Figure 1A to D). There has been a wealth of research into its preconditioning and cause, both on vertical walls and on mountain slope topography (e.g., Benjamin et al, 2020;D'Amato et al, 2016;Frayssines and Hantz, 2006;Grenon and Hadjigeorgiou, 2008;Matasci et al, 2018;Messenzehl et al, 2017;Wieczorek et al, 1992;Williams et al, 2019).…”

Planetary geomorphology

“…A consequence of rock breakdown is rockfalls, which have been observed to occur in repeat imaging of Mars (Grindrod et al, 2021;Vijayan et al, 2021) (Figure 9b). Roll/bounce marks left in the regolith in the wake of boulders (Figure 9c) have shown rockfall to be a recently active process on the Moon (Arvidson et al, 1975;.…”